IBM's SOMA approach
The SOMA approach is based on a service-oriented architecture template
The architecture template describes a service-oriented hierarchical structure. The bottom layer is the business system layer, which includes all the existing legacy systems of the enterprise, such as the mainframe system, ERP or CRM system developed by the enterprise, or object-oriented system. The second layer is the enterprise-level component layer. These components implement the packaging of existing system functions or provide new functions. In any case, they are the basis for realizing services, so they must also meet the requirements of SLA. In terms of implementation technology, these components are generally components in an application server. The third layer is the service layer, these services can be dynamically discovered, or can be combined into more complex services, they can be reused. The fourth layer is the process layer, which combines the services of the third layer through certain specifications to achieve a specific purpose. The top layer is the presentation layer, which provides interaction with the user. The sixth layer is the integration layer, which is generally implemented by the enterprise business bus, providing basic message routing and some conversion mechanisms, etc., which is independent of the protocol and is the basis for the communication between services. The seventh layer is the service quality layer, which provides monitoring and management of services to ensure the healthy operation of the entire service-oriented architecture.
On the basis of this architectural template, SOMA proposes a methodology for service analysis and design, if 3-9
If shown in 3-9, SOMA mainly consists of three steps, service discovery, service specification and service implementation. Service discovery is service analysis, and service specification belongs to the category of service design. So the three steps actually correspond to the three stages of service-oriented analysis, service-oriented design and implementation. The following mainly introduces service-oriented analysis and design.
In the process of service discovery, SOMA combines top-down, meet-in-the-middle, and bottom-up approaches to discover services. In a top-down approach, domain decomposition is used to divide the business domain into business functional areas and subsystems, and the process is refined into sub-processes and business use cases, which are potential candidate businesses. This method is generally used to identify large-grained services. In the bottom-up approach, through the analysis of the existing system, the existing system is packaged as a service, so as to determine the small-grained service. In the meet-in-the-middle approach, the candidate services that are not captured by the top-down and bottom-up approaches are mainly captured by modeling the target service. In this approach, the business goal is decomposed into sub-goals, key business performance indicators, metrics, etc. are listed, and then possible related services to achieve the goal are analyzed.
Through the above method, a series of candidate services can be obtained. As the number of services increases, it will bring a series of management problems, and lead to system performance degradation, poor scalability and so on. So there needs to be some way to manage the service effectively. After SOMA discovers candidate services, it stratifies services according to its architecture model. Some services that provide the most basic functions can be attributed to the enterprise-level component layer; other services that are composed of other services and provide a more advanced function can be attributed to the service layer; include complex functions and realize the business process. Services are classified as the process layer, thus obtaining the service hierarchy.