docs(basics/structure.md): [translate] (#970)

docs/source/en/basics/structure.md

@@ -0,0 +1,67 @@
+title: Structure
+---
+
+In the [Quick Start](../intro/quickstart.md), we should have a preliminary impression on the framework, next let us simply understand the directory convention specification.
+
+```bash
+egg-project
+├── package.json
+├── app.js (optional)
+├── agent.js (optional)
+├── app
+|   ├── router.js
+│   ├── controller
+│   |   └── home.js
+│   ├── service (optional)
+│   |   └── user.js
+│   ├── middleware (optional)
+│   |   └── response_time.js
+│   ├── schedule (optional)
+│   |   └── my_task.js
+│   ├── public (optional)
+│   |   └── reset.css
+│   ├── view (optional)
+│   |   └── home.tpl
+│   └── extend (optional)
+│       ├── helper.js (optional)
+│       ├── request.js (optional)
+│       ├── response.js (optional)
+│       ├── context.js (optional)
+│       ├── application.js (optional)
+│       └── agent.js (optional)
+├── config
+|   ├── plugin.js
+|   ├── config.default.js
+│   ├── config.prod.js
+|   ├── config.test.js (optional)
+|   ├── config.local.js (optional)
+|   └── config.unittest.js (optional)
+└── test
+    ├── middleware
+    |   └── response_time.test.js
+    └── controller
+        └── home.test.js
+```
+
+As above, directories by conventions of framework:
+
+- `app/router.js` used to configure URL routing rules, see [Router](./router.md) for details.
+- `app/controller/**` used to parse the input from user, return the corresponding results after processing, see [Controller](./controller.md) for details.
+- `app/service/**` used for business logic layer, optional, recommend to use，see [Service](./service.md) for details.
+- `app/middleware/**` uesd for middleware, optional, see [Middleware](./middleware.md) for details.
+- `app/public/**` used to place static resources, optional, see built-in plugin [egg-static](https://github.com/eggjs/egg-static) for details.
+- `app/extend/**` used for extensions of the framework, optional, see [Extend EGG](./extend.md) for details.
+- `config/config.{env}.js` used to write configuration files, see [Configuration](./config.md) for details.
+- `config/plugin.js` used to configure the plugins that need to be loaded, see [Plugin Development](../advanced/plugin.md) for details.
+- `test/**` used for unit test, see [Unit Test](../core/unittest.md) for details.
+- `app.js` and `agent.js` are used to customize the initialization works at startup, see [Application Startup Configuration](./app-start.md) for details. For the role of `agent.js` see [Agent Mechanism](../core/cluster-and-ipc.md#agent-mechanism).
+
+Directories by conventions of built-in plugins:
+
+- `app/public/**` used to place static resources, optional, see built-in plugin [egg-static](https://github.com/eggjs/egg-static) for details.
+- `app/schedule/**` used for scheduled tasks, optional, see [Scheduled Task](./schedule.md) for details.
+
+**To customize your own directory specification, see [Loader API](../advanced/loader.md)**
+
+- `app/view/**` used to place view files, optional, by view plugins conventions, see [View Rendering](../core/view.md) for details.
+- `app/model/**` used to place the domain model, optional, by the domain related plugins conventions, such as [egg-sequelize](https://github.com/eggjs/egg-sequelize).