I would like to compile my java code tointo javascript.
I tried using GWT but the resulting javascript doesnt look nice (even in "pretty" mode).
The main problem is that it looses the connection between the objects and the functions - the functions do not belong to the object or to its prototype.
Any idea how I can achieve a more OO connection between the java and javascript code?
I think your complaining about the fact that the this context is passed as the first argument in each function call. This was probably done to ensure the correct context is used in all cases.
The generated javascript in pretty mode is quite readable. GWT supports all the java / oo constructs such as polymorphism etc so why the complaint ?
I believe that GWT does modify the String object's prototype.
> I would like to compile my java code tointo javascript.
i too was once on the same mission and probably had similar expectations to you.
> I tried using GWT but the resulting javascript doesnt look nice (even > in "pretty" mode).
having it look pretty is the least of the problems.
> The main problem is that it looses the connection between the objects > and the functions - the functions do not belong to the object or to its > prototype.
the approach taken my the gwt compiler reminds of the translation of eiffel to C that i used moons ago. that is, it seemed to have flattened everything in its rendering.
> Any idea how I can achieve a more OO connection between the java and > javascript code?
i once had a vision of fusing java2script[1] (aka. pacemaker/j2s) and gwt together so that i could leverage reflection and swt widgets, but these two technologies are orthogonal.
to save you a j2s investigation i have coded a sample for you to analyse the translation:
1. bootstrap <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> <head> <title>org.javaongems.j2s.test.Rectangle</title> <script type="text/javascript" src="../../tool/eclipse-3.2/plugins/net.sf.j2s.lib_1.0.0/j2slib/j2slib.z.js "></script>
c$.main = Clazz.defineMethod (c$, "main", function (args) { if (args.length > 0) throw new IllegalArgumentException ("sample does not accept input params"); var app = new org.javaongems.j2s.test.Rectangle (); for (var i = 0, j = 0; i < 10; i++, j++) { app.moveBy (i, j); System.out.println ("loc: " + app);
} }, "~A");
{ System.out.println ("loading Rectangle");
}});
---
imho, there is a lot to like about what j2s does and how it does it.
when the gwt team gets around to looking at how to address large applications and dynamic module loading we may see a low level architectural change in script generation. although, i suspect this is some time away.
both gwt and j2s use java source as their input. there is another very interesting project named xml11[2] which uses java byte code as the input and can send xmlvm[3] instruction sets which eventually gets rendered as javascript.
there are so many great technologists out there that are severley under resourced. i can only hope that the google open-source team can sponsor some of these guys and then consider leveraging concepts into gwt.
I can tell you the motivation behind GWT's code generation: to be as small and as efficient as possible :-)
A few interesting specifics...
- We do explicitly remove polymorphism as much as possible. Calls that are polymorphic at runtime take longer to dispatch and require extra code to set up. So, we do whole program analysis to turn polymorphic calls into static ones wherever possible.
- Static calls can often be inlined, which can be a big win for simple methods.
- Even if we don't inline, knowing exactly which method is being called statically allows the compiler to discard more code. For example, what if a superclass method is always overidden, so that the superclass method could never be called? The compiler can identify this and completely remove the method in the superclass. That alone saves code, and even better, may cause several other classes not to be instantiated (e.g. locals in the superclass method), which increases the odds that an entire class may be able to be discarded. And so on, recursively...
- This one's funny. When you turn an instance method into a static one, you have to explicitly pass in 'this', right? Well, 'this' is a keyword that cannot be obfuscated, yet it's used a lot. Making functions static has this weird and great size benefit: you can obfuscate the explicit 'this' (since it's just a parameter), which reduces code size due to fewer uses of the 'this' keyword.
It wouldn't necessarily be a big deal to turn off these optimizations so that the generated JavaScript can look prettier, more like it was handwritten. But that actually defeats the big-picture point: the benefit of compiling is that *your* source looks nice (Java) and the object code is very efficient (JavaScript). When's the last time you thought about the readability of the binary produced by your C compiler?
But...all that said, it is important for people to be able to understand what's going on in the output, so that they feel comfortable with the translation process. That's why we added PRETTY and DETAILED. However, if there's enough demand, maybe we could add a "-slowerBiggerPrettier" compiler flag :-) I'm kidding, of course. Please comment if you disagree with my point of view or if there's some important use case we're not thinking about.
br...@google.com wrote: > - This one's funny. When you turn an instance method into a static > one, you have to explicitly pass in 'this', right? Well...
LOL. I just can't get enough of these. Keep 'em commin'. Ok, maybe I got a little carried away there... ;-).
> However, if there's enough demand, maybe we could add a > "-slowerBiggerPrettier" compiler flag :-) I'm kidding, of course.
