If we need to expand our system to meet our business needs we are talking about scalability. We can expand by adding extra hardware, like extra servers, or by upgrading the existing hardware, like adding extra hard drives or CPU power. Note that we are not talking about optimizing our application’s software.

If we take a look at BizTalk Server we talk about scalability when we want to scale BizTalk to increase our throughput or if we want to reduce latency times. The BizTalk Server architecture enables us to scale-up and to scale-out.

• Scaling-out
  Adding extra hardware to our environment like servers to spread the work load. We can double the throughput by adding an identical server.
• Scaling-up
  Of course we can keep the solution inside the same box. We might try to improve our system by upgrading from a single-core CPU system to a dual-core CPU.

MSDN provides an useful piece of documentation on the situations and ways we can scale BizTalk.

When we compare all the different ESB solutions we can define a common set of characteristics that apply to an ESB:

• Brokered Communication
  The basic function of a ESB is to send data between processes on a single or multiple computers. The brokered communication is offered by the use of a software intermediary between the sender and the receiver.
• Routing
  Based on a predefined set of criteria ESBs are capable of routing messages to subscribers
• Endpoint Metadata
  ESBs normally maintain metadata that describe the service interfaces and message schemas.
• Basic Web Services
  An ESB supports basic Web service standards like SOAP, WSDL and foundational standards like TCP/IP and XML to communicate.

A lot of venders try to position their ESB as the single solution that solves all integration needs, but an ESB product can rarely do this as it misses features like business activity monitoring and business rules.

Does Microsoft deliver an ESB? No they do not. Of course you can build an ESB with the toolset from Microsoft, but they believe in delivering a broader set of important integration requirements that go beyond the ESB. Microsoft offers message validation and transformation, BAM, Business rules management and business process orchestration & management.

BPEL stands for Business Process Execution Language. When we connect the systems of two or more organizations, it might be useful or even necessary to know something about the business process from each company.

There are “easy” ways to share business process information between Business Process Management (BPM) systems when they are created by the same vendor. For example, with BizTalk Server 2006 you can use the Trading Partner Management technology to exchange this information. However, in real life, most companies use systems from different vendors.

To allow insight in each other Business processes Microsoft, IBM and others have created the BPEL language. The language is particularly useful to describe and sharing externally visible parts of a business process. BPEL is an Orchestration language which is built entirely on Web services. Inside BizTalk it is possible to export business processes that are designed with the Orchestration Designer into BPEL.

BPEL isn’t a complete language for defining business processes. For that reason it is hard to view it as a fully mature technology, but of course it keeps evolving. A more thorough explanation of BPEL can be found here.

BizTalk provides ways to make separate systems communicate with each other, without them knowing of each other’s existence. In the dynamic business world of today you often want to have a fast way to connect your systems with each other to exchange information through the company in a manageable way. Yes we are talking about Enterprise integration, which is a complex problem, even with a great and flexible product like BizTalk Server 2006.

Microsoft BizTalk Server solves this problem by creating an abstraction layer on which you connect each system. Inside this layer you can orchestrate multiple process flows and interaction between the systems. This can be inside your own company but also with your vendors or customers. As a result you can now easily change business rules and business processes, saving time, saving money. Thanks to the business activity monitoring (BAM) it is easy to keep track of the critical business operations, allowing you to jump into action on time.

With the help of normal tools like Microsoft Visio, Analysts and programmers can create a clear view of the business processes and implement them in the IT-structure. BizTalk Server uses mainly XML messaging which enables it to talk with an almost unlimited number of applications, devices, services, and many more possible objects written in a variety of programming languages.