CAF: Call Legs Resync

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= Call Legs Resynchronization =
 
= Call Legs Resynchronization =
 
Since the [[Toolpack]] framework has been designed for HA ([[High_Availability_Overview]]), it's mandatory that an application that manage calls through [[CAF_Call_interface]] is able to deal with call legs re-synchronization.
 
Since the [[Toolpack]] framework has been designed for HA ([[High_Availability_Overview]]), it's mandatory that an application that manage calls through [[CAF_Call_interface]] is able to deal with call legs re-synchronization.
 +
 +
The current page contains an overview of how re-synchronization works. For more details, please refer to the following section of the this page:
 +
 +
[[CAF:_Working_With_Caf_Call_Legs#Re-synchronizing_with_toolpack_engine]]
  
 
== Situations where call leg resynchronization is required ==
 
== Situations where call leg resynchronization is required ==
 
Call legs re-synchronization is required whenever the CAF application looses communication with [[Toolpack_Application:toolpack_engine|toolpack_engine]]:
 
Call legs re-synchronization is required whenever the CAF application looses communication with [[Toolpack_Application:toolpack_engine|toolpack_engine]]:
−
- CAF application was restarted
+
* The CAF application was restarted
−
- [[Toolpack_Application:toolpack_engine|toolpack_engine]] was restarted
+
* The [[Toolpack_Application:toolpack_engine|toolpack_engine]] was restarted
−
- HA swithover caused CAF application, [[Toolpack_Application:toolpack_engine|toolpack_engine]], or both, to be activated on a redundant host
+
* Network connection between CAF application and [[Toolpack_Application:toolpack_engine|toolpack_engine]] was momentarily down
−
- Network communication was interrupted between CAF application and [[Toolpack_Application:toolpack_engine|toolpack_engine]]
+
  
 
== General principles of call legs re-sync ==
 
== General principles of call legs re-sync ==
 
=== Toolpack Engine ===
 
=== Toolpack Engine ===
 
The [[Toolpack_Application:toolpack_engine|toolpack_engine]] application, when restarted, will re-build it's call leg contexts by querying information on the TMedia Units.
 
The [[Toolpack_Application:toolpack_engine|toolpack_engine]] application, when restarted, will re-build it's call leg contexts by querying information on the TMedia Units.
−
- Transient calls (not yet answered) will be dropped
+
* Transient calls (not yet answered) will be dropped
−
- Terminating calls will be dropped
+
* Terminating calls will be dropped
−
- Active (answered) calls will be re-build like they were before [[Toolpack_Application:toolpack_engine|toolpack_engine]] was restarted
+
* Active (answered) calls will be re-build like they were before [[Toolpack_Application:toolpack_engine|toolpack_engine]] was restarted
  
−
=== [[CAF_Call_interface]] application ===
+
=== CAF application ===
−
The call control application based on the [[CAF_Call_interface]] API will re-build it's call leg contexts by getting information from [[Toolpack_Application:toolpack_engine|toolpack_engine]].
+
The CAF call control application that was disconnected from [[Toolpack_Application:toolpack_engine|toolpack_engine]] will update (or re-build) it's call leg contexts by getting information automatically pushed by [[Toolpack_Application:toolpack_engine|toolpack_engine]] upon re-connection.
  
 
All active (answered) calls will be re-synchronized from [[Toolpack_Application:toolpack_engine|toolpack_engine]].
 
