Handling of DIMSE_N_CREATE_RQ messages

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cisco
Posts: 6
Joined: Sat, 2004-12-11, 17:56

Handling of DIMSE_N_CREATE_RQ messages

#1 Post by cisco » Sat, 2005-01-08, 01:10

Hello,
I would like to create an executable for an MPPS SCP. So far, I have made a copy of the wlmscpfs source and started a new project called mppsscpfs. I am at the point that I am receiving the DIMSE_N_CREATE_RQ command, but now I need to write a routine to handle this command. After the DIMSE_N_CREATE_RQ is created, my understanding is that a different type of command will be received (N-SET ?). My inmediate goal is to send back to the SCU the correct response it needs, and get the ascession number so that I can use to flag the worklist entry.

Does anybody have a sample of how to handle this command?

My application currently provides a worklist service using the standard wlmscpfs binary, a storescp using the corresponding binary, and would like to provide an mpps service to flag an item in the worklist as being worked on, and therefore not serving it in the wlmscpfs module.

Thanks
- Cisco

cisco
Posts: 6
Joined: Sat, 2004-12-11, 17:56

handleNCreate() and handleNSet() from dvpsprt.cxx looks like it has the answer!

#2 Post by cisco » Sat, 2005-01-08, 03:11

I found the handleNCreate() and handleNSet() functions in the module mentioned and it looks like I can get all that I need from there!

-Cisco

cisco
Posts: 6
Joined: Sat, 2004-12-11, 17:56

Cancelling a procedure.. is there a notification?

#3 Post by cisco » Sat, 2005-01-08, 08:26

Hello,
I am wondering if there is supposed to be some type of notification when a procedure is cancelled? The problem I am encountering is that I get a N-CREATE message when the procedure is "In Progress", and I get an N-SET when a procedure is complete. The application that I am working with has a cancel option, but it does not appear to generate a message in this regard. If my MPPS SCP uses the N-CREATE to flag the worklist entry in progress, and if the procedure is cancelled, how to I revert the "In progress" flag?

- Cisco

Thomas Wilkens
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#4 Post by Thomas Wilkens » Mon, 2005-01-10, 08:01

In PS 3.4 Annex F.7 ff., the MPPS service is explained in detail. Make sure you have read and understood that part of the standard before you go and implement an application. The implementation is not that difficult, and starting by modifying wlmscpfs is a very good idea, but it is necessary that you understand the standard, otherwise you will run into difficulties.

In particular, please note that for every incoming RQ message, you will have to send a corresponding RSP message back to the SCU. Also, you will have to make up your mind about what attributes your SCP is supposed to support . Table F.7.2-1 gives an overview of "MODALITY PERFORMED PROCEDURE STEP SOP CLASS N-CREATE, N-SET AND FINAL STATE ATTRIBUTES", your SCP should at least support all the mandatory attributes. Moreover, please dont forget to implement a function that checks whether all final state conditions are met once the status is set to completed.

Concerning your "cancelled" problem: In case a procedure is cancelled, you should get an N-Set RQ message containing a status of "DISCONTINUED".

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