Subject: [Speechsc] changing verification servers

From: "Reifenrath, Klaus" <[email-masked]>
Date: Fri, 7 May 2004 08:57:05 -0400

What about changing verification servers (say for load balancing reasons)?
For consistency (see recognizer context block in 9.4 and 9.5), we should add
a verifier-context-block header field to the verification resource (see
below).
Open issues: 
- What happens to the buffered data?
- What happens to an open verification session? Can it be continued on the
next server?
With the current spec client side load-balancing and session failover
becomes very difficult if not impossible!
The same is true for enrollment sessions.

Klaus

Verifier Context Block
    When the client has to change verification servers within a call, 
    this is a block of data that the client MAY collect from the first 
    media server and provide to the second media server. 
    Here the first verifier may have 
    collected acoustic and other data during its verification. When we 
    switch verification servers, communicating this data may allow the 
    second verification server to provide better verification based on the 
    acoustic data collected by the previous verifier. This block of 
    data is vendor-specific and MUST be carried as MIME-type 
    application/octets in the body of the message. 
     
    This block of data is communicated in the SET-PARAMS and GET-PARAMS 
    method/response messages. In the GET-PARAMS method, if an empty 
    verifier-context-block header field is present, then the 
    recognizer should return its vendor-specific context block in the 
    message body as a MIME-entity with a specific content-id.  The 
    content-id value should also be specified in the verifier-context-
    block header field in the GET-PARAMS response.  The SET-PARAMS 
    request wishing to provide this vendor-specific data should send it 
    in the message body as a MIME-entity with the same content-id that 
    it received from the GET-PARAMS.  The content-id should also be sent 
    in the verifier-context-block header field of the SET-PARAMS 
    message. 
     
    Each vendor choosing to use this 
    mechanism to handoff verifier context data among its servers 
    should distinguish its vendor-specific block of data from other 
    vendors by choosing a unique content-id that they should recognize. 

Klaus

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