I worked recently on a design of a lightweight Internet-based payment system using SOAP, and after having done so, I learned a number of valuable lessons that I thought I'd pass on here. First I'll talk about why I chose this route, then I'll talk a little bit about recent changes in the SOAP community, including the directions that this technology appears to be moving.

SOAP is a boon in the quest for interoperability between servers -- but it is still a challenge to deliver SOAP-based solutions which perform well in production environments. Frank Cohen offers tips on overcoming scalability problems, and introduces a free open-source utility to proof performance in SOAP-based Web services.

As you may know by now, SOAP 1.2 has reached Proposed Recommendation (PR) status, which means that the XML Protocol Working Group believes that it's done. A few PR issues have been raised. It can be fun to look at the list, as the issues range from "I found a typ" to "this isn't full XML, send it back to the committee".

The Simple Object Access Protocol (SOAP) is a minimal set of conventions for invoking code using XML and HTTP. DevelopMentor, Microsoft, and UserLand Software submitted SOAP to the IETF as an Internet Draft in December 1999 (available here).

Using a web service involves a sender and a receiver exchanging at least one XML message. The format of that message must be defined so that the sender can construct it and the receiver can process it.

The WSDL Extension for SOAP in DIME is used in a WSDL [1] document to describe the use of DIME [2] for encapsulating a SOAP [3] message with base64Binary and/or hexBinary content in multiple DIME records in a way consistent with Encapsulating SOAP in DIME [4]. The primary features of the extension are:

A combination of the Java 2 Platform, Enterprise Edition (J2EE) connector architecture and Simple Object Access Protocol (SOAP) technologies provides a standard way to use SOAP-encoded Extensible Markup Language (XML) to interact with legacy systems.

Part I and Part II of this document described how to document first untyped, then typed remote procedure calls using WSDL. This third part documents another style of interaction - exchange of well formed and valid documents. For further insight into this perspective about how one should develop distributed applications, see Sean McGrapth's API's Considered Harmful essay.

In this article, Andre Tost examines ways to create and process information that is transferred in the header portion of a SOAP message. Specifically, he looks at how this can be done in applications that are built using the JAX-RPC standard, which is how most, if not all, Java applications will provide and consume Web services.

Last month we built a simple client for the Google API. In this month's column we'll look at how SOAP headers can be used to talk to an intermediate server that adds value to the basic search service.

This object represent a named value in the body of a SOAP request. Instances of this object are used in conjunction with the add method on a SOAP request's body.

Being the new kid on the block, SOAP has to do some explaining in order to gain acceptance. SOAP moves into a neighborhood brimming with other server-to-server communication technologies, including CORBA, RMI, and DCOM.

Calling enterprise beans through SOAP is handled in the same manner as calling Java bean methods through SOAP. The SOAP runtime handles the bean cases for you, such as calling an enterprise bean's create method if the create was not called previously.

In last month's column we put a stake in the ground, offering a definition of "web service". This month we're going to examine one of the underlying protocols upon which such services are being built, namely, SOAP. The original SOAP specification, version 0.9, was published in September 1999 and was revised twice before the publication of SOAP 1.1 in December 1999. SOAP 1.1 has become a de facto standard, with broad industry support from many vendors, large and small, providing client and server implementations.

Web services, at their core, are technologies designed to improve the interoperability between the many diverse application development platforms that exist today.

SOAP Security Extensions: Digital Signature (SOAP-DSIG) defines the syntax and processing rules for digitally signing SOAP messages and validating signatures. This article discusses how SOAP-DSIG is related to SSL, and describes how the two technologies complement each other.

SOAP has become almost synonymous with Web services, even though it is just one of many possible bindings for accessing Web services. This means that applications that make use of Web services usually do so through APIs tied to a specific implementation of SOAP.

The Apache Cocoon framework excels at processing and manipulating XML documents, which makes it an easy and ideal platform for SOAP services. All the necessary components exist in the standard Cocoon release, except for one.

In this article, Andre Tost examines ways to create and process information that is transferred in the header portion of a SOAP message. Specifically, he looks at how this can be done in applications that are built using the JAX-RPC standard, which is how most, if not all, Java applications will provide and consume Web services.

SOAP has become almost synonymous with Web services, even though it is just one of many possible bindings for accessing Web services. This means that applications that make use of Web services usually do so through APIs tied to a specific implementation of SOAP.