final_notes - Final Study Notes December 8, 2008 Please...

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Unformatted text preview: Final Study Notes December 8, 2008 Please notice that the final is accumulative , so please review the material before midterm as well. This note could be considered only as a reference. It wont cover all the details . Please keep this in mind when using. Messerschmitt Ch 5 Client Server Computing Client-Server Architecture [pp140] Three-Tier Client Server Architecture [pp144 146, Table 5.1] Shared data, application logic, presentation Reason: ensure the integrity of data, managing data by DBMS separately, security and relia- bility; data sharing among many applications Thin Clients Keeping application logic out of client = thin client, NC, Sun Fat client, Microsoft Messerschmitt Ch 6 Modularity and Layering Modularity Decompose the system into smaller subsystems which reduces the complexity Module : subsystems after decomposition Granularity [pp 162] Determines the number of modules and the range of functionality of each Fine or coarse - grained Hierarchy Modules are themselves composed of internal modules Enables to define different granularity as appropriate Interfaces actions, parameters, and returns Each module interacts with the others through its interface Interface demonstrates: (1) what functions are performed by this module; (2) how to invoke those functions Interface vs. Implementation 1 Final Review Notes , (Bob) Action : simply something specific that the module does Parameters : data that the server module expects to receive in the course of invoking that action, which customize that action Returns : data that the client module expects to receive back Encapsulation : making a modules implementation details inaccessible to other modules The Layering Principle [pp172 173, Figure 6.5] Each layer is a server to the layer above, providing a standard set of actions but not revealing the implementation. Thus, the implementation of one layer can be changed w/o affecting the layers above. Each layer is a client to the layer below, utilizing its available actions in the course of providing its services to the layer above it. Each layer is permitted to interact w/ only layers immediately above and below. Thus, a layer would hide the layers below it. Layers of computing Infrastructure [pp 175, Table 6.5, Figure 6.7] Applications Application Components Middleware Operating System (OS) Networks Infrastructure : Middleware, OS, Networks Data and Information in Layers Data Information, structure and interpretation; Applications deal w/ information while infrastructure deals w/ data, separation of concerns Package of data = file (in storage context) or message (in communication) Platform heterogeneity = middlewares perform the conversion of various platform-specific representations eg. DBMS, DOM [pp 181, Figure 6.10] Abstraction and Encapsulation Abstraction...
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final_notes - Final Study Notes December 8, 2008 Please...

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