Web Services Framework-The Paper

The vendors developing their own Web Services model, based on the original industry-wide agreements of XML, SOAP and HTTP, foresaw the need for advanced functionality for enterprise-level Web Services. Because of this, both Microsoft and IBM submitted a paper to the W3C in April of 2003 at a Web Services workshop entitled Web Services Framework. The paper contained a laundry list of specifications that the two companies felt would bring about true enterprise-level Web services. These specifications would further the goal of achieving decentralized interoperability.

The paper pinpoints specific functionality that must be developed into specifications for the proposed Web Services Framework. The following section contains the companies' vision of the functionality needed for Web Services.

Message Envelope and Controlled Extensibility

This functionality enables users of SOAP routing to tag parts of the XML message. Tagging reveals what parts of the message can and cannot be ignored by the processors. The SOAP intermediate processors can then work with only those parts of the message meant for them and can ignore the parts meant for the final recipient.

Binary Attachments

This functionality allows for sending of non-textual items along with the SOAP message. It is expensive to serialize and deserialize nontextual items (such as images). If items can be attached to the SOAP message in their binary formats, this serialization process is not needed.

Message Exchange aka Routing

Not all SOAP messages are sent point-to-point. Some messages go through any number of intermediaries. Some of the intermediaries may also send a response back to the original sender. Therefore, the model must allow this type of communication to occur.

Message Correlation

A single message may not always be able to fully encapsulate everything necessary for an application process. Therefore, the model must be able to correlate multiple messages.

Guaranteed Message Exchange

Both parties, the sender and the receiver, want certain message guarantees when a message is sent or received. The sender wants a guarantee or notification that the message was received. The receiver wants to ensure that a message is received only once and that there aren't duplicate messages from the sender.

Digital Signature

Senders must be able to digitally sign the messages that they send so that the recipients have a guarantee that the message is from the anticipated sender and that the message sent has not been altered in transport.

Encryption

The model requires method to encrypt either part of the message or the entire message independent of the protocol. The specification cannot be tied to any particular form of encryption.

Transactions and Activities

SOAP messages require some sort of transactioning capabilities. They must support long-running transactions.

Service Description

A service description specification that fully details the interface of the Web Service can inform the consumer about the consumption including the types of protocols used and the types and parameters required for interaction.

Process Flow Contract Description

A Process Flow Contract Description enhances the service description to show the consumer the sequence that occurs as the messages work through the process. The message that can terminate the entire flow process is also included.

Inspection

Consumers require a way to inspect a known destination for Web service endpoints. They need service descriptions as well as process flow contracts.

Discovery

Discovery means the capability to find specific Web Services and their contracts based upon characteristics of the services themselves.

Since this paper was released, IBM and Microsoft have been working together, releasing a number of different specifications that address these core functions that they discussed in this document. For instance, the functionality of Discovery has been worked out with the UDDI specification created by Microsoft, IBM and others.

In the end, this long list of functionality can be lumped into three distinct categories-those that deal with the wire, those that deal with description, and those that deal with discovery.

The wire specifications include the following functionalities named in the paper:

• q Message envelope and controlled extensibility

• q Message Exchange aka Routing

• q Guaranteed Message Exchange

• q Transactions and Activities

• q Digital Signature

• q Encryption

The description specifications needed include:

• q Service Description

• q Process Flow Contract Description

The discovery specifications include:

• q Inspection

• q Discovery

In the end, this paper submitted by these two major vendors was the roadmap they have worked with since then. You, an IT professional who deals with Web Services, can be assured that the functionality described here will be included in the specifications from all major vendors and their partners. It can provide enterprise clients with the advanced functionality they require in their real-world Web Services.