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Parsing a Message |
The ParseMessage method of the application Engine should be invoked to parse a message. If it successfully recognizes and parses a message, it will invoke one of the message virtual functions. If the parse fails, it will throw a CHMerror exception object. The following code shows an example of how this API can be invoked:
void CMyApp::testMessage()
{
try
{
cout << "Testing..." << endl;
// CHMstring is a string class which ships with the CHM library. You can
// use any string class you like, but we provide this one.
CHMstring Message;
// Load an HL7 message into the string Message.
// Note the use of a double \\ to escape the \ character at the start of the message
// and the use of \r at the end of each segment.
Message = "MSH|^~\\&|REGADT|MCM|RSP1P8|MCM|199601051530|SEC|ADT^A44|00000007|P|2.5\r";
Message = Message + "EVN|A44|199601051530\r";
Message = Message + "PID|||MR2^^^XYZ||JONES^WILLIAM^A^JR||19501010|M|||123 EAST\r";
Message = Message + "STREET^^NY^NY^10021||(212)111-3333|||S||ACCT1\r";
Message = Message + "MRG|MR1^^^XYZ||ACCT1\r" ;
m_Engine.ParseMessage(Message, 0);
}
catch (CHMerror& Error)
{
cout << "Error during parsing:" << Error;
}
}
|
This is a call sequence:
- An object invokes ParseMessage method on the HL7appEngine.
- The HL7appEngine may have an implementation of this method if the user has chosen to override it for error handling and/or logging purposes (see below). After this, the call passes up the chain to the parent stubcode class HL7Engine.
- This method invokes the core Chameleon engine. If a parsing error is found, an exception is thrown. If not, the class calls the virtual function for the appropriate message.
- At this point, the HL7appEngine object now takes over. The user is responsible for creating these functions.
The following code fragment gives an idea of what a typical message virtual method would look like when the user overrides the ServerEngine class:
void HL7appEngine::msgPatientUpdate
(
const HL7MsgPatientUpdate Message,
size_t TransportIndex
)
{
strstream Output;
Output << Message.Patient(0).FirstName() << NewLine();
Output << Message.Patient(0).LastName() << NewLine();
:
// We send the contents of the strstream buffer to the log
// which is implemented in the CHMoutputLog object assigned to this
// engine object.
OutputStream(Output);
)
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