The number of APIs and data formats that developers must learn and support affects the complexity and flexibility of integration. The more interfaces and formats, the greater the cost to implement and maintain an integration framework. SOAP provides a common interface to applications and XML provides a common data format — together, they simplify integration and lower integration costs.
Fewer Application Interfaces
Traditionally, developers create interfaces for each application in an integration project to allow inter-application communication. Because the APIs for each application are different, companies integrating large numbers of applications develop complex integration frameworks that require specialized development skills and lead to increased integration costs. Increased complexity also makes integration architectures less flexible, so that changes in the network and business processes take longer and become more difficult.
Reducing the number of APIs reduces complexity and increases flexibility. Web services based on Internet technologies are not specific to any platform and provide a single API for any application to use. They are loosely coupled and can be invoked directly as traditional APIs, or requests can be sent to a queuing system where transactions can occur at specified dates or times. (Integration using traditional APIs is tightly coupled in that each application accepts input and output using unique data formats. They are usually invoked synchronously and expect to receive an immediate response.)
Web services also provide greater flexibility when designing integration architectures. Because Web services use a common interface, changes to the network or business processes do not affect the ability of individual applications to communicate with each other.
Common Data Formats
Another source of complexity is the proliferation of data formats. In point-topoint integration, each application must transform its own data structures to those of every other application with which they share information. Reducing the number of data formats reduces the number of data transformations that take place as information passes through the integration framework.
Traditional Integration vs. Web Services Integration
Figures 2 and 3 show how reducing the number of APIs and using a common data format based on XML can reduce the complexity in an integration framework. In traditional integration, an application communicates with another application through the target application’s API. Data passing between applications undergoes a transformation from one format to another. Application programmers must be aware of each API and each data format in the framework, which creates a huge learning curve. As you add more applications to the framework, the complexity increases and the burden on developers grows.
Web services integration still requires that one application call another using an API, and data transformation still occurs. However, each application uses SOAP as a common API and XML as a common data format. Therefore, even as the number of applications in the integration framework increases, the burden on the developers remains the same.