RE: How to get started with XML/SOAP

[Michael Brennan <Michael_Brennan@allegis.com>]

The best place to get this sort of help is the SOAP discussion list
(http://discuss.develop.com/soap.html).

> From: hector santos [mailto:xml-dev@winserver.com]
> Sent: Monday, June 11, 2001 3:22 PM
> To: xml-dev@lists.xml.org
> Subject: How to get started with XML/SOAP
> 
> [...]
> So, I want to see what do I need to do to expose our API/SDK
> to the outside world.  What are my choices here?

Sounds like SOAP could be a good fit for what you are doing.

> It seems to me after spending over 1 week researching and
> exploring XML/SOAP, then we can:
> 
> a) Create an SDK converter to create the WSDL URL....?
> b) Prepare our HTTP request processor by adding another
>    layer to handle XML data.

Yes, you could. Are you on the Microsoft platform? If so, check out the
Microsoft SOAP Toolkit and their .NET SOAP toolkit. If you have COM-based
APIs, their SOAP toolkit can generate the WSDL and client-side stubs for
you. If you are not on the Microsoft platform, you are more limited on
available tools (since you are not Java-based), but I think there may still
be other C/C++-based tools out there. Try searching the SOAP list archives
(or post an inquiry if you can't find anything). 

> What is SOAP/RPC?  Can I use SDK converter to create a
> SOAP/RPC "Definition" file? whatever that is?

SOAP is a layered protocol. SOAP may be used to send any arbitrary XML
content. In such a case, you use the SOAP Envelope, but don't conform to
SOAP encoding rules or any other aspect of the spec. However, SOAP also
supports the optional mechanism of "SOAP Encoding", in which XML is used as
a serialization format for common data structures (structs, arrays, and all
of the simple datatypes specified by XML Schema). This places constraints on
the allowable XML constructs (no use of attributes, for instance; they are
reserved for use by the encoding for annotating data with metadata).
SOAP-RPC uses SOAP envelope and SOAP Encoding to encode RPC calls. The root
element of the message payload corresponds to a method call in SOAP-RPC.

There is no such thing as a SOAP/RPC definition file. The closest equivalent
is WSDL, which can be used to describe SOAP-RPC services (using XML Schema
to define the relevant message formats). Some toolkits can generate the WSDL
and XML Schema for you based on a Java or COM interface. Some can also
generate client stubs based on the WSDL (Microsoft's toolkit, for instance,
can expose a web service as a COM component). Many toolkits can also support
a simple interface for invoking a web service without the WSDL. Apache SOAP,
for instance, does not support WSDL; parameters to SOAP calls are simply
passed in via an array or Vector (I believe).

Check out the SOAP list: http://discuss.develop.com/soap.html

Here's some other links that may or may not help:
http://soap-wrc.com/webservices/
http://www.soaprpc.com/software/
http://www.soapware.org/

You may find other useful pointers in the SOAP list archives.