Actually, I think there would be value is a -nonoptimized mode that would retain compatibility. It's not the typical use case, but interoperability with the rest of the web echo system is paramount to some and this is a great tool that could be adopted by those who are driven by that kind of requirement. In building reusable components, this would probably be a big win. A given widget could be reused more effectively by more traditional web shops too.
br...@google.com wrote: > I can tell you the motivation behind GWT's code generation: to be as > small and as efficient as possible :-)
> A few interesting specifics...
> - We do explicitly remove polymorphism as much as possible. Calls that > are polymorphic at runtime take longer to dispatch and require extra > code to set up. So, we do whole program analysis to turn polymorphic > calls into static ones wherever possible.
> - Static calls can often be inlined, which can be a big win for simple > methods.
> - Even if we don't inline, knowing exactly which method is being called > statically allows the compiler to discard more code. For example, what > if a superclass method is always overidden, so that the superclass > method could never be called? The compiler can identify this and > completely remove the method in the superclass. That alone saves code, > and even better, may cause several other classes not to be instantiated > (e.g. locals in the superclass method), which increases the odds that > an entire class may be able to be discarded. And so on, recursively...
"To be as small and as efficient as possible"! I admire GWT team for their excellent 100k ~ 200k final *.js files with very good performance.
Java2Script (http://j2s.sourceforge.net/), as mentioned, is a similar project for Java to JavaScript code generation. But the motivation in Java2Script is something different: "To provide same familiar Java APIs in JavaScript".
I am just a lazy developer, lazy to learn new APIs for some same functions. For example, Swing and SWT are similar GUI toolkit. And using SWT can do all the things that Swing can do and vice versa. I would be lazy to learn one of them only and not to learn the other. And I prefer to SWT. And as now I am familiar with SWT, and if all things done by using GWT can be done by using SWT, I would be lazy not to learn the new GWT APIs but use my familiar SWT. So this lazy programmer will use Java2Script and its Java2Script SWT library.
In order to provide the same familiar Java APIs in JavaScript, Java2Script has to keep all fields, all methods, all inheritances and all polymorphic information of a class in the JavaScript codes so developer will always be happy and feel comfortable with those familiar APIs. Java2Script is actually providing compiler that compiles Java sources into static JavaScript libraries.
And following, I will just try to figure out my understanding of GWT's Java to JavaScript compiling procedure. If I am wrong, please be kind to correct me.
GWT's compiling procedure is somewhat similar to the procedure of compiling C sources into an executable file. In C compiling, C source is first compiled into an *.obj. And then comes a linker, which will link *.obj with other *.lib files into an *.exe. In the linking procedure, not all method calls in those *.lib are linked into *.exe file. Only those which are used in the *.obj will be kept. Others may be discarded so the final *.exe is small and efficient. In order to find out which methods must be kept in linking, some recursive searching algorithm may be required.
In GWT compiling, there are no middle *.obj actually. GWT compiler tracks down those method calls which are related to the application. And if the other methods have no relationship with the application, they will be discarded even they are marked "public". So the final *.js is very small and efficient. Those class meta information discarded may include class inheritances, overriding, polymorphisms and other OO information. So after compiling, there are actually not OO JavaScript. So OO concepts like "this" keyword or reflection calls can not be used. In the whole compiling, the key technology of GWT may be the algorithm to flat those super calls and polymorphic method calls into static calls correctly.
And I admire GWT team for their excellent 100k ~ 200k final *.js files with very good performance.
Even basing on the same JDT toolkit, compilers with different motivations result in different JavaScripts. In a comparison, Java2Script generates 500k+ *.js files, and has its bottleneck on long waiting on loading those bundles of huge *.js files and poor performance on spending most of its CPU time in searching for polymorphic method calls. In fact, Java2Script has many optimizations on reducing the generated *.js file size and improving JavaScript performance, like minimizing variable name identities, generating smart scripts to avoid polymorphic method calls and others. But it seems that Java2Script is still far behind GWT in file size and performance.
But GWT, as the above compiling process described, may have its difficulties in supporting Java refection and dynamical class loading. But Java2Script already has its ClassLoader and is loading classes lazily. And it also has its early Java reflection implementation on JUnit tests (Reusing JUnit tests directly). But the way, GWT APIs and Java2Script SWT APIs is far different for comparison.
In some simple words, GWT compiler is an excellent Java to JavaScript *runtime compiler*, while Java2Script is a Java to JavaScript *library compiler*.
Maybe GWT would be kind to support Java reflection and dynamic class loading, if more developers vote for such features.
claude wrote: > ... It's not the typical use case, but > interoperability with the rest of the web echo system is paramount to > some and this is a great tool that could be adopted by those who are > driven by that kind of requirement.
I didn't mean to appear to be rejecting the idea of nice, simple JS compatibility -- far from it. Automatically generating familiar JS-compatible APIs is something we will be thinking about pretty soon. There's no question that great JS API generation would be valuable for interop, or simply as a way of publishing your widgets to users who don't know/like Java or don't use GWT.
