diff --git a/docs/gh-pages/src/configuration.md b/docs/gh-pages/src/configuration.md
@@ -1,201 +1 @@
-<!-- toc -->
-
-# Usage
-
-This chapter is about the basic setup of the plugin.
-
-You can use this plugin **out of the box** to export/import
-
-- content (posts/pages/nav_menu and media assets)
-
-- FSE content (Full Site Editing assets like blocks, templates, template parts, reusable blocks and theme settings)
-
-For everything else (third-party plugin settings for example) you need to provide custom export/import profile(s).
-
-## Configuration
-
-Impex import and export can be customized by providing **Profiles**.
-
-An **Export profile** defines the Wordpress data to export.
-
-An **Import profile** declares how and which exported data should be consumed.
-
-## Custom profile configuration
-
-**Profiles** are configured and registered using a custom Impex [Wordpress action](https://developer.wordpress.org/plugins/hooks/actions/) :
-
-```php
-\add_action('cm4all_wp_impex_register_profiles', function () {
-  // your Impex profile registration goes here
-  ...
-});
-```
-
-Using a [Wordpress action](https://developer.wordpress.org/plugins/hooks/actions/) for Impex profile registration guarantees that the action callback is only executed if the Impex plugin is activated.
-
-> Implementing a Impex profile in your plugin does not make Impex a required dependency for your plugin since the code is only executed if Impex is avalable and active.
-
-### Export
-
-Let's say you want to export the core Wordpress contents (pages/posts/attachments and stuff) but also
-
-- [Ninja Forms Contact Form](https://wordpress.org/plugins/ninja-forms/) contents and settings
-
-- [Ultimate Maps by Supsystic](https://wordpress.org/plugins/ultimate-maps-by-supsystic/) contents and settings
-
-- [Complianz GDPR](https://wordpress.org/plugins/complianz-gdpr/) contents and settings
-
-- some options of your own plugin
-
-To do so you need to create a **Export profile**.
-
-Fortunately Impex provides some low level building blocks called **ExportProvider** to make our Impex Profile declaration piece of cake :
-
-```php
-\add_action('cm4all_wp_impex_register_profiles', function () {
-  // ensure admin plugin functions are available
-  require_once(ABSPATH . 'wp-admin/includes/plugin.php');
-
-  // register a new export profile
-  $profile = Impex::getInstance()->Export->addProfile('impex-export-profile-example');
-  // give the profile a senseful description
-  $profile->setDescription('Exports posts/pages/media-assets and plugin data of [cm4all-wordpress,complianz-gdpr,ninja-forms,ultimate-maps-by-supsystic]');
-
-  // export pages/posts/comments/block patterns/templates/template parts/reusable blocks
-  $profile->addTask(
-    'wordpress content',
-    cm4all\wp\impex\ContentExporter::PROVIDER_NAME
-  );
-
-  // export media
-  $profile->addTask(
-    'wordpress attachments (uploads)',
-    cm4all\wp\impex\AttachmentsExporter::PROVIDER_NAME
-  );
-
-  // export ninja-forms related tables/options if active
-  $plugin_ninjaforms_disabled = !is_plugin_active("ninja-forms/ninja-forms.php");
-  $profile->addTask(
-    "ninja-forms db tables (nf3_*)",
-    cm4all\wp\impex\DbTablesExporter::PROVIDER_NAME,
-    [cm4all\wp\impex\DbTablesExporter::OPTION_SELECTOR => 'nf3_*',]
-  )->disabled = $plugin_ninjaforms_disabled;
-  $profile->addTask(
-    'ninja-forms wp_options',
-    cm4all\wp\impex\WpOptionsExporter::PROVIDER_NAME,
-    [cm4all\wp\impex\WpOptionsExporter::OPTION_SELECTOR => ['ninja_*', 'nf_*', 'wp_nf_*', 'widget_ninja_*']]
-  )->disabled = $plugin_ninjaforms_disabled;
-
-  // export ultimate_maps related tables/options
-  $plugin_ultimatemaps_disabled = !is_plugin_active("ultimate-maps-by-supsystic/ums.php");
-  $profile->addTask(
-    "ultimate_maps db tables (ums_*)",
-    cm4all\wp\impex\DbTablesExporter::PROVIDER_NAME,
-    [cm4all\wp\impex\DbTablesExporter::OPTION_SELECTOR => 'ums_*',]
-  )->disabled = $plugin_ultimatemaps_disabled;
-  $profile->addTask(
-    'ultimate_maps wp_options',
-    cm4all\wp\impex\WpOptionsExporter::PROVIDER_NAME,
-    [cm4all\wp\impex\WpOptionsExporter::OPTION_SELECTOR => ['ums_*', 'wp_ums_*',]]
-  )->disabled = $plugin_ultimatemaps_disabled;
-
-  // export complianz related tables/options
-  $plugin_complianz_disabled = !is_plugin_active("complianz-gdpr/complianz-gpdr.php");
-  $profile->addTask(
-    "complianz-gdpr db tables",
-    cm4all\wp\impex\DbTablesExporter::PROVIDER_NAME,
-    [DbTablesExporter::OPTION_SELECTOR => 'cmplz_*',]
-  )->disabled = $plugin_complianz_disabled;
-  $profile->addTask(
-    'complianz-gdpr wp_options',
-    cm4all\wp\impex\WpOptionsExporter::PROVIDER_NAME,
-    [cm4all\wp\impex\WpOptionsExporter::OPTION_SELECTOR => ['cmplz_*', 'complianz_*']]
-  )->disabled = $plugin_complianz_disabled;
-
-  // export our own plugin uses wp_options starting with `foo-` or `bar*`
-  $profile->addTask(
-    'custom plugin options',
-    cm4all\wp\impex\WpOptionsExporter::PROVIDER_NAME,
-    [cm4all\wp\impex\WpOptionsExporter::OPTION_SELECTOR => ['foo-*','bar-*']]
-  )->disabled = !is_plugin_active("cm4all-wordpress/plugin.php");
-});
-```
-
-That's it !
-
-Now you can trigger the export using this Impex export configuration in the Impex screen at WP dashboard (or even using the [Impex CLI](./impex-cli.md))
-
-### Import
-
-Thanks to Impex architecture you normally don't need to define a custom import configuration.
-
-Impex sports a generic `all` import provider and profile importing **anything** exported using the Impex building blocks.
-
-> As long as you use the **Exporter** provided by Impex in your custom Export profile, you don't need to define an matching custom import profile.
-
-But sometimes there exist some etch cases when you need to execude PHP code after the import to get everything working.
-
-In our export profile example above we implemented support for [Ninja Forms Contact Form](https://wordpress.org/plugins/ninja-forms/). Unfortunately the forms will be in maintenance mode after importing them.
-
-To fix this we need to execute some PHP code (`WPN_Helper::set_forms_maintenance_mode(0)` from the [Ninja Forms Contact Form Plugin](https://wordpress.org/plugins/ninja-forms/)) after the import.
-
-Impex provides **Events** for exactly that purpose :
-
-```php
-\add_action('cm4all_wp_impex_register_profiles', function () {
-  // ensure admin plugin functions are available
-  require_once(ABSPATH . 'wp-admin/includes/plugin.php');
-
-  // get the 'all' profile
-  $profile = Impex::getInstance()->Import->getProfile('all');
-
-  // attach a listener callback for the `EVENT_IMPORT_END` event
-  $profile->events(ImpexImport::EVENT_IMPORT_END)->addListener(
-    'reset ninja forms mainentance mode',
-    fn () => method_exists('WPN_Helper', 'set_forms_maintenance_mode') && WPN_Helper::set_forms_maintenance_mode(0)
-  );
-});
-```
-
-Tada - thats it !
-
-There ist just one caveat ... what if the Impex 'all' profile gets disabled by someone else ?
-To work around this we can also introduce a custom import profile utilizing the 'all' import provider:
-
-```php
-\add_action('cm4all_wp_impex_register_profiles', function () {
-  // ensure admin plugin functions are available
-  require_once(ABSPATH . 'wp-admin/includes/plugin.php');
-
-  // create a new import profile
-  $profile = Impex::getInstance()->Import->addProfile('impex-import-profile-example');
-  $profile->setDescription('Import everything example with event listener');
-
-  // reuse the 'all' import provider registered by the 'all' import profile
-  $profile->addTask('main', Impex::getInstance()->Import->getProvider('all')->name);
-
-  // attach a listener callback for the `EVENT_IMPORT_END` event
-  $profile->events(ImpexImport::EVENT_IMPORT_END)->addListener(
-    'reset ninja forms mainentance mode',
-    fn () => method_exists('WPN_Helper', 'set_forms_maintenance_mode') && WPN_Helper::set_forms_maintenance_mode(0)
-  );
-});
-```
-
-### (API)
-
-**THIS IS JUST DUMNMY CONTENT**
-
-An example diagram.
-
-```mermaid
-graph TD;
-    A-->B;
-    A-->C;
-    B-->D;
-    C-->D;
-```
-
-- there is
-
-- more to come :-)
+# Configuration
diff --git a/docs/gh-pages/src/impex-cli.md b/docs/gh-pages/src/impex-cli.md
@@ -2,11 +2,11 @@
 
 # CLI
 
-Impex provides a commandline tool to interact with the Impex plugin remotely using Wordpress HTTP REST API.
+Impex provides a commandline tool to interact with the Impex plugin remotely using WordPress HTTP REST API.
 
 Using this tool you can import and export data from and to a remote wordpress installation.
 
-> impex-cli works also fine at _most_ managed wordpress installations since it does'nt need direct Wordpress access like [wp-cli](https://wp-cli.org/).
+> impex-cli works also fine at _most_ managed wordpress installations since it does'nt need direct WordPress access like [wp-cli](https://wp-cli.org/).
 
 # Prerequisities
 
@@ -33,14 +33,14 @@ Using the official PHP 7.4 Docker image :
 
 ```sh
 docker run -it --network host --rm -v "$PWD":/usr/src/myapp -w /usr/src/myapp php:7.4-cli php \
-impex-cli-php7.4.0.php export-profile list -username=admin -password=password -rest-url=http://localhost:8888/wp-json
+impex-cli-php7.4.0.php export-profile list -username=<adminuser> -password=<password> -rest-url=http://localhost:8888/wp-json
 ```
 
 Alternatively using the PHP 8.0 image:
 
 ```sh
 docker run -it --network host --rm -v "$PWD":/usr/src/myapp -w /usr/src/myapp php:8.0-cli php \
-impex-cli.php export-profile list -username=admin -password=password -rest-url=http://localhost:8888/wp-json
+impex-cli.php export-profile list -username=<adminuser> -password=<password> -rest-url=http://localhost:8888/wp-json
 ```
 
 ## Syntax
@@ -73,8 +73,8 @@ Example:
 
 ```sh
 impex-cli.php export-profile \
--username=admin \
--password='password' \
+-username=<adminuser> \
+-password='<password>' \
 -rest-url=http://example.com/wp-json
 ```
 
@@ -90,7 +90,7 @@ Example:
 impex-cli.php export-profile \
 -H="X-foo=bar" \
 -H="X-myrealm=cheers" \
--username=admin -password='password' \
+-username=<adminuser> -password='<password>' \
 -rest-url=http://example.com/wp-json
 ```
 
@@ -107,7 +107,7 @@ Example:
 ```sh
 impex-cli.php export-profile \
 -verbose \
--username=admin -password='password' \
+-username=<adminuser> -password='<password>' \
 -rest-url=http://example.com/wp-json
 ```
 
@@ -120,7 +120,7 @@ Example:
 ```sh
 impex-cli.php export-profile \
 -CURLOPT_VERBOSE \
--username=admin -password='password' \
+-username=<adminuser> -password='<password>' \
 -rest-url=http://example.com/wp-json
 ```
 
@@ -148,7 +148,7 @@ A Impex export results in a directory structure containing
 
 - JSON Files for structured data
 
-  Wordpress content will be stored in JSON files. This gives you also the option to tranform the content locally before re-importing them somewehere else.
+  WordPress content will be stored in JSON files. This gives you also the option to tranform the content locally before re-importing them somewehere else.
 
 - Blobs for attachments/media
 
@@ -158,7 +158,7 @@ Example:
 
 ```sh
 impex-cli.php export \
--username=admin -password='password' \
+-username=<adminuser> -password='<password>' \
 -rest-url=http://localhost:8888/wp-json \
 -overwrite \
 -profile=base \
@@ -175,7 +175,7 @@ export-cm4all-wordpress-created-
 │   ├── slice-0001-logo-fabrics.png
 │   ├── slice-0002-johny-goerend-ou-GkKJm3fc-unsplash.jpg
 │   ├── slice-0002.json
-│   ├── slice-0003.json
+│   └── slice-0003.json
 ...
