When a user logs out, each of the simulators (cm1, cm2, etc) generates a message to each of the logging out user's friends that they are no longer connected. You can see the effect of this in the Simian log when the user diconnects:
DEBUG - 2013-04-01 23:18:30 --> Executed RemoveSession in 3.0020670890808 seconds
DEBUG - 2013-04-01 23:18:31 --> Executed AddUserData in 0.013710975646973 seconds
DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 1f0dee7c-e861-4280-aadc-81034d8bf6b5
DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 1f0dee7c-e861-4280-aadc-81034d8bf6b5
DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.0039119720458984 seconds
DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.010758876800537 seconds
DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 1f0dee7c-e861-4280-aadc-81034d8bf6b5
DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.0097401142120361 seconds
DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.0033140182495117 seconds
DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.0033609867095947 seconds
DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.0034768581390381 seconds
DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 20279ee3-b013-43df-b97f-0f2ce1e5fa90
DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.0037319660186768 seconds
DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 20279ee3-b013-43df-b97f-0f2ce1e5fa90
DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.0030350685119629 seconds
DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 20279ee3-b013-43df-b97f-0f2ce1e5fa90
DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.0031540393829346 seconds
DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.0031540393829346 seconds
DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.0029211044311523 seconds
DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 24560b63-1df1-4373-bd19-02299450fcd8
DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.0035989284515381 seconds
DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.0044519901275635 seconds
DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 24560b63-1df1-4373-bd19-02299450fcd8
DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.0033779144287109 seconds
DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 24560b63-1df1-4373-bd19-02299450fcd8
DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.013105154037476 seconds
DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.011214017868042 seconds
DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.007735013961792 seconds
DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 3271dcd4-2aa4-4ad0-9d56-7f041f5fdc71
DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.0031108856201172 seconds
DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.0045199394226074 seconds
DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 3271dcd4-2aa4-4ad0-9d56-7f041f5fdc71
DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.0032567977905273 seconds
DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.0031249523162842 seconds
DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 3271dcd4-2aa4-4ad0-9d56-7f041f5fdc71
DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.0033278465270996 seconds
DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.0028359889984131 seconds
DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.0085370540618896 seconds
DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 6a506636-1b77-4e25-af62-f02cdfb63aca
DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 6a506636-1b77-4e25-af62-f02cdfb63aca
DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.014625072479248 seconds
DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 6a506636-1b77-4e25-af62-f02cdfb63aca
When a user logs out, each of the simulators (cm1, cm2, etc) generates a message to each of the logging out user's friends that they are no longer connected. You can see the effect of this in the Simian log when the user diconnects:
DEBUG - 2013-04-01 23:18:30 --> Executed RemoveSession in 3.0020670890808 seconds DEBUG - 2013-04-01 23:18:31 --> Executed AddUserData in 0.013710975646973 seconds DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 1f0dee7c-e861-4280-aadc-81034d8bf6b5 DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 1f0dee7c-e861-4280-aadc-81034d8bf6b5 DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.0039119720458984 seconds DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.010758876800537 seconds DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 1f0dee7c-e861-4280-aadc-81034d8bf6b5 DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.0097401142120361 seconds DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.0033140182495117 seconds DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.0033609867095947 seconds DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.0034768581390381 seconds DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 20279ee3-b013-43df-b97f-0f2ce1e5fa90 DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.0037319660186768 seconds DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 20279ee3-b013-43df-b97f-0f2ce1e5fa90 DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.0030350685119629 seconds DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 20279ee3-b013-43df-b97f-0f2ce1e5fa90 DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.0031540393829346 seconds DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.0031540393829346 seconds DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.0029211044311523 seconds DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 24560b63-1df1-4373-bd19-02299450fcd8 DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.0035989284515381 seconds DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.0044519901275635 seconds DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 24560b63-1df1-4373-bd19-02299450fcd8 DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.0033779144287109 seconds DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 24560b63-1df1-4373-bd19-02299450fcd8 DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.013105154037476 seconds DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.011214017868042 seconds DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.007735013961792 seconds DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 3271dcd4-2aa4-4ad0-9d56-7f041f5fdc71 DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.0031108856201172 seconds DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.0045199394226074 seconds DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 3271dcd4-2aa4-4ad0-9d56-7f041f5fdc71 DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.0032567977905273 seconds DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.0031249523162842 seconds DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 3271dcd4-2aa4-4ad0-9d56-7f041f5fdc71 DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.0033278465270996 seconds DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.0028359889984131 seconds DEBUG - 2013-04-01 23:18:31 --> Executed GetSession in 0.0085370540618896 seconds DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 6a506636-1b77-4e25-af62-f02cdfb63aca DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 6a506636-1b77-4e25-af62-f02cdfb63aca DEBUG - 2013-04-01 23:18:31 --> Executed GetUser in 0.014625072479248 seconds DEBUG - 2013-04-01 23:18:31 --> Requesting by UUID - 6a506636-1b77-4e25-af62-f02cdfb63aca