Re: Newbie Needs Design Help
- From: "DJ" <ddjames@xxxxxxxxxxxxxxx>
- Date: Tue, 10 May 2005 23:15:45 GMT
Larry,
Thanks for the great suggestion. I've utilized collections in Word VBA but
had not even considered their use here. I really appreciate the informative
pseudo code and demo examples!
The replies do not always follow the requests (due to a preprocessor
application that takes the raw data and formats it somewhat) so the Seek tip
will definitely come in handy!!
Thanks again!
~ Dave
"Larry Serflaten" <serflaten@xxxxxxxxxxxxxx> wrote in message
news:eYamcAsUFHA.544@xxxxxxxxxxxxxxxxxxxxxxx
>
> "DJ" <ddjames@xxxxxxxxxxxxxxx> wrote
>> I work with text files that contain messages passed between POS systems
>> and
>> financial institutions. The messages are text strings that vary in
>> length,
>> up to 400 characters, with each string being composed of variable length
>> fields. Here's an example of one of the message strings:
>>
>> EFQC000855050413180103ACME004200031403
>> 05041300000000SWTH
>> 780000000000 01010356001234567890123456=14121104485478004008PB09901
>> 05044123 Main Street Home Town RI40008
>> 41020091004663 42020840901000325542
>> 47024002480010990001000000000810100000000000830260101000000009900200606663299
>>
>> The messages themselves are requests sent from the POS terminal to the
>> financial institution, and replies from the institution back to the POS
>> terminal. Reply messages are matched to their corresponding request
>> message
>> when certain fields within the messages (message number, transaction
>> sequence id, etc.) are identical between the two messages.
>>
>> I'm trying to write a vb app that will scan the text file, parse the
>> messages and match request messages to reply messages.
> <...>
>> Any suggestions would be appreciated.
>
>
> If I read your message correctly, you have a large text file where each
> line is
> a recorded transaction (either request, or reply) and you want to match up
> replies with their requests using a few fields to identify the
> request/reply.
>
> Can it be safe to assume that the request will always be ahead of the
> reply?
> (Going on that assumtion....)
>
> Use the file pointer to identify and locate the different lines in the
> file. Build
> a fixed length identifier that will match the replies with the requests
> (using
> the message number, transaction ID, etc). Finally, use 2 collections to
> sort
> the file into replies, and requests. As you read each line in the file,
> first note
> where the file pointer points to, then read the line, then determine if it
> is a
> request, or reply. Build the transaction ID and add the file pointer
> value
> to either the Requests collection, or the Replies collection, using the
> transaction
> ID as its key. If that line was a reply, check for a matching key in the
> Requests
> collection. If it is found there, you have enough info to make a status
> report on
> that transaction.
>
> In pseudo code, it might look similar to:
>
> Open file
> Do While Not EOF
> Get File Pointer (Seek)
> Input line (Line Input)
> Decide Transaction type
> If Request type Then
> Build ID
> Add to request collection
> If Reply type Then
> Build ID
> Check for matching request
> If Request found Then
> Add status to status report
> (Remove Request ???)
>
>
> For a short example (minus any file activity) paste the following
> into a new form:
>
> '------------------
> Option Explicit
> Private ReQ As Collection
> Private ReP As Collection
>
> Private Sub Form_Load()
> Dim msg As String, ID As String
>
> Set ReQ = New Collection ' Requests
> Set ReP = New Collection ' Replies
>
> ' Reading file adds to collections
> ReQ.Add 1, BuildID("9", "1000")
> ReQ.Add 101, BuildID("10", "1001")
> ReP.Add 201, BuildID("9", "1002")
> ReQ.Add 301, BuildID("10", "1014")
> ReQ.Add 401, BuildID("11", "1016")
> ReP.Add 501, BuildID("10", "1001")
>
> ' Test current reply (10, 1001)
> ID = BuildID("10", "1001")
> If IsPresent(ID) Then
> msg = "STATUS:" & vbCrLf & vbCrLf
> msg = msg & "The Request that begins at file position "
> msg = msg & CStr(ReQ(ID)) & vbCrLf
> msg = msg & "is followed by a reply that begins at file position "
> msg = msg & CStr(ReP(ID)) & vbCrLf
> MsgBox msg, vbInformation, "Match Found"
> End If
>
> End Sub
>
>
> Function BuildID(MsgNum As String, TransID As String) As String
> BuildID = Space$(24)
> Mid(BuildID, 1) = MsgNum
> Mid(BuildID, 12) = TransID
> End Function
>
> Function IsPresent(ID As String) As Boolean
> On Error Resume Next
> IsPresent = (ReQ(ID) > 0)
> Err.Clear
> End Function
>
>
> '----------------------------------
>
> Note that keeping the functions separate helps in re-use. Also, once
> you know the positions in the file where the data is at, you can, at your
> next convenience, go back and re-read those lines if needed. (Read
> Seek Function and Seek Statement in VB Help) Leaving the data in the
> file means you won't be using up computer memory as much as storing
> each line would require. Chances are, the file pointer is all you
> need....
>
> If there is only one reply per request, then you could remove any matches
> found (from both collections) so that at the end, you'd know how many
> were not matched in the two collections, and if needed, where they are
> in the file.
>
> HTH
> LFS
>
>
>
>
>
>
.
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- From: DJ
- Re: Newbie Needs Design Help
- From: Larry Serflaten
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