On one of our more recent projects, we were required to display a PDF document by double-clicking in an edit table. No real issue, we can use just use SHELLEXEC as documented here right?

Wrong.

The problem with a SHELLEXEC, is that by default, it launches a browser that has an address bar  containing the full URL to the document in question, allowing the user to modify the URL and potentially access information they were not privy to. (The users don't have browse rights so there isn't a problem of them browsing to other information, but knowing the fully formed URL they could take intelligent guesses at other potential document names). So, we considered looking at turning the address bar off, but then remembered the new WebView control. A control that allows you to embed the Microsoft WebView2 Edge Browser directly into an OpenInsight form and to interact with it.

This looked like it was going to be the easiest hack ever. Create a form with just two controls, the WebView control and a close button. Have it accept as a create parameter the document to display, and all is good, yes?

So we added a quickevent to the form that simply set the URI property of the WebView control, to the value passed in the createParam for the form. 

It ran.

It did nothing.

Puzzled we modified the CREATE quickevent to also update the screen caption with the file name we were trying to display. (This ability to stack quickevents rocks!). 

The caption changed to the correct value but still nada.

Thinking laterally we invoked the system monitor and used the SP command to set the URI of the control to the value we had passed in. 

It displayed.

Rinse and repeat.

Chatting to the developers, it seems the issue here is that the WebView control takes a little time to instantiate itself, so it it might not be finished before the CREATE event runs. So we have to wait for the WebView control to be finished and THEN set the URI.

Sounds like a case for looping, querying status and waiting, yes?

No.

The WebView control is asynchronous. So all we have to do is wait for an event that tells us that the WebView control is ready, and THEN set the URI.

All this took was two quickevents. 

One on the CREATE event, setting a synthetic property to contain the document name

and one on the WEBVIEWCREATED event for the WebView control (which is fired when the WebView is fully instantiated) which retrieves the synthetic property and uses it to set the URI property.

 Occasionally RTI slip out little tools and utilities that they've found useful. If you're very lucky they'll even ship source. One such gem in OI 10 is the OIWIN Date/Time picker - RTI_DATETIME_POPUP to its friends.

If ever you've wanted to offer your user a way of selecting date or time from a calendar/time control, and you've not been too happy with the datetimepicker OCX and the old POPUP_MONTH dialog seems a little dated, then this is the one for you.

It really is stunningly simple to use. Just add a quickevent to call a stored procedure and you're sorted.

For illustrative purposes, here's a sample window -

The cuebanners reflect the conversion on the edit line. The quickevent for the options on each editline is defined thusly - 

Once you've chosen the Target you can just accept the defaults other than DEFPROP which should be replaced with INVALUE.

We only need one options button because we're taking advantage of a newly exposed property - in the property panel under the Behavior section, we're setting ALLOWFOCUS to false and then we can just send an OPTIONS event to @FOCUS.

So how does the routine behave? See the following screen shots -

Now there are a couple of caveats that I need to mention. The first (as you can see) is that DT and DTS provide the same dialog. The second (due to a bug that I leave you to find) is that DTS always returns 1967 as the year. But as you are encouraged to save under a different name and compile your own version it is easily fixed! If you don't want to then it is all fixed with the latest beta.

The examples given below show what displays when you let the system determine default values. Examining the source reveals that, should you wish to, you may have much more granular control over the behaviour of the control. In this endeavour RTI_POPUP_DATETIME_EQUATES are your friend, but to save you having to look at this, we'll document their use here.

If you use DIALOG_BOX to launch the RTI_POPUP_DATETIME window, you can pass in an @Fm delimited create parameter having the following values -

    <1>    Mode, D, DT, DTS, MT, MTS
    <2>    Initial date to use in internal format
    <3>    Initial time to use in internal format
    <4>    Parent
    <5>    Horizontal alignment against owner (L or R)
    <6>    Value mark delimited array containing the screen size of the owner
    <7>    First year in the year dropdown
    <8>    Last year in the year dropdown

We can override date ranges, set default values and even alter dialog positioning by passing in the correct values.

One of the biggest differences between OI TCL and AREV TCL is that the latter made use of the VOC file to allow the user to customise commands and even to add their own commands. This does not seem to be the case in OI, rather a cursory examination of the object code for RTI_IDE_TCL suggests that the command list is hard coded. 

