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I see lot of examples on how to build a Apache Module using perl, C but there is no documentation to describe how to build a Apache Module using java.
Is it possible to build a Apache Module using Java?
This is seldom practiced, because Apache often spawns multiple processes (cf. preforked) and running a Java Virtual Machine in each of them would inflate the RAM requirements to high heavens.
You can configure Apache to use only a single process, threaded. In this mode the arrangement makes more sense. But Apache installations like this are few and far in between.
Anyway, running a Java Apache module isn't much different from using Java in any other C code. You write a JNI-based wrapper around Apache functions in order to make them available to the Java code, you spawn the Java Virtual Machine, again with the help of JNI. JNI is your friend. There's a lot of documentation about it, a lot of books. Basically, you need to know how to write your own Apache module in C and you need to know the JNI and voila, you can build an Apache module in Java.
If you're looking for a library to do the JNI lifting for you, then this is off topic on Stackoverflow. And most library developers don't go there anyway because of the reasons outlined above. Here's an excerpt from one such undertaking: "The original plan for mod_gcj was to embed the libgcj runtime directly into the Apache processes, mucht like mod_perl does. Unfortunately, there was some clash between the traditional processing models with Java using threading and Apache using forking on Unix. As a result of this, mod_gcj is run in a a separate process that is forked from Apache and hosts its multithreaded libgcj runtime." - http://mod-gcj.sourceforge.net/about.html
I really like live smalltalk environment (though I only experimented a bit with Pharo), but there is one thing why I can't really use it for everyday development. It seems that it is not possible to create a native standalone executable from smalltalk system. The native standalone executable means to create a single executable file (PE on windows, ELF on linux, Mach-O on macosx), that a user could run by double clicking it without the need to install any additional execution environments. Am I missing something and it is in fact possible to create native standalone executable with smalltalk?
If we talk about Pharo specifically. I know that Pharo's environment includes efficient just in time compiler (that generates true native code from Pharo's VM bytecode), I know that the VM image can be stripped down by cutting of the code that my application won't ever need. So basically we already have almost everything (except the linker I guess) to be able to create native standalone executables. Cross-compilation shouldn't be a problem too, if we put all code generation stuff (for all target processors) in the image.
I know that in smalltalk world it is considered to be a good thing to deliver the whole VM image separately from the runtime environment, so the user can hack on software he/she is using. However I don't see any good reasons why it shouldn't be possible to deliver your smalltalk software as fully compiled native standalone executable. Could you please explain me why it is not a common thing to do in smalltalk world? Is there any good smalltalk implementation that allow to do it?
To sum all this. I dream of a live smalltalk environment, where I could develop and test my software, but then (when the software is actually ready for delivery) cross-compile it to native executables for windows, linux and macosx from my single development machine. That would be really awesome.
ironically enough there is one thing that an exe needs to be preloaded. Your OS. See the thing is that C/C++ can be so light because already your OS acts pretty much as the image acts with a ton of preloaded libraries. You need to waste several GBs of memory just get a simple calculator starting. Your OS is a collection of C/C++ libraries.
Things are not any prettier with other languages like python, java etc , even if the app is smaller, they still depend on this libs and they come will quite big libraries that would need installation whether your app use them or not.
Pharo and Smalltalk in general is diffirent case because they aspire to be a virtual OS by itself. The diffirence with a real OS , the smalltalk image is made to be hacked the easy way by a user .
Saying that you can rename the pharo executable, change its icon, disable to IDE tools inside Pharo so your user sees only the GUI of your App. Applications like Dr. Geo and Phratch already do this.
Compiling a Pharo project to a native executable will not make much difference, because a) Pharo is already compiled to a native executable b) you dont need to do that since Pharo is already standalone does not need to even be installed.
My advice is stop worrying about things that do not really matter and enjoy learning how powerful and fun Pharo can be.
Not Pharo, but native, compiled (through ANSI C or its own JIT) smalltalk [applications] (with ability to load pre-compiled DLLs or [JIT-]compile code on demand):
Smalltalk/X
http://www.exept.de/en/products/smalltalk-x.html
or (unofficial enhanced development version):
Smalltalk/X JV branch - https://swing.fit.cvut.cz/projects/stx-jv/
Nearly completely open-source. Everything except librun (core runtime - memory management, JIT, etc.) and stc (smalltalk-to-c) compiler is already open-source. Claus Gittinger / Exept also promised/confirmed they would release remaining sources were they to stop further development (AFAIK, those parts are closed only because of concerns of existing clients).
I highly recommend everyone to check it out, it is a wonder such a great implementation is so little known.
You might also check out Dolphin from Object Arts.
