Re: Q: DBMS update framework for use within Apache::DBI?
"Bruce W. Hoylman" wrote: "Gunther" == Gunther Birznieks [EMAIL PROTECTED] writes: Gunther This first criteria seems a tad odd to me. What business Gunther scenario is there for this? The framework is to support an intranet time tracking application. The business rules of the system dictate there are no deletions of previously submitted time ... only inserts/updates. Therefore I can say without question that an existing time record will *always* exist (a modify), albeit in a potentially 'dirty' state (rule #2). Furthermore, if a particular time period has not been accounted for, i.e. no time record has been previously submitted, a default time record will be presented for modification, and subsequent submission (an insert). This is seamless to the client requesting the period. If there is no default time record available, then a 0-hour time record is presented for modification/submission (also an insert). need custom record locking? how about adding a field such as 'lock' which is set when a record is requested, so only one user can modify it? i.e. your script sends a flag to others who've requested a 'lock'ed record. i'd also put a timeout on it so that if a user quits his browser or gets distracted, his page gets updated to another location after freeing up the lock... -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- Their is five errers in this sentance.
Re: Q: DBMS update framework for use within Apache::DBI?
At 12:16 PM 5/17/00 -0600, Bruce W. Hoylman wrote: Ciao! I am searching for the makings of a framework built around or within mod_perl/Apache::DBI that supports the consistent update of a record within a database. Primarily I am wanting to ensure read/write integrity between database accesses by the web client, meaning I wish to ensure the record about to be updated meets the following criteria: 1) It exists. If it does not, perform an insert instead 2) If it exists, check that it is unchanged from the time the web client first retrieved it for update. If it has changed, throw an exception. I do not want a "last update wins" situation. This first criteria seems a tad odd to me. What business scenario is there for this? To me, when a user issues an update they expect that the record exists. In a way, if the record does NOT exist, then you are really going against your rule #2. That is, if they issue an update and the record no longer exists, then that is also a change to the record that someone did (a deletion) and you are effectively overriding someone elses deletion. This is being done in an mod_perl/embperl/Apache::DBI environment. Suggestions or pointers to additional information would be greatly appreciated. Peace. An application which implements #2 and is accelerated when used with mod_perl (Apache::Registry) and Apache::DBI is our latest version of WebDB. You may download a copy at http://www.extropia.com/ and click on download button at the top upper right)... If you want to read about it, the docs are located at http://www.extropia.com/docs/webdb/. Actually it was all generated using Stas Bekman's mod_perl guide generator (except using my pods instead of Stas's mod_perl guide pods) The WebDB will do #2 for you and, in fact, allows configuring the strategy of updates... eg you can choose to check all fields for changes, a subset of fields for changes, or just "key fields" for changes... similar to the PowerBuilder DataWindow model of handling client-server updates. This is done through the use of Extropia::DataSource which is a library that abstracts this stuff away. By default, WebDB is distributed to be configured to use Extropia::DataSource::File, but you just need to take out the file specific stuff from the config and then replace -TYPE = 'File' with -TYPE = "DBI" and add -DSNAME = 'dbi:yourdatabase etc..." and you are pretty much off and running. So the caveat is that the app is configured by default to work on any CGI/Perl environment. But it has been architected to take advantage of mod_perl's benefits (eg Apache::DBI) by just changing config parameters in the setup file. Since all the new extropia apps follow this common architecture, we have documented the mod_perl specific tuning issues in the Advanced Chapter of the Extropia Apps Guide (a supplement to the WebDB Guide) located at http://www.extropia.com/docs/extropia_app/ If you don't like WebDB itself and need to write your own logic, then you may want to just use Extropia::DataSource by itself (which implements the logic you want as an object but no CGI workflow exists around it). The documentation and code for that set is located at http://www.extropia.com/ExtropiaObjects/ Hope this helps, Gunther __ Gunther Birznieks ([EMAIL PROTECTED]) Extropia - The Web Technology Company http://www.extropia.com/
Re: Q: DBMS update framework for use within Apache::DBI?
"Gunther" == Gunther Birznieks [EMAIL PROTECTED] writes: Gunther This first criteria seems a tad odd to me. What business Gunther scenario is there for this? Gunther To me, when a user issues an update they expect that the Gunther record exists. In a way, if the record does NOT exist, then Gunther you are really going against your rule #2. That is, if they Gunther issue an update and the record no longer exists, then that Gunther is also a change to the record that someone did (a Gunther deletion) and you are effectively overriding someone elses Gunther deletion. The framework is to support an intranet time tracking application. The business rules of the system dictate there are no deletions of previously submitted time ... only inserts/updates. Therefore I can say without question that an existing time record will *always* exist (a modify), albeit in a potentially 'dirty' state (rule #2). Furthermore, if a particular time period has not been accounted for, i.e. no time record has been previously submitted, a default time record will be presented for modification, and subsequent submission (an insert). This is seamless to the client requesting the period. If there is no default time record available, then a 0-hour time record is presented for modification/submission (also an insert). Gunther An application which implements #2 and is accelerated when Gunther used with mod_perl (Apache::Registry) and Apache::DBI is Gunther our latest version of WebDB. You may download a copy at Gunther http://www.extropia.com/ and click on download button at Gunther the top upper right)... Thank you for the pointer. I will *gleefully* investigate its offerings. | Hope this helps, | Gunther I'll let you know ... Peace.
Q: DBMS update framework for use within Apache::DBI?
Ciao! I am searching for the makings of a framework built around or within mod_perl/Apache::DBI that supports the consistent update of a record within a database. Primarily I am wanting to ensure read/write integrity between database accesses by the web client, meaning I wish to ensure the record about to be updated meets the following criteria: 1) It exists. If it does not, perform an insert instead 2) If it exists, check that it is unchanged from the time the web client first retrieved it for update. If it has changed, throw an exception. I do not want a "last update wins" situation. This is being done in an mod_perl/embperl/Apache::DBI environment. Suggestions or pointers to additional information would be greatly appreciated. Peace.
