Trap that disconnection error

John Kohan

One thing I've noticed over the years is often interactive programs don't trap for disconnection errors. When any type of maintenance is being done on a file, it's crucial to perform proper clean up. This issue can arise from a user simply terminating his telnet session. If SQL commitment control isn't being used, it can be time-consuming to verify files and potentially have to clean them up.

If you're developing a Radio Frequency (RF) application, the possibility of loosing connection with the device during the program cycle is greater than when you are dealing with a normal workstation. If the program you're writing has multiple communications with the user, it may be necessary to properly "cleanup" the process if its connection with the user is lost.

A simple solution is to add an indicator on the EXFMT in the LO column. Immediately after the EXFMT, check for that indicator to be *ON and execute a subroutine. That subroutine should be written to do any necessary clean up and shut down the program clean. And if necessary, send a message to the appropriate person, depending on the level of the program's importance.

Code:

C                     EXFMTCONTROL                88 
C     *IN88     CASEQ'1'                     $S900           

C****************************************************************
C** $S900 - Screen Error Cleanup                                 
C****************************************************************
C           $S900     BEGSR                                      
C*                                                              
C**Add any processing you wish here
C*                                                              
C                     CALL 'XXXXXXXX'               Physical Disconnect
C                     EXSR $S001                      Exit       
C**                                                              
C                     ENDSR                                      
C**                                  

-----------------------------------------
About the author: John Kohan is a senior programmer analyst at CT Codeworks.

==================================
MORE INFORMATION
==================================

• Top 10 programmer tips We let your votes do the talking as we selected the top tips for January and February. These tips were selected based on your ratings as of March 6. Check them out and see if you agree with how they were rated.
• The Best Web Links on Development: Tips, tutorials and more.
• Ask your programmer questions -- or help out your peers by answering them -- in our live discussion forums.



Rate this Tip To rate tips, you must be a member of Search400.com. Register now to start rating these tips. Log in if you are already a member. Submit a Tip Digg This!     StumbleUpon     Del.icio.us    RELATED CONTENT iSeries programmer tips A power-handling CL program for multiple IBM i servers Enhancing RPG with external SQL stored procedures Tracking data changes on IBM i with triggers Introduction to SQLRPGLE on IBM i: Making a report Implementing a browser interface in COBOL: Displaying database fields Taking advantage of CL advancements, starting with V5R3 TAATOOL: Useful tools for programmers on IBM i Implementing a browser interface in COBOL: Creating your graphic Web page Implementing a browser interface in COBOL: Getting started Making the most of RPG data handling on IBM i Application Development iSeries calling an .exe Top 10 programmer tips Formatted work job scheduler Convert system date and time Mixing free format code with embedded SQL SQL update a field in one file from a field in another file Webcasts for iSeries programmers Programming advice from the pros Easy code copying via the drag and drop method Setting FTP time-outs iSeries CL programming A power-handling CL program for multiple IBM i servers Taking advantage of CL advancements, starting with V5R3 Checking in on your IBM i authorization lists Running PHP open source applications: NOBODY needs authority Simplify the process of converting a spool file from iSeries into an Excel spreadsheet CL program for daily backups An automated CL method of moving a query from AS/400 to Excel Changing user password expiration Eight steps for creating program documentation using AS/400 utilities DAYSPAST CLLE program for AS/400: Compares object creation date with today's date RELATED RESOURCES 2020software.com, trial software downloads for accounting software, ERP software, CRM software and business software systems Search Bitpipe.com for the latest white papers and business webcasts Whatis.com, the online computer dictionary DISCLAIMER: Our Tips Exchange is a forum for you to share technical advice and expertise with your peers and to learn from other enterprise IT professionals. TechTarget provides the infrastructure to facilitate this sharing of information. However, we cannot guarantee the accuracy or validity of the material submitted. You agree that your use of the Ask The Expert services and your reliance on any questions, answers, information or other materials received through this Web site is at your own risk.