It is windows only, but the very best IDE, bar none.
If you do anything in Smalltalk, you should buy a copy.
(They also have a free non-commercial version, but you will
want to support the kind of craftsmanship behind it by buying
the Pro version. An absolutely kick-ass product, IMHO).
It will produce a standalone exe, if that's what you want.
I made an exe of a medium-featured wiki with it - the exe was
less than 1 MB. That is not a typo.
-Jim
The problem is that Pharo, in that case, cannot be compared to any native compiler like C, C++ or others, but more like java, python, ruby and other languages with a Virtual Machine around.
In these languages, you produce jars, eggs or gems to distribute your project.
In Pharo, you produce a "production image" following technics you already mentioned. But nothing prevents you to deliver an artefact including also the PharoVM (it is 2m large, after all), and you can prepare your apps to detect and open your production image (without having to ask for it).
It is about as practical with Smalltalk as with other languages: not very much. As soon as you create a somewhat larger application, you start depending on other libraries/applications being installed. If you compile them statically with the application, you have now created a much larger application that takes longer to download, and needs to be updated at least as soon as a security problem is found in one of the dependencies. If not, your application is no longer double-click startable.
There are two directions for solutions: web applications, and installers and package managers.
Squeak still maintains its one-click installer, allowing the same set of files to work on windows, mac and linux. Pharo used to have that too, but moved to having separate builds. The need hasn't been so large that the one-click build has been reinstated. It is mostly seen as useful to be able to carry around a cross-platform environment on an usb-stick. With the move to the 64-bit spur vm the dependency problems will lessen as more of the needed libraries will come pre-installed on those platforms.
Dolphin Smalltalk can produce a standalone .exe for Windows.
This is a key feature of the Pro version.
Your dream has been around since the mid-80's and it is called Smalltalk/X.
Are there any differences between the original CruiseControl and the .NET port? I've compared the 2, but can't find any big differences except the language it has been developed in. I want to use either one of them for (automated) testing of web applications, using Selenium and Subversion, perhaps even Groovy but don't know which to choose.
[edit]
After looking at CC and Hudson, I've chosen Hudson for it's simplicity, it already has plugins to run Groovy scripts and Selenium as well
Choose me, choose me! (I work on the original CruiseControl.)
I've never used CC.NET but from what I know I agree that they are pretty comparable. Probably the most important difference is cross-platform vs. Windows only.
Now I wonder how long until someone comes by and says their both crap and you should try Hudson? ;)
(And of course there are lots of other choices...)
CruiseControl.NET (cc.net henceforth) has build queues (http://confluence.public.thoughtworks.org/display/CCNET/Project+Configuration+Block), which allows you to serialize builds that depends on a certain build order. I'm in the process of emulating this behavior in the java version of cruisecontrol but the functionality doesn't map one to one. The reason however, that I'm at all moving from the .net to the java version is that the .net version core dumps with mono (cc.net nightly build and mono nightly build as of two months ago). The fault lies with monos thread handling but voids attempts to get cc.net up and running.
The documentation on this can be tricky to find, if you don't notice the version numbers that the configuration examples/documentation adhere to (confluence.public.thoughtworks.org has the updated configuration documentation whereas ccnet.sourceforge.net has not. I know that the ccnet is most likely a dead site, but if your're not carefully reading the datestamps on every page you're visiting, this may bite you).
Furthermore, the sourcecontrol blocks for cvs and svn in cc.net are more granular and featurerich than their counterpart in the java version, but this has not been a problem in my work. The java version is also easy to extend/modify re: plugin behavior, but you would really just like to see this kind of work going upstream instead of forking.
I'm fairly impressed with both the java version and the fork in .net (modulo mono runtime behavior), but you really do not want to try any of the other forks of cruisecontrol. I've had peripheral experience with hudson, and the features were just not compelling enough to veer me from cruisecontrol. Hudson has a (somewhat coloured) comparison map of Hudson and CruiseControl (java) at http://hudson.gotdns.com/wiki/display/HUDSON/Home
A viable alternative is the python implemented buildbot (http://buildbot.net/trac). It does not have fancy gui dashboards and the setup is somewhat more commandline-bound, but if you're doing distributed builds, it's very easy to set up and get running.
I think for you it will come down to operating system, original can run on nix, and .net version runs on windows.
There are other automated build utilities that can do this as well, such as TeamCity in the windows space, and cruisecontrol.rb in the ruby world.
Also there is a PowerShell based build utility called pSake that can poll subversion and perform tasks.
We need to interface to 3rd party app, but company behind the app doesn't disclose message protocol and provides only Windows DLL to interface to.