 ├── chunk-0006
 │   ├── slice-0000.json
@@ -231,7 +231,7 @@ Example usage:
 
 ```sh
 impex-cli.php import \
--username=admin -password='password' \
+-username=<adminuser> -password='<password>' \
 -rest-url=http://localhost:8888/wp-json \
 -profile=all \
 ~/tmp/my-export
@@ -263,7 +263,7 @@ Example usage:
 
 ```sh
 impex-cli.php export-profile list \
--username=admin -password='password' \
+-username=<adminuser> -password='<password>' \
 -rest-url=http://localhost:8888/wp-json
 ```
 
@@ -296,7 +296,7 @@ Example usage:
 
 ```sh
 impex-cli.php import-profile list \
--username=admin -password='password' \
+-username=<adminuser> -password='<password>' \
 -rest-url=http://localhost:8888/wp-json
 ```
 

diff --git a/docs/gh-pages/src/jsonschema/slice-attachment-example.json b/docs/gh-pages/src/jsonschema/slice-attachment-example.json
@@ -0,0 +1,10 @@
+{
+  "$schema": "slice-attachment.json",
+  "version": "1.0.0",
+  "type": "php",
+  "tag": "attachment",
+  "meta": {
+    "entity": "attachment"
+  },
+  "data": "https://www.example.com/attachment.jpg"
+}
diff --git a/docs/gh-pages/src/jsonschema/slice-attachment.json b/docs/gh-pages/src/jsonschema/slice-attachment.json
@@ -0,0 +1,46 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema",
+  "title": "Impex Content Slice",
+  "description": "a Impex slice containing content",
+  "type": "object",
+  "properties": {
+    "$schema": {
+      "type": "string",
+      "description": "The JSON schema for this slice"
+    },
+    "version": {
+      "title": "Impex Provider content version",
+      "description": "Version will be used by Impex to know what data format to expect",
+      "const": "1.0.0"
+    },
+    "type": {
+      "title": "Impex slice type",
+      "description": "Value will be used by Impex to know the content type of the slice",
+      "const": "php"
+    },
+    "tag": {
+      "title": "Impex slice tag",
+      "description": "The Impex slice tag contains information about the responsible Impex provider for this slice",
+      "const": "attachment"
+    },
+    "meta": {
+      "title": "Metadata for the slice",
+      "description": "Metadata is a JSON object used to store additional information about the slice",
+      "const": {
+        "entity": "attachment"
+      }
+    },
+    "data": {
+      "format": "uri-template",
+      "type": "string",
+      "title": "Data portion of this Impex slice",
+      "description": "Attachment slice data is expected to be a URI to the attachment file.\nFor media it has to be the URI to the image.\nURI can be absolute or relative.",
+      "examples": [
+        "./media/image.jpg",
+        "https://www.example.com/attachment.jpg"
+      ]
+    }
+  },
+  "additionalProperties": false,
+  "required": ["version", "type", "tag", "meta", "data"]
+}
diff --git a/docs/gh-pages/src/jsonschema/slice-content-example.json b/docs/gh-pages/src/jsonschema/slice-content-example.json
@@ -0,0 +1,23 @@
+{
+  "$schema": "slice-content.json",
+  "version": "1.0.0",
+  "type": "php",
+  "tag": "content-exporter",
+  "meta": {
+    "entity": "content-exporter"
+  },
+  "data": {
+    "posts": [
+      {
+        "wp:post_id": 1,
+        "title": "Home",
+        "wp:post_content": "<!-- wp:paragraph -->\n<p>Hello from first imported post !</p>\n<!-- /wp:paragraph -->"
+      },
+      {
+        "wp:post_id": 2,
+        "title": "About",
+        "wp:post_content": "<!-- wp:paragraph -->\n<p>Hello from \"second imported post\" !</p>\n<!-- /wp:paragraph -->"
+      }
+    ]
+  }
+}
diff --git a/docs/gh-pages/src/jsonschema/slice-content.json b/docs/gh-pages/src/jsonschema/slice-content.json
@@ -0,0 +1,119 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema",
+  "title": "Impex Content Slice",
+  "description": "a Impex slice containing content",
+  "type": "object",
+  "properties": {
+    "$schema": {
+      "type": "string",
+      "description": "The JSON schema for this slice"
+    },
+    "version": {
+      "title": "Impex Provider content version",
+      "description": "Version will be used by Impex to know what data format to expect",
+      "const": "1.0.0"
+    },
+    "type": {
+      "title": "Impex slice type",
+      "description": "Value will be used by Impex to know the content type of the slice",
+      "const": "php"
+    },
+    "tag": {
+      "title": "Impex slice tag",
+      "description": "The Impex slice tag contains information about the responsible Impex provider for this slice",
+      "const": "content-exporter"
+    },
+    "meta": {
+      "title": "Metadata for the slice",
+      "description": "Metadata is a JSON object used to store additional information about the slice",
+      "const": {
+        "entity": "content-exporter"
+      }
+    },
+    "data": {
+      "type": "object",
+      "properties": {
+        "posts": {
+          "type": "array",
+          "items": {
+            "$ref": "#/definitions/posts-item"
+          },
+          "minItems": 1,
+          "$comment": "@TODO: unique ids are not yet supported by jsonschema",
+          "uniqueItems": true
+        }
+      },
+      "title": "Data portion of this Impex slice",
+      "description": "data contains the real Impex data.",
+      "required": ["posts"]
+    }
+  },
+  "additionalProperties": false,
+  "required": ["version", "type", "tag", "meta", "data"],
+  "definitions": {
+    "posts-item": {
+      "title": "WordPress posts stored in this this Impex slice",
+      "type": "object",
+      "properties": {
+        "wp:post_id": {
+          "type": "integer",
+          "minimum": 1,
+          "title": "WordPress post_id",
+          "description": "The unique WordPress post id of the post"
+        },
+        "title": {
+          "type": "string",
+          "minLength": 1,
+          "title": "WordPress post title",
+          "description": "The title of the WordPress post as it is stored in the database"
+        },
+        "wp:post_content": {
+          "type": "string",
+          "minLength": 1,
+          "title": "WordPress post content",
+          "description": "The content of the WordPress post",
+          "examples": [
+            "<!-- wp:paragraph -->\n<p>Hello from first imported post !</p>\n<!-- /wp:paragraph -->",
+            "<!-- wp:paragraph -->\n<p>Hello world</p>\n<!-- /wp:paragraph -->\n\n<!-- wp:html -->\n<p>A bit of custom html utilizing the Gutenberg html block</p>\n<ul>\n  <li>hi</li>\n  <li>ho</li>\n  <li>howdy</li>\n</ul><!-- /wp:html -->"
+          ]
+        },
+        "wp:post_type": {
+          "title": "WordPress post type",
+          "description": "The type of the WordPress post.\nCcontent related post types are 'post' and 'page'.\nIf not declared, type 'post' will be assumed.",
+          "type": "string",
+          "enum": [
+            "post",
+            "page",
+            "nav_menu_item",
+            "wp_template",
+            "wp_template_part",
+            "wp_block",
+            "wp_global_styles"
+          ],
+          "default": "page"
+        },
+        "wp:status": {
+          "type": "string",
+          "title": "WordPress post status",
+          "description": "The WordPress post status (https://wordpress.org/support/article/post-status/)",
+          "enum": ["publish", "future", "draft", "pending", "private"],
+          "default": "draft"
+        },
+        "wp:post_name": {
+          "type": "string",
+          "title": "WordPress post slug",
+          "description": "Used to generate the permalink. If not given, the sanitized post title will be used instead.",
+          "minLength": 1
+        },
+        "wp:post_parent": {
+          "type": "integer",
+          "minimum": 1,
+          "title": "WordPress post parent id",
+          "description": "The WordPress post id of the parent post.\n If not given, the post will be created as a top level post."
+        }
+      },
+      "required": ["wp:post_id", "title", "wp:post_content"],
+      "additionalProperties": false
+    }
+  }
+}
diff --git a/docs/gh-pages/src/migrating-content.md b/docs/gh-pages/src/migrating-content.md
@@ -0,0 +1,223 @@
+<!-- toc -->
+
+# Migrating content
+
+Migrating existing content into WordPress is a very common task.
+
+Impex provides tooling support for migrating your content to WordPress.
+
+## Preparation
+
+Impex imports data from a directory containing JSON files grouped in `chunk-\*` sub directories.
+
+```
+my-exported-website
+├── chunk-0001
+│   ├── slice-0001.json
+│   ├── slice-0002.json
+│   ├── slice-0003.json
+│   ├── slice-0004.json
+│   └── slice-0005.json
+├── chunk-0002
+│   ├── slice-0001.json
+│   ├── slice-0001-wes-walker-unsplash.jpg
+│   ├── slice-0002-greysen-johnson-unsplash.jpg
+│   ├── slice-0002.json
+│   ├── slice-0003-james-wheeler-unsplash.jpg
+│   └── slice-0003.json
+...
+```
+
+> Why that _chunk-\*_ sub directory structure ?
+>
+> Organizing thousands of content documents and hundreds of images/videos in a single directory slows down file managers like Windows Explorer. That's the one and only reason for `chunk-\*` sub directories.
+
+Both _chunk-\*_ sub directories and the JSON files are suffixed by a 4 digit number.
+
+Impex imports slice files ordered by name. So the slices in sub directory `chunk-0001` will be imported first, then the slices in `chunk-0002` and so on.
+
+Same rule for `slice-*.json` files within the same `chunk-\*` sub directory : `slice-0001.json` will be imported before `slice-0002.json` and so on.
+
+> Know that import order is important. If you import content referencing images/videos in the wrong order, you will get broken links. Impex will rewrite/fix media links in the content if you **import content as first and media afterwards.**
+
+Have a look at this [sample Impex export](https://github.com/IONOS-WordPress/cm4all-wp-impex/tree/develop/impex-cli/tests/fixtures/simple-import) provided by the Impex plugin to get a clue about a minimal working impex export containing content and referencing images.
+
+## Data files
+
+`slice-*.json` files are JSON files containing data.
+
+The real data is stored in the `data` property.
+
+The data might be anything expressed in textual form. Beside the data itself, each `slice-*.json` file contains some json data describing the data so that Impex knows how to import.
+
+An minimal slice file transporting a single Wordpress post looks like this:
+
+```json
+{
+  "version": "1.0.0",
+  "type": "php",
+  "tag": "content-exporter",
+  "meta": {
+    "entity": "content-exporter"
+  },
+  "data": {
+    "posts": [
+      {
+        "wp:post_id": 1,
+        "wp:post_content": "<!-- wp:paragraph -->\n<p>Hello from first imported post !</p>\n<!-- /wp:paragraph -->",
+        "title": "Hello first post!"
+      }
+    ]
+  }
+}
+```
+
+As you can see the real content is located in the `data` property.
+
+Everything except the `data` property are used for versioning and content identification.
+
+### Content (aka WordPress posts/pages)
+
+Content slice files wrap regular WordPress _posts_ and _pages_.
+
+Content slices may also transport further content like comments, custom fields, terms, taxonomies, categories, FSE templates/template-parts, global styles and so on. But that's another story.
+
+> To get a clue about the power of content slices by exporting a FSE enabled WordPress instance and inspecting the resulting `slice-_.json` files.
+
+Below is a [JSONschema](https://json-schema.org/) describing the content slice file format.
+
+Download [JSONschema](https://json-schema.org/) definition for content slices : [slice-content.json](https://github.com/IONOS-WordPress/cm4all-wp-impex/tree/develop/docs/gh-pages/src/jsonschema/slice-content.json)
+
+```json
+{{#include ./jsonschema/slice-content.json}}
+```
+
+A content slice may contain any number of WordPress posts/pages/etc.
+
+> When generating a content slice file, it's best to embed only a single page/post per `slice-_.json` file
+
+Each content document is identified by a unique `wp:post_id` property.
+
+The `title` property is used as the title.
+
+`wp:post_content` transports the content.
+
+_See the Content slice [JSONSchema definition](https://github.com/IONOS-WordPress/cm4all-wp-impex/tree/develop/docs/gh-pages/src/jsonschema/slice-content.json) for all supported properties._
+
+Since WordPress expects [block-annotated HTML](https://wordpress.com/support/wordpress-editor/blocks/) you need to transform your HTML content into [block-annotated HTML](https://wordpress.com/support/wordpress-editor/blocks/).
+
+There are 2 options to do that :
+
+- **The gold solution** : annotate almost every HTML tag with the matching [Gutenberg block](https://wordpress.com/support/wordpress-editor/blocks/custom-html-block/).
+
+  ```html
+  <!-- wp:paragraph -->
+  <p>A bit of custom html utilizing the Gutenberg html block</p>
+  <!-- /wp:paragraph -->
+
+  <!-- wp:list -->
+  <ul>
+    <li>hi</li>
+    <li>ho</li>
+    <li>howdy</li>
+  </ul>
+  <!-- /wp:list -->
+
+  <!-- wp:image -->
+  <figure class="wp-block-image">
+    <img src="./greysen-johnson-unsplash.jpg" />
+    <figcaption>Fly fishing</figcaption>
+  </figure>
+  <!-- /wp:image -->
+  ```
+
+- the quick and dirty solution : wrap the whole html content into a WordPress [Custom HTML block](https://wordpress.com/support/wordpress-editor/blocks/custom-html-block/) :
+
+  ```html
+  <!-- wp:html -->
+  <p>A bit of custom html utilizing the Gutenberg html block</p>
+  <ul>
+    <li>hi</li>
+    <li>ho</li>
+    <li>howdy</li>
+  </ul>
+  <figure>
+    <img src="./greysen-johnson-unsplash.jpg" />
+    <figcaption>Fly fishing</figcaption>
+  </figure>
+  <!-- /wp:html -->
+  ```
+
+  _Why is this solution dirty ?_
+
+  _=> If you open up a page/post containing a - the quick and dirty solution : wrap the whole html content into a WordPress [Custom HTML block](https://wordpress.com/support/wordpress-editor/blocks/custom-html-block/) in the Gutenberg editor, you will see just the HTML content but its not rendered_. So the quick and dirty solution is actually a no-go from a designers perspective.
+
+The HTML content must be encoded as JSON string in the slice file. See [this example content slice](https://github.com/IONOS-WordPress/cm4all-wp-impex/blob/develop/impex-cli/tests/fixtures/simple-import/chunk-0001/slice-0005.json).
+
+See [Attachments (like Pictures and Videos)](#attachments-like-pictures-and-videos) for importing referenced media files.