All active (answered) calls will be re-synchronized from [[Toolpack_Application:toolpack_engine|toolpack_engine]].
−
- Calls already known by the application will remain valid
+
* Calls already known by the application will remain valid
−
- Calls unknown by the application will be re-constructed: ''OnCallLegSync'', ''OnLinkSync''
+
* Calls unknown by the application will be re-constructed (or refused): ''OnCallLegSync'', ''OnLinkSync''
−
- Calls known by the application, but no more present in [[Toolpack_Application:toolpack_engine|toolpack_engine]] are terminated: ''OnCallLegTerminated''
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* Calls known by the application, but no more present in [[Toolpack_Application:toolpack_engine|toolpack_engine]] are terminated: ''OnCallLegTerminated''
 +
 
 +
== Example scenarios ==
 +
[[Image:CAFCallFlow_examples_initial.png|thumb|480px|Example scenario: Initial state]]
 +
 
 +
In all the scenarios below, let's consider the following situation:
 +
* Leg-A:  Ringing
 +
* Leg-B:  Terminating
 +
* Leg-C:  Active (answered)
 +
* Leg-D:  Active (answered)
 +
* Leg-E:  Active (answered)
 +
* Leg-C and Leg-D are joined (connected) together
 +
* Mixer-1: Ready
 +
* Leg-E and Mixer-1 are joined (connected)
 +
 
 +
=== Scenario 1: toolpack_engine quickly restarted ===
 +
[[Image:CAFCallFlow_examples_scenario_1.png|thumb|480px|Example scenario 1]]
 +
 
 +
* CAF Application is notified
 +
** ''OnCmcLibNotReady()''
 +
** ''OnSyncLost()'' for Leg-A, Leg-B, Leg-C, Leg-D and Leg-E
 +
** ''OnMixerSyncLost()'' on Mixer-1
 +
* toolpack_engine restarts
 +
** Queries information from all TMedia units
 +
** Drop incomplete legs and mixers (here Leg-A and Leg-B)
 +
** Re-build contexts for active legs and mixers (here Leg-C, Leg-D, Leg-E and Mixer-1)
 +
** Re-build connections between legs/mixers (here Leg-C with Leg-D, Leg-E with Mixer-1)
 +
* toolpack_engine pushes information to CAF library:
 +
** Legs: Leg-C, Leg-D and Leg-E
 +
** Mixers: Mixer-1
 +
** Connections: Leg-C with Leg-D,  Leg-E with Mixer-1
 +
* CAF library compares with it's own contexts:
 +
** ''OnCallLegTerminated()'' for Leg-A and Leg-B
 +
** ''OnSyncDone()'' for Leg-C, Leg-D and Leg-E
 +
** ''OnMixerSyncDone()'' for Mixer-1
 +
* Ready to continue
 +
** ''OnCmcLibReady()''
 +
 
 +
=== Scenario 2: toolpack_engine stopped (disconnected) for more than 10 seconds ===
 +
[[Image:CAFCallFlow_examples_scenario_2.png|thumb|480px|Example scenario 2]]
 +
 
 +
* CAF Application is notified
 +
** ''OnCmcLibNotReady()''
 +
** ''OnSyncLost()'' for Leg-A, Leg-B, Leg-C, Leg-D and Leg-E
 +
** ''OnMixerSyncLost()'' on Mixer-1
 +
(... 10 seconds elapse...)
 +
* CAF Application declares toolpack_engine "dead", destroys all it's local contexts:
 +
** ''OnCallLegTerminated()'' for all legs: Leg-A, Leg-B, Leg-C, Leg-D and Leg-E
 +
** ''OnMixerTerminated()'' for all mixers: Mixer-1
 +
(... some time elapse...)
 +
* toolpack_engine is restarted
 +
** Queries information from all TMedia units
 +
** Drop incomplete legs and mixers (here Leg-A and Leg-B)
 +
** Re-build contexts for active legs and mixers (here Leg-C, Leg-D, Leg-E and Mixer-1)
 +
** Re-build connections between legs/mixers (here Leg-C with Leg-D, Leg-E with Mixer-1)
 +
* toolpack_engine pushes information to CAF library:
 +
** Legs: Leg-C, Leg-D and Leg-E
 +
** Mixers: Mixer-1
 +
** Connections: Leg-C with Leg-D,  Leg-E with Mixer-1
 +
* CAF library compares with it's own contexts (none!):
 +
** ''OnCallLegSync()'' for Leg-C, Leg-D and Leg-E
 +
*** Application may refuse them: ''RefuseLeg()''
 +
*** Application may re-allocate new contexts for these legs
 +
** ''OnMixerSync()'' for Mixer-1
 +
*** Application may refuse: ''RefuseMixer()''
 +
*** Application may re-allocate new contexts for these mixers
 +
** ''OnLinkSync()'' for Leg-C with Leg-D
 +
*** Application may refuse: ''RefuseLink()''
 +
*** Application may re-allocate new "call flow" contexts, re-bind legs to them (''BindCallLeg'')
 +
** ''OnMixerLinkSync()'' for Leg-E with Mixer-1
 +
*** Application may refuse: ''RefuseMixerLink()''
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*** Application may re-allocate new "call flow" contexts, re-bind legs/mixers to them (''BindCallLeg'', ''BindMixer'')
 +
* Ready to continue
 +
** ''OnCmcLibReady()''
 +
 
