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· Nov 18, 2016

Decode Base64 into a file

#DTL #HL7 #Object Data Model #ObjectScript #Ensemble

I am trying to come up with a way to decode the Base64 we receive in an HL7 message into a PDF file and save it in a directory on our AIX machine. I thought I had the following working at one time but I am having issues. Has anyone done this before?

ClassMethod DecodeBase64HL7ToFile(base64 As %Stream, Ancillary As %String) As %Boolean
{

set Oref = ##class(%FileBinaryStream).%New()
set Oref.Filename = Ancillary
Do base64.Rewind()

While 'base64.AtEnd {
    set ln=base64.ReadLine()
    set lnDecoded=$system.Encryption.Base64Decode(ln)
do Oref.Write(lnDecoded)
}

Do Oref.%Save()
quit 1
}

Thanks

Scott

Discussion (5)1
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Dmitry Maslennikov · Nov 19, 2016

It is not so simple. Before decoding, you should strip any special characters, like line endings. Then you should read input stream in fixed size devisable by 4, and decode this value.

set stream1=##class(%Stream.GlobalBinary).%New()
set stream2=##class(%Stream.GlobalBinary).%New()

while 'base64.AtEnd {
    set temp=base64.Read()
    set temp=$translate(temp, $c(13,10))

    do stream1.Write(temp)
}

do stream1.Rewind()
while 'stream1.AtEnd {
    set temp=stream.Read(4000)
    set temp=$system.Encryption.Base64Decode(temp)

    do stream2.Write(temp)
}
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