Once we have a SOAP message, we will probably want to send it to someone. After all, what good is a message if it never goes anywhere? The transport is the method by which a SOAP message is moved from sender to receiver. One example of a transport is HTTP, the Hypertext Transfer Protocol.

SOAP itself does not handle objects. In fact, the object in "simple object access protocol" lends itself simply to the formation of a outstanding name. Actually, SOAP was intended for RPC use and designed to convert a method's parameters from its native binary form and carry those parameters to the remote server as XML information.

This article starts with the basics of SOAP, SOAP XML model and its data types followed by the integration of SOAP functionality in .NET class library and how .NET developers can take advantages of SOAP in their applications. It also gives you an overview of SOAP tooklit and SOAP extensions and COM late binding integration with SOAP and .NET.

In SOAP, the details about the RPC are in an XML message. In our Simple SOAP Implementation example, details will be in parameters of HTTP request.

XML RPC and SOAP

A web service is a web-based software application that can be located and accessed via a set of standardized protocols and helper applications.

The Simple Object Access Protocol (SOAP) is making profound changes to the communications and interactions landscape. In the truest sense of the phrase, SOAP is a disruptive technology. SOAP is not only being adopted and endorsed by rivals such as Sun and Microsoft and standards bodies such as the United Nations (ebXML), but is also being actively used to solve real-world problems. As the baseline technology for Web services, SOAP is leveraging pervasive Internet technologies to deliver two much spoken-about paradigms: the delivery of software as services and, as a corollary, the integration of online businesses.

SOAP (Simple Object Access Protocol) has become synonymous with XML- based Web services. However, many real-world response-request-type Web services don't use SOAP; instead, they pass XML messages directly over HTTP. This article discusses these two Web service design approaches.

The recent announcement that the backers of ebXML will use the Simple Object Access Protocol (SOAP) in the proposed standard came as a surprise to some. But for those involved in the formation of ebXML, the use of SOAP is a natural progression.

Introduction to SOAP. [PDF]

What is SOAP ? [PPT]

This example shows how to use the SOAP component to submit searches via the Google SOAP API. Testing this example requires a valid license key, which is available for free from http://api.google.com/.

The first part of SOAP defines the Envelope, the top-level element of all SOAP messages. Here's an example from the SOAP 1.1 specification:

The following is a simple example of fetching some data from the service using the eZ SOAP Client.

As Tarak Modi mentioned throughout the first three parts of this series, Apache SOAP client developers end up with a raw deal, since they must complete extra work that they normally would not have to do.

Over the recent years, the introduction of XML has revolutionized the way data is transferred between systems. XML, similar to the popular HTML of common web pages, is a meta-language made up of non-binary ASCII text. [PDF]

Sometimes a client or server wants or needs to send some application-specific binary data to its peer. For example, a service might want to return a picture or audio data. The preferred way of sending these data over SOAP is by using the SOAP with Attachments specification. This specification defines how data is serialized into a MIME Multipart message and how this data is referenced.

The desire to integrate XML with pre-existing data formats has been a long-standing and persistent issue for the XML community. Users often want to leverage the structured, extensible markup conventions of XML without abandoning existing data formats that do not readily adhere to XML 1.0 syntax.

Your identity-management system doesn't have to dictate your corporate security strategy anymore. SAML (Security Assertion Markup Language) provides a standard way to exchange authentication and authorization information between different vendors' other applications so you can switch from LDAP to RADIUS authentication, for instance, without recoding your applications.

I had read about SOAP and attended a few conferences on the subject about a year ago, but didn't have much of a need for the technology back then. Recently our voice applications platform provider, Bevocal, started to make their call logs and telephony functions available via SOAP. Ah, the perfect excuse to finally jump in and start writing some SOAP client software. I found these documents below to be extremely helpful in ramping me back up on XML, SOAP, and the power these bring to interop.