I prefer Velocity for simplicity and, combined with the toolbox and velocity servlet project, you can do all the stuff you can do in JSP's. With XML/XSLT you have 'know' all the stuff you're going to use in a view beforehand (just like using Velocity without the toolbox extention).
Personally I like program 'dirty' at times according to the majority of Java programmers it seems. For instance, I have no problem with getting data from a database with a query that's in a view (that needs no input). Just like PhP :). I think one of the reasons that a lot of starters/ webdesigners prefer PhP and ASP/.NET over Java (at least that what I see around me) is not that it is harder, but that the Java way of programming webapps allways has to be in perfect OO style. So, even for a small site, you *have* to start with an object model. Then translate that (or the other way around) to a RDBMS. Then use something like OJB/ Hibernate/ Castor to talk to your model (and I NEVER have seen a project that did not cost a lot of time thanks to bugs in these mapping layers). Then ofcourse for every trival piece of info to show on your site you have to write an controller (hey, I wonder where the C in MVC is for... could it the controller for INPUT usage?). But then... finally we have build ourselves a nice and clean webapp. Funny thing is though, that for the smaller to average sized web projects your average PhP 'script kiddie' would have build the whole damn thing in one third of the time it took us! And we did not even start thinking about using EJB's. My point? Don't overengineer all the time. Seen it happen too often. AND it gives Java a bad name for the more 'pragmatical' programmers (read PhP/ ASP/ 4GL adepts) and managers in general. Hah that's a relieve. I just had to put this on a mailing list. I seriously have discussions at least once a week on this subject with my Java oriented collegues (who strongly disagree on this, just as they prefer Struts over Maverick as it 'does so much for you' (read: they have the form beans/ tags)), and I have to hear too often from collegues who use PhP/ ASP/ .NET/ Delphi to build applications that they think Java takes too long to develop an application. Be practical! Engineer according to the complexity of your application! Allright... I'm feeling like a scoolteacher/ know-all. Sorry about that. But I *am* wondering what other people think about this. Maybe a new thread? Eelco -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Behalf Of Valeri Sarantchouk Sent: dinsdag 1 april 2003 16:23 To: [EMAIL PROTECTED] Subject: RE: [Mav-user] reusable controllers and session objects Yes, sometimes I loose balance between adhering to initial design and making shortcuts when I encounter a performance bottleneck. I also considered contrast of JSTL simplicity from page author point of view with its complexity from precompiler/VM point of view, and concluded (but I still could be wrong) that even JSF+JSTL don't make JSP ideal View technology. I see XSLT as the cleanest and most elegant approach to build a View. Though, I like XMLC and Velocity for their performance. (I might look unreasonably obsessed with performance issues. I am :) I think that each new software product I develop should perform at least on the same level as its predecessor. Expecially knowing how good PHP- and Perl-based solutions could be in simple applications.) Thanks, Valeri --- On Tue, 1 Apr 2003 10:41:51 Eelco Hillenius wrote: >IMHO a sensible strategy of developping apps is to first focus on the >behavoir and after that focus on performance issues. That does not mean that >it is wrong to take performance issues in account in an early stage, but >just do not let it overtake the main focus of your project. > >In my experience caching CAN make a huge difference though, especially when >you have database heavy apps or - like Jeff said - object that have high >initialisation costs. But ya, things like synchronisation can be killers as >well. And if you use transactions for instance... be smart with them (like: >is it possible to do more in the same transaction... made huge differences >for us when working with OJB). > >And as a side note: three years ago I developed several java webapps for the >AS-400 platform (JDK1.1.x). In that case object creation *was* very >expensive so it did make sense to use object caching. I do not know about >the current performance charactaristics of that platform. > >Second side note: GC can give you problems at times. A recent project where >we made heavy use of JSTL could crash our server! There is/ are memory >leak(s) in JSTL presumably the forEach tag. The strange thing was that in >certain cases when the GC did a run the JVM ended up using more memory than >before this run. On several servers (both on Win and Lunix) the memory usage >could exeed gigabytes within one minute before crashing... >That brings me to an example where caching makes a big difference. If you >look