the transaction type of edi doesn t really matter (850 = order, 875 = grocery po). having written a few edi parsers, here are a few things i ve found:

you should be able to count on the ISA (and the ISA only) being fixed width (105 characters if memory serves). strip off the first 105 characters. everything after that and before the first occurance of "GS" is your line terminator (this can be anything, include a 0x07 - the beep - so watch out if you re outputting to stdout for debugging or you may have a bunch of beeps coming out of the speaker). normally this is 1 or 2 characters, sometimes it can be more (if the person sending you the data adds an extra terminator for some reason). once you have the line terminator, you can get the segment (field) delimiter. i normally pull the 3 character of the GS line and use that, though the 4th character of the ISA line should work as well.

also be aware that you can get a file with multiple ISA s in it. in that case you cannot count on the line or field separators being the same within each ISA.

another thing .. it is also possible (again, not sure if its spec) for an edi file to have a variable length ISA. this is very rare, but i had to accommodate it. if that happens you have to parse the line into its fields. the last field in the ISA is only a character long, so you can determine the real length of the ISA from it. if it were me, i wouldn t worry about this unless you see a file like it. it is a rare occurance.

what i ve said above may not be to the letter of the "spec" ... that is, i m not sure its legal to have different line separators in the same file, but in different ISAs, but it is technically possible and I accommodate it because i have to process files that come through in that manner. the edi processor i use processes upwards of 5000 files a day with over 3000 possible sources of data (so i see a lot of weird stuff).

best regards, don

EDI content is composed of segments and elements.

To parse it, you will need to break it up into segments first, and then elements like so (in PHP):

<?php 

$edi = "YOUR EDIT STRING!";
$segment_delimeter = "~";
$element_delimeter = "*";

//First break it into segments
$segments = explode($segment_delimiter, $edi);

//Now break each segment into elements
$segs_and_elems = array();
foreach($segments as $segment){
    $segs_and_elems[] = explode(element_delimeter, $segment);
}

//To echo out what type of EDI this is for example:
foreach($segs_and_elems as $seg){
    if($seg[0] == "GS"){ echo($seg[1]); }
}

?>

Hope this helps get you started.

For header information the following java will let you get the basic info pretty easy. C# has the split as well and the code looks very similar

try {
    String sCurrentLine;
    fileContent = new BufferedReader(new FileReader(filePathName));

    sCurrentLine = fileContent.readLine();

    // get the delimiter after ISA, if you know your field delimiter just force it.
    // we look at lots of different senders messages so never sure what it will be.

    delimiterElement = sCurrentLine.substring(3,1); // Grab the delimiter they are using
    String[] splitMessage = sCurrentLine.split(delimiterElement,16); // to get the messages if everything is on one line of course
    senderQualifier = splitMessage[5]; //who sent something we need fixed qualifier
    senderID = splitMessage[6]; //who sent something we need fixed alias
    ISA = splitMessage[13]; // Control number
    testIndicator = splitMessage[15]; 
    dateStamp = splitMessage[9];  
    timeStamp = splitMessage[10];

    ... do stuff with the pieces of info ...