Ovidiu Predescu wrote: >On Wed, 10 Apr 2002 11:30:11 -0800, Rob Jellinghaus <[EMAIL PROTECTED]> wrote: > >>At 10:29 AM 4/10/2002 -0700, Ovidiu Predescu wrote: >> >>>Rhino has two ways of running JavaScript scripts. The first one is >>>translating the script in a structure of internal objects, which are >>>then "executed". The second approach, a lot faster that the first one, >>>translates the JavaScript scripts in internal Java classes, which are >>>compiled to bytecodes on-the-fly and executed as normal Java code. >>> >>>Adding support for continuations in the compiler mode is not possible, >>>due to the impossibility to manipulate the Java stack frame. >>> >>This places a lower bound on the speed of any continuation-based Cocoon web >>application. >> >>I would steer clear of using a non-compilable technology in any >>sufficiently large-scale web site. Hence, this ower bound on the flow >>engine's speed may imply an upper bound on the scale of Cocoon deployments >>using the continuation-based flow engine. >> >>It is also curious how this performance constraint is so at odds with >>Cocoon's general predilection to compile everything whenever possible, for >>maximum throughput. >> >>It pains me to say all this, as I think continuations are elegant as hell >>and Ovidiu's work seems quite impressive, but I do not believe that >>continuations will become efficiently implementable in the JVM (or in >>JVM-based languages) anytime in the next few years. Hence, I do not think >>that continuations should become the main focus of Cocoon's flow support, >>if Cocoon has scalability as a primary design goal. >> > >I don't see why we should stay away from non-compilable technology. > >Perl, Python, PHP and lots of other interpreted languages out there >are successfully used to drive very large Web sites. None of them >compiles anything to C, they all interpret the scripts that describe >the Web application. > >Some of these Web applications have tens of thousands of lines of >code, all interpreted. I haven't noticed any problem accessing sites >like Slashdot (Perl), Yahoo Maps! (Python), Yahoo Store! (Common >Lisp), and many others. > >We don't need to have continuations in the JVM to make use of >them. Rhino JavaScript is quite fast as an interpreter even in >interpreted mode. And remember, we use it only to drive the flow of >pages, not to implement the whole application in it (although it is >definitely possible to do it). If used carefully the continuations >based approach to flow control should not add any noticeable overhead >to an application. >
Agree. Rhino shouldn't be used to write the whole app, but only as a continuation-enabled glue between the various business logic components written in Java. Also (Ovidiu, tell me if I'm wrong), Java-written business logic can return objects that are held in flow script variables, and thus benefit from the continuations mechanism. So both worlds are complementary : the intrepreted flow script provides continuation support to compiled Java business logic. Sylvain -- Sylvain Wallez Anyware Technologies Apache Cocoon http://www.anyware-tech.com mailto:[EMAIL PROTECTED] --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, email: [EMAIL PROTECTED]
