17. Interprocess Communication and Networking

The modules described in this chapter provide mechanisms for different processes to communicate.

Some modules only work for two processes that are on the same machine, e.g. signal and subprocess. Other modules support networking protocols that two or more processes can used to communicate across machines.

The list of modules described in this chapter is:

• 17.1. subprocess — Subprocess management
  • 17.1.1. Using the subprocess Module
    • 17.1.1.1. Frequently Used Arguments
    • 17.1.1.2. Popen Constructor
    • 17.1.1.3. Exceptions
    • 17.1.1.4. Security
  • 17.1.2. Popen Objects
  • 17.1.3. Windows Popen Helpers
    • 17.1.3.1. Constants
  • 17.1.4. Replacing Older Functions with the subprocess Module
    • 17.1.4.1. Replacing /bin/sh shell backquote
    • 17.1.4.2. Replacing shell pipeline
    • 17.1.4.3. Replacing os.system()
    • 17.1.4.4. Replacing the os.spawn family
    • 17.1.4.5. Replacing os.popen(), os.popen2(), os.popen3()
    • 17.1.4.6. Replacing functions from the popen2 module
  • 17.1.5. Legacy Shell Invocation Functions
  • 17.1.6. Notes
    • 17.1.6.1. Converting an argument sequence to a string on Windows
• 17.2. socket — Low-level networking interface
  • 17.2.1. Socket families
  • 17.2.2. Module contents
  • 17.2.3. Socket Objects
  • 17.2.4. Notes on socket timeouts
    • 17.2.4.1. Timeouts and the connect method
    • 17.2.4.2. Timeouts and the accept method
  • 17.2.5. Example
• 17.3. ssl — TLS/SSL wrapper for socket objects
  • 17.3.1. Functions, Constants, and Exceptions
    • 17.3.1.1. Socket creation
    • 17.3.1.2. Random generation
    • 17.3.1.3. Certificate handling
    • 17.3.1.4. Constants
  • 17.3.2. SSL Sockets
  • 17.3.3. SSL Contexts
  • 17.3.4. Certificates
    • 17.3.4.1. Certificate chains
    • 17.3.4.2. CA certificates
    • 17.3.4.3. Combined key and certificate
    • 17.3.4.4. Self-signed certificates
  • 17.3.5. Examples
    • 17.3.5.1. Testing for SSL support
    • 17.3.5.2. Client-side operation
    • 17.3.5.3. Server-side operation
  • 17.3.6. Notes on non-blocking sockets
  • 17.3.7. Security considerations
    • 17.3.7.1. Verifying certificates
    • 17.3.7.2. Protocol versions
    • 17.3.7.3. Cipher selection
• 17.4. signal — Set handlers for asynchronous events
  • 17.4.1. General rules
    • 17.4.1.1. Execution of Python signal handlers
    • 17.4.1.2. Signals and threads
  • 17.4.2. Module contents
  • 17.4.3. Example
• 17.5. asyncore — Asynchronous socket handler
  • 17.5.1. asyncore Example basic HTTP client
  • 17.5.2. asyncore Example basic echo server
• 17.6. asynchat — Asynchronous socket command/response handler
  • 17.6.1. asynchat - Auxiliary Classes
  • 17.6.2. asynchat Example