Basics
The Novell Role in the Mono project
Mono and GNOME
Building GUI applications with Mono
Mono and Microsoft
Mono platforms
Compatibility
Mono and the Portable.NET Project
Web Services
Mono and ASP.NET
Mono and ADO.NET
MonoDoc
Development Tools and Issues
Mono and Java
Extending Mono
Portability
Reusing Existing Code
Mono and GCC
Performance
Licensing
Patents
Miscellaneous Questions
Obfuscation
Mono Common Problems
A Spanish translation is also available (it is outdated though) ** Basics Q: What is Mono exactly? A: The Mono Project is an open development initiative sponsored by Ximian that is working to develop an open source, Unix version of the Microsoft .NET development platform. Its objective is to enable Unix developers to build and deploy cross-platform .NET Applications. The project will implement various technologies developed by Microsoft that have now been submitted to the ECMA for standardization. The Mono project has also sparked a lot of interest in developing C#-based components, libraries and frameworks. Today Mono is not limited to implement the .NET Framework, but also contains other components. Some of the components of the Mono platform were developed by the Mono team, and some others we have incorporated from other open source efforts, the most important ones: Q: What is the difference between Mono and the .NET Initiative? A: The ".NET Initiative" is a somewhat nebulous company-wide effort by Microsoft, one part of which is a cross-platform development framework. Mono is an implementation of the development framework, but not an implementation of anything else related to the .NET Initiative, such as Passport or software-as-a-service. Q: What technologies are included in Mono? A: Mono contains a number of components useful for building new software: Windows has compilers that target the virtual machine from a number of languages: Managed C++, Java Script, Eiffel, Component Pascal, APL, Cobol, Perl, Python, Scheme, Smalltalk, Standard ML, Haskell, Mercury and Oberon. The CLR and the Common Type System (CTS) enables applications and libraries to be written in a collection of different languages that target the byte code This means for example that if you define a class to do algebraic manipulation in C#, that class can be reused from any other language that supports the CLI. You could create a class in C#, subclass it in C++ and instantiate it in an Eiffel program. A single object system, threading system, class libraries, and garbage collection system can be shared across all these languages. Q: Where can I find the specification for these technologies? A: You can find the information here: C# http://www.ecma.ch/ecma1/STAND/ecma-334.htm CLI http://www.ecma.ch/ecma1/STAND/ecma-335.htm Q: Will you implement the .NET Framework SDK class libraries? A: Yes, we will be implementing the APIs of the .NET Framework SDK class libraries. Q: Will you offer an ECMA-compliant set of class libraries? A: Eventually we will. Our current focus is on inter-operating with the Microsoft SDK, but we will also offer an ECMA compliant subset of the libraries. Q: What does the name "Mono" mean? A: Mono is the word for `monkey' in Spanish. We like monkeys. Q: Does Mono work today? A: The execution engine works on various platforms, we support Just-in-Time and Ahead-of-Time compilations on Intel x86 machines (and soon PowerPC). The class libraries are mature enough to run various real applications: our C# compiler, ASP.NET, and Gtk#-based applications. Q: When will you ship Mono? A: Please see the Mono Roadmap for more details on the release plans. Q: How can I contribute? A: Check the contributing section. Q: Aren't you just copying someone else's work? A: We are interested in providing the best tools for programmers to develop applications for Free Operating Systems. We also want to help provide the interoperability that will allow those systems to fit in with other standards. For more background, read the Mono Project white paper. the project. Q: Miguel said once that Mono was being implemented in COBOL. Is that true?. A: No. It was a joke. ** The Novell Role in the Mono Project Q: Why is Novell working on .NET? A: Novell is interested in providing the best tools for programmers to develop applications for Free Operating Systems. For more information, read the project rationale page. Q: Will Novell be able to take on a project of this size? A: Of course not. Novell is a supporter of the Mono project, but the only way to implement something of this size is for the entire free software community to get involved. Visit the contributing page if you'd like to help out. Q: What pieces is Novell working on? A: We will devote most of our resources to work on the pieces which are on the critical path to release a development and execution environment. Once