[Building Sakai] Using REST to get a list of sites

[Shaun Donovan]

Hi all.

I am trying to use Sakai's RESTFul services to get a list of sites 
available to the administrator. I am using Sakai 10.3, and PHP with 
Httpful library.

The documentation on http://localhost:8080/direct/describe states:

Entity Collection URL: GET /site <http://localhost:8080/direct/site> 
(xml <http://localhost:8080/direct/site.xml>) (json 
<http://localhost:8080/direct/site.json>) (html 
<http://localhost:8080/direct/site.html>) (form 
<http://localhost:8080/direct/site.form>)
Response Code Details: 200 plus data; 404 if not found, 406 if format 
unavailable
Retrieves the list of all sites that the current user can access. Supply 
a value for '_limit' to specify how many sites should be returned. Note 
that there is a system maximum that will override a specified value if 
it is larger than allowed. Supply a value for '_start' to page through 
results in multiple requests. For example, with 42 sites, requests with 
'_start' = 1, '_limit' = 50 and then '_start' = 51, '_limit' = 50 could 
be used to retrieve the first batch of 42 sites and the second being 
empty would signify the end of available results.

I am writing my code in PHP, so, I log in to Sakai using /direct/session 
and retrieve the session id. I then run my request against /direct/site 
and I add the _start and _limit as in :

GET 
/direct/site.json?_sessionId=a1317f61-2db6-4108-b01d-e9270d4747e7&_start=1&_limit=20

This returns a JSON object with 19 sites in it.

I then submit:

GET 
/direct/site.json?_sessionId=a1317f61-2db6-4108-b01d-e9270d4747e7&_start=21&_limit=20

This returns a JSON object with a single site.

Third submission is:

GET 
/direct/site.json?_sessionId=a1317f61-2db6-4108-b01d-e9270d4747e7&_start=41&_limit=20

This returns a JSON object with a single entry.

My code is looking for count($response->body->site_collection) == 0 to 
indicate that there are no more sites to get. If i set _limit to a low 
number (20), I only find 33 sites, but if I set _limit to a high number 
(800), I find 293 sites. This indicates that on a low _limit, I can get 
an empty result even when there are more sites to find.

My question is therefore twofold:
     What is the system maximum spoken about in describe?
     Is there a better way to check for the end of the list?

Any help is appreciated.

Kind Regards.

Shaun Donovan
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