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In today’s world, implementing distributed systems that provide business value in a reliable fashion presents many challenges. We take many features for granted when developing nondistributed systems that can become issues when working with disparate distributed systems. Although some of these challenges are obvious (such as a loss of connectivity leading to data being lost or corrupted), for other aspects such as tightly coupled systems the dependencies between the various components of a system make it cost prohibitive to make changes as needed to meet the demands of the business.

During the past decade, a lot of research has been done in the field of distributed computing. Microsoft and other leading vendors have come up with various distributed technologies. Each of the technologies reduces the convolution of building rich applications and lowers development costs. The latest from Microsoft is Windows Communication Foundation (WCF), the next-generation uniform way of developing distributed applications by providing a service-oriented programming model.

Building connected systems on the Microsoft platform usually means using multiple technologies and as such different programming models. WCF comes with a unified programming model that makes your life as a developer much easier. Some of the benefits are as follows:

This chapter introduces how to implement WCF services. Much can be said about what constitutes a good service and a strong SOA architecture—Chapter 1 addresses those principles. Additionally, many have described web services and SOA as synonyms. We hope we’ve altered that perspective to clearly indicate that web services are an implementation model for SOA, just as message-oriented middleware and other loosely coupled technologies have provided in the past.

When your business relies on a service-oriented architecture, you need to make sure your services are robust. The most important driver behind the robustness of your application is where/how you host your service. You need to ask yourself several questions when thinking about hosting services: What are the availability requirements of my services? How am I going to manage and deploy my services? Do I need to support older versions of my services?

Any new technology goes through numerous phases in its life cycle. The most exciting phase is the envisioning or evangelizing phase where you are exposed to snazzy marketing material and promises of higher productivity. Then the technology graduates to a phase of gradual implementation by the industry. It is correct to conclude that most people get caught up in the euphoria of technical features in these two phases. Senior managers (that is, CIOs and CTOs) of organizations are keen to deliver the “latest and greatest” technology to their shareholders. However, developers tend to focus their attention on implementing the technology. The development cycle for most of these new applications is much shorter when you compare it to the expected life span of the systems. All these systems need to be maintained efficiently to justify the return on investment (ROI) over a long period of time. Unfortunately, in most cases people tend to overlook the management and operation of new technology. Specifically, how do you continue to support the new system? What are the operational processes that can assist in managing each component? Often, these questions are not appropriately answered when trying to promote new technology.

Security is one of the fundamental features of any software platform. In fact, security requirements have grown exponentially in the past decade because of the increasing popularity of public networks. Securing a distributed enterprise (one that is physically scattered around the world) using a public network such as the Internet is a challenging task. Malicious hackers, identity fraudsters, and disgruntled employees cost organizations millions of dollars every year. So, how do you address these issues as a senior stakeholder of a company? What does WCF offer in the security space to combat these issues?

WCF helps you implement reliable communications over an infrastructure that might be unreliable. Application infrastructure is prone to failure. Network connectivity often breaks, services might not always be available, or messages get lost. WCF provides you with the functionality to overcome these limitations in the infrastructure.

Transactions are fundamental to applications in order to ensure consistent behavior for data. In addition, they are a fundamental building block for ensuring the implementation of atomic, consistent, independent, and durable (ACID) behavior in an application. In the QuickReturns Ltd. application, ACID behavior means that when you do make a trade, it is absolute. It will either be complete in its entirety or be rolled back, leaving no room for ambiguity. If you were to put in a buy order for a stock, you would definitely want to be sure that the trade were absolute, right? Without transactions, you would not be sure that the trade was indeed conducted, and you would have no means of verifying the validity without ambiguity. Having a transactional system ensures that trades are consistently applied and are final. After all, you want to be clear about whether a trade has actually occurred.

This chapter is about working with the past. That past is based upon component technology created by Microsoft to provide, at first, a desktop-oriented protocol for reusing application logic. That technology expanded into a distributed technology that helped better position Microsoft in the enterprise and provide a challenge to competing technologies.