Preface

-David Linthicum

That may seem an odd quote to use when beginning a book about employing a particular product to facilitate the implementation of a service-oriented architecture (SOA). However, I think it sets the tone for what I'd like to accomplish here.

There are countless books available on service-oriented architecture, and nearly as many independent definitions of what SOA actually is. Is it about web services, event-driven design, enterprise architecture, reusability, or maybe just a retread of existing object-oriented design? Depending on whom you ask, any of those preceding themes would be deemed correct. If you're looking to implement a SOA, you would find numerous vendors who claim to offer "SOA in a box" where becoming service oriented is as straightforward as installing a product. However, I prefer to define SOA as an architectural discipline based on loosely-coupled, autonomous chunks of business functionality, which can be used to construct composite applications. There are plenty of vital characteristics that can be teased out of that definition, but the most important point is that building a successful SOA requires an enterprise commitment and a particular way of thinking about software design, which cannot be achieved by simply hitching your wagon to the SOA product de jour.

That said, a service-oriented architecture cannot be implemented using only high-minded strategies recorded with paper and pencil. It requires a technology solution that can realize the goals and vision of the business architecture. In this book, we're going to specifically investigate how to design and build service-oriented solutions using BizTalk Server 2009 as the host platform. The crop of high quality BizTalk Server books currently available all admirably cover the entire suite of capabilities which make up the product. And BizTalk by nature has many built-in service-oriented concepts such as loose coupling and message-oriented design, which are discussed in the existing books on hand. However, there is no book currently available that specifically looks at how to map service-oriented principles and patterns to the BizTalk product. That's where this book fits in.

One might look at Windows Workflow Foundation (WF) and Windows Communication Foundation (WCF) and ask why it matters to keep talking about BizTalk Server. Aren't these exciting technologies shepherding in a new era of Microsoft-based enterprise software design that makes a messaging bus like BizTalk obsolete? Fair question. Today, WF and WCF are foundational platform technologies on which future Microsoft applications will be built upon. They are both excellent at servicing particular problem areas around unified communication and workflow. BizTalk Server is Microsoft's enterprise class product, which enables process integration across disparate entities (such as organizations, platforms, applications) through a robust event-driven infrastructure that provides durable messaging, load balancing, and reliability. Similarly, while one can build a portal solution on top of Microsoft Internet Information Services (IIS) and ASP.NET technologies, the premier, complete portal offering from Microsoft is the SharePoint Server. I can attempt to build my own messaging solution using WCF and WF, but trying to design, build, and test such a solution takes me away from my primary goal of helping my organization solve business problems.

What about the upcoming "Oslo" wave of products from Microsoft, which include the "Dublin" server, "Oslo" repository, and modeling toolset? The "Dublin" server, which fits into IIS and provides a powerful host for WCF and WF applications, solves specific problems around hosting and managing WCF and WF solutions. It is not a replacement of BizTalk Server and serves a different purpose. The "Oslo" modeling platform offers a compelling way to visualize solutions and construct rich models which can turn into actual applications. It is meant to solve problems around overall application design and does not provide any sort of infrastructure for actually running applications.

Take a look at Chapter 12 for more about these upcoming technologies.

Much has been written about the business aspect of SOA and achieving enterprise momentum for designing software in a service oriented fashion. If you are looking at how to engage your CEO or business stakeholders and expound on the virtues of SOA, this book is not your best resource.

You will find that this book is a technical resource for folks looking to implement service-oriented patterns while exposing new services or consuming existing ones. We will take a deep look at how BizTalk Server works with the new WCF service model. We will also see how to take advantage of the BizTalk engine to build asynchronous processes and reusable orchestrations.

This book, at its core, is an explanation of how to construct flexible solutions that are built for change.

Is BizTalk Server the only product that can help you reach a service-oriented nirvana? Of course not. You can very successfully build a SOA without using BizTalk Server, or any single product, for that matter. In fact, your SOA strategy should NOT be dependent on a single vendor or product, but rather support an ecosystem of service enabled platforms. This protects you from future change, while encouraging general SOA patterns that are not product-specific.

That said, I plan to show you that BizTalk Server is an excellent platform for advancing your service-oriented architecture and creating new opportunities for making your environment more agile and flexible. As we work together through the examples in this book, I hope that you'll be able to visualize exactly how to utilize BizTalk Server in the most efficient manner within your organization's IT environment.