"Victor J. Orlikowski" <[EMAIL PROTECTED]> writes: > > One example of where you get into problems is when you have folks > who want to combine taglibs and BSF, and are confused as to why > script variables aren't necessarily immediately available within > taglibs. Sure, someone who understands that BSF is under the > covers realizes that the scripting language execution environment > is running within the generated servlet; one could probably > alleviate the problem by ensuring that accesses to variables by > taglibs are arranged to check in BSF if not found in the generated > servlet.
Sounds good. > But then, you have bigger problems too. Debugging such a mixed > execution environment becomes a flying circus. Are you in the :) Agreed. > generated servlet, or in the scripting language hanging off of > BSF? Assuming you have a debugger that supports stepping in both > bytecode and the script interpreter, if you start stepping in the > BSF code (which normally gets handed off as a string to BSF by the > page compiler, and therefore needs some kind of line information > to point back to the original JSP), do you continue stepping upon > re-entry into the generated servlet when you fall off the end of > the script (You should, but it becomes difficult - granted, > JSR-045 adds debug info to non-Java languages by post-processing > class files to munge the LineNumberTable and SourceFile > attributes; but that means having BSF compile the script to > bytecode - which will improve performance, so long as it is cached > - and then having Jasper post-process the BSF-generated bytecode by > merging it w/ the bytecode from the compilation of the generated > servlet and then munging the LineNumberTable and SourceFile > attributes. This is not fun or easy; I have not had great success > at attempts I have made recently to do so - but I will heap great > praise upon the one who does :). I certainly understand that solving this properly is not easy by any means and may not even be possible. > The crux of the issue, I have found, is that either you have to > manage bytecode so that the correlation to the original source is > maintained, or you deal with the fact that you have an interpreter > running under java, and realize the performance loss and loss of > coherent debugging. So really what you're saying applies whether Rhino, for example, is integrated to Jasper directly or via BSF. If that's true then how do you actually use another language in JSPs? Maybe compile the entire page into a servlet in that language? (That'll work as long as you have the entire page using one language I guess.) > Standard trade-off of performance vs. maintainability, as far as I > can tell. Maintainability? You mean in terms of debugging I assume. > > Matt Duftler first integrated BSF to the WebSphere JSP compiler in > > March '99 in about 4 hours .. we even had XSLT integrated. It > > worked pretty fine. Of course performance was not anywhere close > > to Java and there was no debug story, but it definitely worked > > fine. > > Works, yes. Mostly. There are cross-environmental issues that crop > up. Performance-wise, once the generated servlet is created, the > main BSF hit is re-interpreting the script that is passed to the > engine every time the page is loaded - not bad for only a few > concurrent clients; awful starting around 500 or more. Recompiling the script problem can be fixed easily for scripting languages that support compilation. For those that don't such is life. > Sanjiva, it's not a question of integration; it's a question of > *seamless* integration, that will not confuse new users. That's > what's lacking, and missing a good way to solve. I agree seemless integration would be very nice and my comment about Matt's initial integration was rather stupid .. sorry. However, there are lots of people who are happily developing lots of real applications using LAMP (linux, apache, mysql and php). I'd be surprised to hear that they have fully integrated seamless debugging etc. in that environment. However, it works and they are happily building apps. Do we want to enable a php user to write JSPs and move them to the Java platform? How would you integrate php to Jasper with or without BSF? Sanjiva. --------------------------------------------------------------------- To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED]
