Hecate

OpenStreetMap Inspired Data Storage Backend Focused on Performance and GeoJSON Interchange

Hecate Feature Comparison

Feature	Hecate	ESRI MapServer	OSM Backend
Vector Tile Creation	✔️	✔️	❌
Streaming Query API	✔️	❌	❌
Multi User Support	✔️	✔️	✔️
Feature History	✔️	❌	✔️
Atomic API Operations	✔️	✔️	❌
GeoJSON-LD Based API	✔️	❌	✔️
Mapbox GL JS Styling	✔️	✔️	❌
Integrated Data Stats	✔️	✔️	❌

Table Of Contents

1. Brief
2. Why Use Hecate
3. Table of Contents
4. Related Libraries
5. Build Environment
6. Docker File
7. Feature Format
8. Server
   • Database Connection
   • JSON Validation
   • Custom Authentication
9. API

Related Libraries

• HecateJS Javascript Library & CLI Tool for interacting with the Hecate API
• Hecate-Example Script for importing some fake data for testing

Built something cool that uses the Hecate API? Let us know!

Build Environment

• Start by installing Rust from rust-lang.org, this will install the current stable version

curl https://sh.rustup.rs -sSf | sh

• Hecate is designed to run on the latest stable version of Rust, but has been thoroughly tested with 1.40.0. This will install 1.40.0

curl https://sh.rustup.rs -sSf | sh -s --  --default-toolchain 1.40.0

• Source your bashrc/bash_profile to update your PATH variable

source ~/.bashrc        # Most Linux Distros, some OSX
source ~/.bash_profile  # Most OSX, some Linux Distros

• Download and compile the project and all of it's libraries

cargo build

• Ensure you have database dependencies PostgreSQL and PostGIS installed. PostgreSQL 11 or newer and PostGIS 2.5 or newer are required, because of support for libprotobuf and MapBox Vector Tiles. On OSX Postgres.app is a good option.

• Create the hecate database using the provided schema file. These instructions assume you have set up a role postgres with sufficient privileges.

echo "CREATE DATABASE hecate;" | psql -U postgres

psql -U postgres -f hecate/src/schema.sql hecate

• This step will also create a database role called hecate and hecate_read.

• If the database connection fails due to authentication, here are some tips: Your pg_hba.conf file may not be set up to trust local connections. Your pb_hba file location can be found using echo "show hba_file;" | psql -U postgres. Replace the file with the following:

local all postgres trust
local all all trust
host all all 127.0.0.1/32 trust
host all all ::1/128 trust
host replication postgres samenet trust

• Install Node/Npm for building the frontend code

• Install Yarn for installing frontend dependencies

• Install frontend dependencies

  yarn --cwd hecate_ui install

• Build frontend UI

  yarn --cwd hecate_ui build

  Note: if actively working on developing the UI, a live reloading server can be started via:

  yarn --cwd hecate_ui dev

• Start the server

  cargo run

• Test it is working. The HTTP healthcheck URL / should respond with "Hello World!".

  curl localhost:8000

• The admin UI is available at http://localhost:8000/admin/

You will now have an empty database which can be populated with your own data/user accounts.

If you want to populate the database with sample data for testing, ingalls/hecate-example has a selection of scripts to populate the database with test data.

Docker File (Coverage Tests)

The Docker file is designed to give the user a testing environment to easily run rust tests.

Install docker and then run

docker build .

docker run {{HASH FROM ABOVE}}

Feature Format

Hecate is designed as a GeoJSON first interchange and uses standard GeoJSON with a couple additions and exceptions as outlined below.

Supported Geometry Types

• Point
• MultiPoint
• LineString
• MultiLineString
• Polygon
• MultiPolygon

Unsupported Geometry Types

• GeometryCollection

Additional Members

The following table outlines top-level members used by hecate to handle feature creation/modification/deletion.

Key/Value pairs in the .properties of a given feature are never directly used by the server and are simply passed through to the storage backend. This prevents potential conflicts between user properties and required server members.