the project is at a stage where it is useful in the real world, it will achieve a critical mass of developers to improve it further. Q: Will Novell offer Mono commercially? A: When Mono is ready to be shipped Ximian will offer a commercial support and services for Mono. Mono components are also available to be licensed commercially. For licensing details, contact mono-licensing@ximian.com Q: Does Novell provide consulting services around Mono? A: Yes, Novell does provide consulting services around Mono to make it suitable to your needs. Porting the runtime engine, customizing it, working on specific classes or tuning the code for your particular needs. Please contact mono-licensing@ximian.com for consulting services information. Q: Will you wait until Mono is finished? A: Mono will ship on various stages as they mature. Some people require only a subset of the technologies, those will ship first, see the Mono Roadmap for details ** Mono and GNOME Q: How is Mono related to GNOME? A: In a number of ways. This project was born out of the need of providing improved tools for the GNOME community, and will use existing components that have been developed for GNOME when they are available. For example, we plan to use Gtk+ and Libart to implement Winforms and the Drawing2D API and are considering GObject support. Mono team members work actively on the Gtk# project: a binding of the GNOME class libraries for .NET and Mono. Q: Has the GNOME Foundation or the GNOME team adopted Mono? A: Mono is too new to be adopted by those groups. We hope that the tools that we will provide will be adopted by free software programmers including the GNOME Foundation members and the GNOME project generally. Q: Should GNOME programmers switch over to Mono now? A: It is still far to early for discussions of "switching over." No pieces of Mono will be ready within the next six months, and a complete implementation is roughly one year away. We encourage GNOME developers to continue using the existing tools, libraries and components. Improvements made to GNOME will have an impact on Mono, as they would be the "back-end" for various classes. Q: Will Mono include compatibility with Bonobo components? What is the relationship between Mono and Bonobo? A: Yes, we will provide a set of classes for implementing and using Bonobo components from within Mono. Mono should allow you to write Bonobo components more easily, just like .NET on Windows allows you to export .NET components to COM. Q: Does Mono depend on GNOME? A: No, Mono does not depend on GNOME. We use a few packages produced by the GNOME team like the `glib' library, we also use other third-party open source libraries like Cairo and ICU. Q: But will I be able to build GNOME applications? A: Yes, we will enable people to write GNOME applications using Mono. Q: Do you have C# bindings for GNOME?. A: Yes, the Gtk# project provides bindings for Gtk+, Gdk, Atk, libgnome, libgnomecanvas, and libgnomeui. Other libraries under the GNOME framework will be added on an as-needed (and as-requested) basis. ** GUI applications Q: Will Mono enable GUI applications to be authored? A: Yes, you will be able to build GUI applications. Indeed, that is our main focus. Today you can use Gtk# or #WT to develop GUI applications, and support for Windows.Forms is underway. Q: What is the difference between Gtk# and System.Windows.Forms? A: Gtk# is a set of bindings for the Gtk+ toolkit for C# (and other CIL-enabled languages), it integrates natively with the Gnome desktop. System.Windows.Forms is an API defined by Microsoft to build GUI applications. Q: What are you using to implement Windows.Forms? A: Windows.Forms is currently being implemented on top of a modified version of Wine that can be used as a library: WineLib. Essentially Wine is used as a library that happens to implement the "Win32" toolkit and our Windows.Forms becomes a managed layer on top of this toolkit. There are several advantages in this approach: we get Wndproc message compatibility for free (Wndproc is an overridable method in the Control class and it is used to perform advanced tricks with the GUI toolkit) as well as allowing third-party controls that are used to P/Invoke into Win32 in the Windows world to work out of the box on Linux/MacOS. Q: Why not implement System.Windows.Forms on top of Gtk# or Qt#? A: Compatibility. Although it is possible to run simple Windows.Forms applications with the Gtk#-based backend of Windows.Forms, it is very unlikely that the implementation will ever implement everything needed for full compatibility with Windows.Forms. The reason is that Windows.Forms is not a complete toolkit, and to work around this problem some of the underlying Win32 foundation is exposed to the programmer in the form of exposing the Windows message handler (WndProc). Any