The JMS 2.0 specification adds support for shared subscriptions. QPIDJMS-220 outlines how the Qpid JMS client maps the JMS semantics to AMQP terms. This document outlines how the broker responds to those AMQP performatives.

Link Attach

Assumptions:*

• If source is set the address is specified as “exchange/binding” and exchange with name “exchange” exists. If exchange with name “exchange” does not exist the link is refused with error “not found”

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• Link does not exist. for Link reattachment see below.

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• Terminus durability : NO means 0, YES means 1 or 2.

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• When creating a queue its life time policy will be derived from source expiry policy as follow:

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  • • “link-detach” becomes “delete on no outbound link”

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  • • “session-end” becomes “delete on session end”

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  • • “connection-close” becomes “delete on connection close”

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  • • “never” becomes “permanent"

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  • SHARED and GLOBAL are derived from Source capabilities if Source is set and from Link capabilities otherwise

  Assumptions:
      If source is set the address is specified as “exchange/binding” and exchange with name “exchange” exists. If exchange with name “exchange” does not exist the link is refused with error “not found”.
      Link name “foo|bar”.
      Link does not exist.
      Terminus durability : NO means 0, YES means 1 or 2.
      When creating a queue its life time policy will be derived from source expiry policy as follow:
      “link-detach” becomes “delete on no outbound link”
      “session-end” becomes “delete on session end”
      “connection-close” becomes “delete on connection close”
      “never” becomes “permanent
      SHARED and GLOBAL are derived from Source capabilities if Source is set and from Link capabilities otherwise 

  Not Null Source	SHARED	GLOBAL	TERMINUS DURABILITY	outcome
  YES	NO	NO	NO	Create a non-durable queue with random name and exclusivity policy “link”. Bind queue to exchange “exchange”

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  using binding key “binding”. Broker replies with attach having capability “topic” on a source and attach offered capability “SHARED_SUB”.
  YES	NO	NO	YES	Create a durable queue with name derived from link name, container id and source durability. Exclusivity policy is set to “link”. Bind queue to exchange. Broker replies with attach having capability “topic” on a source and attach offered capability “SHARED_SUB”. If queue already exists the link should be refused with error “resource locked”
  YES	NO	YES	NO	The same as for SHARED=NO, GLOBAL=NO and DURABLE=NO
  YES	NO	YES	YES	Create a durable queue with name derived from link name, global name space and source durability. Exclusivity policy is set to “link”. Bind queue to exchange. Broker replies with attach having capabilities “topic” and “global” on a source and attach offered capability “SHARED_SUB”. If queue already exists the link should be refused with error “resource locked”
  YES	YES	NO	NO	Create a non-durable queue with name derived

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  from link name (up to “|”), container id and source durability. Exclusivity policy is set to “shared”. Bind queue to exchange. Broker replies with attach having capabilities “topic” and “shared” on a source and attach offered capability “SHARED_SUB”. If queue already exists and filters and/or binding key are not the same as derived from attach source, then:

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  if there is/are existing consumer(s), refuse the link with error “resource locked”

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  if there is no consumer, rebind queue using new filters and/or binding key If existing queue exclusivity policy is not “shared”, then link creation is refused with error “resource locked”. If existing queue lifetime and/or durability are different from expected, then link creation is allowed but the source fields in the reply should be modified accordingly.
  YES	YES	NO	YES	Create a durable queue with name derived from link name (up to “|”), container id and source durability. Exclusivity policy is set to “shared”. Bind queue to exchange. Broker replies with attach having capabilities “topic” and “shared” on a source and attach offered capability “SHARED_SUB”. See above, if queue exists
  YES	YES	YES	NO	Create a non-durable queue with name derived from link name (up to “|”), global namespace and source durability. Exclusivity policy is set to “shared”. Bind queue to exchange. Broker replies with attach having capabilities “topic”, “shared” and “global” on a source and attach offered capability “SHARED_SUB”. See above, if queue exists
  YES	YES	YES	YES	Create a durable queue with name derived from link name (up to “|”), global name space and source durability. Exclusivity policy is set to “shared”. Bind queue to exchange. Broker replies with attach having capabilities “topic”, “shared” and “global” on a source and attach offered capability “SHARED_SUB”. See above, if queue exists
  NO	NO	NO	N/A	Look for queue with name derived from link name, container id and “true” durability. If queue exists and there is no consumer, delete queue. Reply with attach having null source. If queue exists but there is/are consumer(s), refuse the link with error “resource locked”. If queue does not exist, refuse the link with error “not found”. TODO: This breaks the AMQP spec
  NO	NO	YES	N/A	Look for queue with name derived from link name, global name space and “true” durability. If queue exists and there is no consumer, delete queue. Reply with attach having null source. If queue

