Space Link Extension - Service Management - CCSDS

DRAFT RECOMMENDED STANDARD FOR SPACE LINK EXTENSION SERVICE MANAGEMENT
documents transmitted at different times, then the underlying communication service must
also be sequence-preserving, but any such sequence preservation requirements are outside
the scope of this Recommended Standard.
3.3 SLE-SM DOCUMENT EXCHANGE PROTOCOL
3.3.1 PURPOSE
In order to ensure that related messages are transferred across the SLE-SM interface with
their intended sequencing preserved regardless of the underlying communication service, the
SLE-SM document exchange protocol is used to exchange SLE-SM documents between
SLE-SM entities (i.e., UM and CM). An SLE-SM document is one of two types: a message
set or an exception response.
The message set carries the SLE-SM operation messages that are exchanged by UM and CM.
A message set contains operation invocation, return, notification, or confirmation messages.
In the case of invocations, multiple invocations may be contained within a single message set
(hence the set) in order to preserve the sequential ordering among related invocation
messages that must be processed by the receiver in a specific order (e.g., a new Space Link
Session Profile must be processed before any Service Packages can reference it), even when
the underlying delivery mechanism does not guarantee sequence preservation (e.g., email).
Message sets are exchanged between communicating SLE-SM entities via the SLE-SM
message set ports of those entities.
An exception response is generated in response to a document which is received as a
purported message set, but which cannot be interpreted as a valid and authentic message set,
or in response to a message contained in a message set that cannot be submitted to the target
service management operation. Exception responses of the first kind are
UnrecognizedMessageSetResponses; those of the second kind are
InvalidMessageResponses. Exception responses are exchanged between
communicating SLE-SM entities via the SLE-SM exception response ports of those entities.
Figure 3-2 illustrates the exchange of message sets and exception responses between the port
pairs of the Sender and Receiver, where in this particular example UM is the Sender and CM
is the Receiver.
CCSDS 910.11-R-2 Page 3-4 March 2008