Our application is Linux-based so I cannot directly communicate with DLL. I couldn't find any existing solution so I'm considering writing socket-based bridge between Linux and Windows, however I'm sure it is not such a unique problem and somebody should have done it before.
Are you aware of any solution that allows to call Windows DDL functions from C app on Linux? It can use Wine or separate Windows PC - doesn't matter.
Many thanks in advance.
I wrote a small Python module for calling into Windows DLLs from Python on Linux. It is based on IPC between a regular Linux/Unix Python process and a Wine-based Python process. Because I have needed it in too many different use-cases / scenarios myself, I designed it as a "generic" ctypes module drop-in replacement, which does most of the required plumbing automatically in the background.
Example: Assume you're in Python on Linux, you have Wine installed, and you want to call into msvcrt.dll (the Microsoft C runtime library). You can do the following:
from zugbruecke import ctypes
dll_pow = ctypes.cdll.msvcrt.pow
dll_pow.argtypes = (ctypes.c_double, ctypes.c_double)
dll_pow.restype = ctypes.c_double
print('You should expect "1024.0" to show up here: "%.1f".' % dll_pow(2.0, 10.0))
Source code (LGPL), PyPI package & documentation.
It's still a bit rough around the edges (i.e. alpha and insecure), but it does handle most types of parameters (including pointers).
Any solution is going to need a TCP/IP-based "remoting" layer between the DLL which is running in a "windows-like" environment, and your linux app.
You'll need to write a simple PC app to expose the DLL functions, either using a homebrew protocol, or maybe XML-RPC, SOAP or JSON protocols. The RemObjects SDK might help you - but could be overkill.
I'd stick with a 'real' or virtualized PC. If you use Wine, the DLL developers are unlikely to offer any support.
MONO is also unlikely to be any help, because your DLL is probably NOT a .NET assembly.
This is a common problem. Fortunately, it now has a solution. Meet LoadLibrary, developed by Tavis Ormandy:
https://github.com/taviso/loadlibrary
I first stumbled across LoadLibrary in an article on Phoronix by Michael Larabel:
A Google researcher has been developing "LoadLibrary" as a means of
being able to load Windows Dynamic Link Libraries (DLLs) that in turn
can be used by native Linux code.
LoadLibrary isn't a replacement for Wine or the like but is intended
to allow Windows DLL libraries to be loaded that can then be accessed
by native Linux code, not trying to run Windows programs and the like
on Linux but simply loading the libraries.
This project is being developed by Tavis Ormandy, a well known Google
employee focused on vulnerability research. He worked on a custom
PE/COFF loader based on old ndiswrapper code, the project that was
about allowing Windows networking drivers to function on Linux.
LoadLibrary will handle relocations and imports and offers an API
inspired by dlopen. LoadLibrary at this stage appears to be working
well with self-contained Windows libraries and Tavis is using the
project in part for fuzzing Windows libraries on Linux.
Tavis noted, "Distributed, scalable fuzzing on Windows can be
challenging and inefficient. This is especially true for endpoint
security products, which use complex interconnected components that
span across kernel and user space. This often requires spinning up an
entire virtualized Windows environment to fuzz them or collect
coverage data. This is less of a problem on Linux, and I've found that
porting components of Windows Antivirus products to Linux is often
possible. This allows me to run the code I’m testing in minimal
containers with very little overhead, and easily scale up testing."
More details on LoadLibrary for loading Windows DLLs on Linux via
GitHub where he also demonstrated porting Windows Defender libraries
to Linux.
Sometimes it is better to pick a small vendor over a large vendor because the size of your business will give you more weight for them. We have certainly found this with AV engine vendors.
If you are sufficiently important to them, they should provide either a documented, supported protocol, a Linux build of the library, or the source code to the library.
Otherwise you'll have to run a Windows box in the loop using RPC as others have noted, which is likely to be very inconvenient, especially if the whole of the rest of your infrastructure runs Linux.
Will the vendor support the use of their library within a Windows VM? If performance is not critical, you might be able to do that.
Calling the DLL's functions themselves is of course only the tip of the iceberg. What if the DLL calls Win32, then you'd have a rather massive linking problem. I guess Wine could help you out there, not sure if they provide a solution.
IMO, the best bet is to use Sockets. I have done this previously and it works like a charm.
An alternate approach is to use objdump -d to disassemble the DLL, and then recompile/reassemble it. Don't expect to be able to recompile the code unedited. You might get pure, unadulterated rubbish, or code full of Windows calls, or both. Look for individual functions. Functions are often delimited by a series of push instructions and end with a ret instruction.
