RPC - SOAP

[SaiPrasad Jukalkar]

hi all,
i have started my study about SOAP technology recently and i have few questions about this technology.
how is SOAP related to RPC, how does SOAP technology enables communication between client and server and how other technologies like WSDL, UDDI, ebXML go with SOAP
these questions might be very basic, but i need to know about them, to go any further in my study.
thanks in advance.
Saiprasad.

[Andy Rodriguez]

Let me start by saying , this forum was very much missing on javaranch and i am glad to be atleast the 3rd person to post here !
In answer to your question : i found an article by Chad Dickerson (InfoWorld's CTO) talking about the same stuff. http://www.infoworld.com/articles/op/xml/01/09/10/010910opconnection.xml

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My ramblings @
http://javarecon.tripod.com

[Andy Rodriguez]

One more post relating to the same - In a nutshell XML-RPC is the dad of SOAP .And now soap is getting slippery primarily as they keep adding more stuff ontop of the existing Http and XML . http://www.w3.org/2000/03/29-XML-protocol-matrix.html

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My ramblings @
http://javarecon.tripod.com

[Kyle Brown]

Welcome SaiPrasad. I've answered a few of your questions in the text.

Originally posted by SaiPrasad Jukalkar:
hi all,
i have started my study about SOAP technology recently and i have few questions about this technology.
how is SOAP related to RPC

Well, let's start with a definition of what SOAP is. SOAP is the Simple Object Access Protocol. It's defined in the W3C spec as being:
SOAP is a lightweight protocol for exchange of information in a decentralized, distributed environment. It is an XML based protocol that consists of three parts: an envelope that defines a framework for describing what is in a message and how to process it, a set of encoding rules for expressing instances of application-defined datatypes, and a convention for representing remote procedure calls and responses.

how does SOAP technology enables communication between client and server

Well, theat's the cool part. SOAP is a protocol for building message-based or RPC communication. SOAP implementations must come with (at least) a binding for HTTP, although bindings for other transports like SMTP and JMS are also defined. So SOAP is a way of phrasing your client-server communication, either one-way (messaging) or RPC over these transports.

and how other technologies like WSDL, UDDI, ebXML go with SOAP

Well, let's define these terms:
WSDL -- Web Services Definition Language. According to the W3C Spec, WSDL is "...an XML format for describing network services as a set of endpoints operating on messages containing either document-oriented or procedure-oriented information. The operations and messages are described abstractly, and then bound to a concrete network protocol and message format to define an endpoint." In fact, it's easiest to think of WSDL as being the IDL (interface definition language) for SOAP services. If SOAP is how you define how a message flows across the network from client to server then WSDL is how you define the interfaces for the "classes" that implement the messages.
UDDI -- From the UDDI.org web site: "The Universal Description, Discovery and Integration (UDDI) project is a sweeping industry initiative. The project creates a platform-independent, open framework for describing services, discovering businesses, and integrating business services using the Internet, as well as an operational registry that is available today." This is marketing-speak What a UDDI server really is is the equivalent of a naming service in CORBA or RMI (and also a Broker Service in CORBA). A UDDI Server allows you to find servers that implement specific WSDL documents, or that meet other requirements.
ebXML -- From the ebXML.org site: "ebXML is a modular suite of specifications that enables enterprises of any size and in any geographical location to conduct business over the Internet" Again, this is marketing-speak. What ebXML tries to be is a global definition of the types of XML documents that businesses will use to communicate with in a B2B scenario. (Personally, I'm not as convinced about this one as I am the others...)

thanks in advance.
Saiprasad.

The other postings have given good starting points for your research. Good luck!
Kyle
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Kyle Brown,
Author of Enterprise Java (tm) Programming with IBM Websphere
See my homepage at http://members.aol.com/kgb1001001 for other WebSphere information.
[This message has been edited by Kyle Brown (edited October 24, 2001).]
[This message has been edited by Kyle Brown (edited October 24, 2001).]