+
+### Attachments (like Pictures and Videos)
+
+Attachments a binary files like images/videos or anything else stored in the WordPress `uploads` directory.
+
+Such binary data is handled a bit differently than textual - because it cannot be easily embedded into a JSON file.
+
+Below is a [JSONschema](https://json-schema.org/) describing the attachment slice file format.
+
+Download [JSONschema](https://json-schema.org/) definition for media files : [slice-attachment.json](https://github.com/IONOS-WordPress/cm4all-wp-impex/tree/develop/docs/gh-pages/src/jsonschema/slice-content.json)
+
+```json
+{{#include ./jsonschema/slice-attachment.json}}
+```
+
+Let's say you have a reference to an image in your content :
+
+```html
+<img src="./greysen-johnson-unsplash.jpg" />
+```
+
+So you need to import the image into your WordPress instance. To do so, you need to
+
+- create a `slice-*json` file (let's name it `slice-0002.json`) declaring the attachment :
+
+  ```json
+  {
+    "version": "1.0.0",
+    "type": "resource",
+    "tag": "attachment",
+    "meta": {
+      "entity": "attachment"
+    },
+    "data": "./greysen-johnson-unsplash.jpg"
+  }
+  ```
+
+  As you can see, there is actually only the `data` property referencing the image. Rest of the slice file is just boilerplate code.
+
+- provide the image in the same chunk directory as it's slice json file and **prefixed** with the slice json file name (`slice-0002.json`) :
+
+  ```
+  slice-0002-greysen-johnson-unsplash.jpg
+  ```
+
+Thats it ! If you import the slice file using Impex, the image will appear in the WordPress `uploads` directory and in the WordPress media page. If you referenced the image in your content, it will also appear in your imported pages/posts.
+
+> Remember: Content slices referencing media files should **ALWAYS** be imported **before** the attachment slices.
+>
+> This can be achieved by naming content slicing with a lower number than the media slices or - much simpler - keeping the content slices in a lower numbered `chunk-*` directory than the attachments.
+>
+> See [simple-import](https://github.com/IONOS-WordPress/cm4all-wp-impex/tree/develop/impex-cli/tests/fixtures/simple-import) example for a full featured generated import at the [Impex Github page](https://github.com/IONOS-WordPress/cm4all-wp-impex).
+
+### Other data
+
+Although Impex provides a simple way to import content and media, you may also want to import more advanced data like database tables or settings into WordPress.
+
+Impex can import
+
+- relational data like database tables
+
+- key/value based settings
+
+into WordPress.
+
+@TODO: Add JSONSchema / examples for other data.
diff --git a/impex-cli/impex-cli.php b/impex-cli/impex-cli.php
@@ -36,71 +36,98 @@ function rmdir_r($dir)
   }
 }
 
-function _die($options, $message, ...$args)
+class DieException extends \RuntimeException
 {
-  fprintf(STDERR, $message, ...array_map(fn ($_) => is_array($_) || is_object($_) ? json_encode($_) : $_, $args));
-  exit(1);
+  function __construct($message, $code = 0, \Exception $previous = null)
+  {
+    parent::__construct($message, $code, $previous);
+  }
 }
 
-function main($argv)
+function _die($options, $message, ...$args)
 {
-  $argc = count($argv);
+  $message = sprintf($message, ...array_map(fn ($_) => is_array($_) || is_object($_) ? json_encode($_) : $_, $args));
 
-  $operation = 'help';
-  $options = ['header' => []];
-  $arguments = [];
+  throw new DieException($message, 1);
+}
 
-  switch ($argc) {
-    case 1:
-      break;
-    default:
-      switch ($argv[1]) {
-        case 'import':
-        case 'export':
-        case 'export-profile':
-        case 'import-profile':
-          $operation = $argv[1];
-          _parseCommandlineArguments(array_slice($argv, 2), $options, $arguments);
-
-          [$result, $status, $error] = _curl(
-            $options,
-            "",
-            null,
-            fn ($curl) => curl_setopt($curl, \CURLOPT_URL, $options['rest-url'])
-          );
-
-
-          // ensure we can connect to the wordpress rest api
-          if ($error) {
-            _die(
+function main($argv)
+{
+  try {
+    $argc = count($argv);
+
+    $operation = 'help';
+    $options = ['header' => []];
+    $arguments = [];
+
+    switch ($argc) {
+      case 1:
+        break;
+      default:
+        switch ($argv[1]) {
+          case 'import':
+          case 'export':
+          case 'export-profile':
+          case 'import-profile':
+            $operation = $argv[1];
+            _parseCommandlineArguments(array_slice($argv, 2), $options, $arguments);
+
+            [$result, $status, $error] = _curl(
               $options,
-              "Could not connect to wordpress rest endpoint(='%s'): %s\nEnsure param '-rest-url' is correct.\nCheck wordpress rest api is enabled.\n",
-              $options['rest-url'],
-              $error
+              "",
+              null,
+              fn ($curl) => curl_setopt($curl, \CURLOPT_URL, $options['rest-url'])
             );
-          } else {
-            // ensure impex plugin rest namespace is available
-            if (!in_array('cm4all-wp-impex/v1', $result['namespaces'])) {
+
+
+            // ensure we can connect to the wordpress rest api
+            if ($error) {
               _die(
                 $options,
-                "Wordpress plugin cm4all-wp-impex seems not to be installed in the wordpress instance - expected rest endpoint(='cm4all-wp-impex/v1') is not available : Available rest endpoints %s'\n",
-                json_encode($result['namespaces'])
+                "Could not connect to wordpress rest endpoint(='%s'): %s\nEnsure param '-rest-url' is correct.\nCheck wordpress rest api is enabled.\n",
+                $options['rest-url'],
+                $error
               );
+            } else {
+              if (is_string($result) && $status === 301) {
+                _die(
+                  $options,
+                  "Wordpress JSON Rest API Endpoint is probably misconfigured - request returned(http status='%s') : %s'\n",
+                  $status,
+                  'HTTP/1.1 301 Moved Permanently'
+                );
+              } else {
+                // ensure impex plugin rest namespace is available
+                if (!in_array('cm4all-wp-impex/v1', $result['namespaces'])) {
+                  _die(
+                    $options,
+                    "Wordpress plugin cm4all-wp-impex seems not to be installed in the wordpress instance - expected rest endpoint(='cm4all-wp-impex/v1') is not available : Available rest endpoints %s'\n",
+                    json_encode($result['namespaces'])
+                  );
+                }
+              }
             }
-          }
 
-          break;
-        case 'help':
-        case '--help':
-          break;
-        default:
-          $arguments[] = sprintf("Invalid option(s): %s", join(' ', array_slice($argv, 1)));
-      }
-  };
+            break;
+          case 'help':
+          case '--help':
+            break;
+          default:
+            _die($options, "Invalid operation: %s", join(' ', array_slice($argv, 1)));
+        }
+    };
 
-  [$json, $status] = call_user_func(__NAMESPACE__ . '\\' . str_replace(['-'], ['_'], $operation), $options, ...$arguments);
-  if ($status === 200) {
-    echo json_encode($json, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE) . PHP_EOL;
+    [$json, $status] = call_user_func(__NAMESPACE__ . '\\' . str_replace(['-'], ['_'], $operation), $options, ...$arguments);
+    if ($status === 200) {
+      echo json_encode($json, JSON_PRETTY_PRINT | JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE) . PHP_EOL;
+    }
+  } catch (DieException $ex) {
+    if (php_sapi_name() === "cli" && !str_ends_with($_SERVER['argv'][0], 'phpunit')) {
+      fprintf(STDERR, $ex->getMessage());
+      exit(1);
+    } else {
+      throw $ex;
+    }
   }
 }
 
@@ -142,8 +169,7 @@ function _parseCommandlineArguments($argv, &$options, &$arguments)
   if (isset($options['username']) && isset($options['password'])) {
     foreach ($options['header'] as $header) {
       if (preg_match('/^authorization: Basic$/', $header, $matches)) {
-        fprintf(STDERR, "Can't use both username and password options and Authorization header\n");
-        exit(1);
+        _die($options, "Can't use both username and password options and Authorization header\n");
       }
     }
 
@@ -250,7 +276,7 @@ function _curl($options, string $endpoint, $method = null, $callback = __NAMESPA
   if (((string)$http_status)[0] !== '2') {
     _log(
       $options,
-      "accessing '%s' returned http statuscode(=%s) : %s",
+      "accessing '%s' returned http status code(=%s) : %s",
       curl_getinfo($curl, CURLINFO_EFFECTIVE_URL),
       $http_status,
       curl_error($curl),
@@ -590,7 +616,10 @@ function _saveSlicesChunk($options, $export_directory, $response, $chunk)
 ]);
 */
 
-main($argv);
+// if we are running in cli mode and not as phpunit test then run main
+if (php_sapi_name() === "cli" && !str_ends_with($_SERVER['argv'][0], 'phpunit')) {
+  main($argv);
+} 
 
 /*
 main([

diff --git a/impex-cli/tests/.dockerignore b/impex-cli/tests/.dockerignore
@@ -0,0 +1 @@
+*
diff --git a/impex-cli/tests/Dockerfile b/impex-cli/tests/Dockerfile
@@ -0,0 +1,91 @@
+# PHPUnit Docker Container.
+FROM alpine:latest as builder
+LABEL mantainer="Lars Gersmann <lars.gersmann@cm4all.com>"
+
+WORKDIR /tmp
+
+RUN apk --no-cache add \
+  bash \
+  ca-certificates \
+  curl \
+  git \
+  php8 \
+  php8-bcmath \
+  php8-ctype \
+  php8-curl \
+  php8-dom \
+  php8-exif \
+  php8-fileinfo \
+  php8-json \
+  php8-mbstring \
+  php8-pecl-mcrypt \
+  php8-mysqli \
+  php8-opcache \
+  php8-openssl \
+  php8-pcntl \
+  php8-pdo \
+  php8-pdo_mysql \
+  php8-pdo_pgsql \
+  php8-pdo_sqlite \
+  php8-phar \
+  php8-session \
+  php8-simplexml \
+  php8-soap \
+  php8-tokenizer \
+  php8-xdebug \
+  php8-xml \
+  php8-xmlreader \
+  php8-xmlwriter \
+  php8-zip \
+  php8-zlib \
+  unzip 
+
+# composer expects command "php" available in path
+RUN ln -s /usr/bin/php8 /usr/bin/php
+
+# install composer
+RUN wget https://getcomposer.org/installer -O composer-setup.php && php composer-setup.php --install-dir=/usr/bin --filename=composer && rm composer-setup.php
+
+# install phpunit 
+RUN composer require "phpunit/phpunit:^9.5" --prefer-source --no-interaction 
+# RUN composer require "phpunit/php-invoker" --prefer-source --no-interaction 
+RUN ln -s /tmp/vendor/bin/phpunit /usr/local/bin/phpunit 
+
+# Enable X-Debug
+RUN sed -i 's/\;z/z/g' /etc/php8/conf.d/*xdebug.ini 
+# RUN php -m | grep -i xdebug
+
+# pear support
+RUN wget https://pear.php.net/go-pear.phar -O go-pear.phar && echo 'Y' | php go-pear.phar && rm go-pear.phar
+# add your pear packages to be installed using --build-arg in the docker run command
+ARG PEAR_PACKAGES=""
+ONBUILD RUN \
+  { \
+  [ "${PEAR_PACKAGES}" != "" ]; \
+  } || exit 0 && pear install ${PEAR_PACKAGES}
+
+# see https://phpunit.readthedocs.io/en/9.5/installation.html#recommended-php-configuration
+RUN echo $'memory_limit=-1\n\
+  error_reporting=-1\n\
+  log_errors_max_len=0\n\
+  zend.assertions=1\n\
+  assert.exception=1\n\
+  xdebug.show_exception_trace=0\n' >> /etc/php8/php.ini
+
+#####################################################################################################
+
+FROM alpine:latest
+# simple trick to get rid of intermediate layers
+# https://stackoverflow.com/questions/56117261/how-to-merge-dockers-layers-of-image-and-slim-down-the-image-file
+COPY --from=builder / /
+
+VOLUME ["/workdir"]
+WORKDIR /workdir/tests
+
+# add a entrypoint script to enable CTRL-C abortion in terminal
+# (see https://stackoverflow.com/a/57526365/1554103)
+# RUN echo "#!/bin/bash" > /usr/local/bin/docker-entrypoint.sh && \
+#   echo '$@' >> /usr/local/bin/docker-entrypoint.sh && \
+#   chmod a+x /usr/local/bin/docker-entrypoint.sh
+
+# ENTRYPOINT ["/usr/local/bin/docker-entrypoint.sh"]
diff --git a/impex-cli/tests/README.md b/impex-cli/tests/README.md
@@ -0,0 +1,25 @@
+# About
+
+a tiny (alpine based) docker image for phpunit testing.