With this in mind it might be useful to document exactly what commands are supported, and where unclear, what they actually do. For the purposes of this article it will be assumed that the reader is familiar with the syntax of AREV TCL commands. When optional variables are nominated they will normally be in the order TABLE ROW(S) OPTIONS.

So in alphabetical order, the commands are as follows - 

 Recently we were stumped by a compilation error when using pipes to create a multi line statement, this sort of thing,

    if value then

        on inlist("ALPHA,BRAVO,CHARLIE", value, ",") goSub |

            doAlpha, |

            doBravo, |

            doCharlie

    end

the compiler just kept complaining about an unmatched then/end else. We thought that the only way to get to the bottom of this was to look at what the precompiler produced to see where the error was. Struggling we tried to recall the syntax of the pragma to save the precompiled output. 

Fortunately a more knowledgeable team member pointed out that using the pipe stripped spaces by design, to allow aesthetic alignments of strings. What this meant was that the compiler was not compiling goSub doAlpha, but rather, goSubdoAlpha.

The solution, repeating pipes. Using two pipes prevents the spaces being stripped and 

    if value then

        on inlist("ALPHA,BRAVO,CHARLIE", value, ",") goSub ||

            doAlpha, |

            doBravo, |

            doCharlie

    end

compiled just fine. 

Anyway it's been 16 years since our article on using pragmas and it's still as relevant as ever, so why not check it out and refresh your memory!

We recently came across a situation that we have literally never encountered in our decades of working with Linear Hash. Basically a FIXLH operation was interrupted mid process and hi-jinks ensued. The resultant mess took a while to sort out but our findings may prove useful if you ever find yourself in a similar situation.

This specific issue was encountered on an AREV 3.12 system but the logic for FIXLH remains roughly the same so the information remains applicable.

Basically, the FIXLH operation was interrupted about 10% of the way through processing (the NTVDM abended). A quick check of the table header revealed that it believed itself to be a clean empty table with no rows. Yet listing the table produced a set of row ids after an initial pause while nothing was apparently happening.

What had happened was that the table header had been reset to that of an empty table, and the first 10% or so of the primary frames had been blanked. This caused us to investigate the processing undertaken by FIXLH and we can confirm that it is as follows:

    Create and/or clear the temporary dumpfix table

    grab frame zero group

    write rows in group to temporary dumpfix table

    set frame zero header to that of an empty table

    loop

        grab next group

        write rows in group to temporary dumpfix table

        wipe primary frame to null

    until no groups left

    repeat

    copy rows in temporary table back to source table

So if the operation is interrupted, some of the data will be in the source table and some will be in the temporary dump fix table. 

As an additional caveat, note that if the rows in the temporary dump fix table are not stored off elsewhere, they will be lost next time FIXLH is run.

Since the advent of the UD we've never had to actually fix a GFE for quite some time, so this was an eye-opening operation!

Backups are your friend...

Recently at a client site, we encountered an error that was a little more baffling than normal.  Under very specific circumstances,    RLIST would bail with no results.  Eventually, we had a duplicatable test sentence which was basically

    SELECT TABLE BY CALC_COL_1 WITH REAL_FIELD_1 = ‘XXX’ AND WITH CALC_COL_2 = ‘YYY’

When we removed the BY clause (CALC_COL_1) our sentence ran to completion.   This put the problem squarely on CALC_COL_1, which is where we started debugging.  

We changed CALC_COL_1 to a simple “@ANS=1” and ran the sentence again.  This worked correctly.  To prove to ourselves that CALC_COL_1 was the problem, we put back the original code and changed our sentence to 

    SELECT TABLE BY CALC_COL_1 WITH REAL_FIELD_1 = ‘XXX’ AND WITH CALC_COL_3= ‘ZZZ’

This also worked.   

Now we’re starting to get a little confused.  Modifying CALC_COL_1 solved the problem.  Replacing CALC_COL_2 also solved the problem.  It has to be some sort of interaction with the calculated columns, because there’s no obvious consistency lining up the errors with the sentence structure.

It’s time to break out the profile log and see if something jumps out, and it did.  Something appeared off with EXTERNAL.SORT.  It seems like it executed a few times, and then everything stopped.  We dusted off our copy of PROCMON.EXE ¹ and ran the process again.  PROCMON showed that the sort file was being opened, but that it was not being closed.  It also showed a lot of file access  We’re now convinced this has something to do with sorting in general, and not with the specific field being sorted.

