Ordered routing process

To achieve session affinity, the plug-in will parse the client's session information, extract the previous CloneID, and match this CloneID with the CloneIDs in the server cluster object. When the matching cluster member is found, the server will retrieve this client's session from the in-memory cache. When the matched appserver is not available, the plug-in will route the client to another server, and appends the new server's CloneID into the client's session. WebSphere V5 uses the weight-based ordered routing, which eliminates the possibility that two different servers are selected after a failover for concurrent (multiple thread) clients (which might have been a problem in WebSphere V4.x where the adoptive server selection was random).

Example 9-8 Trace ordered routing process

TRACE: ws_common: websphereParseCloneID: Returning list of clone ids

TRACE: ws_server_group: serverGroupFindClone: Looking for clone

TRACE: ws_server_group: serverGroupGetFirstPrimaryServer: getting the first 
primary server

TRACE: ws_server_group: serverGroupFindClone: Comparing curCloneID 
'u307p2vq' to server clone id 'u307p2vq'

TRACE: ws_server_group: serverGroupFindClone: Match for clone 
'HAClusterServer1'

TRACE: ws_server_group: serverGroupCheckServerStatus: Checking status of 
HAClusterServer1, ignoreWeights 1, markedDown 1, retryNow 0, wlbAllows 0

TRACE: ws_server_group: serverGroupCheckServerStatus: Server 
HAClusterServer1 is marked down; retry in 58

TRACE: ws_server_group: serverGroupGetNextPrimaryServer: getting the next 
primary server

TRACE: ws_server_group: serverGroupFindClone: Comparing curCloneID 
'u307p2vq' to server clone id 'u307p62u'

TRACE: ws_server_group: serverGroupGetNextPrimaryServer: getting the next 
primary server

TRACE: ws_server_group: serverGroupGetFirstPrimaryServer: getting the first 
primary server

TRACE: ws_server_group: serverGroupFindClone: Comparing curCloneID 
'u307p62u' to server clone id 'u307p2vq'

TRACE: ws_server_group: serverGroupGetNextPrimaryServer: getting the next 
primary server

TRACE: ws_server_group: serverGroupFindClone: Comparing curCloneID 
'u307p62u' to server clone id 'u307p62u'

TRACE: ws_server_group: serverGroupFindClone: Match for clone 
'HAClusterServer3'

TRACE: ws_server_group: serverGroupCheckServerStatus: Checking status of 
HAClusterServer3, ignoreWeights 1, markedDown 0, retryNow 0, wlbAllows 1

TRACE: ws_server_group: lockedServerGroupUseServer: Server HAClusterServer3 
picked, weight 3.

TRACE: ws_common: websphereHandleSessionAffinity: Setting server to 
HAClusterServer3

TRACE: ws_common: websphereFindTransport: Finding the transport

TRACE: ws_common: websphereFindTransport: Setting the transport: 9.5.90.84 
on port 9081

TRACE: ws_common: websphereExecute: Executing the transaction with the app 
server

TRACE: ws_common: websphereGetStream: Getting the stream to the app server

TRACE: ws_transport: transportStreamDequeue: Checking for existing stream 
from the queue

TRACE: ws_common: websphereSocketIsClosed: Checking to see if socket is 
still open

TRACE: ws_common: websphereGetStream: Using existing stream from transport 
queue

TRACE: lib_htrequest: htrequestWrite: Writing the request:

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