Re: [sca-bindings] Further thoughts on issue BINDINGS-85

[ashok malhotra <ashok.malhotra@oracle.com>]

Simon:
Let me analyze this from the other side i.e. what the reliability 
intents map to in terms of the DIMS binding config params.
The Policy Framework defines 4 reliability intents.  Here is what, in my 
understanding, they map to in
terms of DIMS delivery mode:

- atLeastOne: Persistent   (this is more than what is requested but that 
may be OK)
- atMostOnce: Non-Persistent
- exactlyOnce (atLeastOnce+atMostOnce): Persistent
- ordered:  No appropriate config param.  Supported by the runtime.
So, two questions:
- Simon, is this what you suggested?
- Others, does this make sense?
All the best, Ashok


Simon Holdsworth wrote:
>
> The JMS 1.1 specification has the following to say about the 
> deliveryMode attribute (Section 4.7, Message Delivery Mode):
>
> A JMS provider must deliver a NON_PERSISTENT message /at-most-once. 
> /This means that it may lose the message, but it must not deliver it 
> twice.
> A JMS provider must deliver a PERSISTENT message /once-and-only-once/. 
> This means a JMS provider failure must not cause it to be lost, and it 
> must not deliver it twice.
>
> So it seems quite reasonable to map the SCA atMostOnce intent to JMS 
> delivery mode of NON_PERSISTENT, and exactlyOnce to PERSISTENT, 
> although exactlyOnce is a profile intent that combines atMostOnce and 
> atLeastOnce, which would imply to me that atLeastOnce maps to a JMS 
> delivery mode of PERSISTENT.  Although this does make life quite 
> difficult, because bindings that require exactlyOnce do also require 
> atLeastOnce.
>
> The only question I have left with regards to removing the 
> deliveryMode attribute as the resolution to this issue is whether we 
> should mandate in the JMS binding spec a specific mapping of these 
> intents to deliveryMode values, or remain silent and leave that 
> interpretation up to the SCA runtime.
>
> If we were to mandate the mapping, then the resolution to the issue 
> would be to remove the deliveryMode attribute, and replace the 
> following paragraph in section 5:
>
> Deployers/assemblers can configure NON_PERSISTENT for @JMSDeliveryMode 
> in order to provide higher performance with a decreased quality of 
> service. A binding.jms element configured in this way cannot satisfy 
> the "atLeastOnce" policy intent. The SCA runtime MUST raise an error 
> for this invalid combination at deployment time.
>
> with:
>
> The JMS delivery mode used to send messages from a JMS binding 
> instance which requires the atMostOnce intent and not the atLeastOnce 
> intent MUST be NON_PERSISTENT [BJM5000X]
> The JMS delivery mode used to send messages from a JMS binding 
> instance which requires the atLeastOnce intent MUST be PERSISTENT 
> [BJM5000Y]
>
> Given the deliveryMode default is PERSISTENT, we could also say:
>
> The JMS delivery mode used to send messages from a JMS binding 
> instance which does not require either of these intents MUST be 
> PERSISTENT [BJM5000Z]
>
> In fact these could all be collapsed into a single statement:
>
> The JMS delivery mode used to send messages from a JMS binding 
> instance MUST be NON_PERSISTENT if it requires the atMostOnce intent 
> and not the atLeastOnce intent, and PERSISTENT otherwise [BJM5000X]
>
> Comments?
>
> Regards, Simon
>
> Simon Holdsworth
> STSM, SCA Bindings Architect; Master Inventor; OASIS SCA Bindings TC Chair
> MP 211, IBM UK Labs, Hursley Park, Winchester SO21 2JN, UK
> Tel +44-1962-815059 (Internal 245059) Fax +44-1962-816898
> Internet - Simon_Holdsworth@uk.ibm.com
>
>
> ------------------------------------------------------------------------
>
> /
> /
>
> /Unless stated otherwise above:
> IBM United Kingdom Limited - Registered in England and Wales with 
> number 741598.
> Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 
> 3AU/
>
>
>
>
>
>