Server Programming in C

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Server Programming in C

• Wesley Bao, November 2005

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Agenda

• The myth and reality of design
• Purpose and overview of the slides
• Architectural perspectives
• Implementation perspectives
• Its decision time
• Analysis of real-world implementations
• Q A

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The Myth of Design

• Rumor had it that you can follow some design
  process/methodology and come out with a great
  design from scratch
• Rumor had it that you can explore and prototype
  alternatives, learn from failures and then choose
  the most suitable architecture/design
• That is the case in research labs and (to some
  extent) OSS world

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The Reality of Design

• In reality, you seldom program to a brand new
  domain you seldom have the luxury to explore
  alternatives prototypes can prove something
  wrong but cannot prove something right.
• Thats why they hire experienced engineers who
  had already familiarized with the domain and
  explored alternatives elsewhere before to
  architect and design solutions people are not
  very much willing to pay for trial-and-error
• Patterns are a good way to document and pass on
  experience (due diligence)

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Purpose and Overview

• Server programming domain knowledge in a nutshell
• Explore architecture, design and implementation
  alternatives, demonstrate their pros and cons
  backed by real data
• Analyze a few real-world examples to see why they
  choose certain alternatives

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Architectural Perspectives

• Iterative
• Kernel thread (process) per Connection
• User space thread (fiber) per Connection
• Thread per Request (active connection)
• Leader/Follower
• Half Sync/Half Async
• Active Objects
• Reactor (level triggered)
• Proactor (edge triggered)
• How to manage session state
• Clustered servers load balancing routing server

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Implementation Perspectives

• blocking I/O in threads
• select, poll, dev/poll
• epoll, rt signal, aio
• kqueue
• IOCP
• Build server into the kernel
• A survey of platform capabilities
• Resource Pooling

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Its Decision Time

• Short vs. long-duration sessions
• Fixed packet length or you have to find the
  boundary
• How long will the idle time likely be
• Request/Response characteristics
• Protocol Examples
• Target user SMB? Enterprise? xSP?
• Target platforms cross-platform? Dedicated to
  few platforms? Appliance?
• Use wrappers to build in flexibility? How
  flexible can it be?

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Real-world Implementations

• Frameworks (aka half-cooked applications)
• ACE
• Indy
• Infrastructures
• JVM on various platforms
• Server-side applications
• QTSS
• others