Receiving data

As the File adapter reads the file, it returns FileLine events to your application. Each line is associated with a specific sessionId, and the data is stored within a sequence of strings. The definition of FileLine events is as follows:

event FileLine
{
/* The name of the transport being used within the file adapter */
string transportName;

/* When receiving these events in response to read line events,
this field can be ignored, as the protocol does not
distinguish between ReadLine requests for the same session.*/
integer requestId;

/* The session Id this FileLine event is for or from */
integer sessionId;

/* The data as a sequence of strings. */
sequence<string> data;
}

Notice that the data field is a sequence of strings, rather than a string. However, when you use the null codec for reading, the sequence contains only one element, which contains the entire line read:

//the whole line is stored in the first element, we used null codec
string line := fileLine.data[0];

//The app knows which field contains the data we are interested in:
string symbol := fileLine.data[0];
string exchange := fileLine.data[1];
string currentprice := fileLine.data[2];
//and so on

After the File adapter opens a file for reading, the file remains open as long as the adapter is running. If you want to close a file, you must send a CloseFile event that specifies the sessionId of the file you want to close. For example, if you want to replace the contents of a file, you must close the file before you send an OpenFileForWriting event. The definition of the CloseFile event is as follows:

event CloseFile
{
/* The name of the transport being used within the file adapter */
string transportName;
/* Request ID for this CloseFile event. If an error occurs,
the response will contain this ID */
integer requestId;

/* The session ID the file to close is associated with */
integer sessionId;
}

If there is an error, the File adapter sends a FileError event. Otherwise, the File adapter closes the file and sends a FileClosed event, and then it is available to be opened again for writing or for reading.