final_notes

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 won’t 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 module’s 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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