I'm planning to write a C library which will act as an umbrella "wrapper" around several other libs. Some of the libraries will be GPL and some will be proprietary. Moreover, some of the libraries may not be available at compile time, so I plan to have autotools detect them during configure. I'm also wondering if I should build in support for these weak dependencies and then also detect them at run-time -- particularly for the proprietary libs. Here's why:
Without going into specifics, the library is intended to provide an API for talking to various devices, some of which don't have open source drivers. Currently it's difficult to program for these devices because there is no standard, easily available API to use. Each vendor provides its own. There are a few other APIs available that attempt to wrap them, but they are by and large
C++-only.
Designed for a Windows environment, with *nix as an afterthought.
Fail to build unless you have dependencies in the right places, i.e., complete lack of a proper configure/build system.
Most importantly, designed in such a way that they often link directly to proprietary libs, making me almost 100% sure it would be impossible to get these APIs into Debian.
Therefore my end-goal is to build a very simple and straight-forward C API that has a chance in hell of making it into distros so that people can actually write programs for these devices with a simple apt-get.
My question is, how should I best design the library to be GPL-compatible and Debian-friendly, but still be able to call out to proprietary libs when necessary?
Ideally I'd like the user to be able to apt-get a program using this library, and then as long as the vendor's user-level driver is installed to the expected place, everything should work out of the box.
My concern is two-fold:
having dependencies on optional, proprietary libs means the binary distro of the library can't be compiled to dynamically link to these libs, since they may or may not be available.
the user should not have to install dependencies for devices he does not have, open or proprietary.
How do other packages handle this problem of linking to proprietary libs and having run-time weak dependencies? Is dlopen the right way to go for everything? Should I dlopen only the proprietary stuff? What are reasons why or cases when Debian might reject such a package?
Lastly, I realize this probably isn't the right forum for this question about Debian policy, so can anyone point to me a better place to ask this question?
Thanks.
I have no relationship to Debian and cannot speak about their policies. However, for your framework, this seems a reasonable approach:
Define a simple header file that expresses the functionality you need from these plugins
Create a useful GPL/LGPL/BSD plugin that uses that interface
Have your main program load that using libdl, as you mentioned (if your main program is GPL, you need to have a licence exception to allow linking proprietary plugins)
Submit those for inclusion in Debian, and don't mention about the proprietary stuff
The main point is that your plugin system should be useful for free software, and not just be a Trojan horse to allow proprietary code to be loaded.
Using dlopen does not change the fact that you are writing a program to deliberately link to proprietary libraries and GPL libraries at the same time, it just shifts the linking from compile time to run time. While common consensus among the masses is that the GPL does not cover linking dynamically at runtime in this way, it is not safe legal advice to rely on such common understanding. The way I would solve the problem is to write a program with a single generic API for plugins (which can use dlopen, but the key is that you have not specifically written this program to link to proprietary libraries). The program must be under a free license that is compatible with all the plugins you eventually want it to be used with (ie LGPL, or GPL with exception for that API). Then write separate plugins for the GPL libraries and the proprietary libraries, and distribute them separately. If only one plugin can be loaded at a time, then there is no legal problem. If it is necessary to allow more than one plugin at once, then you need to be careful to separate your distribution. As the GPL is a distribution license, what the end users do is not a concern.
Related
Please, don't consider my question as a rant.
Every package in a typical Linux distro has a dependency tree.
Let's suppose we want a specific package in a specific architecture
(amd64, i386, mips, sparc, powerpc). I may need it for training assembly
languages of these architectures with high-level libraries. If this package depends on some
libraries, we must have these libraries also in this architecture. And my idea is to make
a tool that tries to compile all the dependency tree of libraries
(without scripts and programs like python), beginning with compiling the cross-compiler and libc.
This tool must be aware of different build systems like Autotools, Cmake, Meson. And the system
is intended to work on Debian. Source packages will be downloaded via "apt source" and "apt download"
will be used to assess whether the package is a library. One level dependencies of a package will be listed
using "apt-cache show". Dependencies will be installed in non standard locations (in a common parent directory of all)
and environmental variables (like C_INCLUDE_PATH, LIBRARY_PATH) will be used to denote where they are. I am going to implement this in Perl.
I am aware that many package compilations yield errors when they are run first times when we don't know yet
what options to use and what must be fixed in our system. We don't know what package we compile, so we cannot adjust the compilation.
We only may guess what things can turn up. There exist projects with tree compilation (like proton) but it is known what we are compiling
(faudio and gstreamer). Therefore I think that the task may be difficult and successful compilations may be a little fraction of all.
If it were easy, there would be something like that. The bigger the dependency tree, the bigger chance of failure.
I wonder whether to propose this topic for my graduation work.
My questions are: is something like that already invented or thought of? Is it a difficult task?
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.
The mono installation provided at mono-project.com comes packed with several libraries, such as gkt, making the installation quite large (~280MB or so).
Is there any way to provide users with an installation of "just" the mono environment? I am targeting Windows, MacOSX and Linux.
You might be looking for mkbundle which merges your application, the libraries it uses and the Mono runtime into a single executable image. See under "Bundles" in that page.
If you do this though, it may mean that you are distributing LGPL code with all that this implies.
If you are distributing your app for Mac OS X, there is also MonoMacPackager which offers more advanced support for this. I think they have done a bunch of work in the linker to really minimize the amount of Mono that you have to include. It will actually remove unused code from assemblies that you reference.
Our C++/QT desktop application for Mac, Windows and Linux needs an installer. I'd rather we have a single installer for all three platforms. I do know it's a bit tricky, I guess what I wanted ask is if a framework already exists for that (Java maybe?).
