Three-tier architecture/N -tier architecture. Another limitation is caused by the dimension of the data to maintain, manage, and access, which might be prohibitive for a single computation node or too large for serving the clients with satisfactory performance. In particular, as the number of users increases the performance of the server might dramatically decrease. This architecture is suitable for systems of limited size and suffers from scalability issues. The server component is generally deployed on a powerful machine that is capable of processing user requests, accessing data, and executing the application logic to provide a client with a response. The client is responsible for the presentation tier by providing a user interface the server concentrates the application logic and the data store into a single tier. This architecture partitions the systems into two tiers, which are located one in the client component and the other on the server. The mapping between the conceptual layers and their physical implementation in modules and components allows differentiating among several types of architectures, which go under the name of multitiered architectures. Presentation, application logic, and data maintenance can be seen as conceptual layers, which are more appropriately called tiers. In the fat-client model, the client encapsulates presentation and most of the application logic, and the server is principally responsible for the data storage and maintenance. In the thin-client model, the client embodies only the presentation component, while the server absorbs the other two. The three major components in the client-server model: presentation, application logic, and data storage. In this model, the client component is also responsible for processing and transforming the data before returning it to the user, whereas the server features a relatively light implementation that is mostly concerned with the management of access to the data. In this model, the load of data processing and transformation is put on the server side, and the client has a light implementation that is mostly concerned with retrieving and returning the data it is being asked for, with no considerable further processing. For the client design, we identify two major models: This consideration has implications on both client design and server design. In general, multiple clients are interested in such services and the server must be appropriately designed to efficiently serve requests coming from different clients. The client/server model is suitable in many-to-one scenarios, where the information and the services of interest can be centralized and accessed through a single access point: the server.
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