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Note for Cloud Computing - CC By Sonam Choudhary

  • Cloud Computing - CC
  • Note
  • Maharaja Ganga Singh University - MGSU
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Tier Architecture Presentation Logic 7 Business Logic Client (dumb) - Server Model Data Source 2 Tier - Fat Client Server Client Client Server Presentation Logic 2 Tier - Thin Client (or Fat Server) Client Network Server Application Logic 3 Tier Client Application Server DBMS Database Server True Client-Server Model 9 Distributed Client-Server Model Server Client Application Logic Application Logic Network 10 Server Client Application Logic Presentation Logic 8 Network DBMS DBMS Presentation Logic Client/Server Computing  Logical extension of modular programming  11 Client/Server Computing  appropriate hardware and software platforms for with assumption that separation of a huge program into their functions. modules can create  Clients and Servers are running separately on  For example, database management system servers  the possibility for further modification  easier development running on platforms specially designed and  better maintainability. configured to perform queries, or file servers running on platforms with special elements for managing files. All large modules need not all be executed within the same memory space.  Components in Client-Server Computing  Client  the calling module becomes the client( requesting service)  Server  the called module becomes the server (providing service).  Middleware In client-server computing major focus is on SOFTWARE 12

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Middleware Software 13 It is the (/) between client and server which glues them together  Allowing the client request for a service and the server providing it  Middleware can also be between server/server  Two broad classes  General calling procedure 14 called procedure  3. results Six types of middleware 2. called procedure (client) Network Remote Procedure Call 1. arguments Database specific: SQL request message Internet specific: HTTP  arguments  reply message Groupware specific: SMTP results Used to accomplish a specific task  server stub network transport reply message Application specific  results LAN servers, TCP/IP, Communication stacks, Queuing services, etc. request message  arguments  client stub network transport calling procedure (client) 15 Local Procedure Call Six types of middleware 16 Asynchronous Remote Procedure Calls (RPC) 4. Message-Oriented Middleware (MOM) • client makes calls to procedures running on remote computers but does not wait for a response • If connection is lost, client must re-establish the connection and send request again. • High scalability but low recovery, largely replaced by type 2 • asynchronous – sends messages that are collected and stored until they are acted upon, while the client continues with other processing. 5. Object Request Broker (ORB) Synchronous RPC • distributed program may call services on different computers • makes it possible to achieve this without detailed coding (e.g. RMI in Java) • object-oriented management of communications between clients and servers. • ORB tracks the location of each object and routes requests to each object. Publish/Subscribe (often called push technology) • server monitors activity and sends information to client when available. • It is asynchronous, the clients (subscribers) perform other activities between notifications from the server. • Useful for monitoring situations where actions need to be taken when particular events occur. Computing Model File Transfer Model Distributed Computing Model Client/Server Model • middleware between applications and database servers. 17 Computing Model Terminal Host Model 6. SQL-oriented Data Access Peer to Peer Model • Has the capability to translate generic SQL into the SQL specific to the database References  Farid Farahmand, "An Introduction to Client/Server Architecture"  Rajkumar Buyya, "Client/Server Computing (the wave of the future)"  Albert Yau, "Client Server Computing", http://www.doc.ic.ac.uk/~nd/surprise_95/journal/vol1/wcy/article1.html 18

Lecture Notes