Support for paging in the RHQ REST-api (updated)

I have just pushed some changes to RHQ master that implement paging for (most) of the REST-endpoints that return collections of data.



If you remember, I was asking the other day if there is a "standard" way to do this. Basically there are two
"big options":

1. Put paging info in the Http-Header
2. Put paging info in the body of the message

While I think paging information are meta data that should not "pollute" the body, I understand the arguments from the JavaScript side that says that they don't easily have access to the http headers
within AJAX requests. So what I have now done is to implement both:

1. Paging in the http header: this is the standard way that you get if you just request the "normal" media types of application/xml or application/json (output from running RestAssured):
   
   [update]
   My colleague Libor pointed out that the links do not match with format from RFC 5988 Web Linking, which is now fixed.
   [/update]

   
   Request method:	GET
   Request path:	http://localhost:7080/rest/resource
   Query params:	page=1
   				ps=2
   				category=service
   Headers:		Content-Type=*/*
   				Accept=application/json
   HTTP/1.1 200 OK
   Server=Apache-Coyote/1.1
   Pragma=No-cache
   Cache-Control=no-cache
   Expires=Thu, 01 Jan 1970 01:00:00 CET
   Link=<http://localhost:7080/rest/resource?ps=2&category=service&page=2>; rel="next"
   Link=<http://localhost:7080/rest/resource?ps=2&category=service&page=0>; rel="prev"
   Link=<http://localhost:7080/rest/resource?ps=2&category=service&page=152>; rel="last"
   Link=<http://localhost:7080/rest/resource?page=1&ps=2&category=service>; rel="current"
   Content-Encoding=gzip
   X-collection-size=305
   Content-Type=application/json
   Transfer-Encoding=chunked
   Date=Thu, 23 May 2013 07:57:38 GMT
   
   [
       {
           "resourceName": "/",
           "resourceId": 10041,
           "typeName": "File System",
           "typeId": 10013,
   …..
   

2. Paging as part of the body - there the "real collection" is wrapped inside an object that also contains paging meta data as well as the paging links. To request this representation, a media type of application/vnd.rhq.wrapped+json needs to be used (and this is only available with JSON at the moment):
   

   
   Request method:	GET
   Request path:	http://localhost:7080/rest/resource
   Query params:	page=1
   				ps=2
   				category=service
   Headers:		Content-Type=*/*
   				Accept=application/vnd.rhq.wrapped+json
   Cookies:		
   Body:			
   HTTP/1.1 200 OK
   Server=Apache-Coyote/1.1
   Pragma=No-cache
   Cache-Control=no-cache
   Expires=Thu, 01 Jan 1970 01:00:00 CET
   Content-Encoding=gzip
   Content-Type=application/vnd.rhq.wrapped+json
   Transfer-Encoding=chunked
   Date=Thu, 23 May 2013 07:57:40 GMT
   
   {
       "data": [
           {
               "resourceName": "/",
               "resourceId": 10041,
               "typeName": "File System",
               "typeId": 10013,
   …
       ],
       "pageSize": 2,
       "currentPage": 1,
       "lastPage": 152,
       "totalSize": 305,
       "links": [
           {
               "next": {
                   "href": "http://localhost:7080/rest/resource?ps=2&category=service&page=2"
               }
           },
   …
   }
   

Please try this if you can. We want to get that into a "finished" state (as for the whole REST-Api) for RHQ 4.8