Member	Notes
id	The unique integer id of a given feature. Note that all features get a unique id accross GeoJSON Geometry Type
version	The version of a given feature, starts at 1 for a newly created feature
action	Only used for uploads, the desired action to be performed. One of create, modify, delete, or restore
key	Optional A String containing a value that hecate will ensure remains unique across all features. Can be a natural id (wikidata id, PID, etc), computed property hash, geometry hash etc. The specifics are left up to the client. Should an attempt at importing a Feature with a differing id but identical key be made, the feature with will be rejected, ensuring the uniqueness of the key values. By default this value will be NULL. Duplicate NULL values are allowed.
force	Optional Boolean allowing a user to override version locking and force UPSERT a feature. Disabled by default

Examples

Downloaded Features

{
    "id": 123,
    "key": "Q1234",
    "version": 2,
    "type": "Feature",
    "properties": {
        "shop": true,
        "name": "If Pigs Could Fly"
    },
    "geometry": {
        "type": "Point",
        "coordinates": [0,0]
    }
}

Downloaded Features will return the integer id of the feature, the current version and the user supplied properties and geojson. action is not applicable for downloaded features, it is only used on upload.

Create Features

{
    "action": "create",
    "key": "11-22-33-44-1234",
    "type": "Feature",
    "properties": {
        "shop": true,
        "name": "If Pigs Could Fly"
    },
    "geometry": {
        "type": "Point",
        "coordinates": [0,0]
    }
}

A features being uploaded for creation must have the action: create property. Since an id and version have not yet been assigned they must be omitted. Should an id be included it will be ignored. Adding a version property will throw an error.

Optionally create actions can use the force: true option to perform an UPSERT like option. In this mode the uploader must specify the key value. Hecate will then INSERT the feature if the key value is new, if the key is already existing, the existing feature will be overwritten with the forced feature. Note that this mode ignores version checks and is therefore unsafe.

Force Prerequisites

• Disabled by default, must be explicitly enabled via Custom Authentication
• Can only be performed on a feature with action: create
• Must specify a valid key

Modify Features

{
    "id": 123,
    "key": "Fn4aAsJ30",
    "version": 1,
    "action": "modify",
    "type": "Feature",
    "properties": {
        "shop": true,
        "name": "If Pigs Could Fly"
    },
    "geometry": {
        "type": "Point",
        "coordinates": [0,0]
    }
}

A feature being uploaded for modification must have the action: modify as well as the id and version property. The id is the integer id of the feature to modify and the version property is the current version of the feature as stored by the server. If the version uploaded does not match the version that the server has stored, the modify will fail. This prevents consecutive edits from conflicting.

Note that the modify operation is not a delta operation and the full feature with the complete Geometry & All Properties must be included with each modify.

Also note that since the id pool is shared accross geometry types, an id is allowed to change it's geometry type. eg. If id: 1 is a Point and then a subsequent action: modify with a Polygon geometry is performed, id: 1 is allowed to switch to the new Polygon type.

Delete Features

{
    "id": 123,
    "version": 1,
    "action": "delete",
    "type": "Feature",
    "properties": null,
    "geometry": null
}

A feature being uploaded for deletion must have the action: delete as well as the id and version property. See Modify Features above for an explanation of those properties.

Note the properties and geometry attributes must still be included. They can be set to null or be their previous value. They will be ignored.

Restore Features

{
    "id": 123,
    "version": 2,
    "key": "new-optional-key",
    "action": "restore",
    "type": "Feature",
    "properties": {
        "test": true,
        "random_array": [1, 2, 3]
    },
    "geometry": {
        "type": "Point",
        "coordinates": [ 12.34, 56.78 ]
    }
}

A feature being uploaded for restoration must have the action: restore as well as the id and version properties. A restore action is just a modify on a deleted feature.

Restore places the new given geometry/properties at the id specified. It does not automatically roll back the feature to it's state before deletion, if this is desired, one must use the Feature History API to get the state before deletion and then perform the restore action.

Note: Restore will throw an error if an feature still exists.

Server

This section of the guide goes over various options for launching the server

Hecate can be launched with default options with

cargo run

Database

Main Connection

By default hecate will attempt to connect to hecate@localhost:5432/hecate for read/write operations and simultaneously connect to hecate_read@localhost:5432/hecate for sandboxed read only operations.

Note that only postgres w/ postgis enabled is supported.

This database should be created prior to launching hecate. For instructions on setting up the database see the Build Environment section of this doc.

A custom database name, postgres user or port can be specified using the database flag.