control can override this method. Also developers often P/Invoke into Win32 to get to functionality that was not wrapped. To achieve full compatibility, we would have to emulate this, and it would take too long. For more details see the winforms page Q: Wine applications do not look like native applications, what are you going to do about this? A: We have already a few patches into our version of Windows.Forms that makes Wine use the colors and font settings from your desktop, improving the integration a lot. In the future, we will continue to improve this interoperability scenario. Q: Will I be able to run my smart clients on systems powered by Mono? A: As long as your applications are 100% .NET and do not make use of P/Invoke to call Win32 functions, your smart client applications will run on Mono platforms. Q: Where can I learn more about Gtk#? A: The following link sends you to the page of the project. Q: What can I do with Gtk#?. A: Gtk# is becoming very usable and you can create applications and applets like those you see in a GNOME desktop environment. It's easy to install so it's worth a try. Q: How can I compile my HelloWorld.cs which uses Gtk#?. A: Try: mcs -r:gtk-sharp HelloWorld.cs Q: Is there any way how to connect DataAdapter to some GTK# controls? A: There is a sample file called `DbClient' in gtk-sharp/samples that you might to look at. It is a sample program in Gtk# that adds/updates/deletes information on a Postgress database. When we have the new table/tree widgets, I am sure someone would write an adapter for System.Data (in Gtk2 the tree/list widgets are written using a view/model, so you only need to write a model that maps to the database). You can have a look at gtk-sharp/sample/DbClient, where there is a GTK# application that uses System.Data. It does not use DataAdapter, but DataReader though. Q: Do you have an estimate for when Windows.Forms will be released? A: The plan currently is aimed at Q4/2004. Q: Do you have a comparission chart about the various toolkit offerings? A: A document explaining this is available at: http://primates.ximian.com/~miguel/toolkits.html. ** Mono and Microsoft Q: Is Microsoft helping Ximian with this project? A: There is no high level communication between Ximian and Microsoft at this point, but engineers who work on .NET or the ECMA groups have been very friendly, and very nice to answer our questions, or clarify part of the specification for us. Microsoft is interested in other implementations of .NET and are willing to help make the ECMA spec more accurate for this purpose. Ximian was also invited to participate in the ECMA committee meetings for C# and the CLI. Q: Are Microsoft or Corel paying Ximian to do this? A: No. Q: Do you fear that Microsoft will change the spec and render Mono useless? A: No. Microsoft proved with the CLI and the C# language that it was possible to create a powerful foundation for many languages to inter-operate. We will always have that. Even if changes happened in the platform which were undocumented, the existing platform would a value on its own. Q: Are you writing Mono from the ECMA specs? A: Yes, we are writing them from the ECMA specs and the published materials in print about .NET. Q: If my applications use Mono, will I have to pay a service fee? A: No. Mono is not related to Microsoft's initiative of software-as-a-service. Q: Is the Mono Project is related to the Microsoft Hailstorm effort? Is Ximian endorsing Hailstorm? A: No. The Mono Project is focused on providing a compatible set of tools for the Microsoft .NET development platform. It does not address, require, or otherwise endorse the MS Passport-based Hailstorm single sign-on system that is part of Windows XP and other services. Q: Will Mono or .NET applications depend on Microsoft Passport? A: No. MS Passport is unrelated to running .NET compatible applications produced with the Mono tools. The only thing you will need is a just-in-time compiler (JIT). Q: If Microsoft will release a port of their .NET platform under the `Shared Source' license, why should I bother with anything else? A: The Shared Source implementation will be expensive and its uses will be tightly restricted, especially for commercial use. We are working towards an implementation that will grant a number of important rights to recipients: use for any purpose, redistribution, modification, and redistribution of modifications. This is what we call Free Software Q: Is Mono a free implementation of Passport? A: No. Mono is just a runtime, a compiler and a set of class libraries. Q: Will the System.Web.Security.PassportIdentity class mean that my software will depend on Passport? A: No. Applications may use that API to contact a Passport site, but are not required to do so. As long as your application does not use Passport, you