at the performance gain Tomcat 4.1.x got compared to Tomcat 4.0.x: for >our apps it was the caching of the custom tags in Tomcat 4.1.x that made the >difference (about 1500 milis!). Funny thing though is that, allthough Tomcat >4.0.x is a lot slower with our JSTL intensive project than Tomcat 4.1.x, the >former never crashes. This is to illustrate that, allthough caching can make >a huge difference at times, it also adds complexity thus usually more bugs >(can confirm that from personal experience too!) > >So my bottom line is to be practical. First build your app only addressing >the most obvious performance issues. When all works/ is stable look at >performance characteristics. IF you want to cache be aware of the added >complexity, maybe using something like JCS >(http://jakarta.apache.org/turbine/jcs/index.html) can help reducing that >(allthough I never used it). > >The reason that I sometimes use singleton controllers is that those >controllers do a lot of initialisation that is equal for all users and >should be done only once. > >Eelco > > >-----Original Message----- >From: [EMAIL PROTECTED] >[mailto:[EMAIL PROTECTED] Behalf Of Schnitzer, >Jeff >Sent: maandag 31 maart 2003 23:42 >To: [EMAIL PROTECTED] >Subject: RE: [Mav-user] reusable controllers and session objects > > >> From: Valeri Sarantchouk [mailto:[EMAIL PROTECTED] >> >> I am trying to avoid creating new objects at every request. >> Is it possible to use a servlet as a (Trhowaway2) >> Controller? Or other reusable accross requests conroller. >> >> [...] >> >> ClientModel has 38 fields and its creation and rendering >> are costly operations. Plus we have at least 70 concurrent >> users (accessing the same view at the same time) at low >> periods and 350+ at high, so creating new objects for each >> request and passing old ones to gc doesn't look good from >> performace point of view. >> >> In "old" application, I use an object pool to get instances >> of Client objects for new users; and re-use Client objects >> found in user's session for logged-in users. >> >> Can you advise me on how to replicate an object pool with >> Maverick and how to reuse the same object found in session? > >I see you found the ControllerSingleton (and presumably FormBeanUser) >controller base classes. However, are you sure of the performance >characteristics of your application? > >Much research has gone into this subject, and the general conclusion has >been that the performance cost of object creation and collection is >vastly less than the performance cost of synchronization. The >generational garbage collection scheme in modern JVMs is very efficient, >especially with short-lived objects such as Throwaway controllers. On >the other hand, the thread synchronization required for an object pool >is tortuous for an application with high concurrency. Search the JBoss >list for this subject - they concluded that the object pooling of EJBs >is only of value when the initialization cost of a bean is very high >(establishing network connections, etc). > >My own experience confirms this. The Sims Online player website >produces zillions of objects (much, much more than a typical website) >yet when maxed out under load testing I find that threads are always >waiting for monitor locks. > >Just to give you some more idea of relative scale, a single Tomcat >request produces a flurry of objects. Populating bean properties with >BeanUtils produces a flurry of objects. Every JDBC driver I've ever >seen produces *vast* quantities of garbage. Watching an application >under a profiler is an enlightening experience - you'll be amazed at how >many char[] and String objects a running Java app produces. > >A minimal Maverick invocation produces 3 or 4 short-lived objects >(including String manipulation). This is like shouting into a jet >engine - nobody is going to hear it on the other side. > >Jeff Schnitzer >[EMAIL PROTECTED] > > >------------------------------------------------------- >This SF.net email is sponsored by: ValueWeb: >Dedicated Hosting for just $79/mo with 500 GB of bandwidth! >No other company gives more support or power for your dedicated server >http://click.atdmt.com/AFF/go/sdnxxaff00300020aff/direct/01/ >[INVALID FOOTER] > > > >------------------------------------------------------- >This SF.net email is sponsored by: ValueWeb: >Dedicated Hosting for just $79/mo with 500 GB of bandwidth! >No other company gives more support or power for your dedicated server >http://click.atdmt.com/AFF/go/sdnxxaff00300020aff/direct/01/ >[INVALID FOOTER] > _____________________________________________________________ Get 25MB, POP3, Spam Filtering with LYCOS MAIL PLUS for $19.95/year. http://login.mail.lycos.com/brandPage.shtml?pageId=plus&ref=lmtplus ------------------------------------------------------- This SF.net email is sponsored by: ValueWeb: Dedicated Hosting for just $79/mo with 500 GB of bandwidth! 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