I'd really like to avoid having to write three different installers.
The link that Kyle mentions is pretty comprehensive, but I wanted to provide a bit more of information about InstallBuilder for Qt (Disclaimer, I am one of the developers) since most of the cross platform installation programs referenced there are Java-based. This requires bundling a JRE, etc. and adds a significant overhead that is not required with a Qt-based installer, like ours. It is able to generate wizard-like executable installers for all platforms from a single project file as well as native packages such as DEB and RPM. If you ship your software in DVDs, you can create a single multi-platform DVD that shares data across platforms but still have native launchers.
Having said this, since your application is Desktop-oriented, for the particular case of OS X if it does not require complex installation you may be better off creating a .app file and package it inside a DMG. Users can then drag the file directly to the Applications folder.
Finally, I wanted to mention that InstallBuilder is commercial, but we offer free licenses for open source projects and discounts for small development firms.
IzPack rocks: http://izpack.org. It is truly crossplatform, very lightweight, easy to master, and produces excellent results.
After fully integrating both Izpack and InstallBuilder into our builds (using Windows, OSX, and Ubuntu 14 build servers for testing purposes), I will say I believe InstallBuilder is well worth the money (and free for open source projects according to wojciechka).
Izpack is a bit slow, a bit large if you need to package a JVM, and has an amateurish user interface. Version 5 (release candidate 3) was also not generating uninstallers properly. That said, as long as you use a 4.x version and require a JVM anyway, it may be enough for your needs. The extension interface is not terribly easy to deal with, but is almost infinitely flexible. The Windows installers do not register with the Control Panel uninstaller list.
InstallBuilder has a great, fast UI in the produced installers and has a serviceable UI for creating installers. The XML is pretty easy to deal with, too. Downloads are about as small as possible. It also includes nice hooks for doing all sorts of custom stuff easily. The only slightly annoying thing I ran into was that the Windows server required that I manually add some configuration to set executable bits on the other systems' packages (other systems didn't require this configuration).
Note: I was using the three-platform version of standard InstallBuilder (not InstallBuilder for QT).
I have a plan to build a web-site which running CGI made with Cocoa.
My final goal is develop on Mac OS X, and run on FreeBSD.
Is this possible?
As I know, there is a free implementation of some NextStep classes, the GNUStep.
The web-site is almost built with only strings. I read GNUStep documents, classes are enough. DB connection will be made with C interfaces.
Most biggest problem which I'm concerning is linking and binary compatibility. I'm currently configuring FreeBSD on VirtualBox, but I wanna know any possibility informations about this from experts.
This is not a production server. Just a trial. Please feel free to saying anything.
--edit--
I confused Foundation and Cocoa frameworks. What I said was Foundation. Basic classes which just enough to manipulating strings.
It’s entirely possible to cross-develop using Xcode. The Cocotron does this – and provides an implementation of Foundation – but doesn’t currently target FreeBSD. You could probably use it as a template to set up cross-development for BSD targets using GNUstep, but it won’t be easy.
You should be OK with the GNUstep Foundation on FreeBSD 9.0 with Objective-C 2 (clang). See these instructions.
Note: Do not installing under '/' with a FreeBSD default install, because it has little space on the '/' partition. I've used /usr/local/gnustep instead, and made some links as the instructions suggest.
Note II: GNUstep sources from subversion repository didn't compile for me, so I used the latest stable GNUstep sources.
Yes, you can do this, and I am doing it right now successfully using FreeBSD 8.2 and Xcode 4.0, running the Foundation class from The Cocotron. Here is a link: describing exactly what I did to build the cross compiler and set everything up. I also detail in that post, how I attempted to get AppKit (GUI) to work. I failed, it may work in the future, it doesn't fully work yet.
So far it's great. I use a common codebase to write iPhone App (game client) and FreeBSD Game Server; after my server compiles I even have a target rsync the files to my dev box.
One more note, you mention DB, I'm successfully using mysqlclient libraries within my App and my post details how to do that. Since you're building a cross-compiler with The Cocotron you can use any library. Just install the library on FreeBSD first, then create the platform as described.
Sounds like your trying to shoehorn tools onto OS and hardware they were not designed for. There are hacks to get almost anything running on top of anything else but why ask for all the grief?
The entire point of the entire Apple API is that you have integration from hardware to OS to development tools. You supposed to pay more up front in return for greater robustness and lower over all lifecycle cost. (It doesn't always work just like Linux doesn't always save money and Windows doesn't always provide the software choices you need but that is the design goal.) When you break Apple's hardware-OS-Dev trinity you have to start fighting the API and the hardware instead of letting it work for you.
I don't think what you're doing will work and even if it does it will cost a lot of time and in the end time is money. Unless your being forced by external circumstances beyond your control to use this configuration, I would strongly suggest you do whatever it takes to find another way to accomplish what you want.
You won't get binary compatibility. Mac OS X uses the Mach-O object format and FreeBSD uses ELF, like linux. Cocoa won't work on platforms other than Mac OS, but if you stick to POSIX and open-source libraries though, you shouldn't have too much trouble building your CGI (and any dependencies) on your FreeBSD machine.
Also, Cocoa for a website? It's the Mac OS standard library for GUIs, associated datastructures, and various helpers. Apple used to promote something called WebObjects which was similar to Cocoa for the web, but I haven't heard anything about it in ages. I don't think Cocoa will work for a website, unless you just mean write a custom web server that has a graphical front-end in Cocoa.