[INFOD-WG] Implementation Issues.

[Dieter Gawlick]

Vijay,

You are right. dynamic consumer constraints have to be handled by the 
publisher; we have to correct lines 172 and 221.

I do not think that we solved the second issues. Lines 1789 & 1790 in 
the specifications may need to be extended by saying that the 
information only contains the static consumers - it is in many cases 
impossible to create the dynamic consumer list. With this in mind, there 
is no notification.

With the previous comments in mind we have to reformulate the 3rd 
question:  How do publishers become aware of consumers that may have 
become eligible  dynamic consumers?

Steve,

Should be create an addendum file for the Base specifications and create 
an integrated version on some regular basis?

Dieter


Vijay Dialani wrote:
>
> Hi All,
>
> When helping Raghul with implementation issues, three questions were 
> raised from his side:
> 1. Implementation and use of Dynamic Constraints (Status: solved)
> 2. How does the publish messages (with TTL) as it become aware of that 
> new dynamic consumers? (Status: solved)
> 3. How does publisher handle frequent notifications about consumers? 
> (Status: Unsolved)
>
> For the first issue, I found that the specification is ambiguous, in 
> some section it requires consumer to handle the Dynamic Constraints, 
> in some other sections it requires publishers to handle the Dynamic 
> Constraints. Attached are the text excerpts from the base specification:
>
>
> From section 1.1.1
>
> In addition a subscription may include dynamic consumer constraints. 
> These are constraints which are evaluated* **by the consumer* rather 
> than the registry by looking at the contents of a potential message.
>
> From Glossary
>
> _Constraint_        Constraints are used to specify which conditions 
> must be satisfied to be eligible for an interaction. Constraints must 
> be formulated in the constraint language(s) that are associated to the 
> vocabularies, which are used to structure the referenced data. Most 
> constraints are evaluated by the registry but dynamic consumer 
> constraints are *dealt with by the consumer*. The absence of 
> constraints shows that the interaction is unrestricted.
>
>
> From section 2.4.1 and section 2.4.2
>
> These Constraints are designed to determine the consumers of each 
> message based on its content; i.e., a Dynamic Consumer Constraint 
> cannot be applied by the INFOD registry and is *processed by the 
> publishers*.
>
> This clearly show inconsistency in the specification. We assume that 
> the DynamicConsumerConstraints need to be evaluated by the publisher 
> and will like to know uses cases for evaluation by consumer, if any.
>
> The dynamic consumer constraints will be based on data vocabulary and 
> we are working on actual mechanisms for implementation,
>
> Second, issue:
> The Publisher internally associated TTL with every message and retains 
> them as its internal state. When it receives the notification about a 
> new consumer, it examines the internal queue of messages and notifies 
> the consumer in appropriate order.
>
> Third issue:
> We will be seeking help from Oracle team to help with DB internals 
>  and choice of appropriate indexing mechanism.
>
>
> Regards,
> Vijay Dialani, Ph.D.
> IBM Almaden Research Center, B2-237
> 650 Harry Road
> San Jose, CA 95120 USA
> Email; vdialani at us.ibm.com
> Phone: 408-927-1406 Tie line: 457-1406
> Fax: 408-927-1780
>
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>
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Dieter Gawlick | Architect | 650.506.8706
Oracle Server Technologies
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