I guess the thing I really didn't make clear is that in my mind it's two separate goals: (1) Create highly optimized JS output (2) Optionally, publish selected parts of your code with a JS-compatible API
I don't want to sacrifice #1 to get #2, because I'm certain that with the right design and thought (and hard work), we can have both at once.
Dynamic class loading and reflection are cool features, no doubt, and I think it's awesome that your compiler is able to cross-compile so many of the existing Java idioms as-is.
I think several of us on the GWT team would have a hard time justifying supporting those features in GWT for several big reasons:
1) They completely devastate the compiler's ability to optimize aggressively. How can the compiler remove code when some subtle reflection logic might actually need it at runtime? How can the compiler fully understand the call graph?
2) Reflection and dynamic loading are affordable when running JITted bytecode on 2GHz CPUs and when you can load new classes directly from disk (or from a filesystem cache in RAM). However, it's a whole different story when you consider paying those extra costs on top of an already-interpreted scripting language.
3) Dynamic class loading and reflection both introduce the possibility of new kinds of runtime errors. Things like "method not found" and "class not found on server" seem like things you'd want to avoid, so to me GWT's "limitation" is actually an aid to quality.
4) Loading code dynamically over HTTP has two big weirdnesses. First, at what granularity do you load code dynamically? Per class? I guess that's what the ClassLoader model would dictate. But if that's true, then that is a *huge* number of HTTP round-trips...and a network hiccup during any one of them would stall the entire application. Second, more subtle, is that ClassLoader.loadClass() is synchronous. That means, I guess, that to implement it you have to use XMLHttpRequest in synchronous mode to fetch the JS of a class, but that causes terrible browser behavior in that it locks up the chrome completely (and in FF it actually pegs the CPU, too). [That's why GWT doesn't do blocking RPC calls at all!]
In GWT, we do compile-time code generation instead of runtime reflection. GWT code generators are free to use reflection to spit out non-reflective translatable code. That way, you get the advantages of reflection, but only at compile-time. The generated source can be optimized just like handwritten code.
Those are just some thoughts while I'm killing time here in a hotel room at JAOO. I'd like to hear your thoughts if you see things differently or if you've solved the problem in some clever way we never thought of.
first let me thank you both for participating in a thread that is close to my heart. clearly both of you are the domain experts in these respective technologies and i value these discussions.
in a different thread, i spoke about the gwt design principles. these principles have always aligned well with me and my values since the first day i discovered gwt, warts and all.
however, there is one principle or motivation that i value which appears to be causing tension. we have all experienced conflicting or competing principles, but it only becomes an issue when a principle is so highly valued.
josson hinted at it when he said he was a lazy developer. but there is more to it than that.
the reason why i have had the thoughts of quitting my day job and joining either josson's or Arno Puder's (xml11 guy) crusade is because they both are geared towards: - minimise re-invention and leverage as much as you can
background in my first large gwt application i found myself porting parts of apache commons lang. i found myself being constrained by the emulation JRE subsystem. at the time i had a deadline and i was so high on smoking what the gwt team was shipping that it didnt really matter. but after a while the two things that i disliked most about gwt (ie. 1. limited JRE and 2. the ui widget library) started to take its toll. even though i _love_ so much of gwt's concepts and architecture, i found myself investigating other options. why? because: * i dont want see all these core oss java projects being duplicated and ported to gwt (like i found myself doing) * clearly there is more to an oss project than the codebase, there is the thinking, the community, the test-suite. many social things do not make the port * there are standard and/or defacto standard projects that large organisations have approved for consumption as part of their software governance. gwt ports of these projects would not stand a chance. * the ui widgets and their layout consistency lacks the crispness of alternatives without significant domain knowledge in css and some graphics skills * up until recently when konstantin shipped his gwt designer, i needed introspection and reflection and i knew late binding wouldnt cut it. i also started to feel the need for dynamically linked modules.
i dont expect gwt to solve world hunger, but i could see how the tension points identified above could possibly be addressed with either j2s or xml11.
perhaps the fact that these other oss projects are so under resourced is a good thing because they are forced to leverage well known libraries, idioms, and standards and honour the reuse/release equivalence principle for common oss java assets.
---
bruce, what does a healthy gwt community look like? to me based on our current trajectory: * there a lot of small, fragmented and duplicated widget offerings that attempt to simulate the standard desktop widget set available in swing/swt/winforms. * there is a jaxen port and probably more other ports out there. (it is creditable that this has been done, but should it have been done?)
at the moment, having a large organisation depend on any of these oss offerings is currently considered a risk which prohibits enterprise adoption. which brings me to "are we on the right trajectory?" please dont get me wrong, i want gwt to be the killer development platform, but i feel that many of our current community outcomes are a direct result of that one neglected principle.
