Multitier Client/Server SolutionsIn general, client/server is a style of computing that distributes the workload of acomputer application across several cooperating computer programs.This type of computing separates user-oriented, application, and data management tasks.Client/server is mainly a software concept that includes a set of service providers andservice requesters. In client/server computing, individual software components act asservice providers, service requesters, or both. These software services communicate witheach other via predefined interfaces.With the emergence of the Web and Web standards and the ability to have an Internetbrowser as user interface, together with the development of the ITS, the classic threetieredclient/server architecture became a multitier system.Major advantages of the client/server approach are as follows: Flexible configuration. With the deployment of standard communicationinterfaces, there are many possibilities for distributing and planning a client/serverinstallation: from a centralized configuration to a highly distributed system. SeeFigure 1-11. Workload distribution. Because application servers work in parallel andcommunicate with the database, users can be evenly distributed based on their jobtasks. Also, there is the possibility of deploying dedicated application servers tospecific business areas. High scalability. Client/server permits users to adapt the capacity of theirhardware according to the performance needs of their businesses, such as addingadditional application servers when there is an increase in number of users, whenSAP R/3 Handbook, Third Edition31additional modules start production, and when the database becomes larger. Thisenables companies to protect software and hardware investments.Figure 1-11: SAP client/server configurationsOne of the widely used client/server configurations with SAP systems is the three-tieredarchitecture (see Figure 1-12), which separates a system's computers into three functiongroups: presentation, application, and database. Since client/server is a software concept,it must be clear that an application server includes the software components that make upthe provider services for the presentation, acting as a server, but also acting as servicerequester of the database services.Figure 1-12: Classical SAP three-tier architectureThe Internet layer became a new special layer, as can be seen in Figure 1-13.