+
+## Features
+
+- php 8
+
+  - including xdebug support
+
+- phpunit 9.5
+
+# Development
+
+build : `DOCKER_BUILDKIT=1 docker build -t cm4all-wp-impex/impex-cli-phpunit .`
+
+- (optional) you can add `--build-arg PEAR_PACKAGES="<space-separated-list-of-pear-packages>"` to auto install pear packages into the image
+
+jump into : `docker run -ti --rm cm4all-wp-impex/impex-cli-phpunit bash`
+
+php.ini : `/etc/php8/php.ini`
+
+# Usage
+
+`docker run --add-host=host.docker.internal:host-gateway -it -v $(pwd)/..:/workdir --rm cm4all-wp-impex/impex-cli-phpunit phpunit .`
diff --git a/impex-cli/tests/abstract-impex-cli-testcase.php b/impex-cli/tests/abstract-impex-cli-testcase.php
@@ -0,0 +1,49 @@
+<?php
+
+namespace cm4all\wp\impex\tests\phpunit;
+
+use PHPUnit\Framework\TestCase;
+
+require_once __DIR__ . '/../impex-cli.php';
+
+function impex_cli($operation, ...$args): array
+{
+  $retval = [
+    'stderr' => '',
+    'stdout' => '',
+    'exit_code' => 0,
+  ];
+
+  ob_start();
+
+  try {
+    \cm4all\wp\impex\cli\main([
+      realpath(__DIR__ . '/../impex-cli/impex-cli.php'),
+      $operation,
+      '-rest-url=http://host.docker.internal:8889/wp-json',
+      '-username=admin',
+      '-password=password',
+      ...$args,
+    ]);
+  } catch (\cm4all\wp\impex\cli\DieException $ex) {
+    $retval['stderr'] = $ex->getMessage();
+    $retval['exit_code'] = $ex->getCode();
+  } finally {
+    $retval['stdout'] = ob_get_clean();
+  }
+
+  return $retval;
+}
+
+abstract class AbstractImpexCLITestCase extends TestCase
+{
+  function setUp(): void
+  {
+    parent::setUp();
+  }
+
+  function tearDown(): void
+  {
+    parent::tearDown();
+  }
+}
diff --git a/impex-cli/tests/fixtures/empty-snapshot/.gitkeep b/impex-cli/tests/fixtures/empty-snapshot/.gitkeep
diff --git a/impex-cli/tests/fixtures/simple-import/chunk-0001/slice-0001.json b/impex-cli/tests/fixtures/simple-import/chunk-0001/slice-0001.json
@@ -0,0 +1,17 @@
+{
+  "version": "1.0.0",
+  "type": "php",
+  "tag": "content-exporter",
+  "meta": {
+    "entity": "content-exporter"
+  },
+  "data": {
+    "posts": [
+      {
+        "wp:post_id": 1,
+        "wp:post_content": "<!-- wp:paragraph -->\n<p>Hello from first imported post !</p>\n<!-- /wp:paragraph -->",
+        "title": "Hello first post!"
+      }
+    ]
+  }
+}
diff --git a/impex-cli/tests/fixtures/simple-import/chunk-0001/slice-0002.json b/impex-cli/tests/fixtures/simple-import/chunk-0001/slice-0002.json
@@ -0,0 +1,20 @@
+{
+  "version": "1.0.0",
+  "type": "php",
+  "tag": "content-exporter",
+  "meta": {
+    "entity": "content-exporter"
+  },
+  "data": {
+    "posts": [
+      {
+        "wp:status": "publish",
+        "wp:post_type": "page",
+        "wp:post_name": "hello-world",
+        "wp:post_id": 2,
+        "wp:post_content": "<!-- wp:paragraph -->\n<p>Hello from import !</p>\n<!-- /wp:paragraph -->",
+        "title": "Hello world!"
+      }
+    ]
+  }
+}
diff --git a/impex-cli/tests/fixtures/simple-import/chunk-0001/slice-0003.json b/impex-cli/tests/fixtures/simple-import/chunk-0001/slice-0003.json
@@ -0,0 +1,20 @@
+{
+  "version": "1.0.0",
+  "type": "php",
+  "tag": "content-exporter",
+  "meta": {
+    "entity": "content-exporter"
+  },
+  "data": {
+    "posts": [
+      {
+        "wp:status": "publish",
+        "wp:post_type": "page",
+        "wp:post_name": "page-with-image",
+        "wp:post_id": 3,
+        "wp:post_content": "<!-- wp:paragraph -->\n<p>Hello world</p>\n<!-- /wp:paragraph -->\n<!-- wp:image --><figure class=\"wp-block-image\"><img src=\"./wes-walker-unsplash.jpg\"/></figure><!-- /wp:image -->",
+        "title": "A page with an image block"
+      }
+    ]
+  }
+}
diff --git a/impex-cli/tests/fixtures/simple-import/chunk-0001/slice-0004.json b/impex-cli/tests/fixtures/simple-import/chunk-0001/slice-0004.json
@@ -0,0 +1,20 @@
+{
+  "version": "1.0.0",
+  "type": "php",
+  "tag": "content-exporter",
+  "meta": {
+    "entity": "content-exporter"
+  },
+  "data": {
+    "posts": [
+      {
+        "wp:status": "publish",
+        "wp:post_type": "page",
+        "wp:post_name": "page-with-gallery-multiple-images",
+        "wp:post_id": 4,
+        "wp:post_content": "<!-- wp:paragraph -->\n<p>Hello world</p>\n<!-- /wp:paragraph -->\n<!-- wp:gallery -->\n<figure class=\"wp-block-gallery has-nested-images columns-default is-cropped\">\n  <!-- wp:image -->\n  <figure class=\"wp-block-image\"><img src=\"./james-wheeler-unsplash.jpg\"/></figure>\n  <!-- /wp:image -->\n\n  <!-- wp:image -->\n  <figure class=\"wp-block-image\"><img src=\"./greysen-johnson-unsplash.jpg\"/></figure>\n  <!-- /wp:image -->\n\n  <!-- wp:image -->\n  <figure class=\"wp-block-image\"><img src=\"./wes-walker-unsplash.jpg\"/></figure>\n  <!-- /wp:image -->\n</figure>\n<!-- /wp:gallery -->",
+        "title": "A page with gallery block."
+      }
+    ]
+  }
+}
diff --git a/impex-cli/tests/fixtures/simple-import/chunk-0001/slice-0005.json b/impex-cli/tests/fixtures/simple-import/chunk-0001/slice-0005.json
@@ -0,0 +1,20 @@
+{
+  "version": "1.0.0",
+  "type": "php",
+  "tag": "content-exporter",
+  "meta": {
+    "entity": "content-exporter"
+  },
+  "data": {
+    "posts": [
+      {
+        "wp:status": "publish",
+        "wp:post_type": "page",
+        "wp:post_name": "page-with-custom-html-including-media",
+        "wp:post_id": 5,
+        "wp:post_content": "<!-- wp:paragraph -->\n<p>Hello world</p>\n<!-- /wp:paragraph -->\n\n<!-- wp:html -->\n<p>A bit of custom html utilizing the Gutenberg html block</p>\n<ul>\n  <li>hi</li>\n  <li>ho</li>\n  <li>howdy</li>\n</ul>\n<figure class=\"wp-block-image\">\n<img src=\"http://localhost:8889/wp-content/uploads/2022/03/greysen-johnson-unsplash.jpg\" alt=\"\">     <figcaption>Fly fishing</figcaption>\n</figure>\n<!-- /wp:html -->",
+        "title": "A page using Gutenberg HTML block."
+      }
+    ]
+  }
+}
diff --git a/...-cli/tests/fixtures/simple-import/chunk-0002/slice-0001-wes-walker-unsplash.jpg b/...-cli/tests/fixtures/simple-import/chunk-0002/slice-0001-wes-walker-unsplash.jpg
diff --git a/impex-cli/tests/fixtures/simple-import/chunk-0002/slice-0001.json b/impex-cli/tests/fixtures/simple-import/chunk-0002/slice-0001.json
@@ -0,0 +1,9 @@
+{
+  "version": "1.0.0",
+  "type": "resource",
+  "tag": "attachment",
+  "meta": {
+    "entity": "attachment"
+  },
+  "data": "./wes-walker-unsplash.jpg"
+}
diff --git a/...tests/fixtures/simple-import/chunk-0002/slice-0002-greysen-johnson-unsplash.jpg b/...tests/fixtures/simple-import/chunk-0002/slice-0002-greysen-johnson-unsplash.jpg
diff --git a/impex-cli/tests/fixtures/simple-import/chunk-0002/slice-0002.json b/impex-cli/tests/fixtures/simple-import/chunk-0002/slice-0002.json
@@ -0,0 +1,9 @@
+{
+  "version": "1.0.0",
+  "type": "resource",
+  "tag": "attachment",
+  "meta": {
+    "entity": "attachment"
+  },
+  "data": "./greysen-johnson-unsplash.jpg"
+}
diff --git a/...i/tests/fixtures/simple-import/chunk-0002/slice-0003-james-wheeler-unsplash.jpg b/...i/tests/fixtures/simple-import/chunk-0002/slice-0003-james-wheeler-unsplash.jpg
diff --git a/impex-cli/tests/fixtures/simple-import/chunk-0002/slice-0003.json b/impex-cli/tests/fixtures/simple-import/chunk-0002/slice-0003.json
@@ -0,0 +1,9 @@
+{
+  "version": "1.0.0",
+  "type": "resource",
+  "tag": "attachment",
+  "meta": {
+    "entity": "attachment"
+  },
+  "data": "./james-wheeler-unsplash.jpg"
+}
diff --git a/impex-cli/tests/phpunit.xml b/impex-cli/tests/phpunit.xml
@@ -0,0 +1,21 @@
+<phpunit
+  backupGlobals="false"
+	colors="true"
+	convertErrorsToExceptions="true"
+	convertNoticesToExceptions="true"
+	convertWarningsToExceptions="true"
+  cacheResult="false"
+>
+	<testsuites>
+		<testsuite name="impex-cli">
+			<directory 
+        phpVersion="8.0.0" 
+        phpVersionOperator=">=" 
+        prefix="test-" 
+        suffix=".php"
+      >
+        ./
+      </directory>
+		</testsuite>
+	</testsuites>
+</phpunit>
diff --git a/impex-cli/tests/test-import-profile.php b/impex-cli/tests/test-import-profile.php
@@ -0,0 +1,25 @@
+<?php
+
+use cm4all\wp\impex\tests\phpunit\AbstractImpexCLITestCase;
+
+use function cm4all\wp\impex\tests\phpunit\impex_cli;
+
+require_once __DIR__ . "/abstract-impex-cli-testcase.php";
+
+final class ImportProfileTest extends AbstractImpexCLITestCase
+{
+  function testImportProfiles()
+  {
+    // curl -v 'http://host.docker.internal:8889/wp-json/cm4all-wp-impex/v1/export/profile' -H 'accept: application/json' -H 'authorization: Basic YWRtaW46cGFzc3dvcmQ='
+
+    $result = impex_cli(
+      'import-profile',
+      // '-CURLOPT_VERBOSE',
+      // '-verbose',
+      // __DIR__ . '/fixtures/impex-cli/simple-snapshot',
+    );
+
+    $this->assertEquals('', $result['stderr'], 'stderr should be empty');
+    $this->assertEquals(0, $result['exit_code'], 'should succeed');
+  }
+}
diff --git a/impex-cli/tests/test-import.php b/impex-cli/tests/test-import.php
@@ -0,0 +1,43 @@
+<?php
+
+use cm4all\wp\impex\tests\phpunit\AbstractImpexCLITestCase;
+
+use function cm4all\wp\impex\tests\phpunit\impex_cli;
+
+require_once __DIR__ . "/abstract-impex-cli-testcase.php";
+final class ImportTest extends AbstractImpexCLITestCase
+{
+  function testInvalidOptions()
+  {
+    $result = impex_cli(
+      '-overwrite',
+      '/tmp/test-export.zip',
+    );
+
+    $this->assertEquals(1, $result['exit_code'], 'should fail because of misplaced options/arguments');
+  }
+
+  function testImportEmptySnapshotDirectory()
+  {
+    $result = impex_cli(
+      'import',
+      '-overwrite',
+      '-profile=all',
+      __DIR__ . '/fixtures/empty-snapshot',
+    );
+
+    $this->assertEquals(0, $result['exit_code'], 'should succeed');
+  }
+
+  function testSimpleImport()
+  {
+    $result = impex_cli(
+      'import',
+      '-overwrite',
+      '-profile=all',
+      __DIR__ . '/fixtures/simple-import',
+    );
+
+    $this->assertEquals(0, $result['exit_code'], 'should succeed');
+  }
+}
diff --git a/package-lock.json b/package-lock.json
diff --git a/package.json b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "cm4all-wp-impex",
-  "version": "1.2.0",
+  "version": "1.2.1",
   "scripts": {
     "dev": "make dev",
     "build": "make",

diff --git a/plugins/cm4all-wp-impex-example/plugin.php b/plugins/cm4all-wp-impex-example/plugin.php
@@ -4,7 +4,7 @@
  * Plugin Name: cm4all-wp-impex-example
  * Plugin URI: http://dev.intern.cm-ag/trinity/research/cm4all-wp-impex
  * Description: Example Plugin contributing additional Importer/Exporter facilities to Impex Plugin 
- * Version: 1.2.0
+ * Version: 1.2.1
  * Tags: import, export, migration
  * Requires PHP: 8.0
  * Requires at least: 5.7

diff --git a/plugins/cm4all-wp-impex/inc/class-impex-export-rest-controller.php b/plugins/cm4all-wp-impex/inc/class-impex-export-rest-controller.php
@@ -117,7 +117,7 @@ public function get_item_slices($request)
         global $wpdb;
 
         $rows = $wpdb->get_results(
-          $wpdb->prepare("SELECT * from {$wpdb->prefix}" . ImpexExport::DB_CHUNKS_TABLENAME . ' WHERE export_id=%s ORDER BY position LIMIT %d OFFSET %d', $id, $per_page, $page * $per_page + $offset)
+          $wpdb->prepare("SELECT * from {$wpdb->prefix}" . Impex::DB_SNAPSHOTS_TABLENAME . ' WHERE snapshot_id=%s ORDER BY position LIMIT %d OFFSET %d', $id, $per_page, $page * $per_page + $offset)
         );
         $data = [];
         foreach ($rows as $row) {
@@ -128,7 +128,7 @@ public function get_item_slices($request)
         }
 
