Hi Hanumath,
I had the same issue too and asked a question here regarding REST services and API-Key.
Unfortunatelly nobody answered.
From my understanding api keys are not supported using REST even though you can define them.
Regarding using GET and multiple parameters:
I did not experience this issue, however I did not use it extensively so I might have missed something.
Assuming your code is correct:
Did you try to build the URL manually (i.e. adding the parameters to the URL) instead of using the url parameter collection?
Imho if the later has an issue with multiple parameters then it should be possible to build your query string yourself.
Unfortunately I am not aware of any blog entry regarding REST services. I could have used them myself.
Best regards,
Ludger
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