# AWS RPC API's with dynamic params

**URL:** <https://www.ruby-forum.com/t/aws-rpc-apis-with-dynamic-params/91236>\
**Category:** Rails\
**Created:** [April 5, 2007, 9:51pm UTC](https://www.ruby-forum.com/t/aws-rpc-apis-with-dynamic-params/91236 "2007-04-05T21:51:18Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![jmaenpaa](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/j/9de053/32.png) [@jmaenpaa](https://www.ruby-forum.com/u/jmaenpaa)\
**Post date:** [April 5, 2007, 9:51pm UTC](https://www.ruby-forum.com/t/aws-rpc-apis-with-dynamic-params/91236/1 "2007-04-05T21:51:18Z")

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Hi All,

I’ve been looking at the ActiveWebService::Base::API in rails. I’m  
trying to creat several function that are generally like  
set\_state(statename, \*args). There is simply not a good way to  
determine the type or number of args in advance, though I can be sure  
that they will be one of the types allowed by the xmlrpc protocol.  
(structs in most cases.)

Looking at Rails implementation of RPC’s it appears that I must know the  
signature of the call in advance. Is this the case and if so, what was  
the reasoning behind it?

I have not gone very far into SOAP, but I believe bot it an XMLRPC’s  
give enough information in the request to allow for this and Ruby is  
certianly does not have a limitation on method calls. This seems like a  
strange limitation, and one I am tempted to code around unless someone  
can give me a good reason not to.

Thanks

John M.