The document discusses the composite message pattern, which organizes communication between components by packaging all data into message objects. This simplifies interaction, minimizes communication overhead, and allows components to be easily added or removed with minimal changes. The pattern supports efficient memory management and reflexibility in networked systems.

1. YoungSu, Son [email_address] Microsoft MVP EvaCast Leader Devpia Architecture Sysop EvaCast ( http://www.EvaCast.net )

3. Motivation (cont’d) Data Layer Composite Message Messages UnMarshaling Marshaling Layer Decomposite Message Dispatching

4. Motivation (cont’d)

8. Composite Pattern

9. Factory Method Pattern

14. Virtual File System Fault Address Space (Page Table) Read Communicate Communicate Page-Frame Physical Page Disk Block File Contents

17. Distributed Virtual System

21. Loosely Coupled Component

22. Loosely Coupled Component Data Layer pushPacket() calls makeHeader() / marshal() Messages UnMarshaling Marshaling Layer popPacket() calls headerSize() / unmarshal Dispatching

29. Static Participants #1 - loosely Coupled System

33. Static Participants #2 - Tightly Coupled System

36. Dynamic Participants

55. DVMMessage Code Class DVMMessage { /* Network Protocol Header */ //Leave space for Underlying Protocol Header // such as the Ethernet Header; unsigned _underlyingHeaderSize; unsigned _packetSize; //DVM Protocol using local identifiers DVMMessageType _type; unsigned _source; unsigned _destination; unsigned _timestamp; unsigned _checksum; /* Header and Auxiliary Header */ //Page List Header unsigned _totalNumberOfPages; unsigned _thisPageNumber; unsigned _offsetInPages; unsigned _pageFramentSize; } // List of pages to marshal from and unmarshal to. Page * _pageList; Page * _pageBeingProcessed /* Getter and Setter Functions */ //Expose using friend interfaces. … . public: //add pages to the list similar to add() //for the abstract message void addPages (Page * morePages); //marshal to buffer from page void marshal (unsigned *buffer, unsigned bufferSize); //unmarshal from buffer into page void unmarshal (unsigned* buffer, unsigned bufferSize); };

56. Fragmentation Message Code class Fragmenation { public : //calculate proper framents and ask message // to marshal parts of itself into the buffer. void makeFrags ( DVMMessage *m , unsigned * buffer, unsigned * bufferSize);