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· Dec 10, 2018

Try to send the JSON stream from Process to Operation and generate file

#Business Operation #Business Process (BPL) #JSON #Object Data Model #Ensemble

I created the Process to extract the required data from ADT message to a Dynamic Object. I wanted to send the JSON stream to EnsLib.File.PassthroughOperation operation and generate a file with the content of JSON stream.

Here are the codes for Process:

set oMetadata = ... /// metadata is from ADT message which is dynamic object

set jsonRequest = ##class(%ZEN.Auxiliary.jsonProvider).%ObjectToJSON(oMetadata)
set tSC = ..SendRequestAsync(..JSONOperation,jsonRequest,0,,..MetadataContext)  /// send the jsonRequest to operation

Here are the errors in the operation: "ERROR <Ens>ErrGeneral: No MessageBody classname for MessageHeader"

I know there is no such messagebody class for the jsonRequest as it is a custom object. My question is how I should do to create the message body for the custom jsonRequest and how to generate a file with this jsonRequest content in the operation that utilizes EnsLib.File.PassthroughOperation or other proper class?

Discussion (8)0
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Ting Wang · Dec 12, 2018

Hi Eduard,

I got another question for you: once I create the Json stream from dynamic object and send it to the operation, I got the message body as follows:

<StreamContainer><Stream>{
    "_class":"%Library.DynamicObject"
}</Stream><Type>BG</Type></StreamContainer>

, which is totally different from what I have in the dynamic object. The dynamic object is supposed to have several key-value pairs like:

{"a": "1", "b": "2", ...}

. How could I get the correct content from that JSON stream? Thanks so much.

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Eduard Lebedyuk · Dec 12, 2018

%ObjectToJSON writes stream to current device. You need to write to stream:

set oMetadata = ... /// metadata is from ADT message which is dynamic object
set stream = ##class(%Stream.GlobalCharacter).%New()
set tSC = ##class(%ZEN.Auxiliary.jsonProvider).%WriteJSONStreamFromObject(stream, oMetadata)
quit:$$$ISERR(tSC) tSC
set request = ##class(Ens.StreamContainer).%New(stream)
set tSC = ..SendRequestAsync(..JSONOperation,stream,0,,..MetadataContext)  /// send the stream to operation

And your JSONOperation should be able to accept messages of Ens.StreamContainer class.

I just checked Ens.BusinessService:SendRequestAsync signature and it's:

Method SendRequestAsync(pTargetDispatchName As %String, pRequest As %Library.Persistent, pDescription As %String = "") As %Status
So maybe the last line should be just:

 set tSC = ..SendRequestAsync(..JSONOperation, stream)

Finally, use %ZEN.Auxiliary.altJSONProvider instad of %ZEN.Auxiliary.jsonProvider. It's faster.

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Eduard Lebedyuk · Jan 9, 2019

SendRequestAsync is available in all Ensemble Hosts (Services, Operations, Processes).

For Operations and Services the signature is:

Method SendRequestAsync(pTargetDispatchName As %String, pRequest As %Library.Persistent, pDescription As %String = "") As %Status

And for Processes the signature is:

Method SendRequestAsync(pTargetDispatchName As %String, pRequest As Request, pResponseRequired As %Boolean = 1, pCompletionKey As %String = "", pDescription As %String = "") As %Status
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