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  exists but there is/are consumer(s), refuse the link with error “resource locked”. If queue does not exist, refuse the link with error “not found”. TODO: This breaks the AMQP spec
  NO	YES	NO	N/A	Look for queue with name derived from link name (up to “|”), container id and “true” durability. If queue exists and there is no consumer, delete queue. Reply with attach having null source. If queue

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  exists but there is/are consumer(s), refuse the link with error “resource locked”. If queue does not exist, refuse the link with error “not found”.
  NO	YES	YES	N/A	Look for queue with name derived from link name (up to “|”), global name space and “true” durability. If queue exists and there is no consumer, delete queue. Reply with attach having null source. If queue

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  exists but there is/are consumer(s), refuse the link with error “resource locked”. If queue does not exist, refuse the link with error “not found”.

   

  TODO: Attach with null Source from an AMQP perspective should not error with resource-locked or not-found. The JMS mapping seems to require this.

  Link re-Attach

  If link exists and the queue exists see the instructions for the existing queue for SHARED=YES.  
  If link exists and the queue does not exist, recreate a queue as described in corresponding instructions above.

  Pseudo Code

  The above described behaviour results in the following pseudo code. Where the below differs from the above the above is considered normative:
  
  

  No Format
  if Link does not exists

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  if Source is set if Source has SHARED capability subscription_name = Link name up to (excluding) “|” exclusivity_policy = “SHARED” else subscription_name = Link name exclusivity_policy = “LINK” if Source has GLOBAL capability name_space = global name space else name_space = container-id name space name = get_queue_name( name_space, subscription_name, Source Durability) if queue with name exists if has same exclusivity_policy if different binding key or filter if no consumer rebind queue else error(resource-locked) else error(resource-locked) else create_queue( queue_name exclusivity_policy, Source Durability, Source Expiry Policy) bind queue send Attach else queue_name = get_queue_name( name_space, subscription_name, TRUE_DURABILITY) if queue exists if queue has consumers error(resource-locked) // This breaks the AMQP spec else delete queue Attach Link with null Source else error(not-found) // This breaks the AMQP spec else queue_name = get_queue_name( name_space, subscription_name, TRUE_DURABILITY) if queue exists if has same exclusivity_policy if different binding key or filter if no consumer rebind queue else error(resource-locked) else error(resource-locked) else create_queue( queue_name exclusivity_policy, Source Durability, Source Expiry Policy) bind queue send Attach

   

  If link exists and the queue exists see the instructions for the existing queue for SHARED=YES.

  If link exists and the queue does not exist, recreate a queue as described in corresponding instructions above.

   

   

  The above described behaviour results in the following pseudo code. Where the below differs from the above the above is considered normative:

   

  if Link does not exists

  if Source is set

  if Source has SHARED capability

  subscription_name = Link name up to (excluding) “|”

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  exclusivity_policy = “SHARED”

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  else

  subscription_name = Link name

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  exclusivity_policy = “LINK”

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  if Source has GLOBAL capability

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  name_space = global name space

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  else

  name_space = container-id name space

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  name = get_queue_name(

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  name_space,

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  subscription_name,

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  Source Durability)

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  if queue with name exists

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  if has same exclusivity_policy

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  if different binding key or filter

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  if no consumer

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  rebind queue

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  else

  error(resource-locked)

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  else

  error(resource-locked)

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  else

  create_queue(

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  queue_name

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  exclusivity_policy,

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  Source Durability,

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  Source Expiry Policy)

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  bind queue

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  send Attach

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  else

  queue_name = get_queue_name(

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  name_space,

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  subscription_name,

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  TRUE_DURABILITY)

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  if queue exists

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  if queue has consumers

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  error(resource-locked) // This breaks the AMQP spec

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  else

  delete queue

  Attach Link with null Source

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  else

  error(not-found) // This breaks the AMQP

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  spec

  else

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  queue_name = get_queue_name(

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  name_space,

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  subscription_name,

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  TRUE_DURABILITY)

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  if queue exists

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  if has same exclusivity_policy

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  if different binding key or filter

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  if no consumer

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  rebind queue

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  else

  error(resource-locked)

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  else

  error(resource-locked)

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  else

   create_queue(

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  queue_name

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  exclusivity_policy,

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  Source Durability,

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  Source Expiry Policy)

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  bind queue

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  send Attach

   

  TODO: Attach with null Source from an AMQP perspective should not error with resource-locked or not-found. The JMS mapping seems to require this.