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Subject: Proposal for REL-31
Here is a proposal for REL31:
Guaranteed delivery:
To deliver a message from a sender RMP to a receiver RMP without failure, or to report failure to the sender's application. To realize guaranteed delivery,the message MUST be persisted in the sender RMP until it delivery to it's receiver is acknowledged, or until the ultimate failure is reported to it's requestor. There is a requirement of the underlying transport protocol that the message MUST be transported without corruption. When message persistence is lost for any reason,
it is no longer possible to continue to guarantee message delivery. Since
the reliability of message persistence is A property of the system
implementation, the conditions under which guaranteed message delivery holds is
also a property of the system implementation..
Example 1). A PC Server may use a HDD for it's
persistent Storage, and those messages persisted in the HDD are reliably
maintained even if the the system software crashes and the system is rebooted.
However, if the HDD itself crashes, it is no longer possible to guarantee
message
delivery Example 2) . A message persisted in a mobile
phone may be lost when it's battery is detached. In this case, message delivery
is only guaranteed by proper battery maintenance of the mobile
phone.
--
REL-31 Spec 1.1.2 def Design Unassigned
Peter Furniss
Title: Meaning of gaurantee Description: Meaning of gaurantee needs to be defined (i.e. it is OK to announce failure of meeting guantee in a particular
case)
Related to crash tolerance, see REL-5 When is a guarantee not a guarantee? Message corruption issue may come up here. Should be specifying a protocl and its
failure modes (relatively complete).
One case: Recipient loses all of their message identifier store and can no longer detect duplicates. Recipient system failed and
sender is not notified. Outside
the scope of the protocol, one of the partners no
longer playing. Need to
document the limitations of the protocol. (Cannot
document correct error
message for case where sender of that error does
not know what is going on.)
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