Contents
Table of Contents |
---|
Placement in NetarchiveSuite software
Every channel is named after the set of applications application instances that are expected to receive messages sent to it. All channel names are constructed privately in the dk.netarkivet.common.distribute.ChannelID
class. To get a channel, you must use one of the public methods in the dk.netarkivet.common.distribute.Channels
class.
Channel Behavior
There are used to two types of channels used in the JMS protocol:
- Queue where only one listener takes a message from the queuechannel. 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 sectionIn NetarchiveSuite we use a naming convention that topic channel names include the string "_ALL_" and the suffix "_TOPIC".
Naming Conventions
The structure of channel names are is as follows:
Code Block |
---|
<Environment Name>_<ReplicaID>_[<Channel Specifier Prefix>_]<Channel Specifier>[_<Machine>][_<Application Instance>][_topicTOPIC] |
- 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 (ie the "location" in a distributed system), 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 areChannel Specifier Prefix if presentis one of the following:- 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
andsettings.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
THE_SCHED
JOB_PARTIAL_FOCUSED
JOB_SNAPSHOT_SNAPSHOT
THIS_REPOS_CLIENT
- Channel Specifier simply expresses what the channel is used for. By convention this (usually) describes what kind of application should listen on this channel.
Here is a complete list of the channels in an actual realistic distributed NAS system (IP addresses have been anonymised for security reasons).
Channel Name | Function |
---|---|
SystemTest_COMMON_HARVESTER_STATUS_TOPIC | Topic used by the harvesters to call in ready for new jobs (to the HarvestJobManager) |
SystemTest_COMMON_HARVESTMON | Queue to which harvesters send messages showing crawl progress for display in the GUI |
SystemTest_COMMON_HCHAN_VAL_REQ | Queue for harvesters to register the harvest channel they are processing jobs from. |
SystemTest_COMMON_HCHAN_VAL_RESP | Queue for response from the HarvestManager to the Harvesters requesting HarvestChannel registrations. |
SystemTest_COMMON_INDEX_SERVER | Queue for sending messages to the IndexServer |
SystemTest_COMMON_JOB_PARTIAL_HIGHPRIORITY | Queue used to send jobs to the selective harvesters in the highpriority pool. |
SystemTest_COMMON_JOB_SNAPSHOT_LOWPRIORITY | Queue used for sending jobs to the harvester configured for snapshot harvesting. |
SystemTest_COMMON_MONITOR_TOPIC | Topic for the monitor registry |
SystemTest_COMMON_THE_REPOS | Queue for sending messages to the ArcRepository. |
SystemTest_COMMON_THE_SCHED | Queue on which HarvestControllers reply with status messages to the HarvestScheduler. |
SystemTest_COMMON_THIS_INDEX_CLIENT_xxx_225_xx_140_HCS_SBHIGH_H3 | Queue on which a specific HarvestControllerServer listens for responses from the IndexServer |
SystemTest_COMMON_THIS_INDEX_CLIENT_xxx_226_xxx_11_HCS_KBHIGH_H3 | |
SystemTest_COMMON_THIS_REPOS_CLIENT_ |
xxx_225_xx_xxx_HCS_ |
SBHIGH_H3 | One-per-client queue on which client (in this case a HarvestControllerServer) receives replies from the repository. |
SystemTest_COMMON_THIS_REPOS |
QUICKSTART_COMMON_THE_REPOS
Queue for sending messages to the Repository are.
THE_BAMON
QUICKSTART_A_THE_BAMON
ALL_BA
QUICKSTART_A_ALL_BA_TOPIC
ANY_BA
QUICKSTART_A_ANY_BA
THIS_INDEX_CLIENT
QUICKSTART_COMMON_THIS_INDEX_CLIENT_192.168.1.7_HCS_FOCUSED
Queue for Harvesters status messages to the HarvestManager.
INDEX_SERVER
QUICKSTART_COMMON_INDEX_SERVER
MONITOR
QUICKSTART_COMMON_MONITOR_TOPIC
ERROR
QUICKSTART_COMMON_ERROR_COMMON
THE_CR
_CLIENT_xxx_226_xxx_xx_WI | One-per-client queue on which client (in this case a WaybackIndexer) receives replies from the repository. |
SystemTest_COMMON_THIS_REPOS_CLIENT_xxx_226_xxx_11_HCS_KBHIGH_H3 | |
SystemTest_COMMON_THIS_REPOS_CLIENT_xxx_226_xxx_11_HCS_KBLOW002_H3 | |
SystemTest_COMMON_THIS_REPOS_CLIENT_xxx_226_xxx_5_IS | One-per-client queue on which client (in this case an IndexServer) receives replies from the repository. |
SystemTest_COMMON_THIS_REPOS_CLIENT_xxx_226_xxx_5_VP | One-per-client queue on which client (in this case a ViewerProxy) receives replies from the repository. |
SystemTest_COMMON_THIS_REPOS_CLIENT_xxx_226_xxx_9_HCS_KBLOW001_H3 | |
SystemTest_CS_THE_CR | Queue for sending messages to a specific Checksum replica (the replica named CS). |
SystemTest_ |
KB_ |
ALL_ |
BA_ |
TOPIC |
The examples are using values
HCS_FOCUSED
(for HarvestControllerApplication with instance id FOCUSED
)Topic for broadcasting messages to all bit archives at KB | |
SystemTest_KB_ANY_BA | Queue for sending a message to any one of the bitarchive applications at KB |
SystemTest_KB_THE_BAMON | |
SystemTest_SB_ALL_BA_TOPIC | |
SystemTest_SB_ANY_BA | |
SystemTest_SB_THE_BAMON | Queue for sending messages to the bitarchive monitor at SB - ie to run batch jobs on the SB replica. |