 +
=== Scenario 3: CAF application is restarted ===
 +
[[Image:CAFCallFlow_examples_scenario_3.png|thumb|480px|Example scenario 3]]
 +
 
 +
* If the application is quitting in a 'clean' manner
 +
** 'OnLegFreed()' is called for all call legs (Leg-A, Leg-B, Leg-C, Leg-D and Leg-E)
 +
** Destructor of all call flows is called
 +
* When the application is restarted
 +
** => This is exactly same scenario as the end of Scenario 2 after step 'toolpack_engine pushes information to CAF library'.
 +
 
 +
= For more information... =
 +
The current page contains an overview of how re-synchronization works. For more details, please refer to the following page:
  
−
=== CAF application was restarted ===
+
[[CAF:_Working_With_Caf_Call_Legs#Re-synchronizing_with_toolpack_engine]]
−
In this situation, the CAF application was restarted (on purpose, or after a crash). It does a cold start up, without any call leg contexts.
+

Latest revision as of 06:32, 23 January 2014

Contents

Call Legs Resynchronization

Since the Toolpack framework has been designed for HA (High_Availability_Overview), it's mandatory that an application that manage calls through CAF_Call_interface is able to deal with call legs re-synchronization.

The current page contains an overview of how re-synchronization works. For more details, please refer to the following section of the this page:

CAF:_Working_With_Caf_Call_Legs#Re-synchronizing_with_toolpack_engine

Situations where call leg resynchronization is required

Call legs re-synchronization is required whenever the CAF application looses communication with toolpack_engine:

  • The CAF application was restarted
  • The toolpack_engine was restarted
  • Network connection between CAF application and toolpack_engine was momentarily down

General principles of call legs re-sync

Toolpack Engine

The toolpack_engine application, when restarted, will re-build it's call leg contexts by querying information on the TMedia Units.

  • Transient calls (not yet answered) will be dropped
  • Terminating calls will be dropped
  • Active (answered) calls will be re-build like they were before toolpack_engine was restarted

CAF application

The CAF call control application that was disconnected from toolpack_engine will update (or re-build) it's call leg contexts by getting information automatically pushed by toolpack_engine upon re-connection.

All active (answered) calls will be re-synchronized from toolpack_engine.

  • Calls already known by the application will remain valid
  • Calls unknown by the application will be re-constructed (or refused): OnCallLegSync, OnLinkSync
  • Calls known by the application, but no more present in toolpack_engine are terminated: OnCallLegTerminated

Example scenarios

Example scenario: Initial state

In all the scenarios below, let's consider the following situation:

  • Leg-A: Ringing
  • Leg-B: Terminating
  • Leg-C: Active (answered)
  • Leg-D: Active (answered)
  • Leg-E: Active (answered)
  • Leg-C and Leg-D are joined (connected) together
  • Mixer-1: Ready
  • Leg-E and Mixer-1 are joined (connected)

