Chapter 2: Emergence of Standard Middleware

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Chapter 2 Emergence of Standard Middleware

• Textbook
• IT Architectures and Middleware, Second Edition
• Chris Britton and Peter Bye
• AIT 600
• Jeff Schmitt
• September 22, 2008

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Early Days
3
OSI Seven Layer Stack
4
Remote Procedure Call
5
Marshalling
6
Distributed Transaction Processing
7
Message Queuing
8
Client Server Message Queuing
9
DTP Example
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Transaction using Message Queuing
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Transaction with Reversal
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Summary

• You can build distributed applications without
  middleware there is just a lot of work to do
• Broad categories of middleware (real time,
  message queue, remote DB access).
• Real time good for quick request/response
• Remote DB can have poor performance
  fortransaction processing, but is excellent for
  ad hoc queries on remote databases
• Message queue excels where sender is not
  interested in an immediate response

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Summary

• Real time category widest niche, most variation
• RPCs and various forms of transaction processing
• RPC technology
• makes remote procedure syntactically the same for
  the programmer as a local procedure call
• Disadvantage caller is blocked while waiting for
  server to respond can be alleviated by
  multithreading
• can be large overhead with many clients,
  especially with DB access

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Summary

• Alternatives to RPC -- Tuxedo and IBM LU 6.2
• support distributed transaction processing can
  synchronize transactions in multiple databases
  across the network
• Using message queues
• can be synchronized with database transactions,
  making it possible to build system with message
  integrity
• does not synch DB transactions but reversal
  transactions can be used for similar consistency

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Summary

• Transactions ACID properties are important for
  building systems with high integrity
• Atomicity
• Consistency
• Isolation
• Durability
• Middleware standards are important, although
  development has been long and faltering

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SQL Parsing
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SQL Parsing
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Open Group DTP model