I believe reflection will be easy to add from a developer's point of view to GWT once browsers are equipped with better javascript engines... and projects like j2js will benefit far more from them than gwt will. So far I'm happy about the really small code GWT produces since I live & work in a region where a fast internet connection still is a previlege.
There are actually good reasons justifying dynamic code loading. One application I wrote rendered XML into widgets, which caused the browser to download a huge arsenal of widgets when the forms displayed actually involved merely a small subset of them. I propose that code loading occurs on a per 'jar' basis, loading a set of classes at once, grouped manually together by the programmer. In respect to the need for asynchronous loading, I'd be comfortable with observing the load operation like:
GWT.create(SomeClassName, new AsyncCallback(){ void onSuccess(Class c){
} ... }
);
... or whatever in this direction is that you feel appropriate provided that once onSuccess is called, code in the main application that explicitly refers to the class like:
SomeClass obj = new SomeClass();
will execute fine and not throw a ClassNotFoundException.
On 10/4/06, georgeuoa <g.georgovassi...@gmail.com> wrote:
> I believe reflection will be easy to add from a developer's point of > view to GWT once browsers are equipped with better javascript > engines... and projects like j2js will benefit far more from them than > gwt will.
I didn't mean to imply that some form of reflection would be *difficult* to support in GWT, just that it doesn't seem affordable at present. If it ever becomes affordable (don't hold your breath :-) and people want it, then I could see it happening in GWT.
So far I'm happy about the really small code GWT produces
> since I live & work in a region where a fast internet connection still > is a previlege.
Great! We still want to make the code smaller and faster.
There are actually good reasons justifying dynamic code loading [...] I
> propose that code loading > occurs on a per 'jar' basis, loading a set of classes at once, grouped > manually together by the programmer.
I completely understand the need for dynamic loading -- in fact, that's going to be in the works after 1.2. I just meant that the ClassLoader technique (i.e. loading one class at a time) specifically isn't a good match for the realities of the browser and HTTP.
In respect to the need for
> asynchronous loading, I'd be comfortable with observing the load > operation like: [...]
That seems to have the right kind of feel: it doesn't pretend to be Class.forName(), but it's still relatively simple.
> Dynamic class loading and reflection are cool features, no doubt, and I > think it's awesome that your compiler is able to cross-compile so many > of the existing Java idioms as-is.
> I think several of us on the GWT team would have a hard time justifying > supporting those features in GWT for several big reasons:
> 1) They completely devastate the compiler's ability to optimize > aggressively. How can the compiler remove code when some subtle > reflection logic might actually need it at runtime? How can the > compiler fully understand the call graph?
> 2) Reflection and dynamic loading are affordable when running JITted > bytecode on 2GHz CPUs and when you can load new classes directly from > disk (or from a filesystem cache in RAM). However, it's a whole > different story when you consider paying those extra costs on top of an > already-interpreted scripting language.
> 3) Dynamic class loading and reflection both introduce the possibility > of new kinds of runtime errors. Things like "method not found" and > "class not found on server" seem like things you'd want to avoid, so to > me GWT's "limitation" is actually an aid to quality.
> 4) Loading code dynamically over HTTP has two big weirdnesses. First, > at what granularity do you load code dynamically? Per class? I guess > that's what the ClassLoader model would dictate. But if that's true, > then that is a *huge* number of HTTP round-trips...and a network hiccup > during any one of them would stall the entire application. Second, > more subtle, is that ClassLoader.loadClass() is synchronous. That > means, I guess, that to implement it you have to use XMLHttpRequest in > synchronous mode to fetch the JS of a class, but that causes terrible > browser behavior in that it locks up the chrome completely (and in FF > it actually pegs the CPU, too). [That's why GWT doesn't do blocking > RPC calls at all!]
> In GWT, we do compile-time code generation instead of runtime > reflection. GWT code generators are free to use reflection to spit out > non-reflective translatable code. That way, you get the advantages of > reflection, but only at compile-time. The generated source can be > optimized just like handwritten code.
> Those are just some thoughts while I'm killing time here in a hotel > room at JAOO. I'd like to hear your thoughts if you see things > differently or if you've solved the problem in some clever way we never > thought of.
> -- Bruce
Hi Bruce,
First, there are no clever ways for ClassLoader. Second, in my conception, there are another term "asynchronous programming" besides "synchronous programming". Third, Java2Script compiler does perform very poorly at loading huge arsenal of SWT classes.
