This page is meant to start as a conceptual design for a 2nd generation REST API for ESME. The idea is to learn from the discussions around and use of the original REST API.
REST API Design
Methods, Resources, and Descriptions
Resource |
Method |
Description/Payload schema/Response schema |
---|---|---|
api/sessions |
GET |
(It might make sense for this to return only the current session, but in theory it would return all sessions that the current session is allowed to access, so for an administrator, it might return all open sessions. An individual session would be accessed at GET api/sessions/SESSIONID.) |
api/sessions |
POST |
Parameters: ?token=API_TOKEN |
api/sessions/SESSIONID |
DELETE |
or |
api/users |
GET |
|
api/users/USERID/messages |
GET |
(get USERID from api/session) |
api/users/USERID/messages |
GET |
(long-poll?) |
api/users/USERID/followees |
GET |
|
api/users/USERID/followers |
GET |
|
api/users/USERID/followees/USERID2 |
POST |
or POST api/users/USERID/followees?user=USERID2 |
api/users/USERID/followees/USERID2 |
DELETE |
or DELETE api/users/USERID/followees?user=USERID2 |
api/users/USERID/tracks |
GET |
|
api/users/USERID/tracks |
POST |
Parameters: ?track=TEXT_TO_TRACK |
api/users/USERID/tracks/TRACKID |
DELETE |
|
api/users/USERID/actions |
GET |
(Actions probably don't make sense outside of the context of a specific user.) |
api/users/USERID/actions |
POST |
Parameters: ?name=NAME&test=TEST&action=ACTION |
api/users/USERID/actions/ACTIONID |
PUT |
Parameters: ?enabled=true|false (This is actually a general outlet to update any attribute of an action, including whether or not it is enabled.) |
api/users/USERID/actions/ACTIONID |
DELETE |
|
api/messages/MESSAGEID |
GET |
Gets a particular message. |
api/messages |
POST |
parameters: message=MESSAGE_BODY&via=CLIENT&tags=TAGS&metadata=XML&replyto=MESSAGEID |
api/messages/MESSAGEID |
PUT |
(payload the same as POST) |
api/messages/MESSAGEID |
DELETE |
|
api/tags |
GET |
Return all of the tags, or user-specific tags (GET api/tags/USERID?) and let the front-end decide what to do with it. |
api/tags/TAGID |
GET |
Gets the information about a particular tag |
api/conversations/CONVERSATIONID |
GET |
|
One point to note is that most HTTP clients do not currently support the "PUT" or "DELETE" methods, so these have to be simulated through POST methods with an extra parameter. I think that because of the close mapping to resource verbs, is worth using these methods in the specification and defining the simulation method for the entire API separately.
Resource/Object Hierarchy
The above is based on a rough object hierarchy as follows:
- ESME API instance (api/)
- Sessions (api/sessions)
- Users (api/users)
- Messages posted by a user (api/users/USERID/messages)
- Users followed by a user (api/users/USERID/followees)
- Users following a user (api/users/USERID/followers)
- Trackers belonging to a user (api/users/USERID/tracks)
- Actions belonging to a user (api/users/USERID/actions)
- Messages (api/messages)
- Tags (api/tags)
- Conversations (api/conversations)
- Pools (api/pools)
- ?
- Searches ??
- Trends ??
Each of these bullets represents a set of objects. The resource representing an individual object lives at api/objects/OBJECTID. For example, api/sessions/SESSIONID. As much as is reasonable, one would expect to be able to GET (read), POST (create), PUT (update/amend), or DELETE (delete) any individual member of each of these object sets. Going through each of these objects to ask what it would mean to create, read, update, or delete that object may reveal holes in the existing API, some of which I have filled in above.
Formats
Request formats
Format specification
If there is a request body, format should be specified using the Content-Type HTTP header.
Formats to be supported
- XML ?
- JSON ?
- Multi-part Form-encoded ?
- Form-encoded
Response formats
Format specification
Format could be specified using the HTTP Accept header - http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html
Another option (though not as robust) would be to append the format to the resource request url. For example /api/users/USERID.json
Formats to be supported
- XML ?
- JSON ?
- ...
Points for discussion, resolution, further work
- Is the use of HTTP sessions necessary? Is it desirable?
- Request signing methods?
- Payload and response schemas must be defined
- Should API contain admin functions?
- Webhooks (http://blog.webhooks.org/)
- ESME has webhooks as part of its actions framework, but we may want to document their existence as part of the API, and possibly improve the functionality if there are use cases (http://incubator.apache.org/esme/actions.html)
- What is a conversation?