chapter04 - Heterogeneity Applies to all of the following...

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Heterogeneity Applies to all of the following: networks Internet protocols mask the differences between networks computer hardware e.g. data types such as integers can be represented differently operating systems e.g. the API to IP differs from one OS to another programming languages data structures (arrays, records) can be represented differently implementations by different developers they need agreed standards so as to be able to interwork Middleware provides a programming abstraction and masks the heterogeneity of networks etc.
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Middleware layers Applications Middleware layers Request reply protocol External data representation Operating System RMI, RPC and events Programming model Interprocess communication
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Chapter 5: Middleware programming models Procedure call model via remote procedure call ( RPC ) E.g. Sun RPC Object-based model via remote method invocation ( RMI ) E.g. Java RMI or CORBA Event-based model via remote event notification E.g. Jini distributed event specification
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Introduction The API for the Internet protocols External data representation and marshalling Client-Server communication Group communication Case study: interprocess communication in UNIX Summary Chapter 4: Interprocess Communication
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Introduction The API for the Internet protocols External data representation and marshalling Client-Server communication Group communication Case study: interprocess communication in UNIX Summary Chapter 4: Interprocess Communication
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Synchronous and asynchronous a queue associated with message destination, Sending process add message to remote queue, Receiving process remove message from local queue Synchronous: send and receive are blocking operations asynchronous: send is unblocking, receive could be blocking or unblocking (receive notification by polling or interrupt) Message destination Internet address + local port service name: help by name service at run time location independent identifiers, e.g. in Mach Reliability validity: messages are guaranteed to be delivered despite a reasonable number of packets being dropped or lost Integrity: messages arrive uncorrupted and without duplication Ordering the messages be delivered in sender order The characteristics of interprocess communication
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Endpoint for communication between processes Both forms of communication (UDP and TCP ) use the socket abstraction Originate from BSD Unix, be present in most versions of UNIX Socket message agreed port any port socket socket Internet address = 138.37.88.249 Internet address = 138.37.94.248 other ports client server
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UDP datagrams are sent without acknowledgement or retries Issues relating to datagram communication Message size : not bigger than 64k in size, otherwise truncated on arrival blocking : non-blocking sends (message could be discarded at destination if
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This note was uploaded on 06/12/2011 for the course CS 551 taught by Professor Staff during the Summer '08 term at Colorado State.

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chapter04 - Heterogeneity Applies to all of the following...

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