         $total = absint($wpdb->get_var(
-          $wpdb->prepare("SELECT COUNT(*) from {$wpdb->prefix}" . ImpexExport::DB_CHUNKS_TABLENAME . ' WHERE export_id=%s', $id)
+          $wpdb->prepare("SELECT COUNT(*) from {$wpdb->prefix}" . Impex::DB_SNAPSHOTS_TABLENAME . ' WHERE snapshot_id=%s', $id)
         ));
         $total_pages = ceil($total / $per_page);
 

diff --git a/plugins/cm4all-wp-impex/inc/class-impex-export.php b/plugins/cm4all-wp-impex/inc/class-impex-export.php
@@ -15,21 +15,10 @@
 
 abstract class ImpexExport extends ImpexPart
 {
-  const DB_CHUNKS_TABLENAME = 'impex_export_chunks';
   const WP_OPTION_EXPORTS = 'impex_exports';
   const WP_FILTER_SLICE_SERIALIZE = 'impex_export_filter_serialize';
   const WP_FILTER_SLICE_DESERIALIZE = 'impex_export_filter_deserialize';
 
-  protected string $_db_chunks_tablename;
-
-  public function __construct()
-  {
-    parent::__construct();
-
-    global $wpdb;
-    $this->_db_chunks_tablename = $wpdb->prefix . self::DB_CHUNKS_TABLENAME;
-  }
-
   protected function _createProvider(string $name, callable $cb): ImpexExportProvider
   {
     return new class($name, $cb) extends ImpexExportProvider
@@ -52,65 +41,6 @@ public function __construct($name, $context)
     };
   }
 
-  public function  __install(string|bool $installed_version): bool
-  {
-    global $wpdb;
-
-    if ($installed_version === false) {
-      // plugin was newly installed
-      $charset_collate = $wpdb->get_charset_collate();
-
-      $sql = "CREATE TABLE {$this->_db_chunks_tablename} (
-        id mediumint(9) NOT NULL AUTO_INCREMENT,
-        export_id CHAR(36) NOT NULL,
-        position mediumint(9) NOT NULL,
-        slice json NOT NULL,
-        PRIMARY KEY  (id)
-      ) $charset_collate;";
-
-      require_once(ABSPATH . 'wp-admin/includes/upgrade.php');
-      \dbDelta($sql);
-    } else if ($installed_version !== Impex::VERSION) {
-      // new plugin version is now installed, try to upgrade
-      /*
-      $sql = "CREATE TABLE {$this->_db_chunks_tablename} (
-        id mediumint(9) NOT NULL AUTO_INCREMENT,
-        time datetime DEFAULT '0000-00-00 00:00:00' NOT NULL,
-        name tinytext NOT NULL,
-        text text NOT NULL,
-        url varchar(100) DEFAULT '' NOT NULL,
-        PRIMARY KEY  (id)
-      );";
-  
-      require_once(ABSPATH . 'wp-admin/includes/upgrade.php');
-      dbDelta($sql);
-      */
-    }
-
-    return $this->__install_data($installed_version);
-  }
-
-  protected function __install_data(string|bool $installed_version): bool
-  {
-    /*
-    global $wpdb;
-
-    $welcome_name = 'Mr. WordPress';
-    $welcome_text = 'Congratulations, you just completed the installation!';
-
-    $wpdb->insert(
-      $this->_db_chunks_tablename,
-      [
-        'time' => current_time('mysql'),
-        'name' => $welcome_name,
-        'text' => $welcome_text,
-      ]
-    );
-    */
-
-    return true;
-  }
-
   function extract(ImpexExportTransformationContext $transformationContext): \Generator
   {
     foreach ($transformationContext->profile->getTasks() as $task) {
@@ -152,7 +82,7 @@ function save(ImpexExportProfile $profile, array $options = [],  string $name =
         $this->_db_chunks_tablename,
         [
           'position' => $position,
-          'export_id' => $transformationContext->id,
+          'snapshot_id' => $transformationContext->id,
           'slice' => $json,
         ]
       );
@@ -171,11 +101,11 @@ function save(ImpexExportProfile $profile, array $options = [],  string $name =
     return $transformationContext;
   }
 
-  function update(string $export_id, array $data): array|bool
+  function update(string $snapshot_id, array $data): array|bool
   {
     $exports = \get_option(self::WP_OPTION_EXPORTS, []);
     foreach ($exports as &$export) {
-      if ($export['id'] === $export_id) {
+      if ($export['id'] === $snapshot_id) {
         foreach ($data as $key => $value) {
           // prevent updating 'id', 'options', 'profile', 'user', 'created'
           if (!in_array($key, ['id', 'options', 'profile', 'user', 'created'])) {
@@ -196,12 +126,12 @@ function update(string $export_id, array $data): array|bool
     return false;
   }
 
-  function remove(string $export_id): bool|array
+  function remove(string $snapshot_id): bool|array
   {
     /* @var array<array> */
     $exports = \get_option(self::WP_OPTION_EXPORTS, []);
     foreach ($exports as $index => $export) {
-      if ($export['id'] === $export_id) {
+      if ($export['id'] === $snapshot_id) {
         $transformationContext = ImpexExportTransformationContext::fromJson($export);
 
         global $wpdb;
@@ -210,7 +140,7 @@ function remove(string $export_id): bool|array
         \WP_Filesystem();
 
         // remove matching export table rows
-        $rowsDeleted = $wpdb->delete($this->_db_chunks_tablename, ['export_id' => $transformationContext->id,]);
+        $rowsDeleted = $wpdb->delete($this->_db_chunks_tablename, ['snapshot_id' => $transformationContext->id,]);
         if ($rowsDeleted === false) {
           throw new ImpexExportRuntimeException(sprintf('failed to delete jsonized slices from database : %s', $wpdb->last_error));
         }

diff --git a/plugins/cm4all-wp-impex/inc/class-impex-import-rest-controller.php b/plugins/cm4all-wp-impex/inc/class-impex-import-rest-controller.php
@@ -160,9 +160,9 @@ public function upsert_item_slice($request)
     global $wpdb;
 
     /** @var string */
-    $import_id = $request->get_param('id');
+    $snapshot_id = $request->get_param('id');
     foreach (\get_option(ImpexImport::WP_OPTION_IMPORTS, []) as $import) {
-      if ($import['id'] === $import_id) {
+      if ($import['id'] === $snapshot_id) {
         $transformationContext = ImpexImportTransformationContext::fromJson($import);
 
         $position = $request->get_param('position');
@@ -175,7 +175,7 @@ public function upsert_item_slice($request)
 
         $slice = \apply_filters(self::WP_FILTER_IMPORT_REST_SLICE_UPLOAD, $slice, $transformationContext, $request);
 
-        $success = Impex::getInstance()->Import->_upsert_slice($import_id, $position, $slice);
+        $success = Impex::getInstance()->Import->_upsert_slice($snapshot_id, $position, $slice);
 
         if ($success === false) {
           throw new ImpexImportRuntimeException(sprintf('failed to insert/update jsonized slice(=%s) to database : %s', $slice, $wpdb->last_error));
@@ -192,14 +192,14 @@ public function upsert_item_slice($request)
   public function consume($request)
   {
     //$profile = Impex::getInstance()->Import->getProfile($request->get_param('profile'));
-    $import_id = $request->get_param('id');
+    $snapshot_id = $request->get_param('id');
     //$options = $request->get_json_params();
 
     $limit = $request->get_param('limit');
     $offset = $request->get_param('offset');
 
     foreach (\get_option(ImpexImport::WP_OPTION_IMPORTS, []) as $import) {
-      if ($import['id'] === $import_id) {
+      if ($import['id'] === $snapshot_id) {
         $transformationContext = ImpexImportTransformationContext::fromJson($import);
 
         $notConsumedSlices = Impex::getInstance()->Import->consume($transformationContext, $limit, $offset);

diff --git a/plugins/cm4all-wp-impex/inc/class-impex-import.php b/plugins/cm4all-wp-impex/inc/class-impex-import.php
@@ -15,21 +15,10 @@
 require_once __DIR__ . '/class-impex-import-runtime-exception.php';
 abstract class ImpexImport extends ImpexPart
 {
-  const DB_CHUNKS_TABLENAME = 'impex_import_chunks';
   const WP_OPTION_IMPORTS = 'impex_imports';
 
   const EVENT_IMPORT_END = 'cm4all_wp_import_end';
 
-  protected string $_db_chunks_tablename;
-
-  public function __construct()
-  {
-    parent::__construct();
-
-    global $wpdb;
-    $this->_db_chunks_tablename = $wpdb->prefix . self::DB_CHUNKS_TABLENAME;
-  }
-
   protected function _createProvider(string $name, callable $cb): ImpexImportProvider
   {
     return new class($name, $cb) extends ImpexImportProvider
@@ -52,66 +41,7 @@ public function __construct($name, $context)
     };
   }
 
-  public function  __install(string|bool $installed_version): bool
-  {
-    global $wpdb;
-
-    if ($installed_version === false) {
-      // plugin was newly installed
-      $charset_collate = $wpdb->get_charset_collate();
-
-      $sql = "CREATE TABLE {$this->_db_chunks_tablename} (
-        id mediumint(9) NOT NULL AUTO_INCREMENT,
-        import_id CHAR(36) NOT NULL,
-        position mediumint(9) NOT NULL,
-        slice json NOT NULL,
-        PRIMARY KEY  (id)
-      ) $charset_collate;";
-
-      require_once(ABSPATH . 'wp-admin/includes/upgrade.php');
-      \dbDelta($sql);
-    } else if ($installed_version !== Impex::VERSION) {
-      // new plugin version is now installed, try to upgrade
-      /*
-      $sql = "CREATE TABLE {$this->_db_chunks_tablename} (
-        id mediumint(9) NOT NULL AUTO_INCREMENT,
-        time datetime DEFAULT '0000-00-00 00:00:00' NOT NULL,
-        name tinytext NOT NULL,
-        text text NOT NULL,
-        url varchar(100) DEFAULT '' NOT NULL,
-        PRIMARY KEY  (id)
-      );";
-  
-      require_once(ABSPATH . 'wp-admin/includes/upgrade.php');
-      dbDelta($sql);
-      */
-    }
-
-    return $this->__install_data($installed_version);
-  }
-
-  protected function __install_data(string|bool $installed_version): bool
-  {
-    /*
-    global $wpdb;
-
-    $welcome_name = 'Mr. WordPress';
-    $welcome_text = 'Congratulations, you just completed the installation!';
-
-    $wpdb->insert(
-      $this->_db_chunks_tablename,
-      [
-        'time' => current_time('mysql'),
-        'name' => $welcome_name,
-        'text' => $welcome_text,
-      ]
-    );
-    */
-
-    return true;
-  }
-
-  function _upsert_slice(string $import_id, int $position, array $slice): bool
+  function _upsert_slice(string $snapshot_id, int $position, array $slice): bool
   {
     $json = json_encode($slice);
     if ($json === false) {
@@ -123,12 +53,12 @@ function _upsert_slice(string $import_id, int $position, array $slice): bool
 
     $data = [
       'position' => $position,
-      'import_id' => $import_id,
+      'snapshot_id' => $snapshot_id,
       'slice' => $json,
     ];
 
     $existing_id = $wpdb->get_var(
-      $wpdb->prepare("SELECT DISTINCT id from {$this->_db_chunks_tablename} WHERE import_id=%s and position=%d", $import_id, $position)
+      $wpdb->prepare("SELECT DISTINCT id from {$this->_db_chunks_tablename} WHERE snapshot_id=%s and position=%d", $snapshot_id, $position)
     );
 
     if ($existing_id !== null) {
@@ -162,12 +92,12 @@ function create(ImpexImportProfile $profile, array $options = [], string $name =
   /**
    * @return Generator|array[]
    */
-  function get_slices(string $import_id, int $limit = PHP_INT_MAX, int $offset = 0): \Generator
+  function get_slices(string $snapshot_id, int $limit = PHP_INT_MAX, int $offset = 0): \Generator
   {
     global $wpdb;
 
     $rows = $wpdb->get_results(
-      $wpdb->prepare("SELECT * from {$this->_db_chunks_tablename} WHERE import_id=%s ORDER BY position LIMIT %d OFFSET %d", $import_id, $limit, $offset)
+      $wpdb->prepare("SELECT * from {$this->_db_chunks_tablename} WHERE snapshot_id=%s ORDER BY position LIMIT %d OFFSET %d", $snapshot_id, $limit, $offset)
     );
     foreach ($rows as $row) {
       yield json_decode($row->slice, JSON_OBJECT_AS_ARRAY);
@@ -181,7 +111,7 @@ function get_slices(string $import_id, int $limit = PHP_INT_MAX, int $offset = 0
