RE: [sca-j] NEW ISSUE: Clarify what a Component Implementation can do with threads - JAVA-62

This has been raised as http://www.osoa.org/jira/browse/JAVA-62

Mark Combellack| Software Developer| Avaya | Eastern Business Park | St. Mellons | Cardiff |
CF3 5EA | Voice: +44 (0) 29 2081 7624 | 

From:
Mark Combellack [mailto:] 

Sent: 11 September 2008 11:17

To: 

Subject: [sca-j] NEW ISSUE:
Clarify what a Component Implementation can do with threads

 

TARGET: Java CAA

 

DESCRIPTION:

 

The current SCA-J specification does not mention any
restrictions regarding threading that a developer must comply with when implementing
a SCA Component. The SCA-J specification is silent on whether a component
implementation can create new threads, kill threads, suspend threads, etc.

 

Implementations of SCA-J SCA Runtime are likely to use
ThreadLocals to implement accessing the RequestContext, security credentials,
Conversation IDs on Service Proxies, etc. If the developer is allowed to create
their own threads, then these ThreadLocals may not function as intended.

 

The EJB 3 specification contains the following comment
regarding threads (page 546 of ejb-3_0-fr-spec-ejbcore.pdf [1])

 

The enterprise bean must
not attempt to manage threads. The enterprise bean must not attempt to start,
stop, suspend, or resume a thread, or to change a thread’s priority or
name. The enterprise bean must not attempt to manage thread groups.

 

These
functions are reserved for the EJB container. Allowing the enterprise bean to
manage threads would decrease the container’s ability to properly manage
the runtime environment.

 

This issue is related to JAVA-61 which describes what the
Component Implementation can expect from the SCA Runtime for each Scope with
regards to threading. However, it is different since this issue describes what
the SCA Runtime can expect from the Component Implementation with regards to
threads.

 

 

PROPOSAL:

 

Nothing concrete as yet but we have at least the following
options available to us for consideration:

 

1)   Do nothing
– Leave the SCA-J specification as is and remain silent on threading

2)   Restrict
threading (like EJB3) so that threads cannot be created, stopped, suspended,
etc

3)   Allow
creation of new threads in SCA-J and describe how it works and what are the
restrictions

 

 

 

[1] EJB 3 final Specifications - http://jcp.org/aboutJava/communityprocess/final/jsr220/index.html

 

Mark Combellack| Software Developer| Avaya | Eastern Business Park | St. Mellons | Cardiff |
CF3 5EA | Voice: +44 (0) 29 2081 7624 |