Is it possible to create custom REST web service in community edition?
Yes it is possible, though you have to do it manually.
Currently the only way is to export an existing one and then modify it, carefully,
regards
Seán
PS: While you may not like the answer, it gives a possible solution, please mark as resolved.
PPS: I must get on and write the howto I was supposed to do…
You can make it with eclipse and maven.
With rest-api-sql-datasource example you can watch this