Once you have created a form for your application, the next step is to define the VMD file that the application will use to generate ADT^A04 messages. To do this, you must use Chameleon to create a VMD file that contains this message information.

To create the VMD file:

• Start Chameleon.

• Select Options from the toolbar, click the Misc tab, and select the Use .NET properties when generating .NET code check box. If this check box is not selected, your VB.NET application may not work properly.

• Create a sample message, and use the sample message to import the ADT^A04 message and its segments from the Chameleon library. For the purposes of this tutorial, you can use this sample message. The message definition you create should be named PatientRegister.

• Create a segment grammar consisting of the MSH and PID segments.

• Create a table named MessageInfo, and define a field for it named MessageControlID. This field is of type String, and will be included as part of the MSH segment of the message. Its value will be supplied by the VB.NET code that you will be writing later on.

• Create a table named Patient, and define fields for it named PatientID, Surname, FirstName and SocialSecurityNumber. All of these fields are of type String. This table will be used to generate the PID segment of the message.

	Since this tutorial is a simplified example, the HL7 message that is generated only contains two segments: The MSH segment, which is generated from the MessageInfo table and from Segment Outbound scripts that you create later in this section; The PID segment, which is generated from the Patient table. For an example of the tables you might create when generating an HL7 message, see Application to HL7.

• Add the MessageInfo table to the Table Grammar, and specify Message as the grammar root.

• Map the MessageControlID field of the MessageInfo table to field 10 of the MSH segment (MessageControlID).

• Add the Patient table to the Table Grammar, and specify Message as the grammar root.

• Use the following mappings to map fields in the Patient table to fields in the PID segment:

The final step is to create Segment Outbound scripts to set default values for fields that will be the same for every generated message:

• In the Segment Outbound script for field 3 of the MSH segment (Sending Application), add the script value = "SAMPLE CLIENT".

• In the Segment Outbound script for field 4 of the MSH segment (Sending Facility), add the script value = "SAMPLE LABS".

• In the Segment Outbound script for field 11 of the MSH segment (Processing ID), add the script value = "P".

• In the Segment Outbound script for field 12 of the MSH segment (Version ID), add the script value = "2.5". This field specifies the version of HL7 that this message is using.

	This tutorial assumes that the application is expecting HL7 messages that conform to version 2.5 of the HL7 standard. If your application is using a different version of HL7, change the script for field 12 of the MSH segment as needed.

• In the Segment Outbound script for field 7 of the MSH segment (Date/time Of Message), add the following script:

import time

value = time.strftime("%Y%m%d%H%M")

This sets the date/time of the message to be the current date and time.

When you have completed these steps, save the VMD file and remember its location. You will need to supply this location to your application so that it can generate messages.

	A copy of the VMD file for this tutorial is located in vbnet_client.vmd. For more details on how to create a VMD file for generating HL7 messages, see Application to HL7 tutorial.

Once you have created the VMD file, the next step is to use this file to create stubcode for your application.