ok, I got it to work, I think .
Accomplishing the goal requires two steps. First, find the "taxonomy vocabulary" for forums. Then query the tree for that "taxonomy vocabulary".
Step 1:
curl -i -X GET \
-H Cookie:SESSe6a353351dfbaaadbeef=B0ZkiW3-TNZ34dfe-uywhw3-UIWJJww \
'http://myserver/rest/taxonomy_vocabulary?parameters\[machine_name\]=forums'
Result:
[{
"vid": "1",
"name": "Forums",
"machine_name": "forums",
"description": "Forum navigation vocabulary",
"hierarchy": "0",
"module": "forum",
"weight": "-10",
"uri": "http://myserver/rest/taxonomy_vocabulary/1"
}]
Step 2: Using that vid, Query the tree (via POST!!)
curl -i -X POST \
-H Cookie:SESSe6a353351dfbaaadbeef=B0ZkiW3-TNZ34dfe-uywhw3-UIWJJww \
-H Accept:application/json \
-H content-type:application/json \
'http://myserver/rest/taxonomy_vocabulary/getTree' \
-d '{ "vid" :"1" }'
Result:
[{
"tid": "1",
"vid": "1",
"name": "General discussion",
"description": "",
"format": null,
"weight": "0",
"uuid": "dbf914e7-42c2-45f6-b77a-e66a0da72310",
"depth": 0,
"parents": ["0"]
}, {
"tid": "4",
"vid": "1",
"name": "Security and Privacy Issues",
"description": "",
"format": null,
"weight": "1",
"uuid": "7496bfd7-2cb8-4f87-a1e4-f45b1956a01e",
"depth": 0,
"parents": ["0"]
}, {
"tid": "5",
"vid": "1",
"name": "etc....",
"description": null,
"format": null,
"weight": "2",
"uuid": "9fde5519-16b2-453d-852b-a8c416189e30",
"depth": 0,
"parents": ["0"]
}, ...]
Or, you can do a parameterized GET:
curl -i -X GET \
-H Cookie:SESSe6a353351dfbaaadbeef=B0ZkiW3-TNZ34dfe-uywhw3-UIWJJww \
-H Accept:application/json \
'http://myserver/rest/taxonomy_term?parameters\[vid\]=1'
The same data is returned.
My next challenge will be to retrieve the list of posts for each particular forum.
Editorial comment: I saw this documented NO WHERE. I really don't understand how developers who use Drupal manage to use the Services module.