In the implementation of Java2Script ClassLoader (not full APIs implemented), it mainly supports three modes: 1. Asynchronous over SCRIPT tags (mainly in used) 2. Asynchronous over XMLHttpRequest (not used a lot) 3. Synchronous over XMLHttpRequest (seldom used),
Up until now, I seldom use ClassLoader.loadClass in synchronous XHR mode, as the browser may be locked. Instead, an asynchronous ClassLoader wrapper is introduced:
public class AClass { // Java2Script compiler will generate different scripts without Thread for this method body public static void load(final String clazzName, final Runnable afterLoaded) { new Thread(new Runnable() { public void run() { try { Class clz = Class.forName(clazzName); if (afterLoaded instanceof ARunnable) { ARunnable runnable = (ARunnable) afterLoaded; runnable.setClazz(clz); } } catch (ClassNotFoundException e) { e.printStackTrace(); return ; } afterLoaded.run(); } }).start(); }
}
Java2Script recommends using this kind of asynchronous ClassLoader, in which the compiler will modify AClass.load with JavaScript codes without java.lang.Thread but with asynchronous XMLHttpRequest or SCRIPT-tag class loading codes.
And now it comes to something about "Asynchronous Programming" v.s. "Synchronous Programming", if we use asynchronous class loading.
We know that JavaScript does not support Thread like Java. But when you use Java, lots of Thread things will be introduced. For example, when you use GUI toolkit to open a dialog, there are threads running already. But when we introduce UI widgets in JavaScript, we have no Threads. What we can use are asynchronous callbacks. And we do use use asynchronous callbacks a lot in XMLHttpRequest. So if we take asynchronous callbacks for granted, we should always considering "Asynchronous Programming" pattern. That is to say, when we know some calls are *time-consuming*, we should put following codes into a callback and let that method call to call back later. So RPC and Class.forName call should be wrapped into a callback by developer intentionally.
Here is an example for scenario of using asynchronous class loader. There is a page, with many tabs. And each tab will present a different thing (a different class). We need not to load all those tab classes in starting up. We just need to load that tab class only when user switches to that tab. When user switches, here asynchronous class loader should be used to load the tab page class:
tabFolder.addSelectionListener(new SelectionAdapter() { public void widgetSelected(SelectionEvent e) { //... Object data = item.getData(); // class name actually if (data != null) { // ASWTClass#shellLoad is actually similar to AClass#load
Here when asynchronous class loader is loading classes, show some texts saying "fetching data ..." should be fine.
The problem of *huge* number of HTTP round-trips is a *huge* problem of Java2Script compiler. So packed *.z.js, which is similar to *.jar, is introduced. First ClassLoader is designed to load class in per class mode but is also designed to load all related classes when one class is required. For example, when instantiating class A must require instantiating class B, then ClassLoader will try to load class B when class A is required, and only marks class A as loaded after class B or other classes are loaded. This may require algorithm to calculate class dependencies, which may be similar to GWT's call graph. So if class A and class B have their relationship, we can pack A.js and B.js together to reduce the number of HTTP round-trips. In practical implementation of J2S' SWT, ToolBar and ToolItem are packed as ToolBar.z.js, Shell.js, Decorations.js and Display.js are packed as Shell.z.js. This is a way Java2Script compiler trying to reduce *huge* number of HTTP round-trips. But as mentioned, the loading performance is not good enough. And the packing algorithm may require professional design besides compiler's capabilities.
Actually, the original design was to pack most of library *.js into some (less than 15 or 20) *.z.js files. And those *.z.js are static with different release versions. Other pages (or other websites' pages) may load these static libraries when necessary. As different pages have common *.z.js URLs. There are no needs to download them again once they are already downloaded by other visited pages (Just like Flash is required to install once). And if the *.js is distributed on a fast network (like Google network or other distributed publishing network). In fact, maybe these library *.z.js are not too huge for such publishing and not small enough to be efficient libraries, as this design is not yet proved.
GWT's *.js seems to be project-dependent. And different projects only share a bootstrap library and not share some big *.js libraries (But do share in Java source level). Am I right?
Currently Java2Script's ClassLoader just ignore "Class not found" silently when SCRIPT-tag gets nothing. And this should be fixed. "Method not found" exceptions existed already before Java reflection was implemented.
As mentioned in my last post, I admired GWT team for the motivation of "to be as small and as efficient as possible" and "excellent 100k ~ 200k final *.js files with very good performance". And I learned that two separate goals: (1) Create highly optimized JS output (2) Optionally, publish selected parts of your code with a JS-compatible API For such design, without ClassLoader and Java reflection should be OK for me. But I am still wondering whether it's a must feature or not for enterprise edition of GWT projects. OK, I am just wondering from my lazy perspective.
Maybe I should learn something from GWT's motivation and goals. Maybe it's direction for JavaScript, also for Java2Script. And may
...
ash wrote: > first let me thank you both for participating in a thread that is close > to my heart. clearly both of you are the domain experts in these > respective technologies and i value these discussions.
> in a different thread, i spoke about the gwt design principles. these > principles have always aligned well with me and my values since the > first day i discovered gwt, warts and all.
> however, there is one principle or motivation that i value which > appears to be causing tension. we have all experienced conflicting or > competing principles, but it only becomes an issue when a principle is > so highly valued.
> josson hinted at it when he said he was a lazy developer. but there is > more to it than that.
