TM :: Transaction stateful proxy support

The TM module enables stateful processing of SIP transactions. More...

Files

• file callid.c

  TM :: Fast Call-ID generator.

  
  

• file callid.h

  TM :: Fast Call-ID generator.

  
  

• file tm/config.c

  TM :: Runtime configuration variables.

  
  

• file modules/tm/config.h

  TM :: Runtime configuration variables.

  
  

• file tm/defs.h

  TM :: Definitions.

  
  

• file dlg.c

  TM ::

  
  

• file dlg.h

  TM ::

  
  

• file h_table.c

  TM ::

  
  

• file h_table.h

  TM :: hash table, flags and other general defines.

  
  

• file tm/sip_msg.c

  TM :: Message cloning functionality.

  
  

• file tm/sip_msg.h

  TM :: Message cloning functionality.

  
  

• file t_mi.c

  TM :: MI functions.

  
  

• file t_mi.h

  TM :: MI functions.

  
  

• file modules/tm/timer.c

  TM :: timer support.

  
  

• file modules/tm/timer.h

  TM :: timer support.

  
  

• file tm/tm.c

  TM :: Module API (core).

  
  

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Detailed Description

The main use of stateful logic, which is costly in terms of memory and CPU, is some services that inherently need state.

For example, transaction-based accounting (module acc) needs to process transaction state as opposed to individual messages, and any kinds of forking must be implemented statefully. Other use of stateful processing is it trading CPU caused by retransmission processing for memory. That however only makes sense if CPU consumption per request is huge. For example, if you want to avoid costly DNS resolution for every retransmission of a request to an unresolvable destination, use stateful mode. Then, only the initial message burdens server by DNS queries, subsequent retransmissions will be dropped and will not result in more processes blocked by DNS resolution. The price is more memory consumption and higher processing latency.

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