XML-RPC

XML-RPC

Responses are much like requests, with a few extra twists. If the response is successful - the procedure was found, executed correctly, and returned results - then the XML-RPC response will look much like a request, except that the methodCall element is replaced by a methodResponse element and there is no methodName element:

<?xml version="1.0"?> <methodResponse> <params> <param> <value><double>18.24668429131</double></value> </param> </params> </methodResponse>

• An XML-RPC response can only contain one parameter.
  
• That parameter may be an array or a struct, so it is possible to return multiple values
  
• It is always required to return a value in response. A "success value" - perhaps a boolean set to true (1)
  

Like requests, responses are packaged in HTTP and have HTTP headers. All XML-RPC responses use the 200 OK response code, even if a fault is contained in the message. Headers use a common structure similar to that of requests, and a typical set of headers might look like:

HTTP/1.1 200 OK Date: Sat, 06 Oct 2001 23:20:04 GMT Server: Apache.1.3.12 (Unix) Connection: close Content-Type: text/xml Content-Length: 124

• XML-RPC only requires HTTP 1.0 support, but HTTP 1.1 is compatible.
  
• The Content-Type must be set to text/xml
  
• The Content-Length header specifies the length of the response in bytes.
  

A complete response, with both headers and a response payload, would look like:

HTTP/1.1 200 OK Date: Sat, 06 Oct 2001 23:20:04 GMT Server: Apache.1.3.12 (Unix) Connection: close Content-Type: text/xml Content-Length: 124 <?xml version="1.0"?> <methodResponse> <params> <param> <value><double>18.24668429131</double></value> </param> </params> </methodResponse>

After the response is delivered from the XML-RPC server to the XML-RPC client, the connection is closed. Follow-up requests need to be sent as separate XML-RPC connections.