[Andy Rodriguez]

Kyle,
Do you know where i can find Doug Tidwell's presentation on webservices ? About a month ago , I did attend Doug's webservices presentation in london and i dont see the presentation posted on developerworks yet . The thing i liked about that presentation was that it outlined the complete webservices "development lifecycle" usage of tools ...and example used was the magic 8 ball webservices consumption demo , and it was comprehensive in terms of outlining whitepages , private uddi , green pages , etc ., i think it will be great to get a link to that presentation or anyother similar presentation that you might be aware of which would concisely get the point across .
Regards -

[SaiPrasad Jukalkar]

hi kyle brown, thanks for the reply, notes given by you is really informative.
continuing the same discussion, can we implement certificates in SOAP and how do we encrept the data that is in xml format?
you wrote UDDI is equivalent to CORBA, due to its compatiblity to XML will this technology replace CORBA?
Saiprasad.

[SaiPrasad Jukalkar]

hi Skinner Seymour thanks for the reply, the links provided my you are very informative.
Saiprasad.

[Kyle Brown]

Originally posted by Skinner Seymour:
Kyle,
Do you know where i can find Doug Tidwell's presentation on webservices ? About a month ago , I did attend Doug's webservices presentation in london and i dont see the presentation posted on developerworks yet . The thing i liked about that presentation was that it outlined the complete webservices "development lifecycle" usage of tools ...and example used was the magic 8 ball webservices consumption demo , and it was comprehensive in terms of outlining whitepages , private uddi , green pages , etc ., i think it will be great to get a link to that presentation or anyother similar presentation that you might be aware of which would concisely get the point across .
Regards -

I'm not sure but I THINK that the same presentation he did in London is the one on this live webcast: http://www.itworld.com/itwebcast/IBM_WebSphere/XML/.
If that's not it, let me know and I'd be glad to ask Doug for a link tomorrow at work.
Kyle

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Kyle Brown,
Author of Enterprise Java (tm) Programming with IBM Websphere
See my homepage at http://members.aol.com/kgb1001001 for other WebSphere information.

[Kyle Brown]

Originally posted by SaiPrasad Jukalkar:
hi kyle brown, thanks for the reply, notes given by you is really informative.
continuing the same discussion, can we implement certificates in SOAP and how do we encrept the data that is in xml format?

SaiPrasad. You're getting into two areas that are still being worked out. The security aspects of SOAP are not yet fully decided. There are RFC's out for both of the issues you mention. A good place to start would be in looking at the Apache Axis project, which aims to address all of these issues with a flexible plugin architecture.

you wrote UDDI is equivalent to CORBA, due to its compatiblity to XML will this technology replace CORBA?
Saiprasad.

I think you meant I said that Web Services in general (SOAP + UDDI + WSDL) are equivalent to CORBA. As to whether it will replace it -- probably not. I see coexistence instead for a long time. There is a lot of good infrastructure already implemented for CORBA that Web Services implementations are just now starting on. However as to whether new projects will use Web Services instead of CORBA -- definitely. I'm seeing that trend already in spades.
Kyle

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Kyle Brown,
Author of Enterprise Java (tm) Programming with IBM Websphere
See my homepage at http://members.aol.com/kgb1001001 for other WebSphere information.

[faisal mahmood]

This post has good information.
What is RPC? is that remote procedure calls in C language.
fm

[raj betapudi]

Kyle:
Thanks for your informative reply.
What is difference between XML-RPC and SOAP? Do SOAP use RPC technology?
Thanks,
Raj
[This message has been edited by raj betapudi (edited November 06, 2001).]

[faisal mahmood]

An XML-RPC message is an HTTP-POST request. The body of the request is in XML. A procedure executes on the server and the value it returns is also formatted in XML. Here is an example XML-RPC request:
<?xml version="1.0"?>
<methodCall>
<methodName>someMethod</methodName>
<params>
<param>
<value><string>someValue</string></value>
</param>
</params>
</methodCall>
There are predefined types that can be passed, e.g. <int>, <string>, <dateTime.iso8601> etc. It also supports structures like C and array with any type of elements.

Faisal

[faisal mahmood]

Hi Raj,
And the desctiption about SOAP is given in the previous posts. SOAP does same thing as XML-RPC, but I think SOAP is well structured then XML-RPC. One example is that in XML-RPC arrays needs to be complete (all the elements need to be supplied), while in SOAP you can create array elements by giving only a subset of indexed elements.
Faisal

[faisal mahmood]

Here is a small article regarding this topic:
http://xmlrpc-c.sourceforge.net/xmlrpc-howto/xmlrpc-howto-soap.html
It's mainly about XML-SPC
Faisal