will not need Passport. Q: Will Mono running on Linux make Passport available for Linux? A: No. However, the Passport toolkit for Linux-based web servers is available from Microsoft. Q: Will Mono allow me to run Microsoft Office on Linux? A: No, it will not. Microsoft Office is a Windows application. To learn more about running Windows applications on Intel Unix systems refer to the Wine Project. Q: Can mono run the WebMatrix? A: No. That requires System.Windows.Forms support which is not currently implemented. Q: Does mono have something like Passport? Will mono have a server side Passport/Similar framework for XSP as well as client classes? A: Not yet, but the client side API for authentication is not the problem. We will likely have a lot of other authentication APIs, like the Liberty Alliance APIs. The problem is people on the web provider end that might use this for authentication. ** Mono Platforms Q: What operating systems does Mono run on? A: Mono is known to run on Linux, Unix and Windows systems. Q: Can I run Mono applications without using `mono program.exe'? A: Yes, this is possible on Linux systems, to do this, use something like: 
if [ ! -e /proc/sys/fs/binfmt_misc/register ]; then
	/sbin/modprobe binfmt_misc
	mount -t binfmt_misc none /proc/sys/fs/binfmt_misc
fi

if [ -e /proc/sys/fs/binfmt_misc/register ]; then
	echo ':CLR:M::MZ::/usr/bin/mono:' > /proc/sys/fs/binfmt_misc/register
else
	echo "No binfmt_misc support"
	exit 1
fi
Q: What architectures does Mono support? A: Mono today ships with a Just-in-Time compiler for x86, PowerPC and SPARC-based systems. It is tested regularly on Linux, FreeBSD and Windows (with the XP/NT core). There is also an interpreter, which is slower that runs on the s390, SPARC, HPPA, StrongARM and PowerPC architectures. Q: Can Mono run on Windows 9x, or ME editions? A: Mono requires Unicode versions of Win32 APIs to run, and only a handful of *W functions is supported under Win9x. There is Microsoft Layer for Unicode that provides implementation of these APIs on 9x systems. Unfortunately it uses linker trick for delayed load that is not supported by ld, so some sort of adapter is necessary. You will need MSLU and one of the following libs to link Mono to unicows.dll http://mono.eurosoft.od.ua/files/unimono.zip or alternatively search the net for "libunicows". No changes to Mono source code required, the only thing is to make sure that linker will resolve imports to adapter library instead of Win32 libs. This is achieved by inserting -lunimono before -lkerner32/user32 in the linker's specs file. Q: Why support Windows, when you can run the real thing? A: There are various reasons: ** Compatibility Q: Can Mono run applications developed with the Microsoft.NET framework? A: Yes, Mono can run applications developed with the Microsoft .NET Framework on Unix. There are a few caveats to keep in mind: Mono has not been completed yet, so a few API calls might be missing; And in some cases the Mono behavior *might* be incorrect. Q: Will missing API entry points be implemented? A: Yes, the goal of Mono is to implement precisely the .NET Framework API (as well as compile-time selectable subsets, for those interested in a lighter version of Mono). Q: If the behavior of an API call is different, will you fix it? A: Yes, we will. But we will need your assistance for this. If you find a bug in the Mono implementation, please fill a bug report in http://bugzilla.ximian.com. Do not assume we know about the problem, we might not, and using the bug tracking system helps us organize the development process. Q: Can I develop my applications on Windows, and deploy on a supported Mono platform (like Linux)? A: Yes, you can. As of today, Mono is not 100% finished, so it is sometimes useful to compile the code with Mono, to find out if your application depends on unimplemented functionality. Q: Will applications run out the box with Mono? A: Sometimes they will. But sometimes a .NET application might invoke Win32 API calls, or assume certain patterns that are not correct for cross-platform applications. Q: What is a 100% .NET application? A: A `100% .NET application' is one that only uses the APIs defined under the System namespace and does not use P/Invoke. These applications would in theory run unmodified on Windows, Linux, HP-UX, Solaris, MacOS X and others. Note that this requirement also holds for all assemblies used by the application. If one of them is Windows-specific, then the entire program is not a 100% .NET application. Furthermore, a 100% .NET application must not contain non-standard data streams in the assembly. For example, Visual Studio .NET will insert a #- stream into assemblies built under the "Debug" target. This stream contains debugging information for use by Visual Studio .NET; however, this stream can