If you need to send a PDF file, an image, or any other binary file to another HL7 application, you can use Chameleon to encode the binary file as a string and transmit it as a segment field of an HL7 message.

To do this, you must add the following to your VMD file:

• A Segment Outbound Script that converts the binary file to a string and stores it as a field;
• A Transformation Script that processes the segments of your message, invokes the segment script that you have just defined, and generates a transformed HL7 message that includes the string version of the binary file.

The following Python script reads a binary file, converts it to a string, and defines it to be the value of a segment field:

import base64

myfile = open("D:\\sample\\mybinaryfile.pdf", "rb")
line = myfile.read()
myfile.close()
value = base64.encodestring(line)

In this code, the mybinaryfile.pdf file is read (in its entirety) into the line variable. The function encodestring() then converts this into string format. The result is assigned to value, which is the special Python variable that represents the value of the segment field.

The next step is to write a Transformation Script that calls this Segment Outbound script:

current_segment = environment.input_segment_iterator()

current_segment.apply_transform()
output = current_segment.output()

while current_segment.move_one():
      current_segment.apply_transform()  # apply segment scripts
      output = output + current_segment.output()

value = output

This Transformation Script calls apply_transform() to run all of the segment scripts that you have defined, including the one shown above.

For this method to work, your receiving application must be able to process the HL7 message that you have created. In particular, it must be able to convert the field containing the encoded information back to the original binary file. If the receiving application uses Chameleon to receive its incoming message, the following Python script can be used to convert the field to a binary file:

import base64

decoded = base64.decodestring(value)
myfile = open("D:\\sample\\mybinaryfile.pdf", "wb")
myfile.write(decoded)
myfile.close()
value = ""

	If the binary file that you want to send is large, the HL7 message containing the encoded binary file might become too large for your application or your network. If this is the case, an alternative is to send the URL of the binary file as a segment field in your HL7 message: OBX|5|TX|502^CHEST XRAY^L|1|http://www.abchospital/xray.jpg||||||F OBX|6|TX|502^CHEST XRAY^L|1|http://www.abchospital/test_results.pdf||||||F For more information on the scripts used in this example, see the following sections: Segment Outbound Scripts Scripted Transformation