    */
   function consume(ImpexImportTransformationContext $transformationContext, int $limit = PHP_INT_MAX, int $offset = 0): array
   {
-    $uncomsumed_slices = [];
+    $unconsumed_slices = [];
 
     $options = $transformationContext->options;
     $profile = $transformationContext->profile;
@@ -204,24 +134,24 @@ function consume(ImpexImportTransformationContext $transformationContext, int $l
       }
 
       if (!$consumed) {
-        $uncomsumed_slices[] = $slice;
+        $unconsumed_slices[] = $slice;
       }
     }
 
     $profile->events(self::EVENT_IMPORT_END)($transformationContext, [
-      'uncomsumed_slices' => &$uncomsumed_slices,
+      'unconsumed_slices' => &$unconsumed_slices,
       'limit' => $limit,
       'offset' => $offset,
     ]);
 
-    return $uncomsumed_slices;
+    return $unconsumed_slices;
   }
 
-  function update(string $import_id, array $data): array|bool
+  function update(string $snapshot_id, array $data): array|bool
   {
     $imports = \get_option(self::WP_OPTION_IMPORTS, []);
     foreach ($imports as &$import) {
-      if ($import['id'] === $import_id) {
+      if ($import['id'] === $snapshot_id) {
         foreach ($data as $key => $value) {
           // prevent updating 'id', 'options', 'profile', 'user', 'created'
           if (!in_array($key, ['id', 'options', 'profile', 'user', 'created'])) {
@@ -242,11 +172,11 @@ function update(string $import_id, array $data): array|bool
     return false;
   }
 
-  function remove(string $import_id): bool|array
+  function remove(string $snapshot_id): bool|array
   {
     $imports = \get_option(self::WP_OPTION_IMPORTS, []);
     foreach ($imports as $index => $import) {
-      if ($import['id'] === $import_id) {
+      if ($import['id'] === $snapshot_id) {
         $transformationContext = ImpexImportTransformationContext::fromJson($import);
 
         global $wpdb;
@@ -255,7 +185,7 @@ function remove(string $import_id): bool|array
         \WP_Filesystem();
 
         // remove matching export table rows
-        $rowsDeleted = $wpdb->delete($this->_db_chunks_tablename, ['import_id' => $import_id,]);
+        $rowsDeleted = $wpdb->delete($this->_db_chunks_tablename, ['snapshot_id' => $snapshot_id,]);
         if ($rowsDeleted === false) {
           throw new ImpexExportRuntimeException(sprintf('failed to delete jsonized slices from database : %s', $wpdb->last_error));
         }

diff --git a/plugins/cm4all-wp-impex/inc/class-impex-part.php b/plugins/cm4all-wp-impex/inc/class-impex-part.php
@@ -19,7 +19,7 @@ abstract class ImpexPart
 
   protected /* ImpexSet */ $_profiles;
 
-  public function __construct()
+  public function __construct(protected string $_db_chunks_tablename)
   {
     $this->_providers = new class implements \IteratorAggregate
     {
@@ -98,8 +98,6 @@ public function removeProfile(string $name): ImpexProfile|null
     return $this->_profiles->remove($name);
   }
 
-  public abstract function __install(string|bool $installed_version): bool;
-
   /*
     make it not serializable 
   */

diff --git a/plugins/cm4all-wp-impex/inc/class-impex-transformation-context.php b/plugins/cm4all-wp-impex/inc/class-impex-transformation-context.php
@@ -11,7 +11,7 @@
 
 require_once __DIR__ . '/class-impex-part.php';
 require_once __DIR__ . '/class-impex-runtime-exception.php';
-
+require_once ABSPATH . 'wp-admin/includes/file.php';
 /**
  * ImpexTransformationContext is a superset of ImpexImportTransformationContext and ImpexExportTransformationContext
  * 
@@ -69,7 +69,7 @@ protected function __construct(
       $this->_name = $name;
     }
     $this->_description = $description ?? '';
-    $this->_uploads_subpath ??= 'impex/' . ($this->_isExportPart ? 'export/' : 'import/') . $this->_id;
+    $this->_uploads_subpath ??= 'impex/snapshots/' . $this->_id;
 
     $this->_options = $options ?? [];
 

diff --git a/plugins/cm4all-wp-impex/inc/class-impex.php b/plugins/cm4all-wp-impex/inc/class-impex.php
@@ -57,13 +57,17 @@ class Impex
   protected $_export = null;
   protected $_import = null;
 
+  const DB_SNAPSHOTS_TABLENAME = 'impex_snapshots';
+
   protected function __construct()
   {
-    $this->_export = new class extends ImpexExport
+    global $wpdb;
+    $_db_chunks_tablename = $wpdb->prefix . self::DB_SNAPSHOTS_TABLENAME;
+    $this->_export = new class($_db_chunks_tablename) extends ImpexExport
     {
     };
 
-    $this->_import = new class extends ImpexImport
+    $this->_import = new class($_db_chunks_tablename) extends ImpexImport
     {
     };
   }
@@ -82,7 +86,42 @@ public function __install(): bool
     /* @var string */
     $installed_version = \get_option('impex_version');
 
-    $successful = $this->Export->__install($installed_version) && $this->Import->__install($installed_version);
+    global $wpdb;
+
+    if ($installed_version === false) {
+      // plugin was newly installed
+      $charset_collate = $wpdb->get_charset_collate();
+
+      $_db_chunks_tablename = "{$wpdb->prefix}" . Impex::DB_SNAPSHOTS_TABLENAME;
+
+      $sql = "CREATE TABLE {$_db_chunks_tablename} (
+        id mediumint(9) NOT NULL AUTO_INCREMENT,
+        snapshot_id CHAR(36) NOT NULL,
+        position mediumint(9) NOT NULL,
+        slice json NOT NULL,
+        PRIMARY KEY  (id)
+      ) $charset_collate;";
+
+      require_once(ABSPATH . 'wp-admin/includes/upgrade.php');
+      \dbDelta($sql);
+    } else if ($installed_version !== Impex::VERSION) {
+      // new plugin version is now installed, try to upgrade
+      /*
+      $sql = "CREATE TABLE {$this->_db_chunks_tablename} (
+        id mediumint(9) NOT NULL AUTO_INCREMENT,
+        time datetime DEFAULT '0000-00-00 00:00:00' NOT NULL,
+        name tinytext NOT NULL,
+        text text NOT NULL,
+        url varchar(100) DEFAULT '' NOT NULL,
+        PRIMARY KEY  (id)
+      );";
+  
+      require_once(ABSPATH . 'wp-admin/includes/upgrade.php');
+      dbDelta($sql);
+      */
+    }
+
+    $successful = $this->__install_data($installed_version);
 
     if ($installed_version === false) {
       \add_option('impex_version', Impex::VERSION);
@@ -92,6 +131,27 @@ public function __install(): bool
 
     return $successful;
   }
+
+  protected function __install_data(string|bool $installed_version): bool
+  {
+    /*
+    global $wpdb;
+
+    $welcome_name = 'Mr. WordPress';
+    $welcome_text = 'Congratulations, you just completed the installation!';
+
+    $wpdb->insert(
+      $this->_db_chunks_tablename,
+      [
+        'time' => current_time('mysql'),
+        'name' => $welcome_name,
+        'text' => $welcome_text,
+      ]
+    );
+    */
+
+    return true;
+  }
 }
 
 Impex::getInstance();
diff --git a/plugins/cm4all-wp-impex/inc/impex-import-extension-attachment.php b/plugins/cm4all-wp-impex/inc/impex-import-extension-attachment.php
@@ -97,7 +97,12 @@ function __invoke()
     }
 
     $post = $this->slice[Impex::SLICE_META]['data'];
-    $url = $post['guid'];
+    $url = $post['guid'] ?? null;
+    if ($url === null) {
+      $path = $this->slice[Impex::SLICE_DATA];
+      $fileExtension = pathinfo($path, PATHINFO_EXTENSION);
+      $url = './' . \sanitize_title($post['post_title'] ?? pathinfo($path, PATHINFO_FILENAME)) . '.' . $fileExtension;
+    }
 
     /* 
       code more or less duplicated from wordpress-importer function process_attachment
@@ -112,6 +117,19 @@ function __invoke()
     $post['guid'] = $upload['url'];
     unset($post['ID']);
 
+    // if post_mime_type is not set the media will not appear correctly resized within media uploader
+    if (!isset($post['post_mime_type'])) {
+      $post_mime_type = \wp_get_image_mime($upload['file']);
+
+      if (!$post_mime_type) {
+        $post_mime_type = mime_content_type(basename($upload['file']));
+      }
+
+      if (is_string($post_mime_type)) {
+        $post['post_mime_type'] = $post_mime_type;
+      }
+    }
+
     // as per wp-admin/includes/upload.php
     $post_id = \wp_insert_attachment($post, $upload['file']);
 
@@ -152,7 +170,7 @@ function fetch_remote_file($url, $post, $slice)
     // Extract the file name from the URL.
     $file_name = basename(parse_url($url, PHP_URL_PATH));
 
-    $uploads = wp_upload_dir($post['post_date']);
+    $uploads = wp_upload_dir($post['post_date'] ?? null);
     if (!($uploads && false === $uploads['error'])) {
       return new \WP_Error('upload_dir_error', $uploads['error']);
     }

diff --git a/plugins/cm4all-wp-impex/inc/impex-import-extension-content.php b/plugins/cm4all-wp-impex/inc/impex-import-extension-content.php
@@ -116,7 +116,7 @@ function _import_posts(array $options, array $slice, array $author_mapping, arra
     // @TODO: should we do it (adapted from wp importer) ? it makes actually no sense since the given data is different ...
     $post = \apply_filters('wp_import_post_data_raw', $post);
 
-    if (!\post_type_exists($post[ContentExporter::SLICE_DATA_POSTS_TYPE])) {
+    if (!\post_type_exists($post[ContentExporter::SLICE_DATA_POSTS_TYPE] ?? 'post')) {
       throw new ImpexImportRuntimeException(
         "Failed to create post(title='{$post['post_title']}, post_type={$post['post_title']}') : post_type does not exist."
       );
@@ -181,6 +181,7 @@ function _import_posts(array $options, array $slice, array $author_mapping, arra
       $author = \sanitize_user($post[ContentExporter::SLICE_DATA_POSTS_CREATOR], true);
       $author = $author_mapping[$author] ?? (int) get_current_user_id();
 
+      // see defaults here : https://developer.wordpress.org/reference/functions/wp_insert_post/
       $postdata = [
         'import_id'      => $post[ContentExporter::SLICE_DATA_POSTS_ID],
         'post_author'    => $author,
@@ -200,6 +201,13 @@ function _import_posts(array $options, array $slice, array $author_mapping, arra
         'post_password'  => $post[ContentExporter::SLICE_DATA_POSTS_PASSWORD],
       ];
 
+      // filter out undefined properties
+      foreach ($postdata as $key => $value) {
+        if ($value === null) {
+          unset($postdata[$key]);
+        }
+      }
+
       $original_post_id = $post[ContentExporter::SLICE_DATA_POSTS_ID];
       $postdata = \apply_filters('wp_import_post_data_processed', $postdata, $post);
 
@@ -312,7 +320,7 @@ function _import_posts(array $options, array $slice, array $author_mapping, arra
 
     foreach ($newcomments as $key => $comment) {
       // if this is a new post we can skip the comment_exists() check
-      if (!$post_exists || !comment_exists($comment['comment_author'], $comment['comment_date'])) {
+      if (!$post_exists || !\comment_exists($comment['comment_author'], $comment['comment_date'])) {
         if (isset($inserted_comments[$comment['comment_parent']])) {
           $comment['comment_parent'] = $inserted_comments[$comment['comment_parent']];
         }

diff --git a/plugins/cm4all-wp-impex/plugin.php b/plugins/cm4all-wp-impex/plugin.php
@@ -4,7 +4,7 @@
  * Plugin Name: cm4all-wp-impex
  * Plugin URI: https://github.com/IONOS-WordPress/cm4all-wp-impex
  * Description: Impex contributes extendable Import / Export functionality to WordPress
- * Version: 1.2.0
+ * Version: 1.2.1
  * Tags: import, export, migration
  * Requires PHP: 8.0
  * Requires at least: 5.7

diff --git a/plugins/cm4all-wp-impex/src/components/screen.mjs b/plugins/cm4all-wp-impex/src/components/screen.mjs
@@ -33,7 +33,7 @@ export default function () {
         {!isFileystemApiAvailable && (
           <components.Modal