> the reason why i have had the thoughts of quitting my day job and > joining either josson's or Arno Puder's (xml11 guy) crusade is because > they both are geared towards: > - minimise re-invention and leverage as much as you can
Yes, "minimise re-invention" was another motivation of Java2Script. Once I had to design some wrappers to wrap Swing dialogs into SWT/JFace's wizard-style dialogs, I got lots of pains. And when Java2Script ideas came up, I did not think I could design a better UI framework than JFace, so I chose to implement a JavaScript version of SWT library. By such library, lots of GUI builders, and lots of other tools can be reused.
By the way, if you have any ideas or thoughts about Java2Script, Java2Script team will appreciate for your discussion on its development mail-list.
> background > in my first large gwt application i found myself porting parts of > apache commons lang. i found myself being constrained by the emulation > JRE subsystem. at the time i had a deadline and i was so high on > smoking what the gwt team was shipping that it didnt really matter. but > after a while the two things that i disliked most about gwt (ie. 1. > limited JRE and 2. the ui widget library) started to take its toll. > even though i _love_ so much of gwt's concepts and architecture, i > found myself investigating other options. why? because: > * i dont want see all these core oss java projects being duplicated and > ported to gwt (like i found myself doing)
Reusing existed OSS Java projects is challenging. An easy way to reuse or port those projects should be developed.
> * clearly there is more to an oss project than the codebase, there is > the thinking, the community, the test-suite. many social things do not > make the port > * there are standard and/or defacto standard projects that large > organisations have approved for consumption as part of their software > governance. gwt ports of these projects would not stand a chance. > * the ui widgets and their layout consistency lacks the crispness of > alternatives without significant domain knowledge in css and some > graphics skills > * up until recently when konstantin shipped his gwt designer, i needed > introspection and reflection and i knew late binding wouldnt cut it. i > also started to feel the need for dynamically linked modules.
> i dont expect gwt to solve world hunger, but i could see how the > tension points identified above could possibly be addressed with either > j2s or xml11.
> perhaps the fact that these other oss projects are so under resourced > is a good thing because they are forced to leverage well known > libraries, idioms, and standards and honour the reuse/release > equivalence principle for common oss java assets.
> ---
> bruce, what does a healthy gwt community look like? > to me based on our current trajectory: > * there a lot of small, fragmented and duplicated widget offerings that > attempt to simulate the standard desktop widget set available in > swing/swt/winforms.
Simulating desktop widgets is a unavoidable way to expand GWT. But what about a stable API? Can GWT's API be stable sooner? Swing and SWT took years to become stable. So it seems that a little longer waiting should be required for stable GWT APIs.
> * there is a jaxen port and probably more other ports out there. (it is > creditable that this has been done, but should it have been done?)
> at the moment, having a large organisation depend on any of these oss > offerings is currently considered a risk which prohibits enterprise > adoption. which brings me to "are we on the right trajectory?" > please dont get me wrong, i want gwt to be the killer development > platform, but i feel that many of our current community outcomes are a > direct result of that one neglected principle.
Josson Smith wrote: > By the way, if you have any ideas or thoughts about Java2Script, > Java2Script team will appreciate for your discussion on its development > mail-list.
thx for the invitation. ill cross post so both lists can take their dig at me <g>. the purpose of this post is to present some random thoughts that i have had.
josson,
thanks again for your contribution to the thread. i appreciate your openness about the j2s classloader issues & ideas, and also your interest in understanding the motivations of the gwt compiler.
i find myself routinely getting svn updates of your commits and monitoring your progress. there is something that is very right about your approach, that for me keeps gwt in check.
first, let me state where i think your project is positioned (pls correct me where im wrong). i believe j2s is positioned b/n xml11 and gwt. my rationale is: * xml11 is server heavy and renders any awt based application to a browser by sending delta DOM changes over the wire in a similar fashion to ZK as one of its two approaches. there is work in progress to support both swing and swt. the point being is that if you had existing desktop java software that needed to be accessible via a browser, then this may well become the most effective solution when xml11 maturity improves. * gwt is almost completely client based, has created a new ui widget API that is coupled to the DOM, and does not attempt to leverage existing java gui APIs
now lets discuss ui. note, whilst im not a huge fan of the gwt widget API, there are the following things that i do like: * it is very light weight * it uses the clever gwt browser module strategy approach for addressing browser independence * it aims to be simple
to be honest, im not a big fan of swing or swt either. however, having said that, what i do like about j2s is that: 1. java developers can leverage a matured, well understood, and documented gui api 2. all widgets work out of the box (ie. no css files to hack) 3. it leverages an existing tools market built around swt
however, let us consider how important these points are to a community like gwt. im sure the community will correct me where i am wrong.
