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Marc Mundt · Sep 16, 2022

Hopefully this can save you some work. It uses a much larger chunk size (which is a multiple of 57) and works with or without CR/LFs (set the argument pAddCRLF):

Class Example.B64.Util Extends %RegisteredObject
{

/// Be cautious if changing CHUNKSIZE. Incorrect values could cause the resulting encoded data to be invalid.
/// It should always be a multiple of 57 and needs to be less than ~2.4MB when MAXSTRING is 3641144
Parameter CHUNKSIZE = 2097144;

ClassMethod B64EncodeStream(pStream As %Stream.Object, pAddCRLF As %Boolean = 0) As %Stream.Object
{
    set tEncodedStream=##class(%Stream.GlobalCharacter).%New()
    
    do pStream.Rewind()
    
    while ('pStream.AtEnd) {
        set tReadLen=..#CHUNKSIZE
        set tChunk=pStream.Read(.tReadLen)
        
        do tEncodedStream.Write($System.Encryption.Base64Encode(tChunk,'pAddCRLF))
        if (pAddCRLF && 'pStream.AtEnd) {
            do tEncodedStream.Write($c(13,10))
        }
    }
    
    do tEncodedStream.Rewind()
    
    quit tEncodedStream
}

}
Marc Mundt · Jul 21, 2022

My experience with Zebras was quite a few years ago, so this may or may not still apply... Using Zen reports at the time, the print server would end up rendering the label as a bitmap and sending that over to the Zebra. ZPL code to print an equivalent label was much smaller than a bitmap, so ZPL labels tended to print faster than those rendered by a report.

Marc Mundt · Jun 14, 2022

Ok, so the flow would look roughly like this:

  • The GenericService accepts an inbound REST request, populates a GenericMessage, and sends it to your business process
  • Business process extracts the JSON payload from the GenericMessage, and pulls out any relevant details needed for the call to Athena
  • Business process creates a new GenericMessage, populates any items needed by Athena, uses %SYS.OAuth2 (and the OAuth client profile you created) to request an OAuth token and adds it to the GenericMessage, and passes the new GenericMessage to the business operation.
  • Business operation makes the outbound REST call to Athena, and returns a new GenericMessage containing the response to your business process.
  • Business process extracts JSON payload from the GenericMessage, uses a transformation to create the payload required by your internal REST client.
  • Business process creates a new GenericMessage, populates it with the response payload, and returns it to the GenericService
  • GenericService returns response to REST client
Marc Mundt · Jun 14, 2022

For the outbound REST calls, I would typically create a custom operation class that calls methods in %SYS.OAuth2.* to fetch a token from the downstream system and then places that in the HTTP header.

If it's essential for you to avoid creating a custom class, you could call the %SYS.OAuth2 methods from a BPL and then add the token to the header fields in the EnsLib.HTTP.GenericMessage that you send to the GenericOperation.

You haven't said what needs to happen between the business service and business operation, so it's hard to discuss how everything fits together as you asked.

Marc Mundt · Jun 13, 2022

You'll want to configure the passthrough service to use "Standard Requests". This means REST requests will pass through a web server (IIS, Apache, etc) to get to IRIS:
https://docs.intersystems.com/irisforhealth20221/csp/docbook/DocBook.UI....

For TLS, you'll enable HTTPS on your web server.

And see this docs on enabling OAuth for web services:
https://docs.intersystems.com/irisforhealth20221/csp/docbook/DocBook.UI....

Marc Mundt · Jun 13, 2022

Yes, the GenericService will send an EnsLib.HTTP.GenericMessage object to your business process. The GenericMessage includes the headers and content of the inbound HTTP request. Your DTL can use these fields to transform to another format.

Similarly, the GenericOperation accepts the same GenericMessage type and uses the values in it to issue an HTTP request to the downstream system.

So all together, this allows you to create a REST web service and/or call out to external REST services using only the GUI.

https://docs.intersystems.com/irisforhealth20221/csp/docbook/DocBook.UI....

Marc Mundt · Jun 6, 2022

Here's a sample class to Base64 encode a stream:

Class Example.B64.Util Extends %RegisteredObject
{

/// Be cautious if changing CHUNKSIZE. Incorrect values could cause the resulting encoded data to be invalid.
/// It should always be a multiple of 57 and needs to be less than ~2.4MB when MAXSTRING is 3641144
Parameter CHUNKSIZE = 2097144;

ClassMethod B64EncodeStream(pStream As %Stream.Object, pAddCRLF As %Boolean = 0) As %Stream.Object
{
    set tEncodedStream=##class(%Stream.GlobalCharacter).%New()
    
    do pStream.Rewind()
    
    while ('pStream.AtEnd) {
        set tReadLen=..#CHUNKSIZE
        set tChunk=pStream.Read(.tReadLen)
        
        do tEncodedStream.Write($System.Encryption.Base64Encode(tChunk,'pAddCRLF))
        if (pAddCRLF && 'pStream.AtEnd) {
            do tEncodedStream.Write($c(13,10))
        }
    }
    
    do tEncodedStream.Rewind()
    
    quit tEncodedStream
}
}