Example

cargo run -- --database "<USER>:<PASSWORD>@<HOST>/<DATABASE>"

cargo run -- --database "<USER>@<HOST>/<DATABASE>"

Sandbox Connection

A second read-only account should also be created with permissions to SELECT from the geo & deltas table. This endpoint will only be used for the query endpoint, which allows arbitrary user query execution. A sample implementation can be found in the schema.sql document

Note: It is up to the DB Admin to ensure the permissions are limited in scope for this user. Hecate will expose access to this user via the query endpoint.

If multiple instances of database_sandbox are present, hecate will load balance accross the multiple read instances.

cargo run -- --database_sandbox "<USER>:<PASSWORD>@<HOST>/<DATABASE>"

cargo run -- --database_sandbox "<USER>@<HOST>/<DATABASE>"

cargo run -- --database_sandbox "<USER>@<HOST>/<DATABASE>" --database_sandbox "<USER>@<HOST>/<DATABASE>"

Replica Connection [optional]

Finally, optionally multiple --database_replica conncetions can be specified which hecate will use to load balance read traffic accross, alleviating capacity on the master db for write operations.

cargo run -- --database_replica "<USER>:<PASSWORD>@<HOST>/<DATABASE>"

cargo run -- --database_replica "<USER>@<HOST>/<DATABASE>"

cargo run -- --database_replica"<USER>@<HOST>/<DATABASE>" --database_replica "<USER>@<HOST>/<DATABASE>"

JSON Validation

By default Hecate will allow any property on a given GeoJSON feature, including nestled arrays, maps, etc.

A custom property validation file can be specified using the schema flag.

Example

cargo run -- --schema <PATH-TO-SCHEMA>.json

Note hecate currently supports the JSON Schema draft-04. Once draft-06/07 support lands in valico we can support newer versions of the spec.

Custom Authentication

By default the Hecate API is most favourable to a crowd-sourced data server. Any users can access the data/vector tiles, users can create & manage data, and admins can manage user accounts.

This provides a middle ground for most users but all endpoints are entirely configurable and can run from a fully open server to fully locked down.

If the default values aren't suitable for what you intend, passing in an authentication configuration JSON document will override the defaults.

Example

cargo run -- --auth path/to/auth.json

Contents of auth.json

{
    "endpoints": {
        "server": "public",
        "schema": null,
        "mvt": {
            "get": "user",
            "regen": "admin",
            "meta": null
        },
        "users": {
            "info": "admin",
            "create": "admin",
            "create_session": null
        },

        ....

    }
}

It is important to note that if custom authentication is used, every category must be either disabled or have an option for every sub category within it set. One cannot conditionally override only a subset of of the default options. This is for the security of private servers, since adding a new API endpoint is a non-breaking change, the server checks that you have specified a policy for every endpoint or are happy with just the defaults before it will start.

IE:

The below schema is invalid. Each category (schema, user, style) etc. must be specified as disabled or have a map containing the auth for each subkey.

{
    "endpoint": {
        "schema": null
    }
}

Behavior Types

Type	Description
"public"	Allow any authenticated or unauthenticated user access
"admin"	Allow only users with the access: 'admin' property on their user accounts access
"user"	Allow any user access to the endpoint
"self"	Only the specific user or an admin can edit their own metadata
"disabled"	Disable all access to the endpoint