> 1. java developers can leverage a well understood and documented gui api
sure there are many old swing/swt hacks that are in this community, but to my surprise there are many non java folks. most of these guys would probably look at swing/swt code and proclaim: "what the ...". furthermore, there is a large advocacy for a middle ground between social based web apps and traditional desktop style application in a browser. perhaps this is where the openlazlo folks are headed. claude has spoken at lengths on this subject (consider searching his posts) on this group. therefore, should this motivation have a high priority as we both originally anticipated?
> 2. all widgets work out of the box (ie. no css files to hack)
imho this is one of the most undervalued benefits of j2s. ive also experienced this with zk and openlazlo - things just work without configuration or deep knowledge. not only do u provide a near complete swt widget impl., but it actually renders as expected. being part of the client/server generation and developing apps in win3.1, win95, etc. it became evident what tooling was required to attract the masses. i think gwt (or gwt tool community) has a long road ahead and relies too heavily on css/graphic expertise for the masses to arrive any time soon.
> 3. it leverages an existing tools market built around swt
here again is another instance of the "minimise duplication, maximise leverage" prinicple. however, having enough weight behind gwt, there are 2 tools at present to support gui building for gwt. i use instantiations' windowsbuilder pro::gwt-designer edition which is slowly doing to gwt, what it did for swing/swt. therefore again, should is this motivation have a high priority as we both originally antipicated.
finally, lets discuss some of the pain points experienced by some members of the gwt community. 1. developing applications with modules that can be dynamically linked and shared accross multiple modules/projects 2. the limited jre causes engineers to duplicate code from existing oss java projects when required 3. there is no support for reflection. gwt does support a powerful compile-time concept called defered binding. admittedly, most things can be pushed to either defered binding or the server side, but very occasionally you do discover the need for reflection
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i have never looked at j2s and gwt as competitors, rather ive always looked to complement gwt with j2s and attempt to address some the paint points above. i have often thought wouldn't it be cool if: * j2s could achieve a static (way ahead of time) compile like gcj and render an entire appl as a single html/js like gwt, and/or offer a partitioned html/js with shared objects (designers can choose with compiler switches) * j2s could let me statically link my library with apache commons lang (etc.) and render a js that i could call from gwt. hence, whenever gwt could not do the heavy lifting, i could turn to j2s. * all of j2s's swt widgets could be synthesized into gwt, but leverage the low level DOM and Event abstractions rather than gwt ui widget api. this time focus on a more common listener interface, build drag'n'drop into the base and also consider component serialization and convenient component to component assignment
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in your blog u felt that this thread became x v's y. im sorry u felt like that. as indicated above, i and im sure many others here are uninterested in competition, but better solution.
im convinced that there is a market for your work. what and how this community can leverage it within the context of gwt depends on the roadmap of gwt.
>> By the way, if you have any ideas or thoughts about Java2Script, >> Java2Script team will appreciate for your discussion on its development >> mail-list.
> thx for the invitation. ill cross post so both lists can take their dig > at me <g>. the purpose of this post is to present some random thoughts > that i have had.
> thanks again for your contribution to the thread. i appreciate your > openness about the j2s classloader issues & ideas, and also your > interest in understanding the motivations of the gwt compiler.
> i find myself routinely getting svn updates of your commits and > monitoring your progress. there is something that is very right about > your approach, that for me keeps gwt in check.
> first, let me state where i think your project is positioned (pls > correct me where im wrong). i believe j2s is positioned b/n xml11 and > gwt. my rationale is: > * xml11 is server heavy and renders any awt based application to a > browser by sending delta DOM changes over the wire in a similar fashion > to ZK as one of its two approaches. there is work in progress to > support both swing and swt. the point being is that if you had existing > desktop java software that needed to be accessible via a browser, then > this may well become the most effective solution when xml11 maturity > improves. > * gwt is almost completely client based, has created a new ui widget > API that is coupled to the DOM, and does not attempt to leverage > existing java gui APIs
Some of my earlier thoughts: As both client(browser) and server are implemented in Java, developers can add annotations (or javaDoc tag) to leverage whether a *static* method is executed on client side or on server side. For example, there is a task to compare two files. If such a task is executed on browser side, browser will read (HTTP GET) two files, and make the comparison and show differences. If such a task is executed on server side, the server reads two files and make the comparison and return differences to browser and the browser display them.
If most of the methods are marked as being executed on server side(in most cases, one of two methods would be marked so), it would be just the same as ZK or XML11.
Currently, J2S has not yet implemented the above javaDoc annotations. So, IMO, it is much more similar to GWT than to XML11 currently. That is to say, it's client based, with SWT APIs supported.
> now lets discuss ui. note, whilst im not a huge fan of the gwt widget > API, there are the following things that i do like: > * it is very light weight > * it uses the clever gwt browser module strategy approach for > addressing browser independence > * it aims to be simple
One or two months ago, I realized that SWT is somewhat heavy for most RIAs' requirement.