After trying well over a dozen different variations on the RLIST sentences, we finally worked out that we needed two things to happen for the error to occur.  The first was that we had to have CALC_COL_1 as the sort column.  The second was that the WITH clauses needed to return enough keys to force the system into using EXTERNAL.SORT instead of a simple in-memory sort.

Normally, when OpenInsight starts behaving very oddly, the culprit is usually a function that’s not clearing set_status() before calling get_status.  When that happens, the get_status() call could be returned an error from 10 programs back.  We reworked the calculated columns to ensure we clear set_status, and feeling very proud of ourselves, sat back and waited to bask in the glory offered to us by our client.  Obviously, the report failed again.

Sitting back, we start wondering if maybe there’s a small part of the RLIST code that’s still thinks it’s Advanced Revelation and it’s actually checking the pseudo STATUS() variable.  So, we reworked the calculated columns to ensure we clear set_status and status(), and feeling very proud of ourselves, sat back and waited to bask in the glory offered to us by our client.  Obviously, the report failed yet again.
 
Surely there can’t be three ways to set an error condition in OpenInsight?  It turns out that there is.  We suddenly remembered @FILE.ERROR.  So, we rework the calculated columns to ensure we clear set_status and status() and @FILE.ERROR, and feeling very proud of ourselves, sat back and waited to bask in the glory offered to us by our client.  And this time there was much rejoicing and basking.

With the solution in hand, we set out to find out exactly why this happened and where the system was registering the failure.  What we found was the calculated field was doing a lot of file access and would attempt to access records that didn’t exist.  This was what was setting @FILE.ERROR.  But, we hit a two-fer, as they say.  Some of the randomness had to do with the amount of data returned.  If enough sort data was returned the system would call EXTERNAL.SORT to sort the data.  EXTERNAL.SORT writes to temporary OS files, and the OS file commands use @FILE.ERROR to check for errors.  EXTERNAL.SORT would execute an OS operation, check @FILE.ERROR, find the pre-existing error, and abort the process.  But, this would only happen if the very last row processed set @FILE.ERROR.  Otherwise RTP57 would clear any prior @FILE.ERROR settings, and @FILE.ERROR would be null during the EXTERNAL.SORT call. 

1.  PROCMON and other useful tools are available as part of the Sysinternals suite of development tools, which no programmer should be without.

Those of you who've been in the industry for a while will remember the smugness with which we treated the Y2K issues the rest of the world were experiencing. It didn't affect us, we stored our dates in internal numerical format. I'm sure we all have favourite anecdotes. Mine was being called into the Press Office of a major Government department to certificate their AREV tracking system. I sat down and gave the system a cursory glance. "Ermmm - it doesn't seem to use dates?". "No, it doesn't". "Well, here's your certificate"... turns out they couldn't get the budget for system tweaks but they could for Y2K compliance. I spent the rest of the day implementing their desired changes.

Anyway, this week wiped the smile off of our collective faces (if you'd ignored the advice in KB 42 thirty or so years ago - which to be honest you could be forgiven for) with the advent of our very own variant - we'll call it the 20100 bug, although it's not a bug, it's an unfortunate feature.

Users began reporting that date searches were failing for values after the 10th of January 2023. At first we couldn't see an obvious reason. We built a database containing date values going back to the previous century with five rows per date and indexed it. We wrote a test program and ran it

RUN ZZ_POP 10/01/2023

RUN ZZ_POP 20099

What we've fallen foul of is discussed in the KB reference earlier. Basically BTREE.EXTRACT takes what it is given and tries to ICONV it to use for the look up. If it can't ICONV it (20099 isn't a viable date) it uses the value passed. If it CAN ICONV it, is uses the ICONVed value. And guess what? 20100 ICONVs to the 2nd of January 2000 as you can see above.

Of course, this won't be the first time this has happened in the wild - for example looking for the 7th of December 1998 using 11299 would have returned the 1st of December 1999 and so on.

Note that the same issue will be experienced when using internal date formats with RLIST statements.

The solution? When calling BTREE.EXTRACT use EXTERNAL values as it will try and ICONV the data before using it.

Addendum

We've been asked to share the code we used to locate btree.extracts in client systems to enable a manual inspection to determine possible failure points. This is a rough and dirty hack which met our requirements. Feel free to tailor to your own requirements.