             title="Ouch - your browser does not support the File System Access API :-("
-            onRequestClose={() => {}}
+            isDismissible={false}
           >
             <p>
               Impex Import / Export requires a browser implementing the{" "}

diff --git a/plugins/cm4all-wp-impex/src/wp.impex.dashboard.scss b/plugins/cm4all-wp-impex/src/wp.impex.dashboard.scss
@@ -7,6 +7,9 @@ button > svg {
 }
 
 .components-modal__screen-overlay {
+  // do not span over the wp admin menu on the left
+  margin-left: 160px;
+
   &.blocking {
     cursor: wait;
   }

diff --git a/...4all-wp-impex/tests/phpunit/fixtures/impex-cli/simple-snapshot/chunk-0001/slice-0000.json b/...4all-wp-impex/tests/phpunit/fixtures/impex-cli/simple-snapshot/chunk-0001/slice-0000.json
@@ -0,0 +1,200 @@
+{
+  "tag": "content-exporter",
+  "version": "1.0.0",
+  "meta": {
+    "entity": "content-exporter",
+    "options": []
+  },
+  "data": {
+    "wp:bloginfo_title": "cm4all-wp-impex",
+    "wp:bloginfo_url": "http://localhost:8888",
+    "wp:bloginfo_description": "Just another WordPress site",
+    "wp:bloginfo_language": "en-US",
+    "wp:bloginfo_rss_url": "http://localhost:8888",
+    "authors": [
+      {
+        "wp:author_id": 0,
+        "wp:author_login": null,
+        "wp:author_email": null,
+        "wp:author_display_name": null,
+        "wp:author_first_name": null,
+        "wp:author_last_name": null
+      },
+      {
+        "wp:author_id": 1,
+        "wp:author_login": "admin",
+        "wp:author_email": "wordpress@example.com",
+        "wp:author_display_name": "admin",
+        "wp:author_first_name": "",
+        "wp:author_last_name": ""
+      }
+    ],
+    "taxonomies": [],
+    "categories": {
+      "1": {
+        "wp:term_id": 1,
+        "wp:term_slug": "uncategorized",
+        "wp:term_parent": "",
+        "wp:term_name": "Uncategorized",
+        "wp:term_description": "",
+        "wp:term_meta": []
+      }
+    },
+    "tags": [],
+    "terms": [
+      {
+        "wp:term_id": 1,
+        "wp:term_taxonomy": "category",
+        "wp:term_slug": "uncategorized",
+        "wp:term_parent": "",
+        "wp:term_name": "Uncategorized",
+        "wp:term_description": "",
+        "wp:term_meta": []
+      },
+      {
+        "wp:term_id": 3,
+        "wp:term_taxonomy": "wp_theme",
+        "wp:term_slug": "trinity-core",
+        "wp:term_parent": "",
+        "wp:term_name": "trinity-core",
+        "wp:term_description": "",
+        "wp:term_meta": []
+      }
+    ],
+    "posts": [
+      {
+        "title": "Header Vorlage",
+        "link": null,
+        "pubDate": false,
+        "dc:creator": "",
+        "guid": null,
+        "guid_isPermaLink": false,
+        "description": null,
+        "wp:post_content": "<!-- wp:cover {\"url\":\"/wp-content/themes/trinity-core/reusable-blocks/images/content_0002_david-gavi-Ijx8OxvKrgM-unsplash.jpg\",\"customOverlayColor\":\"rgba(0,0, 0, 1)\",\"focalPoint\":{\"x\":\"0.54\",\"y\":\"0.85\"},\"minHeight\":600,\"minHeightUnit\":\"px\",\"align\":\"full\",\"cm4allBlockId\":\"4accb986-dd24-4029-bfb3-ee9bfca557a5\"} -->\n<div class=\"wp-block-cover alignfull has-background-dim\" style=\"min-height:600px\"><img class=\"wp-block-cover__image-background \" alt=\"\" src=\"/wp-content/themes/trinity-core/reusable-blocks/images/content_0002_david-gavi-Ijx8OxvKrgM-unsplash.jpg\" style=\"object-position:54% 85%\" data-object-fit=\"cover\" data-object-position=\"54% 85%\" /><div class=\"wp-block-cover__inner-container\"><!-- wp:group {\"align\":\"wide\",\"className\":\"is-style-cm4all-theme-blocku002du002dshrink-center\",\"cm4allBlockId\":\"f9f61c5f-5133-40cf-b663-c9a9c30de4e2\"} -->\n<div class=\"wp-block-group alignwide is-style-cm4all-theme-block--shrink-center\"><!-- wp:heading {\"textAlign\":\"center\",\"level\":1,\"style\":{\"color\":{\"text\":\"rgba(255,255, 255, 1)\"}},\"className\":\"\",\"cm4allBlockId\":\"b6b44337-ebaa-4058-8d6c-cdbc7d11ab28\"} -->\n<h1 class=\"has-text-align-center has-text-color\" style=\"color:rgba(255,255, 255, 1)\">Willkommen bei<br>[Unternehmen]</h1>\n<!-- /wp:heading -->\n\n<!-- wp:paragraph {\"align\":\"center\",\"style\":{\"color\":{\"text\":\"rgba(255,255, 255, 1)\"}},\"className\":\"\",\"cm4allBlockId\":\"fd614a2c-0500-4e6c-847c-10855869f1f0\"} -->\n<p class=\"has-text-align-center has-text-color\" style=\"color:rgba(255,255, 255, 1)\">Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Aenean commodo ligula eget dolor. Aenean massa. Cum sociis natoque penatibus et magnis dis parturient montes, nascetur ridiculus mus.</p>\n<!-- /wp:paragraph -->\n\n<!-- wp:buttons {\"contentJustification\":\"center\",\"className\":\"\",\"cm4allBlockId\":\"e4b5b644-a252-440a-99c7-919d72037ad3\"} -->\n<div class=\"wp-block-buttons is-content-justification-center\"><!-- wp:button {\"className\":\"is-style-outline\",\"cm4allBlockId\":\"bd5bfa00-38a4-4901-b0c0-e5bd61bac962\"} -->\n<div class=\"wp-block-button is-style-outline\"><a class=\"wp-block-button__link\">Jetzt kontaktieren</a></div>\n<!-- /wp:button --></div>\n<!-- /wp:buttons --></div>\n<!-- /wp:group --></div></div>\n<!-- /wp:cover -->",
+        "wp:post_excerpt": "",
+        "wp:post_id": 4,
+        "wp:post_date": "2022-03-08 08:06:47",
+        "wp:post_date_gmt": "2022-03-08 08:06:47",
+        "wp:post_modified_gmt": "2022-03-08 08:06:47",
+        "wp:comment_status": "closed",
+        "wp:ping_status": "closed",
+        "wp:post_name": "header-vorlage",
+        "wp:status": "publish",
+        "wp:post_parent": 0,
+        "wp:menu_order": 0,
+        "wp:post_type": "wp_block",
+        "wp:post_password": "",
+        "wp:is_sticky": 0,
+        "wp:attachment_url": null,
+        "taxonomy_terms": [],
+        "meta": [],
+        "comments": []
+      },
+      {
+        "title": "Footer Vorlage",
+        "link": null,
+        "pubDate": false,
+        "dc:creator": "",
+        "guid": null,
+        "guid_isPermaLink": false,
+        "description": null,
+        "wp:post_content": "<!-- wp:group {\"align\":\"full\",\"style\":{\"spacing\":{\"padding\":{\"top\":\"80px\",\"bottom\":\"80px\"}}},\"backgroundColor\":\"trinity-theme-secondary-contrast-variant\",\"layout\":{\"wideSize\":\"px\"},\"cm4allBlockId\":\"2fdfc9fd-cceb-42cc-8cca-2a59fbbb682c\"} -->\n<div class=\"wp-block-group alignfull has-trinity-theme-secondary-contrast-variant-background-color has-background\" style=\"padding-top:80px;padding-bottom:80px\"><!-- wp:columns {\"align\":\"wide\",\"cm4allBlockId\":\"82bde859-29a4-4d42-85db-0e289580a623\"} -->\n<div class=\"wp-block-columns alignwide\"><!-- wp:column {\"cm4allBlockId\":\"89db2977-3e48-4428-bc36-76f732bd0b5b\"} -->\n<div class=\"wp-block-column\"><!-- wp:group {\"style\":{\"spacing\":{\"padding\":{\"bottom\":\"20px\"}}},\"cm4allBlockId\":\"0eb1eaa6-0f66-4ba0-8b3c-78d81a3f0ca1\"} -->\n<div class=\"wp-block-group\" style=\"padding-bottom:20px\"><!-- wp:heading {\"level\":3,\"style\":{\"typography\":{\"fontSize\":\"53px\"},\"color\":{\"text\":\"rgba(255,255, 255, 1)\"}},\"className\":\"\",\"cm4allBlockId\":\"2e5f3d2c-3a9e-4d50-bd45-13065fd6ba38\"} -->\n<h3 class=\"has-text-color\" style=\"color:rgba(255,255, 255, 1);font-size:53px\">Wir freuen<br>uns auf Sie! </h3>\n<!-- /wp:heading --></div>\n<!-- /wp:group --></div>\n<!-- /wp:column -->\n\n<!-- wp:column {\"cm4allBlockId\":\"e91bf9e1-5c80-402e-a2b5-2d3960f06565\"} -->\n<div class=\"wp-block-column\"><!-- wp:group {\"style\":{\"spacing\":{\"padding\":{\"bottom\":\"20px\"}}},\"cm4allBlockId\":\"0976f56a-d803-4b6f-9b26-778e3e4c7263\"} -->\n<div class=\"wp-block-group\" style=\"padding-bottom:20px\"><!-- wp:heading {\"level\":4,\"style\":{\"color\":{\"text\":\"rgba(255,255, 255, 1)\"}},\"className\":\"\",\"cm4allBlockId\":\"0f22ba45-55fd-4d7b-ae02-136ad33eddb4\"} -->\n<h4 class=\"has-text-color\" style=\"color:rgba(255,255, 255, 1)\">IHR Unternehmen</h4>\n<!-- /wp:heading -->\n\n<!-- wp:paragraph {\"style\":{\"color\":{\"text\":\"rgba(255,255, 255, 1)\"}},\"className\":\"\",\"cm4allBlockId\":\"b5936153-094a-494d-97fa-af6fefa3a6b5\"} -->\n<p class=\"has-text-color\" style=\"color:rgba(255,255, 255, 1)\">Inhaber: Max Mustermann<br>[Musterstraße 654]<br>[12345 Musterstadt]</p>\n<!-- /wp:paragraph --></div>\n<!-- /wp:group --></div>\n<!-- /wp:column -->\n\n<!-- wp:column {\"cm4allBlockId\":\"ee0ae707-f0cf-45aa-8b60-f381f918635e\"} -->\n<div class=\"wp-block-column\"><!-- wp:group {\"style\":{\"spacing\":{\"padding\":{\"bottom\":\"20px\"}}},\"cm4allBlockId\":\"363034b5-1348-4c42-b902-21a151520056\"} -->\n<div class=\"wp-block-group\" style=\"padding-bottom:20px\"><!-- wp:heading {\"level\":4,\"style\":{\"color\":{\"text\":\"rgba(255,255, 255, 1)\"}},\"className\":\"\",\"cm4allBlockId\":\"8bc1d89a-58fb-4791-a488-76df05f93532\"} -->\n<h4 class=\"has-text-color\" style=\"color:rgba(255,255, 255, 1)\">Kontakt</h4>\n<!-- /wp:heading -->\n\n<!-- wp:paragraph {\"style\":{\"color\":{\"text\":\"rgba(255,255, 255, 1)\"}},\"className\":\"\",\"cm4allBlockId\":\"c3279e95-3f56-42dd-824d-738fd32521ae\"} -->\n<p class=\"has-text-color\" style=\"color:rgba(255,255, 255, 1)\">Tel.: [+49 (0) 123 45 67 89]<br>Fax: [+49 (0) 123 45 67 10]<br>E-Mail: [info@musterfirma.de]</p>\n<!-- /wp:paragraph --></div>\n<!-- /wp:group --></div>\n<!-- /wp:column -->\n\n<!-- wp:column {\"cm4allBlockId\":\"b55a91ae-0aff-47c1-a164-d371236d29e7\"} -->\n<div class=\"wp-block-column\"><!-- wp:group {\"style\":{\"spacing\":{\"padding\":{\"bottom\":\"20px\"}}},\"cm4allBlockId\":\"79f52c29-43c2-4bf9-b54e-633fe92a4af6\"} -->\n<div class=\"wp-block-group\" style=\"padding-bottom:20px\"><!-- wp:heading {\"level\":4,\"style\":{\"color\":{\"text\":\"rgba(255,255, 255, 1)\"}},\"className\":\"\",\"cm4allBlockId\":\"f6dce74e-6cdd-4e99-ac7e-7e97bd2c12d5\"} -->\n<h4 class=\"has-text-color\" style=\"color:rgba(255,255, 255, 1)\">Weitere Links</h4>\n<!-- /wp:heading -->\n\n<!-- wp:paragraph {\"style\":{\"color\":{\"text\":\"rgba(255,255, 255, 1)\"}},\"className\":\"\",\"cm4allBlockId\":\"26ce4fbf-3aae-461c-9aa1-d4ef23aa46dd\"} -->\n<p class=\"has-text-color\" style=\"color:rgba(255,255, 255, 1)\">&gt; <a href=\"#\">Impressum</a><br>&gt; <a href=\"#\">Datenschutz</a></p>\n<!-- /wp:paragraph --></div>\n<!-- /wp:group --></div>\n<!-- /wp:column --></div>\n<!-- /wp:columns --></div>\n<!-- /wp:group -->",
+        "wp:post_excerpt": "",
+        "wp:post_id": 5,
+        "wp:post_date": "2022-03-08 08:06:47",
+        "wp:post_date_gmt": "2022-03-08 08:06:47",
+        "wp:post_modified_gmt": "2022-03-08 08:06:47",
+        "wp:comment_status": "closed",
+        "wp:ping_status": "closed",
+        "wp:post_name": "footer-vorlage",
+        "wp:status": "publish",
+        "wp:post_parent": 0,
+        "wp:menu_order": 0,
+        "wp:post_type": "wp_block",
+        "wp:post_password": "",
+        "wp:is_sticky": 0,
+        "wp:attachment_url": null,
+        "taxonomy_terms": [],
+        "meta": [],
+        "comments": []
+      },
+      {
+        "title": "my-page",
+        "link": null,
+        "pubDate": false,
+        "dc:creator": "admin",
+        "guid": null,
+        "guid_isPermaLink": false,
+        "description": null,