Endpoint Lookup

Example Endpoint	Config Name	Default	Supported Behaviors	Notes
GET /api	server	public	All
Server Meta	meta		null	2
GET /api/meta/<key>	meta::get	public	All
POST /api/meta/<key>	meta::set	admin	user, admin, disabled
JSON Schema	schema		null	2
GET /api/schema	schema::get	public	All
Custom Auth JSON	auth		null	2
GET /api/auth	auth::get	public	All
Mapbox Vector Tiles	mvt		null	2
DELETE /api/tiles	mvt::delete	admin	All
GET /api/tiles/<z>/<x>/<y>	mvt::get	public	All
GET /api/tiles/<z>/<x>/<y>/regen	mvt::regen	user	All
GET /api/tiles/<z>/<x>/<y>/meta	mvt::meta	public	All
Users	user		null	2
GET /api/users	user::list	user	All
GET /api/user/info	user::info	self	self, admin, disabled
GET /api/create	user::create	public	All
GET /api/create/session	user::create_session	self	self, admin, disabled
Mapbox GL Styles	style		null	2
POST /api/style	style::create	self	self, admin, disabled
PATCH /api/style	style::patch	self	self, admin, disabled
POST /api/style/<id>/public	style::set_public	self	All
POST /api/style/<id>/private	style::set_private	self	self, admin, disabled
DELETE /api/style/<id>	style::delete	self	self, admin, disabled
GET /api/style/<id>	style::get	public	All	1
GET /api/styles	style::list	public	All	1
Deltas	delta		null	2
GET /api/delta/<id>	delta::get	public	All
GET /api/deltas	delta::list	public	All
Webhooks	webhooks		null	2
GET /api/webhooks/<id>	webhooks::get	admin	All
POST /api/webhooks/<id>	webhooks::set	admin	All
Data Stats	stats	public	All
GET /api/data/stats	stats::get	public	All
Features	feature		null	2
POST /api/data/feature(s)	feature::create	user	user, admin, disabled
GET /api/data/feature/<id>	feature::get	public	All
GET /api/data/feature/<id>/history	feature::history	public	All
POST /api/data/feature(s) w/ force`	feature::force	admin	user, admin, disabled
Clone	clone		null	2
GET /api/data/clone	clone::get	user	All
GET /api/data/query	clone::query	user	All
Bounds	bounds		null	2
GET /api/bounds	bounds::list	public	All
GET /api/bounds/<id>	bounds::get	public	All
POST /api/bounds/<id>	bounds::create	admin	All
DELETE /api/bounds/<id>	bounds:delete	admin	All
OpenStreetMap Shim	osm		null	2
GET /api/0.6/map	osm::get	public	All	3
PUT /api/0.6/changeset/<id>/upload	osm::create	user	user, admin, disabled	3

Notes

1. This only affectes public styles. The private attribute on a style overrides this. A private style can never be seen publicly regardless of this setting.
2. This is a category, the only valid option is null this will disable access to the endpoint entirely
3. OSM software expects the authentication on these endpoints to mirror OSM. Setting these to a non-default option is supported but will likely have unpredicable support when using OSM software. If you are running a private server you should disable OSM support entirely.

API

Our API docs have been moved to hecate.github.io/hecate

OpenStreetMap API

The primary goal of the hecate project is a very fast GeoJSON based Interchange. That said, the tooling the OSM community has built around editing is unparalleled. As such, Hecate provides a Work-In-Progress OpenStreetMap Shim to support a subset of API operations as defined by the OSM API v0.6 document.

Important Notes

• All GeoJSON types can be downloaded via the API and viewed in JOSM
• MultiPoints
  • Are represented using an OSM Relation
  • The type will be multipoint
  • The member type will be point
• MultiLineStrings
  • Are represented using an OSM Relation
  • The type will be multilinestring
  • The member will be line
• Uploading Way & Relation types are not currently supported, attempting to upload them may produce undesirable results.

The following incomplete list of endpoints are implemented with some degree of coverage with the OSM API Spec but are likely incomplete/or written with the minimum flexibility required to support editing from JOSM. See the code for a full list.

GET /api/capabilities

GET /api/0.6/capabilities

Return a static XML document describing the capabilities of the API.

Example

curl -X GET 'http://localhost:8000/api/capabilities'

---

GET /api/0.6/user/details Auth Required

Returns a static XML document describing the number of unread messages that a user has. Every n minutes JOSM checks this and displays in the interface if there is a new message, to cut down on errors it simply returns a 0 message response.

Example

curl -X GET 'http://localhost:8000/api/0.6/user/details'

---

PUT /api/0.6/changeset/create Auth Required

Create a new changeset and set the meta information, returning the opened id.

Example

curl \
    -X PUT \
    -d '<osm><changeset><tag k="comment" v="Just adding some streetnames"/></changeset></osm>' \
    'http://localhost:8000/api/0.6/changeset/create

---

GET /api/0.6/changeset/<changeset_id>/upload Auth Required

Upload osm xml data to a given changeset

Example

curl \
    -X POST \
    -d '<diffResult version="0.6">NODE/WAY/RELATIONS here</diffResult>' \
    'http://localhost:8000/api/0.6/changeset/1/upload'

---

PUT /api/0.6/changeset/<changeset_id>/close Auth Required

Close a given changeset, preventing further modification to it

Example

curl -X PUT 'http://localhost:8000/api/0.6/changeset/1/close'

---