Welcome to CQRS + REST!

While in CQRS commands and queries live in disparate systems, they will be represented as a unified resource at the API Layer.

This prototype exposes Greg Young's m-r sample - which has been the de-facto CRQS+ES (ES = Event Sourcing) sample in the community - through a RESTful interface.

This prototype exemplifies:

• Forming the API's Public Domain abstracing Server/BoundedCountext's internal domain. Public domain is composed of DTOs and separate commands.
• Service has been exposed as resources. Resource accept GET, POST, DELETE and PUT requests - currently OPTIONS is not implemented.

  • GET /api/InventoryItem

    [gets all items]

  • GET /api/InventoryItem/{id}

    [gets detail of a single item]

  • POST /api/InventoryItem

    [creates an item]

  • POST /api/InventoryItem/{id}

    * [checks in stock items to the inventory]

  • POST /api/InventoryItem/{id}

    * [removes stock items from the inventory]

  • PUT /api/InventoryItem/{id}

    [renames an item]

  • DELETE /api/InventoryItem/{id}

    [de-activates an item]
• Operations marked with the * above require passing the command type as described by the 5 levels of media type. This helps to avoid RPC-style URLs where a verb is defined on the top of a resource: so instead of

  /api/InventoryItem/{id}/AddToStock

  , we send a request with media type

  application/json;domain-model=CheckInItemsToInventoryCommand

  . This also moves away from the common misconception that HTTP Verbs must be mapped to CRUD.
• Exposing ES concurrency through HTTP's ETag and If-Match and If-None-Match conditional PUT and GET requests.
• Enabling caching on the top of single resources and returning 304 for resources that are not modified. Also returning 412 (PreconditionFailed) on unsuccessful If-Match conditional PUT calls.
• As per RFC 2616, ETag has been opacified so that the client cannot guess the values - this would have been possible if we had exposed version numbers directly.
• Other HTTP-level semantics such as status codes, populating

  Location

  header after POST, etc.