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  • JMS Channels

Note that the this documentation is for the old 4.4 release.
For the newest documentation, please see the [current release documentation].

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Placement in NetarchiveSuite software

Every channel is named after the set of applications instances that are expected to receive messages sent to it. All channel names are constructed privately in the dk.netarkivet.distribute.ChannelID class. To get a channel, you must use one of the public methods in dk.netarkivet.distribute.Channels.

Channel Behavior

There are used to types of channels:

  • Queue where only one listener takes a message from the queue. For example a queue where a request for doing a harvest is only received by one harvester.
  • Topic where all listeners takes a copy of the message. For example a batch job which has to be executed by all bitarchive applications.
    The type of channel is not affecting the channel name directly. It is indicated by the Channel Prefix, since only channel names starting with ALL are topics, while the rest are queues.

The channel type for different queues is given in a table in the next section.

Naming Conventions

The structure of channel names are as follows:

<Environment Name>_<ReplicaID>_<Channel Prefix>[_<Machine>][_<Application Instance>][_topic]
  • Environment Name value must be the same for all channels on all JVMs belonging to a single NetarchiveSuite installation. It identifies the environment for the queue, e.g.: "DEV", "TEST", "RELEASETEST", "CLOVER", "PROD" or initials of developer running personal environment for e.g. sanity tests. It is read from the setting settings.common.environmentName of the NetarchiveSuite installation.
  • ReplicaID Name of the replica, or COMMON if channel shared by all replicas.

  • Type is constructed by a convention for channel behavior together with denotation of the concerned application(s). For example THE_SCHED uses the convention THE for SCHED denoting the scheduler of the harvesting system.
    The conventions for channel behavior are:
  • THE - communicate with singleton in the system.
    • THIS - communicate with one uniquely identified instance of a number of distributed listeners.
    • ANY - has all instances listening to the same queue.
    • ALL - is used for topics only, i.e. topics are sent to all listeners on the channel.
    • Use Replica Id will result in a channel name with the replica identifier in question (which must match possible replicas in settings). In case of no use of replica id the COMMON will be used.
    • Use IP Node will result in a channel name with the IP address of the machine whether the application in question is placed. It is read directly from the running system.
      . In case of no use of IP Node, nothing will be written.
    • Use Application Instance Id is used, if only one process is expected to listen to the queue. It will result in a channel name with an identification of the individual application instance. It consists of the application abbreviation (uppercase letters of application name) and the application instance identifier from the settings. It is read from the common settings: settings.common.applicationName and settings.common.applicationInstanceId.
      . In case of no use of Application Instance Id, nothing will be written.
    • Channel Type is only here to complete the picture. Please refer to the section on channel behavior.
      Channel names are constructed as described in the below table (columns described after the table).

Channel Prefix

Example

Description

THE_SCHED

QUICKSTART_COMMON_THE_SCHED

Queue on which HarvestControllers reply with status messages to the HarvestScheduler.

JOB_PARTIAL_FOCUSED

QUICKSTART_COMMON_JOB_PARTIAL_FOCUSEDQueue used to send jobs to the selective harvesters in the focused pool.

JOB_SNAPSHOT_SNAPSHOT

QUICKSTART_COMMON_JOB_SNAPSHOT_SNAPSHOTQueue used for sending jobs to the harvester configured for snapshot harvesting.

THIS_REPOS_CLIENT

QUICKSTART_COMMON_THIS_REPOS_CLIENT_192.168.1.7_HCS_FOCUSEDOne-per-client queue on which client receives replies from the repository.

THE_REPOS

QUICKSTART_COMMON_THE_REPOS 

Queue for sending messages to the Repository are.

THE_BAMON

QUICKSTART_A_THE_BAMON 

Queue for sending messages to bitarchive monitors.

ALL_BA

QUICKSTART_A_ALL_BA_TOPIC 

Topic for broadcasting messages to all bit archives. 

ANY_BA

QUICKSTART_A_ANY_BA 

Queue for sending a message to one of the bit archives. 

THIS_INDEX_CLIENT

QUICKSTART_COMMON_THIS_INDEX_CLIENT_192.168.1.7_HCS_FOCUSED

Queue for getting responses from the IndexServer

INDEX_SERVER

QUICKSTART_COMMON_INDEX_SERVER

Queue for sending messages to the IndexServer

MONITOR

QUICKSTART_COMMON_MONITOR_TOPIC

Topic for the monitor registry

ERROR

QUICKSTART_COMMON_ERROR_COMMON

Queue for errors which are not handled elsewhere. Never normally created or used.

THE_CR

QUICKSTART_CS_THE_CR

Queue for sending messages to a specific Checksum replica.
HARVESTER_STATUSQUICKSTART_COMMON_HARVESTER_STATUS_TOPIC

Topic used by the harvesters to call in ready for new jobs

HCHAN_VAL_REQQUICKSTART_COMMON_HCHAN_VAL_REQQueue for harvesters to register the harvest channel they are processing jobs from.
HCHAN_VAL_RESPQUICKSTART_COMMON_HCHAN_VAL_RESPQueue for response from the HarvestManager to the Harvesters requesting HarvestChannel registrations.

The examples are using values

  • Environment name QUICKSTART
  • Possible replica identifiers A, CS
  • IP on machine 192.168.1.7
  • HCS_FOCUSED (for HarvestControllerApplication with instance id FOCUSED )

 

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