> to be honest, im not a big fan of swing or swt either. however, having > said that, what i do like about j2s is that: > 1. java developers can leverage a matured, well understood, and > documented gui api > 2. all widgets work out of the box (ie. no css files to hack) > 3. it leverages an existing tools market built around swt
> however, let us consider how important these points are to a community > like gwt. im sure the community will correct me where i am wrong.
>> 1. java developers can leverage a well understood and documented gui api
> sure there are many old swing/swt hacks that are in this community, but > to my surprise there are many non java folks. most of these guys would > probably look at swing/swt code and proclaim: "what the ...". > furthermore, there is a large advocacy for a middle ground between > social based web apps and traditional desktop style application in a > browser. perhaps this is where the openlazlo folks are headed. claude > has spoken at lengths on this subject (consider searching his posts) on > this group. therefore, should this motivation have a high priority as > we both originally anticipated?
Is GWT API on the way to be another similar Swing/SWT API? I wonder.
And when JavaScript SWT first demo came up, someone said, do we need this complexity?.
>> 2. all widgets work out of the box (ie. no css files to hack)
> imho this is one of the most undervalued benefits of j2s. ive also > experienced this with zk and openlazlo - things just work without > configuration or deep knowledge. not only do u provide a near complete > swt widget impl., but it actually renders as expected. being part of > the client/server generation and developing apps in win3.1, win95, etc. > it became evident what tooling was required to attract the masses. i > think gwt (or gwt tool community) has a long road ahead and relies too > heavily on css/graphic expertise for the masses to arrive any time > soon.
It seems that css/graphic experts would like to use CSS/HTML most.
>> 3. it leverages an existing tools market built around swt
> here again is another instance of the "minimise duplication, maximise > leverage" prinicple. however, having enough weight behind gwt, there > are 2 tools at present to support gui building for gwt. i use > instantiations' windowsbuilder pro::gwt-designer edition which is > slowly doing to gwt, what it did for swing/swt. therefore again, should > is this motivation have a high priority as we both originally > antipicated.
> finally, lets discuss some of the pain points experienced by some > members of the gwt community. > 1. developing applications with modules that can be dynamically linked > and shared accross multiple modules/projects > 2. the limited jre causes engineers to duplicate code from existing oss > java projects when required > 3. there is no support for reflection. gwt does support a powerful > compile-time concept called defered binding. admittedly, most things > can be pushed to either defered binding or the server side, but very > occasionally you do discover the need for reflection
> ---
> i have never looked at j2s and gwt as competitors, rather ive always > looked to complement gwt with j2s and attempt to address some the paint > points above. i have often thought wouldn't it be cool if: > * j2s could achieve a static (way ahead of time) compile like gcj and > render an entire appl as a single html/js like gwt, and/or offer a > partitioned html/js with shared objects (designers can choose with > compiler switches)
Static compiler like gcj requires more hacks over Eclipse JDT. And it seems that GWT already implemented its static compiler. Maybe I may learn something more from GWT.
> * j2s could let me statically link my library with apache commons lang > (etc.) and render a js that i could call from gwt. hence, whenever gwt > could not do the heavy lifting, i could turn to j2s. > * all of j2s's swt widgets could be synthesized into gwt, but leverage > the low level DOM and Event abstractions rather than gwt ui widget api. > this time focus on a more common listener interface, build drag'n'drop > into the base and also consider component serialization and convenient > component to component assignment
> ---
> in your blog u felt that this thread became x v's y. im sorry u felt > like that. as indicated above, i and im sure many others here are > uninterested in competition, but better solution.
I did not mean to be another "vs" thing. Yes, "better solution", the goal of open source software.
> im convinced that there is a market for your work. what and how this > community can leverage it within the context of gwt depends on the > roadmap of gwt.
first of all you should know that we really value for what you did guys. I have seen a lot of "pretty" and "full featured" solutions that are dead now, because they didn't do what they were done for.
br...@google.com wrote: > I'd like to hear your thoughts if you see things > differently or if you've solved the problem in some clever way we never > thought of.
You have already said "A" when you defined GWT Module-concept. You just need to say "B" and ... define dependencies between the modules and put them all together in one application. ;) IMHO it will be great advantage to developers of big applications than.
1. Topology: - application consists of modules - module consists of classes - application must have EntryPoint - module can have EntryPoint
2. Compilation: - the whole application with all its modules must be compiled at once to keep all advantages of current design (optimized generated javascript code and obfuscation)
3. Dynamic module loading: - module is a minimal unit of loading - loding of a new a module requires that all other modules it depends on are loaded - a module can use another module only if both modules were compiled together
That's all. Using this concept I would design my application to have for example 1) java.lang&util, GWT DOM&UI, my own widget's module (actually always loaded) 2, 3, 4, 5, 6) different feature-grouped dynamically loaded modules of my huge application (use module 1 and may also use each other)
