Hi, thanks for you guys replay so fast. After doing the Google search in last Friday, I got link to http://terminalapp.net/dr-optimistic-locking/ And want to understand more about concurrency issue in WO by code, so that 's the reason I am asking here.
Also try to understand what's diff between multi-EOF and DB connection pool in J2EE, (like weblogic, tomcat or webshpere). Further how is J2EE world solve this concurrency issue? WONDER is just trying fix the problem or Apple can accept it in WO release? Thanks for your time, Kevin -----Original Message----- From: webobjects-dev-bounces+kevin.ren=anznational.co...@lists.apple.com [mailto:[email protected] om] On Behalf Of Guido Neitzer Sent: Monday, 30 March 2009 9:26 a.m. To: Ren, Kevin Cc: WebObjects Development Subject: Re: How does concurrency control work in WO? On 29. Mar. 2009, at 13:08 , Ren, Kevin wrote: > I think it's about EOF professing. > But if you have both, that's great. First of all: What EXACTLY is your goal? There are several ways of dealing with concurrency: 1. Switch on concurrent request handling with the property: -DWOAllowsConcurrentRequestHandling=true Note that this was set through JavaMonitor with the -D property notation. Using concurrent request handling has several implications (see EOF part). 2. Use more instances. This might be the least painful way in regard of locking issues, but the most painful in regard of data freshness. 3. Define your bottlenecks better. 4. Use multiple EOF connections to the database (Wonder has ways of doing this automatically). As soon as you have concurrent request handling you need to deal with the following: - Data freshness - Caching - Locking - Valid data (Which write wins? Dealing with freshness again.) You get most of this for free if you use ProjectWonder, which I highly recommend. You need to use correct locking of your editing contexts (see ERXEC from Wonder or MultiECLockManager, search on Google for more information). If you just enable concurrent request handling, EOF will still stay single threaded for one instance as long as you don't use for example a new object store coordinator for long running transactions. Be aware that all this will bring you into dead locking and data freshness hell as long as you don't really know, what you're doing OR as long as you don't use the "make me and the gods of EOF happy features" from Wonder. cug _______________________________________________ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list ([email protected]) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/webobjects-dev/kevin.ren%40anznat ional.co.nz This email sent to [email protected] "This communication is confidential and may contain privileged and/or copyright material. If you are not the intended recipient you must not use, disclose, copy or retain it. If you have received it in error please immediately notify me by return email, delete the emails and destroy any hard copies. ANZ National Bank Limited does not guarantee the integrity of this communication, or that it is free from errors, viruses or interference." _______________________________________________ Do not post admin requests to the list. They will be ignored. Webobjects-dev mailing list ([email protected]) Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/webobjects-dev/archive%40mail-archive.com This email sent to [email protected]