not be interpreted by Mono (unless you're willing to donate support). Thus, it is recommended that all Visual Studio .NET-compiled code be compiled under the Release target before it is executed under Mono. Q: Can I execute my Visual Studio .NET program (Visual Basic .NET, Visual C#, Managed Extensions for C++, etc.) under Mono? A: Yes, with some reservations. The .NET program must either be a 100% .NET application, or (somehow) have all dependent assemblies available on all desired platforms. (How to do so is outside the bounds of this FAQ.) Mono must also have an implementation for the .NET assemblies used. For example the System.EnterpriseServices namespace is part of .NET, but it has not been implemented in Mono. Thus, any applications using this namespace will not run under Mono. With regards to languages, C# applications tend to be most portable. Visual Basic .NET applications are portable, but Mono's Microsoft.VisualBasic.dll implementation is incomplete. It is recommended to either avoid using this assembly in your own code, only use the portions that Mono has implemented, or to help implement the missing features. Additionally, you can set 'Option Strict On', which eliminates the implicit calls to the unimplemented Microsoft.VisualBasic.CompilerServices.ObjectType class. (Thanks to Jörg Rosenkranz.) Managed Extensions for C++ is least likely to operate under Mono. Mono does not support mixed mode assemblies (that is, assemblies containing both managed and unmanaged code, which Managed C++ can produce). You need a fully-managed assembly to run under Mono, and getting the Visual C++ .NET compiler to generate such an executable can be difficult. You need to use only the .NET-framework assemblies, not the C libraries (you can't use printf(3) for example.), and you need to use the linker options /nodefaultlib /entry:main mscoree.lib in addition to the /clr compiler flag. You can still use certain compiler intrinsic functions (such as memcpy(3)) and the STL. You should also see Converting Managed Extensions for C++ Projects from Mixed Mode to Pure Intermediate Language at MSDN. Finally, you can use PEVERIFY.EXE from the .NET SDK to determine if the assembly is fully managed. Thanks to Serge Chaban for the linker flags to use. ** Mono and Portable.NET Q: What are the differences between Mono and Portable.NET? A: Most of Mono is being written using C#, with only a few parts written in C (The JIT engine, the runtime, the interfaces to the garbage collection system). It is easier to describe what is unique about Mono: In general, Mono is more mature and complete since it has been used to develop itself, which is a big motivator for stability and correctness, while Portable.NET remains pretty much an untested platform. Q: I hear Mono keeps changing the P/Invoke API, why? A: We are just fixing our implementation to be compatible with the Microsoft implementation. In other words, the Mono P/Invoke API is more complete when compared to the Portable.NET version, hence various pieces of software that depend on this extended functionality fail to work properly with Portable.NET. ** Web Services Q: How is Mono related to Web Services? A: Mono is only related to Web Services in that it will implement the same set of classes that have been authored in the .NET Framework to simplify and streamline the process of building Web Services. But most importantly, Mono is an Open Source implementation of the .NET Framework. Q: Can I author Web Services with Mono? A: You will be able to write Web Services on .NET that run on Mono and vice-versa. Q: If Mono implements the SDK classes, will I be able to write and execute .NET Web Services with it? A: Yes. When the project is finished, you will be able to use the same technologies that are available through the .NET Framework SDK on Windows to write Web Services. Q: What about Soup? Can I use Soup without Mono? A: Soup is a library for GNOME applications to create SOAP servers and SOAP clients, and can be used without Mono. You can browse the source code for soup using GNOME's Bonsai. Q: Can I use CORBA? A: Yes. The CLI contains enough information about a class that exposing it to other RPC systems (like CORBA) is really simple, and does not even require support from an object. Remoting.CORBA is a CORBA implementation that is gaining momentum. Building an implementation of the Bonobo interfaces once this is ready should be relatively simple. Q: Can I serialize my objects to other things other than XML? A: Yes, although the serializing tools have not yet been planned, and you would probably have to implement them yourself. Q: Will Mono use ORBit? A: There are a few advantages in using ORBit, like reusing existing code and leveraging all the work done on it. Michael Meeks has posted a few reasons, as well as some ideas