+        "wp:post_content": "<!-- wp:paragraph {\"className\":\"\",\"cm4allBlockId\":\"38c1404f-05ac-4a8a-8ef5-d04499b0c5ae\"} -->\n<p>This is just a </p>\n<!-- /wp:paragraph -->\n\n<!-- wp:paragraph {\"className\":\"\",\"cm4allBlockId\":\"9c46ca06-bd0a-4567-9ba9-2c0b50873622\"} -->\n<p>multiline paragraph</p>\n<!-- /wp:paragraph -->\n\n<!-- wp:image {\"id\":160,\"sizeSlug\":\"full\",\"linkDestination\":\"none\",\"cm4allBlockId\":\"6c7fe1df-e801-4ed4-952f-ac82561a1f7a\"} -->\n<figure class=\"wp-block-image size-full\"><img src=\"http://localhost:8888/wp-content/uploads/2022/03/angeln.jpg\" alt=\"\" class=\"wp-image-160\"/><figcaption>Fishing is a nice hobby !</figcaption></figure>\n<!-- /wp:image -->",
+        "wp:post_excerpt": "",
+        "wp:post_id": 161,
+        "wp:post_date": "2022-03-08 11:29:46",
+        "wp:post_date_gmt": "2022-03-08 11:29:46",
+        "wp:post_modified_gmt": "2022-03-08 11:29:47",
+        "wp:comment_status": "closed",
+        "wp:ping_status": "closed",
+        "wp:post_name": "my-page",
+        "wp:status": "publish",
+        "wp:post_parent": 0,
+        "wp:menu_order": 0,
+        "wp:post_type": "page",
+        "wp:post_password": "",
+        "wp:is_sticky": 0,
+        "wp:attachment_url": null,
+        "taxonomy_terms": [],
+        "meta": [
+          {
+            "wp:term_meta_key": "_edit_lock",
+            "wp:term_meta_value": "1646738987:1"
+          },
+          {
+            "wp:term_meta_key": "_edit_last",
+            "wp:term_meta_value": "1"
+          },
+          {
+            "wp:term_meta_key": "cmplz_hide_cookiebanner",
+            "wp:term_meta_value": ""
+          }
+        ],
+        "comments": []
+      },
+      {
+        "title": "Custom Styles",
+        "link": null,
+        "pubDate": false,
+        "dc:creator": "admin",
+        "guid": null,
+        "guid_isPermaLink": false,
+        "description": null,
+        "wp:post_content": "{\"version\": 2, \"isGlobalStylesUserThemeJSON\": true }",
+        "wp:post_excerpt": "",
+        "wp:post_id": 162,
+        "wp:post_date": "2022-03-08 11:28:31",
+        "wp:post_date_gmt": "2022-03-08 11:28:31",
+        "wp:post_modified_gmt": "2022-03-08 11:28:31",
+        "wp:comment_status": "closed",
+        "wp:ping_status": "closed",
+        "wp:post_name": "wp-global-styles-trinity-core",
+        "wp:status": "publish",
+        "wp:post_parent": 0,
+        "wp:menu_order": 0,
+        "wp:post_type": "wp_global_styles",
+        "wp:post_password": "",
+        "wp:is_sticky": 0,
+        "wp:attachment_url": null,
+        "taxonomy_terms": [
+          {
+            "wp:term_taxonomy": "wp_theme",
+            "wp:term_slug": "trinity-core",
+            "wp:term_name": "trinity-core"
+          }
+        ],
+        "meta": [],
+        "comments": []
+      }
+    ]
+  },
+  "type": "php",
+  "date": "2022-03-08 11:29:55 +0000"
+}
diff --git a/...sts/phpunit/fixtures/impex-cli/simple-snapshot/chunk-0001/slice-0001-angeln.jpg b/...sts/phpunit/fixtures/impex-cli/simple-snapshot/chunk-0001/slice-0001-angeln.jpg
diff --git a/...4all-wp-impex/tests/phpunit/fixtures/impex-cli/simple-snapshot/chunk-0001/slice-0001.json b/...4all-wp-impex/tests/phpunit/fixtures/impex-cli/simple-snapshot/chunk-0001/slice-0001.json
@@ -0,0 +1,38 @@
+{
+  "tag": "attachment",
+  "version": "1.0.0",
+  "type": "resource",
+  "meta": {
+    "name": "angeln",
+    "entity": "attachment",
+    "options": [],
+    "data": {
+      "ID": 160,
+      "post_author": "1",
+      "post_date": "2022-03-08 11:28:26",
+      "post_date_gmt": "2022-03-08 11:28:26",
+      "post_content": "",
+      "post_title": "angeln",
+      "post_excerpt": "",
+      "post_status": "inherit",
+      "comment_status": "open",
+      "ping_status": "closed",
+      "post_password": "",
+      "post_name": "angeln",
+      "to_ping": "",
+      "pinged": "",
+      "post_modified": "2022-03-08 11:28:26",
+      "post_modified_gmt": "2022-03-08 11:28:26",
+      "post_content_filtered": "",
+      "post_parent": 0,
+      "guid": "http://localhost:8888/wp-content/uploads/2022/03/angeln.jpg",
+      "menu_order": 0,
+      "post_type": "attachment",
+      "post_mime_type": "image/jpeg",
+      "comment_count": "0",
+      "filter": "raw"
+    }
+  },
+  "data": "2022/03/angeln.jpg",
+  "date": "2022-03-08 11:29:55 +0000"
+}
diff --git a/plugins/cm4all-wp-impex/tests/phpunit/test-impex-export-rest-controller.php b/plugins/cm4all-wp-impex/tests/phpunit/test-impex-export-rest-controller.php
@@ -203,7 +203,7 @@ public function test_delete_item()
     $create_response = $this->server->dispatch($request);
 
     global $wpdb;
-    $rows = $wpdb->get_results("SELECT * from {$wpdb->prefix}" . ImpexExport::DB_CHUNKS_TABLENAME);
+    $rows = $wpdb->get_results("SELECT * from {$wpdb->prefix}" . Impex::DB_SNAPSHOTS_TABLENAME);
     $this->assertCount(1, $rows, 'one slice should be exported');
 
     // delete export
@@ -214,8 +214,8 @@ public function test_delete_item()
     $exports = \get_option(ImpexExport::WP_OPTION_EXPORTS, []);
     $this->assertCount(0, $exports, 'no exports should be avaliable');
 
-    $rows = $wpdb->get_results("SELECT * from {$wpdb->prefix}" . ImpexExport::DB_CHUNKS_TABLENAME);
-    $this->assertCount(0, $rows, 'table ' . $wpdb->prefix . ImpexExport::DB_CHUNKS_TABLENAME . ' should be empty');
+    $rows = $wpdb->get_results("SELECT * from {$wpdb->prefix}" . Impex::DB_SNAPSHOTS_TABLENAME);
+    $this->assertCount(0, $rows, 'table ' . $wpdb->prefix . Impex::DB_SNAPSHOTS_TABLENAME . ' should be empty');
   }
 
   public function test_get_item_slices()

diff --git a/plugins/cm4all-wp-impex/tests/phpunit/test-impex-export.php b/plugins/cm4all-wp-impex/tests/phpunit/test-impex-export.php
@@ -25,7 +25,7 @@ function setUp()
      => so we need to drop the table manually to have a consistent setup
     */
     global $wpdb;
-    $wpdb->query('DROP TABLE IF EXISTS ' . $wpdb->prefix . ImpexExport::DB_CHUNKS_TABLENAME);
+    $wpdb->query('DROP TABLE IF EXISTS ' . $wpdb->prefix . Impex::DB_SNAPSHOTS_TABLENAME);
   }
 
   function tearDown()
@@ -98,7 +98,7 @@ function testExportDbTablesInstalled(): void
       therefore tables created in wp unit tests are not visible using SHOW TABLES LIKE statements.
       that's why we "test" the existence of a table using SELECT COUNT (=> which returns null / error in case the temporary table doesnt exists)
     */
-    $db_chunks_tablename = $wpdb->prefix . ImpexExport::DB_CHUNKS_TABLENAME;
+    $db_chunks_tablename = $wpdb->prefix . Impex::DB_SNAPSHOTS_TABLENAME;
     $db_chunks_tablename_rowCount = $wpdb->get_var("SELECT COUNT(*) FROM $db_chunks_tablename");
     $this->assertNotNull($db_chunks_tablename_rowCount, "ensure $db_chunks_tablename exists");
   }
@@ -223,7 +223,7 @@ function testExportSave(): void
     ], $wp_option_exports[0], 'wp_options item created by save() matches the expected');
 
     global $wpdb;
-    $rows = $wpdb->get_results('SELECT * FROM ' . $wpdb->prefix . ImpexExport::DB_CHUNKS_TABLENAME, ARRAY_A);
+    $rows = $wpdb->get_results('SELECT * FROM ' . $wpdb->prefix . Impex::DB_SNAPSHOTS_TABLENAME, ARRAY_A);
 
     $this->assertCount(count($matchingWpOptions), $rows, 'for each generated slice a row should be created');
 
@@ -258,7 +258,7 @@ function testExportSaveFilters(): void
     $transformationContext = Impex::getInstance()->Export->save($profile);
 
     global $wpdb;
-    $rows = $wpdb->get_results('SELECT * FROM ' . $wpdb->prefix . ImpexExport::DB_CHUNKS_TABLENAME, ARRAY_A);
+    $rows = $wpdb->get_results('SELECT * FROM ' . $wpdb->prefix . Impex::DB_SNAPSHOTS_TABLENAME, ARRAY_A);
 
     $this->assertCount(count($upload_names), $rows, 'for each attachment a slice(and also a row) should be created');
 

diff --git a/plugins/cm4all-wp-impex/tests/phpunit/test-impex-import-rest-controller.php b/plugins/cm4all-wp-impex/tests/phpunit/test-impex-import-rest-controller.php
@@ -277,7 +277,7 @@ function ($_) use ($EXPORT_PATH) {
 
     global $wpdb;
     $inserted_slices = absint($wpdb->get_var(
-      $wpdb->prepare("SELECT COUNT(*) from {$wpdb->prefix}" . ImpexImport::DB_CHUNKS_TABLENAME . ' WHERE import_id=%s', $import_id)
+      $wpdb->prepare("SELECT COUNT(*) from {$wpdb->prefix}" . Impex::DB_SNAPSHOTS_TABLENAME . ' WHERE snapshot_id=%s', $import_id)
     ));
     $this->assertEquals(count($slice_filenames), $inserted_slices, 'all uploaded chunks should be in the database');
 
@@ -318,7 +318,7 @@ function ($_) use ($EXPORT_PATH) {
 
     global $wpdb;
     $inserted_slices = absint($wpdb->get_var(
-      $wpdb->prepare("SELECT COUNT(*) from {$wpdb->prefix}" . ImpexImport::DB_CHUNKS_TABLENAME . ' WHERE import_id=%s', $import_id)
+      $wpdb->prepare("SELECT COUNT(*) from {$wpdb->prefix}" . Impex::DB_SNAPSHOTS_TABLENAME . ' WHERE snapshot_id=%s', $import_id)
     ));
     $this->assertEquals(count($slice_filenames), $inserted_slices, 'uploaded chunks should be replaced in the database (but not newly inserted)');
   }

diff --git a/plugins/cm4all-wp-impex/tests/phpunit/test-impex-import.php b/plugins/cm4all-wp-impex/tests/phpunit/test-impex-import.php
@@ -43,7 +43,7 @@ function setUp()
      => so we need to drop the table manually to have a consistent setup
     */
     global $wpdb;
-    $wpdb->query('DROP TABLE IF EXISTS ' . $wpdb->prefix . ImpexImport::DB_CHUNKS_TABLENAME);
+    $wpdb->query('DROP TABLE IF EXISTS ' . $wpdb->prefix . Impex::DB_SNAPSHOTS_TABLENAME);
 
     $this->user = $this->factory->user->create(['role' => 'administrator', 'user_login' => 'test-admin']);
   }
@@ -176,7 +176,7 @@ function testImportDbTablesInstalled(): void
       therefore tables created in wp unit tests are not visible using SHOW TABLES LIKE statements.
       that's why we "test" the existence of a table using SELECT COUNT (=> which returns null / error in case the temporary table doesnt exists)
     */
-    $db_chunks_tablename = $wpdb->prefix . ImpexImport::DB_CHUNKS_TABLENAME;
+    $db_chunks_tablename = $wpdb->prefix . Impex::DB_SNAPSHOTS_TABLENAME;
     $db_chunks_tablename_rowCount = $wpdb->get_var("SELECT COUNT(*) FROM $db_chunks_tablename");
     $this->assertNotNull($db_chunks_tablename_rowCount, "ensure $db_chunks_tablename exists");
   }
@@ -232,9 +232,9 @@ function ($_) use ($EXPORT_PATH) {
     global $wpdb;
 
     foreach ($slices as $position => $slice) {
-      $wpdb->insert($wpdb->prefix . ImpexImport::DB_CHUNKS_TABLENAME, [
+      $wpdb->insert($wpdb->prefix . Impex::DB_SNAPSHOTS_TABLENAME, [
         'position' => $position,
-        'import_id' => $importTransformationContext->id,
+        'snapshot_id' => $importTransformationContext->id,
         'slice' => json_encode($slice),
       ]);
     }

diff --git a/plugins/cm4all-wp-impex/tests/phpunit/test-impex-transformation-context.php b/plugins/cm4all-wp-impex/tests/phpunit/test-impex-transformation-context.php
@@ -57,7 +57,7 @@ function testArgumentDerivation(): void
       ],
     );
     $this->assertStringStartsWith('Export ', $context->name);
-    $this->assertStringStartsWith('/var/www/html/wp-content/uploads/impex/export/', $context->path);
+    $this->assertStringStartsWith('/var/www/html/wp-content/uploads/impex/snapshots/', $context->path);
   }
 
   function testSerialization(): void
@@ -101,7 +101,7 @@ function testImportContext(): void
 
     $this->assertInstanceOf(ImpexImportTransformationContext::class, $context,);
     $this->assertStringStartsWith('Import ', $context->name);
-    $this->assertStringStartsWith('/var/www/html/wp-content/uploads/impex/import/', $context->path);
+    $this->assertStringStartsWith('/var/www/html/wp-content/uploads/impex/snapshots/', $context->path);
 
     $json = $context->jsonSerialize();