The System Designer


The System Designer

The System Designer is another of the Distributed System Designers. Although seemingly an optional tool, it is arguably at the heart of the entire suite. When you deploy a distributed application system, you actually deploy a configuration of applications. The applications you deploy need to be configured and connected in a carefully considered way. In doing so, you will achieve both the functional goals of the system and realize a successful deployment. The important point is that you actually deploy a configured use of the applications and not the applications themselves. This is easier to think of if you imagine needing to deploy the same system into two datacenters where each requires a different configuration. In this case, you need to provide different customers with a slightly different configuration of the same basic functions.

A system is a description of such a configuration. You might think the application diagram is the center of the design process, but it is simply a foundation on which to design systems. The Application Designer is used to design the applications and how they can be connected. The system diagram, however, defines how they should actually be connected. The system diagram represents the architectural view of the systems as they will look in your datacenter. Although the application diagram may well include applications that are an artifact of the development process (such as test harnesses or stubs of services), these applications will be excluded from the system that is to be deployed.

It's also important to recognize that a system is not required to be a fully self-contained business application. Systems can selectively expose the behavior of the applications they comprise, so they are composable. Systems can then be created as reusable configurations, composed of applications or other systems that allow you to construct architectures with nested subsystems.

For example, an architect might want to group two ASP.NET Web services into a security system. This is done because those Web services implement authentication and authorization. To create a system, the application architect just needs to highlight one or more applications in the Application Designer, right-click one of them, and choose Design Application System. Visual Studio will prompt for the name of the system (as shown in Figure 5-13) and then open the System Designer, allowing the architect to arrange the constituent applications and override any additional settings.

To selectively expose the behavior of a member application in the system, you can select the endpoint to expose, and from the right-click menu select Add Proxy Endpoint. This adds a proxy endpoint on the system that is delegated to the application endpoint. If you now create another system and add it to the system you just built, you will see the proxy endpoint that you just created and be able to connect this to other applications or systems as required. A final system diagram is shown in Figure 5-14.

figure 5-13 naming your new system

Figure 5-13 Naming your new system

figure 5-14 the system designer

Figure 5-14 The System Designer



Working with Microsoft Visual Studio 2005 Team System
Working with Microsoft Visual Studio 2005 Team System (Pro-Developer)
ISBN: 0735621853
EAN: 2147483647
Year: 2006
Pages: 97

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