Scenario 1: toolpack_engine quickly restarted

Example scenario 1
  • CAF Application is notified
    • OnCmcLibNotReady()
    • OnSyncLost() for Leg-A, Leg-B, Leg-C, Leg-D and Leg-E
    • OnMixerSyncLost() on Mixer-1
  • toolpack_engine restarts
    • Queries information from all TMedia units
    • Drop incomplete legs and mixers (here Leg-A and Leg-B)
    • Re-build contexts for active legs and mixers (here Leg-C, Leg-D, Leg-E and Mixer-1)
    • Re-build connections between legs/mixers (here Leg-C with Leg-D, Leg-E with Mixer-1)
  • toolpack_engine pushes information to CAF library:
    • Legs: Leg-C, Leg-D and Leg-E
    • Mixers: Mixer-1
    • Connections: Leg-C with Leg-D, Leg-E with Mixer-1
  • CAF library compares with it's own contexts:
    • OnCallLegTerminated() for Leg-A and Leg-B
    • OnSyncDone() for Leg-C, Leg-D and Leg-E
    • OnMixerSyncDone() for Mixer-1
  • Ready to continue
    • OnCmcLibReady()

Scenario 2: toolpack_engine stopped (disconnected) for more than 10 seconds

Example scenario 2
  • CAF Application is notified
    • OnCmcLibNotReady()
    • OnSyncLost() for Leg-A, Leg-B, Leg-C, Leg-D and Leg-E
    • OnMixerSyncLost() on Mixer-1

(... 10 seconds elapse...)

  • CAF Application declares toolpack_engine "dead", destroys all it's local contexts:
    • OnCallLegTerminated() for all legs: Leg-A, Leg-B, Leg-C, Leg-D and Leg-E
    • OnMixerTerminated() for all mixers: Mixer-1

(... some time elapse...)

  • toolpack_engine is restarted
    • Queries information from all TMedia units
    • Drop incomplete legs and mixers (here Leg-A and Leg-B)
    • Re-build contexts for active legs and mixers (here Leg-C, Leg-D, Leg-E and Mixer-1)
    • Re-build connections between legs/mixers (here Leg-C with Leg-D, Leg-E with Mixer-1)
  • toolpack_engine pushes information to CAF library:
    • Legs: Leg-C, Leg-D and Leg-E
    • Mixers: Mixer-1
    • Connections: Leg-C with Leg-D, Leg-E with Mixer-1
  • CAF library compares with it's own contexts (none!):
    • OnCallLegSync() for Leg-C, Leg-D and Leg-E
      • Application may refuse them: RefuseLeg()
      • Application may re-allocate new contexts for these legs
    • OnMixerSync() for Mixer-1
      • Application may refuse: RefuseMixer()
      • Application may re-allocate new contexts for these mixers
    • OnLinkSync() for Leg-C with Leg-D
      • Application may refuse: RefuseLink()
      • Application may re-allocate new "call flow" contexts, re-bind legs to them (BindCallLeg)
    • OnMixerLinkSync() for Leg-E with Mixer-1
      • Application may refuse: RefuseMixerLink()
      • Application may re-allocate new "call flow" contexts, re-bind legs/mixers to them (BindCallLeg, BindMixer)
  • Ready to continue
    • OnCmcLibReady()

Scenario 3: CAF application is restarted

Example scenario 3
  • If the application is quitting in a 'clean' manner
    • 'OnLegFreed()' is called for all call legs (Leg-A, Leg-B, Leg-C, Leg-D and Leg-E)
    • Destructor of all call flows is called
  • When the application is restarted
    • => This is exactly same scenario as the end of Scenario 2 after step 'toolpack_engine pushes information to CAF library'.

For more information...

The current page contains an overview of how re-synchronization works. For more details, please refer to the following page:

CAF:_Working_With_Caf_Call_Legs#Re-synchronizing_with_toolpack_engine

Retrieved from "https://docs.telcobridges.com/mediawiki/index.php?title=CAF:_Call_Legs_Resync&oldid=14887"
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