Coherence

Oracle Coherence – description of federation member states

States of Oracle Coherence federation are not very well described in the documentation. So I thought it would be good to ask at the source. Thanks for Patrick F for all these explanations!

Stopped states – Federation is not federating data to the destination, nor is it keeping a backlog of changes to send to the destination.  A “start” operation must be performed to start federating data again:
  • STOPPED – A stop operation was issued, or federation was set to start in the stopped state. Stopped states – Federation is not federating data to the destination, nor is it keeping a backlog of changes to send to the destination.  A “start” operation must be performed to start federating data again:
  • ERROR – An error occurred from which federation was unable to continue federating data
Paused state – Federation is not federating data, but is keeping a (growing) backlog of changes to be sent once a “start” operation is issued:
  • PAUSED – A pause operation was issued, or federation was set to start in the paused state.
Normal states – Federation is federating data:
  • INITIAL – default startup state.  A Coherence node will stay in this state until there is data to be federated
  • IDLE – federation is active and connected to the destination.  There is no data currently to send
  • READY – federation is transitioning out of CONNECTING, or YIELDING, or BACKLOG_NORMAL and will go to SENDING
  • SENDING – federation has data to send
  • CONNECTING – federation is connecting to the destination cluster
  • CONNECT_WAIT – federation is disconnected and will make a new connect attempt.  There may be a delay before making the next attempt depending on the circumstances under which federation was disconnected
  • YIELDING – federation has data to send, but is pausing briefly, likely due to a BACKLOG_EXCESSIVE event
  • DISCONNECTED – federation was disconnected from the remote destination.  If there is no data to send, federation may stay in this state. NB: DISCONNECTED is a “normal” state.  It means that a member of the cluster lost its federation connection to the remote cluster (probably because the remote member it was connected to was shut down).  If the member in the DISCONNECTED state has no data to send, it will stay in the DISCONNECTED state – basically the same as being IDLE.  Once there is some data for this member to send it will issue a new connection.
The following states do not exist – although they may have in 12.2.1.0.0 (federation should not be used with this version):
  • BACKLOG_EXCESSIVE 
  • BACKLOG_NORMAL