Defining Deployment Requirements

During the initial application design, the focus is always on gathering business requirements and then prototyping. The end result is to determine an effective approach to solving the burning business issues. The problem is that during these initial phases, any type of deployment requirements is neglected. Many enterprises fail to even review them until the application is ready for signoff. Typically, these requirements include the following:

• The application should be deployed in a secure and controlled manner.

• Web Services must be consistently available.

• Web Services must be scalable based on the number of users and the changing business needs.

• Application upgrades must be as transparent as possible to the current business process.

The end result of these types of requirements is what drives enterprises to create a standard data center configuration. This configuration is designed to allow an enterprise to quickly build and roll out applications that are scalable for its long- term business needs. This often provides the physical architecture but is not always the best practice for success.

The InfoPath Configuration

Figure 10.1 shows a typical InfoPath solution configuration within an SOA. This pattern is designed into three logical tiers. The presentation tier serves as the main interaction point for users. Within an InfoPath solution, this includes the form template and any associated resource task panes. It is important to remember that this layer may also include other solutions like an ASP.NET Web form or even a Microsoft Word template.

Figure 10.1: An InfoPath design pattern.

The middle tier houses the business logic that is presented using Web Services. This layer is responsible for providing business-based logic and the discovery-based mechanisms needed by end users to find, locate, and use their business data. At the same time, this layer is responsible for defining the business rules that are applied across the organization. Typically, this is the tier where application developers spend the majority of their time.

At the back end is the data tier. This logical layer contains the storage entity for all enterprise data. Typically, this includes SQL or Microsoft Access databases but may also include other data sources like the file system.

When deploying applications into this type of architecture, system administrators will deploy the logical tiers into multiple physical layers . For example, the data tier is the easiest to deploy and manage using a separate environment. Many enterprises already have in place an operation set of procedures designed to manage this type of environment. These servers are often a part of a separate physical architecture, which allows you to take advantage of things like network load balancing, clustering, fail over, and backup requirements. Regardless of the actual physical implementation, it is important to remember that when you are reviewing a service, it is a logical unit of deployment.