Mission Operations Reference Model. Draft ... - CCSDS

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DRAFT RECOMMENDED PRACTICE FOR MISSION OPERATIONS REFERENCE MODEL4.4.1 MESSAGE SENDING SEQUENCEFigure 4-8 shows the message sending sequence for the MAL. It includes the error cases asalternative fragments.MO Service Layer MAL Access Control Transport LayerSubmit messagePre-check messagealt MAL Check FailureReturn check erroralt If message from a ProviderTransmit check error message to transaction sourceCheck messagealt Access Control FailureReturn Access Control errorReturn Access Control erroralt If message from a ProviderTransmit Access Control error to Transaction sourceReturn updated messageStore message transaction detailsTransmit messagealt Transport FailureReturn Transport errorReturn Transport errorReturn Transport okReturn message okFigure 4-8: MAL Sending SequenceThe basic outline of this sequence from the high-level sequence (figure 4-2) is that the MALreceives message from the MO Service Layer and passes them down to the relevantTransport layer.a) The MO Service Layer submits the message to the MAL using the MAL’s abstractservice interface.b) The MAL checks the contents of that message to ensure that it contains all therequired aspects for the MAL itself. If it fails these checks, then an error is returned tothe MO Service Layer.<strong>CCSDS</strong> 520.1-R-1 Page 4-9 October 2009
DRAFT RECOMMENDED PRACTICE FOR MISSION OPERATIONS REFERENCE MODELc) If the message is from a provider (determined by examining the interaction patternstage fields of the message), then the error message is also sent to the transactionsource. The transaction details are removed from the Transaction Store.d) If there was an error, then the sequence ends at this point.e) The MAL then submits the message to the Access Control component using itsabstract service interface. The rules that the Access Control component applies aredeployment specific.f) If the Access Control component rejects the message, then it returns an error to theMAL. The MAL creates the relevant Access Control message and passes this back tothe MO Service Layer.g) If the message is from a provider (determined by examining the interaction patternstage fields of the message), then the error message is also sent to the transactionsource. The transaction details are removed from the Transaction Store.h) If there was an error, then the sequence ends at this point.i) If the Access Control component accepts the message, then it returns an updated(with updated security credentials, if applicable) message to the MAL.j) The MAL then stores the transaction details if this is the first message being sent fromthe consumer. If it is a return message from a provider, then the transaction details areremoved from the store if it is the final message for that interaction pattern.k) The MAL then passes the message to the Transport layer for transmission to thedestination.l) If the Transport encounters an error during its attempt to send the message, or part ofthe message, then it returns an error to the MAL. If the sender is a consumer, then theMAL uses the Active Transaction Store to build a return error message to be returnedto the sending application. If it is a provider, then an application error is returned tothe provider.m) If there was an error, then the sequence ends at this point.n) If there are no issues during sending by the Transport it returns a success message tothe MAL which passes that back to the MO Service Layer.<strong>CCSDS</strong> 520.1-R-1 Page 4-10 October 2009
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