Writing records to disk immediately using MIO

Last week, I ran into a scenario where I needed to create two subroutines that are called sequentially by another subroutine. The first sub creates a record and then the second sub queries the database for the record and performs extra processing. The workflow looks like this:

Overall Subroutine Begins
   Subroutine 1: creates a record
   Subroutine 2: does a select to obtain the record created in subroutine 1
Overall Subroutine Ends

There was a problem with this workflow that I was using just a FOR_THE command to create the record in sub 1. Since the record created in sub 1 stays in the running buffer, it never gets written back to disk until the overall sub ends. Because of that, sub 2 never finds the new record.

To get around this, my colleagues at Ferrilli suggested manually changing the MIO level so that sub 1's record is written to disk immediately. The code to be added is:

CALL @MIO.TRANSACTION(MIO.TX.SUSPEND)
FOR_THE record_id
  * set field values
END_THE record_id
CALL @MIO.TRANSACTION(MIO.TX.RESUME)

The two MIO calls modify the level of the buffer and that's where the magic happens. Using MIO.TX.SUSPEND, in effect, temporarily starts a new process level at level 0.  All I/O that is performed after the call to MIO.TRANSACTION using MIO.TX.SUSPEND will be held in MIO's buffers until the call to MIO.TRANSACTION using MIO.TX.RESUME is reached. In our case, as MIO.TX.RESUME is reached, the buffer of the transaction is flushed and the record is written to disk. Afterward, the MIO level returns to the normal running state. So my pseudo code looks like this at the end:

Overall Subroutine Begins
   Subroutine 1: creates a record
      CALL @MIO.TRANSACTION(MIO.TX.SUSPEND)
      FOR_THE record_id
          * set field values
      END_THE record_id
      CALL @MIO.TRANSACTION(MIO.TX.RESUME)
   Subroutine 2: does a select to obtain the record created in subroutine 1
Overall Subroutine Ends

Thanks Neal, Lea, and Geoff for the documentation, and Thomas Mantooth for verifying the code. GO FIGTEAM!

How to get/query the list of files in a folder from Envision

Say you have a list of file in HOLD_SHARED_MYFOLDER directory in Colleague, and you want to read in the list of files in MYFOLDER and do something with them, maybe read or write or both.

What you need is read/write access to MYFOLDER. Your admin should know how to set it up, and a VOC entry should already be created for it. 

In Colleague Studio, use the following code to get back a list of files inside MYFOLDER directory:

X.STMT = 'SELECT HOLD_SHARED_MYFOLDER'
CALL S.EXECUTE(X.STMT)
XL.FILES.NAME = ''
CALL S.READLIST(XL.FILES.NAME,0,X.STATUS)
CONVERT @FM:@SM:@VM:@AM TO @VM:@VM:@VM:@VM IN XL.FILES.NAME

Now you will have all the files' names in MYFOLDER populated in XL.FILES.NAME. To open each file up, you iterate them with S.OPEN.SEQ subroutine

FOR X = 1 to DCOUNT(XL.FILES.NAME, @VM)
   * Open the file
   CALL S.OPEN.SEQ("HOLD_SHARED_MYFOLDER", XL.FILES.NAME<1,X>, X, "R", X.ERROR.MSG)
   * Read from the file
   CALL S.READ.SEQ(X.TEXT, X.EOF, X, X.ERROR, X.MSG)
   * Close the file
   CALL S.CLOSE.SEQ(X, X.ERROR, X.MSG)
NEXT X

Check for record lock

XKV.FILE = Table ID / Record Key
XFV.FILE = Table/File Name
XR.FILE = ""
CALL @MIO.READ.RECORD(MIO.READU.EXIT.ON.LOCKED,XFV.FILE,XKV.FILE,XR.FILE)
IF MIO.STATUS = MIO.STAT.LOCKED THEN
   // File is locked
END ELSE
   // File is not locked
END

RETURN