RE: Sub files in RPGLE

On Monday, October 19, 1998 1:59 AM, Easwar [SMTP:easwar@md3.vsnl.net.in] 
wrote:
> I have a question on ILE RPG. The qestion relates to subfile. In the
> condition where SFLSIZ = SFLPAG + 1, the system takes care of the Page
> Up and Page Down key. Is this particular for ILE ?.  And When I give a
> Page Down key after the last page is displayed, It shows a blank page
> and then the Page Up doesnt work properly. I am using Relative record no
> to navigate through the subfile records. I can give the source file if
> needed. Could someone give me a hint in this? A working RPGLE code would
> be fine.I am working on 9401 and V3R7.

Easwar,
  When SFLSIZ<>SFLPAG, the system does not automatically take care of page 
up/down unless the user is paging within the limits of the subfile records 
already loaded.  If the user tries to page beyond the records already 
loaded, your program gets control, with the PAGExx indicator set on.  At 
that point, it is up to your program to determine what to do.

Many times, people will load a single page of the subfile at a time, to 
minimise the performance issues associated with loading all the records at 
once.  A simple example may serve to enlighten:

Imagine that your application is going to display all the long distance 
telephone calls for a single telephone number.  Any one customer can have 
as few as zero and no limit for the maximum number (imagine the phone bill 
of a large corporation with thousands of employees.)

Scenario 1

SFLSIZ<>SFLPAG
Page Up/Down not specified
If you load all 5000 records into the subfile at once you will be doing 
one read/write for every long distance call that was made.  But what if 
the user looks at the calls on the first page and realises that they are 
looking at the wrong customer?  Then we have spent all that time loading 
thousands of records into the subfile and the user never looked at them 
all.

Scenario 2

SFLSIZ<>SFLPAG
Page Down specified
If you load one page of records into the subfile at a time, the user will 
only have to wait for one page to load, but because SFLSIZ<>SFLPAG, OS400 
will handle the paging between those pages that are already loaded, and 
your program will not get control until the user pages past the end. 
 Then, your program gets control and you can load another page, and 
essentially "expand" the records by one page at a time, something like 
this:

         DoW *In03=*Off
         Exfmt SFLCTL
         If *In03=*Off
         If "pagedown indicator"=*On
         ExSr LoadPage
         EndIf
         EndIf
         EndDo

LoadPage BegSr
         Eval  CurrentRRN=HighestRRN
         Eval  EOF=*Off
         Eval  RecsThisPage=0
         DoW   EOF=*Off
Telnbr   Reade LongDist
         If    %eof
         Eval  EOF=*On
         Else
         Eval  CurrentRRN=CurrentRRN+1
         Write SflRec
         EndIf
         EndDo
         Eval  HighestRRN=CurrentRRN

Check the manual Application Display Programming, SC41-4715 for more 
details.
Also, feel free to check out http:www.midrange.com  Follow the links to 
books (this is amazon.com).  Any books you buy there help fund this mail 
list.

hth,
Buck Calabro
Commsoft, Albany, NY
mailto:mcalabro@commsoft.net

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