BizTalk Server Engine

To enable users to create a business process that spans multiple applications, the Microsoft® BizTalk® Server 2004 engine must provide the following capabilities:

• A way to specify that business process
• A mechanism for communicating between the applications that the business process uses

The following figure shows the main components of the BizTalk Server 2004 engine that provide these capabilities.

A business process is implemented as one or more orchestrations, each of which consists of executable code. Orchestrations are not created by writing code in a language such as C#. Instead, a business analyst uses the Orchestration Designer for Business Analysts (a Microsoft Visio® snap-in) to graphically organize a defined group of shapes to express the conditions, loops, and other behavior of the business process. Business processes can also use the Business Rule Engine, which provides a simpler and more easily modified way to express the rules in a business process.

Each orchestration creates subscriptions to indicate the kinds of messages it receives. As illustrated in the preceding figure, the message processing proceeds as follows:

1. A message is received through a receive adapter. Different adapters provide different communication mechanisms, so a message might be acquired by accessing a Web service, reading from a file, or in some other way.
2. The message is processed through a receive pipeline. This pipeline can contain components that perform tasks such as converting the message from its native format into an XML document and validating its digital signature.
3. The message is delivered to a database called MessageBox database, which is implemented by using Microsoft SQL Server™.
4. When a message arrives in the MessageBox database, that message is dispatched to its target orchestration, which takes whatever action the business process requires.
5. The result of this processing is typically another message, which is produced by the business process and saved in the MessageBox database.
6. The new message is processed by a send pipeline, which may convert it from the internal XML format used by BizTalk Server 2004 to the format required by its destination, add a digital signature, and more.
7. The message is sent out through a send adapter, which uses an appropriate mechanism to communicate with the application for which this message is destined.

Three roles—business analyst, developer, and administrator—are necessary to create and maintain BizTalk Server 2004 applications. These roles perform the following functions with the BizTalk Server 2004 engine.

• Business analyst. Defines the rules and behaviors that make up a business process, and determines the flow of the business process by defining how information is exchanged and how documents are mapped.
• Developer. Implements the business process after the business analyst has defined it. Implementation includes tasks such as defining the XML schemas for the business documents that will be used, specifying the detailed mapping between them, and creating the orchestrations necessary to implement the business process.
• Administrator. Performs tasks such as setting up communication among the parts and deploying the application in an appropriately scalable way.

This section contains:

• Connecting Applications
• Defining Business Processes
• Management and Monitoring
• Enterprise Single Sign-On