[infod-wg] Item 46 and 50.

[vkd00r at ecs.soton.ac.uk]

Please find a proposed resolution of item 46 and 50.
Regards,
Vijay

Item 46
In addition to properties supported by most messaging systems such as JMS
and CORBA that treat messages as lightweight entities consisting of a
header and a body, INFOD provides additional features to enable message
tracking and additional routing capabilities. For example, the message ids
allow the messages to be uniquely attributed to the publishers and uniquely
identify its dissemination path. The header contains fields used for message
routing and identification; the body contains the application data being
sent. The semantics of the header elements are as follows:

•	Id – Uniquely identifies a message and attributes it to a verifiable
publisher.
•	Length – The length of the message, including manifest and payload.
•	Type – Uniquely identifies a message type, for xml message types this
refers to xsd format of the message.
•	Correlation Id – Uniquely identifies a group of messages. For multiple
nested groupings multiple correlation ids may be associated with the
message.
•	Priority – A sender provided priority associated with the message.
•	Retry – The number of times the disseminator will retry to deliver this
message. The sender specifies this parameter for enactment by the
disseminator.
•	SenderEPR – End point reference to enable any routing node to be able to
interact with the sender.
•	DestinationEPR – The end destination EPR where the message routing needs
to be terminated.
•	OriginalId – A message may have resulted by split, merge or join of
different messages, the original id points to the originating message.
•	SequenceNo – For ordered delivery of message in a correlation (as
specified by CorrelationId) the sequence number specifies the order of
consumption of message. This number does not mean that sequence will be
observed at each stage of routing, but is required to be enforced at the
point of consumption.
•	Signature – The encryption key for the message.
•	EncryptionAlgorithm – The name of the encryption algorithm.
•	Characterset – The character set for the message.
•	Form –  single or multi-byte character set
•	OpChar – operational characteristics.
•	userProperty – A set of user defined name value pairs.
•	Flags – A set of property attributes for message routing.

Patterns for dissemination

Following are the important properties of various message deliveries
•	Ordered sequence of message delivery
	Create a correlationId to identify a sequence.
	Associate an incremental sequenceNo with each message.
	End the sequence by creating new correlations.
•	Transactional message delivery
	Create a correlationid
	Set routing flags for transactional and guaranteed delivery.
	Set retry to allow recovery while routing
	Create nested correlationid at each stage of propagation in the
dissemination network.
	Set acknowledgement flag on at each step of routing.

•	Broadcast of messages
	SetDestinationEPR to NULL
	Retry will be ignored by disseminator.
	Priority may be ignored by disseminator.


Item 50
On successful call to consume operation, a message is transferred to the
consumer. As the services supporting the INFOD protocol do not need to know
the details of the message structure the message need not be necessarily
type checked at the web services (soap transport layer). There for a
message may be wrapped inside a soap message as a binary object. As
messages are binary objects, introduction of new message formats does not
require services to be dynamically rebinding for runtime type checking.
Binary format also provides the messages to have a different encryption key
then the messages. Therefore there exists a canonical mapping between SOAP
messages and INFOD messages.