Re: An opes usage question.

My comments are in-line below:

The Purple Streak, Hilarie Orman wrote:

>I think I see your problem, but I don't think you've established a
>need for communication between a specific billing server and a
>specific adaptation server.  If this sort of thing is the model:
>
But I believe a solution is needed that allows communication between a 
specific billing server and a specific adaptation server. I think or 
thought that was clear from the past e-mails.

>
>  ContentServer     ContentServer     ContentServer    
>        |               |                |
>        \               |               /
>         \              |              /
>          ----------------------------
>          |      Load Balancer       |
>          ----------------------------
>            |           |         |
>            |           |         |
>            |           |         |
>  BillingServer  BillingServer   BillingServer
>        |               |                |
>        \               |               /
>         \              |              /
>          ----------------------------
>          |      Load Balancer       |
>          ----------------------------
>            |           |         |
>            |           |         |
>            |           |         |
>       AdaptServer  AdaptServer  AdaptServer
>        |               |                |
>        \               |               /
>         \              |              /
>          ----------------------------
>          |      Load Balancer       |
>          ----------------------------
>                      .....
>
>  
>
Yes, that is the model.

>Then I'd think that a Billing Server, upon seeing a request and
>response, might open a record saying "customer A got 10K bytes at 10
>am", but the Adaptation Server would send back a "request" encoding
>the information "the customer really got 8K bytes at 10am".  Your
>question is "how would that information get back to the same billing
>server?"  and my first reaction is to say it just naturally would
>if they keep their connection open.  
>
I am not sure I understand why this would be true if there is a load 
balancer between stages of the services pipeline?  Also connections can 
be very short lived.

>If they decide to close the connection, then they need to agree on
>some kind of identifier for the transaction.  If the Billing Server
>wants to include an OPES header with a unique ID, it can do that, and
>it can write a billing record into its database saying "8K bytes for
>unique ID xyzzy".  The Adaptation Server then sends back the
>information, using the same ID.  This might not get delivered to the
>same Billing Server, but it doesn't matter, it all goes into one
>database and can be correlated for billing purposes.
>
You are proposing billing system changes. This introduces an additional 
dependency and complicates deployment and can lead to other problems. I 
would prefer not to have to modify the billing system.

>In any case, the Adaptation Server needs to do extra communication,
>above and beyond proxying.  That extra work should be encodable in
>the Rules Language, I believe.  It is what I'd call a "local callout
>service".
>
I believe this extra communication can be done out of band  Is the 
reconciliation of billing information what you are referring to as a 
local call out service?

>
>I agree that in general the problem of identifying entities in a
>pipeline that is interesting.  Load-balancing, hot backup, failover,
>etc. all introduce some interesting problems.  If there are provably
>correct solutions that can be encoded with OPES (without complicating
>it), that would be very interesting.  Perhaps out of charter for OPES,
>but possibly worth a new WG (unless there already is one!).
>
As I mentioned before, I believe that any extra communication (for 
billing reconciliation) can be done out of band and therefore may not 
have to be part of opes, but I believe finding a  flow participant is an 
opes issue that needs resolution.

Thanks for the discussion
Regards John

>
>Inimitably, on Sat, 06 Mar 2004 at 17:11:45 -0500 John G. Waclawsky
>murmured:
>  
>
>> I think we are talking about the same thing which I have been calling a 
>> "flow participant discovery" problem (not a services discovery problem). 
>> The question is how, within the opes framework, do I establish this 
>> business relationship between two proxies in different stages of a 
>> services pipeline separated by a load balancer. Packets can travel 
>> through the billing server and later be changed by any adaptation proxy 
>> where (in the billing by bytes case) bytes could be reduced 
>> (compression) or increased (adding banners or advertisements or other 
>> correlated content). 
>>    
>>
>
>Hilarie
>
>
>  
>