Greetings,
I want to write a small cross-platform utility program with GUI in it. What language/GUI-library should I stick to? Is it possible whatsoever?
This is gonna be a small program, so I don't want to make people download JVM or .NET Framework. Is it possible to develop it natively?
Update 1.
By "natively" I mean that the end result will be native code without intermediate layers like Java Virtual Machine or .NET Common Language Runtime
Update 2.
A FREE solution is preferable ;)
If you know C or C++ the first cross platform GUI framework I can think of are:
QT (C++, proprietary but free with the LGPL licensing)
wxWidgets (C++, the most complete and stable but also huge)
FLTK (C++)
FOX (C++)
IUP (C, simpler and cleaner than the ones above)
If you know Pascal, you can try freepascal+Lazarus. I've never used it, though.
The problem is: If you do not want to have a GUI but you do not want to ask the user to download an eternal API, Framework or virtual machine to run it in, be it TCL/TK, Java or QT etc. then you get lost pretty fast.
The reason is: You would have to rebuild all the (GUI) functionality those APIs, frameworks and virtual machines provide you with to be platform independent. And that's a whole lot of work to do... .
On the other side: The Java virtual machine is installed on nearly any operating system from scratch, why not give this one a shot?
You want to develop a cross-platform program natively? Uh...I don't think that'll work, mainly because that phrase is a paradox. If you write native code, it by its very nature will only run on the platform you programmed it for. ;-) That's what the Frameworks are all about.
So what you should do instead is use a very slim framework if your program is going to be so small. itsmatt's idea of Qt is a possibility.
WxWindows? Oh, it's called WxWidgets now: http://www.wxwidgets.org/
wxWidgets has bindings to all sorts of languages - python for instance, if your app is small enough.
Lazarus is great. GTK2 on Linux, win32/64 on Windows, WINCE on euh, Wince. It even uses Carbon on Mac (working on COCOA). Also easy to sell to your boss (the code is Delphi compatible)
How about Python using Qt or Wx and then using PythonToExe to make a 'distributable'
Thought will have to giving to the development to ensure that no native functionality is used (i.e. registry etc.) Also things like line breaks in text files will have different escape characters so will need to be handled
Which OS's do you have in mind when you say cross-platform?
As Epaga correctly points out, native and cross-platform are mutually exclusive. You can either write multiple versions that run natively on multiple platforms, or you need to use some cross-platform framework.
In the case of the cross-platform framework approach, there will always be extra installs required. For example, many here suggest using Python and one of its frameworks. This would necessitate instructing people to install python - and potentially the framework - first.
If you are aiming at Windows and OS X (and are prepared to experiment with alpha-release code for Linux if support for that OS is required), I'd highly recommend you take a look at using Adobe AIR for cross-platform GUI applications.
I agree with Georgi, Java is the way to go. With a bit of work, you can make your desktop application work as a Java applet too (so that users do not need to actively download anything at all). See http://www.geogebra.org as an example of an application with runs smoothly as a cross-platform Java application AND has a simple port to a web applet.
Two other advantages to using Java are:
They have extensive libraries for building the UI, including UI component builders.
The Java runtime framework is generally updated automatically for the user.
One disadvantage:
The version of Java installed on your end users computer may not be totally compatible with your application, requiring you to code to the lowest likely denominator.
Try RealBasic. Visual Basic-like syntax, targets Win32, OS X and Linux. I don't know any details about targetting Linux, but for any cross-platform development I've done between Win32 and OS X its been a dream.
http://www.realbasic.com
Edit: Generates native executables. There is a small cost - $100.
Have you looked at Qt?
Flash? It's installed pretty much everywhere.
If it "HAS" to be Desktop use Qt. Nothing beats it right now.
However personally I gave up on desktop and any UI based project I do is normally Browser/Server based. You can easily write a little custom server that listens to some port so the program can run locally with no need for your users to install Apache or have access to the net. I have a small Lua, Python and C++ framework I made for that purpose (Want to add Javascript for the backend with V8 :)
If you're going to look at Qt and WxWidgets, don't forget to also check out GTK+ !
I agree with David Wees and Georgi,
Java is cross-platformness par excellence. You literally write once and run everywhere. With no need of compiling your code for each target OS or bitness, no worries about linking against anything, etc.
Only thing is, as you pointed out, that a JRE must be installed, but it's quick and straightforward to do even for novice end-users (it's a matter of clicking "Next>" a few times in the installer).
And with Java Web Start deployment gets even easier: the user just clicks the launch button on a webpage and the application runs (if the proper JVM is installed according to what specified in the JNLP descriptor) or the user gets redirected to the Java download page (if no suitable JVM is found).