Front end Back End Processing Problems

[CHTHOMAS]

Hello Everybody,

I have a Back End which performs some calculations in every 25 seconds. The front end tables are linked to the Backend. Both the front end and Back end lies on the Network. The front end table links to the Back end are refreshed once in every 20 seconds. My problems....

1) when a user opens the fron end and if it is during the time during which the back end perfroms the calculations, the user gets a "reserved error 1601 or 3034" Messages (i believe to my best that is why the error message appears). I tried changing the duration of calculations. But no good.

2) If it is the time during which the fron end tables are linked, the user gets an error message saying "can't find the input table or query" error.

My questions.

1) Is there any way that the back end can flag to the fron end that the processing is taking place and allow the front end to access the data once the processing in the back end is finished.

2) Within the fron end itself when the table links are being refreshed is there any way to wait.

I developed the db, put it on the network for users on trial basis and the result is incrediable... a series of error messages.

Any ideas, suggestions or solutions on how to tackle both or any of the problem will be highly appreciated.

Regards and Thanks

Charley

 

[MichaelRed]

Charley,

Something strasnge this way comes?

Why do you need to refresh the links? Are you changing the location of the backend? Otherwise, the normal approach is to link the dbs at startup and just leave them in place.

Why (and how) are you re-doing calculations on a 25 second interval? Is there some type of (intrerval timed) data feed?

What is the basis for the 25 second interval for recalculation? In many time critical apps, the only "time critical" issue is data collection from a source which is independent of the database app, such as monitoring from a weather station which simply 'puts out' the data on a regular interval. In most of these apps, the calculations are done 'on-demand' (e.g. event based), so there is no repetitive calculation.

If you could provide some brief expliniation of the process involved, the community might be in a better position to help you.



MichaelRed
mred@duvallgroup.com
There is never time to do it right but there is always time to do it over

 

[CHTHOMAS]

Thanks for the response.

I am getting the table values as the output of a time keeping machine. So whenever sombody swipes in or out his status has to be updated at the earliest. That is why i am performing the calculation at a 25 secons time span. Now if i don't refresh the table links from the front end do you thing that i am going to get the most updated information from the back end once the processing is finished in the back end?

Regards

Charley

 

[MichaelRed]

I assume that the time keeping machine is doing 'direct deposit' of the values into the 'back end' tables? If so, You should NOT NEED to re-link the tables.


Further, you should (generally) just let the table information 'lie there' until someone accesses it (from the front end). If you need a 'constant' update, the front end would be based on a recordset which is 'refreshed' whenever the backend table is changed. I would try having a flag in the back-end which is set whenever the table is changed (same mechanisim which feeds data from the timekeeping machine to the table). The "front end" would have a timer to check the flag, and when it is set, refresh it's recordset and re-set the flag.



MichaelRed
mred@duvallgroup.com
There is never time to do it right but there is always time to do it over

 

[CHTHOMAS]

o.k. The detailed explanation

The back end table is getting the value as output of a time keeping
software. The time keeping softwre creates a text file as output. Each time an employee swipes the card, the record in Ascii value is appended to the text file.

What i am doing in the Back end
-------------------------------
One of my back end table is linked to this text file. Also i have an employee master table in the Back end with the current status for each employee. Whenever employees swipes the card, the content of text file changes. Now at a time span of 25 seconds i am updating the Employee current status in the Employee Master table with the content of table which is directly linked to the text file.

What happens in the Front End
-----------------------------

Employee table in the front end is linked to the employee master table in the back end. Now i have an opening form in the front end which displays the names of all employees. This form is being used at the Reception. When the ladies double click the employee name another Pop up form displaying the employee name, his status(in or out), description etc. pops up.

Now if the table links are not refreshed in the front end, then the recently
updated data won't be available in the front end.OR will i get the most updated data in the front end without refreshing the table links? Thats the reason for refreshing table links in the front end in 20 seconds. This refresh rate time interval can be increased.


Everything in a NutShell
------------------------

One of the tables in the Back end is linked to a text file.
Processing updates the Employee Status in the Back end table in every 25 sec.
Employee table in the front end is linked to the back end table.
This front end table link is refreshed in every 20 seconds.

Hope this explains my problem...
I mean PROBLEM


Regagds and Thanks

Charley

 

[CHTHOMAS]

o.k. The detailed explanation

The back end table is getting the value as output of a time keeping
software. The time keeping softwre creates a text file as output. Each time an employee swipes the card, the record in Ascii value is appended to the text file.

What i am doing in the Back end
-------------------------------
One of my back end table is linked to this text file. Also i have an employee master table in the Back end with the current status for each employee. Whenever employees swipes the card, the content of text file changes. Now at a time span of 25 seconds i am updating the Employee current status in the Employee Master table with the content of table which is directly linked to the text file.

What happens in the Front End
-----------------------------

Employee table in the front end is linked to the employee master table in the back end. Now i have an opening form in the front end which displays the names of all employees. This form is being used at the Reception. When the ladies double click the employee name another Pop up form displaying the employee name, his status(in or out), description etc. pops up.

Now if the table links are not refreshed in the front end, then the recently
updated data won't be available in the front end.OR will i get the most updated data in the front end without refreshing the table links? Thats the reason for refreshing table links in the front end in 20 seconds. This refresh rate time interval can be increased.


Everything in a NutShell
------------------------

One of the tables in the Back end is linked to a text file.
Processing updates the Employee Status in the Back end table in every 25 sec.
Employee table in the front end is linked to the back end table.
This front end table link is refreshed in every 20 seconds.

Hope this explains my problem...
I mean PROBLEM


Regagds and Thanks

Charley

 

[MichaelRed]

The refresh in the front end is (should) not be necessary. Your "Pop up" should referenct the "back end" master employee table. All references would then be 'current' as of the "double click" on the employee. This is the essence of "event driven".

The data collection in the back end is somewhat more difficult. It can cause some problems because of the 'more-or-less' replacement of the table. I would think an easier/better way would be to isolate this process to a seperate machine/system. It's (the New/seperate ...) only task would be to 'look at' the time machine output and determine of there are any new records there. If not, just idle/exit. If there are any new records in the text file, append the new records to a native table in the 'backend' database and start an update process in the backend. This leave only a single seperate system doing stuff on an interval/timer basis.

If you have "control" over the timer database/process, I would suggest that the 'records' in that file be deleted (or at least marked) when they are imported into the 'backend', so you don't need to deal with a large ammount of transfer whenever you append new info (or even check for new info). If you can delete the old after it is imported, the file will not grow to a large and cause a time delay in processing.



MichaelRed
mred@duvallgroup.com
There is never time to do it right but there is always time to do it over