[jboss-jira] [JBoss JIRA] Commented: (JGRP-393) NAKACK/UNICAST: headers are removed from message when passing the message up; retransmit will fail

[Bela Ban (JIRA)]

    [ http://jira.jboss.com/jira/browse/JGRP-393?page=comments#action_12349043 ] 
            
Bela Ban commented on JGRP-393:
-------------------------------

First step: made Message.removeHeader() return getHeader()

> NAKACK/UNICAST: headers are removed from message when passing the message up;  retransmit will fail
> ---------------------------------------------------------------------------------------------------
>
>                 Key: JGRP-393
>                 URL: http://jira.jboss.com/jira/browse/JGRP-393
>             Project: JGroups
>          Issue Type: Bug
>    Affects Versions: 2.4
>            Reporter: Bela Ban
>         Assigned To: Bela Ban
>             Fix For: 2.5
>
>
> Issue appears with UNICAST or NAKACK, example below uses NAKACK:
> - Message M1 is received and placed into received_msgs. M1 has a FragHeader attached (FRAG2 was somewhere above NAKACK)
> - M1 is retrieved from received_msgs and passed up
> - FRAG2 *removes* the FragHeader
> - A retransmission request is received for M1
> - M1 is retrieved from received_msgs and passed down. 
> Problem: the FragHeader is missing ! The receiver will not recognize M1 as a fragment and FRAG2 will *not* handle M1 !
> SOLUTION 1: all protocols (maybe only the ones above UNICAST/NAKACK) should *never* remove headers. We could ensure this is the case by simply making removeHeader() a no-op
> SOLUTION 2: investigate into who owns the message and who is allowed to modify it. Look into sealing techniques

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