Etienne Urbah's position on 2010-04-20

• Introduction and Terminology :
  - The 'Activity Service Endpoint' is the Endpoint of the service managing the Activity at one time, and its address MAY vary during Activity lifetime
  - The 'Activity Service Endpoint Name' is the name of the 'Activity Service Endpoint', and MUST NOT change during Activity lifetime
• The Execution Service creating an Activity :
  - MUST store inside a robust Name Server the (name, address) ordered pair of the 'Activity Service Endpoint'
  - MUST store inside the Activity ID the Endpoint of the Name Server, and the 'Activity Service Endpoint Name'
  - MAY store any additional information inside the Activity ID, but MUST NOT assume that Clients are able to extract this additional information
• The Endpoint of the Name Server MUST NOT change during the Activity lifetime
• Each time the service currently managing the Activity changes the address this 'Activity Service Endpoint', it MUST store inside the SAME Name Server the NEW address associated to the 'Activity Service Endpoint Name'
• The precise syntax will be defined later, and only if PGI agrees on this requirement
• Each Client MUST be able to extract from the Activity ID the Endpoint of the Name Server and the 'Activity Service Endpoint Name'
• Each Client MUST be able to submit a query to the Name Server in order to retrieve the current address of the 'Activity Service Endpoint', using the stable 'Activity Service Endpoint Name'
• In order to issue requests concerning the Activity to the service currently managing the Activity, a Client needs only the Endpoint of the Name Server, the 'Activity Service Endpoint Name', and the Activity ID as it is, but does NOT need to extract any further information from the Activity ID
• Each Client MUST be prepared that any request using the address of the 'Activity Service Endpoint' MAY return an 'Unknown Activity' error at any time, and MUST then query the Name Server in order to retrieve the new address
• The Client can NOT anyhow manipulate the content of the Activity ID (except changes allowed by the format of Activity ID and which do not change its syntax, such as whitespaces inside XML)
• This requirement eases implementation of JM4.6 :  At any time, the current Execution Service MAY migrate an Activity to another Execution Service
• This requirement introduces complexity, and the Name Server is a good candidate for a SPOF.  Are we sure that we really need this requirement ?

Morris, Balazs and Etienne on 2010-04-23

• Source = General
• Spreadsheet ID = 52