Apache API Notes

1
Apache API Notes

• Robert S. Thau
• (Presented by Justin Erenkrantz)

2
Introduction

• Allow third-parties to extend product
• Expose as much as possible
• C Modules
• Provides hooks and handlers
• May execute arbitrary code
• May be controlled by configuration directives

3
Approach

• Hooks
• Run at well-defined stages of execution
• Run for all requests
• Handlers
• Responsible for serving content
• Only run for specific requests
• May accept or decline request

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Apache 1.3 Hook Stages

• Translate URI-gtFile
• Check user
• Auth check
• Access check
• Type check

• Fixer Upper
• Logger
• Header Parser
• Child Init
• Child Exit
• Post Read Request

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Apache 1.3 Data Model

• Memory Pools
• No malloc()/free()
• Used to optimize memory allocation
• Cleanups
• request_rec, conn_rec
• Core data structures
• Access to headers, file structure

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Strength and Weaknesses

• Proved worth
• Lots of functionality never envisioned
• Fairly robust

• Tied to HTTP
• Tied to files
• Inability to layer
• No ability to thread

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Observations

• Apache HTTP Server 2.0 addresses some of these
  concerns
• Filters and Bucket Brigades
• Threaded processing
• Multi-protocol support
• Requires rewrite of modules