that could be used to reuse ORBit. Most users are likely to choose a native .NET solution, like Remoting.CORBA ** MonoDoc Q: What is MonoDoc? A: MonoDoc is a graphical documentation browser for the Mono class libraries. Currently, monodoc consists of a Gtk# application and is in heavy development. ** Development Tools and Issues Q: I am having trouble compiling a new version of Mono from CVS, it complains about my runtime being out of sync. A: To upgrade your class libraries and compiler, see the INSTALL.txt in the MCS directory. The single biggest source of confusion seems to be the "Your runtime is out of sync" messages. Realize that this is *normal* while BUILDING. Think about it: you're building a new class library with the old runtime. If the new class library references a function that the old runtime knows nothing about, the runtime system issues this warning. Basically what needs to happen is for a new mono runtime to be compiled, then the corlib class library be compiled, and once this is done, install the new runtime, followed by corlib. Once this is done, you can continue building your entire environment. For instance you just need to: 1.- Upgrade your Mono runtime (you might better do it with the mono-build.sh script available in the download page. 2.- Get the latest mono-lite tarball from the daily snapshots page, unzip and untar and copy all the dll files to your install path lib directory (typically pointed by the $MONO_PATH variable). Copy all the exe files to the install path bin directory. 3.- Then checkout or update your mcs CVS copy. Then follow the steps described in mcs/INSTALL.txt. Q: Will it be possible to use the CLI features without using byte codes or the JIT? A: Yes. The CLI engine will be made available as a shared library. The garbage collection engine, the threading abstraction, the object system, the dynamic type code system and the JIT are available for C developers to integrate with their applications if they wish to do so. Q: Will you have new development tools? A: With any luck, Free Software enthusiasts will contribute tools to improve the developer environment. These tools could be developed initially using the Microsoft implementation of the CLI and then executed later with Mono. We are recommending people to use and contribute to existing projects like SharpDevelop, Anjuta and Eclipse. Q: What kind of rules make the Common Intermediate Language useful for JITers? A: The main rule is that the stack in the CLI is not a general purpose stack. You are not allowed to use it for other purposes than computing values and passing arguments to functions or return values. At any given call or return instruction, the types on the stack have to be the same independently of the flow of execution of your code. Q: Is it true that the CIL is ideal for JITing and not efficient for interpreters? A: The CIL is better suited to be JITed than JVM byte codes, but you can interpret them as trivially as you can interpret JVM byte codes. Q: Isn't it a little bit confusing to have the name of "XSP" (the same as in the Apache Project) for the ASP.NET support in Mono?. A: In Mono, xsp is just the name of the C# code generator for ASP.NET pages. In the Apache Project, it is a term for the "eXtensible Server Pages" technology so as they are very different things, they don't conflict. Q: Is there any plan to develop an aspx server for Mono?. A: The XSP reference server is available and you can also use mod_mono with Apache. Q: Is there any way I can develop the class libraries using Linux yet? A: Yes. Mono has been self hosting since May 2002. Q: Is there any way I can install a known working copy of mono in /usr, and an experimental copy somewhere else, and have both copies use their own libraries? (I'm still not very good at library paths in Linux) A: Yes. Just use two installation prefixes. Q: How should I write tests or a tests suite? A: If you do a test suite for C#, you might want to keep it independent of the Mono C# compiler, so that other compiler implementations can later use it. Q: Would it be too terrible to have another corlib signed as mscorlib? A: We rename corlib to mscorlib also when saving the PE files, in fact, the runtime can execute program created by mono just fine. Q: Is it possible to build a C# file to some sort of intermediate format which can linked into a final module, like the traditional .c -> .o -> .so path? A: You can use: mcs /target:library file1.cs, mcs /target:library file2.cs, mcs /target:exe file1.dll file2.dll /out:mybin.exe Q: Is there any plans for implementing remoting in the near future? A: The remoting infrastructure is in place. We have implementations of the TcpChannel, HttpChannel and the Soap and Binary Formatters. They are compatible with .NET. However, some classes from the library may have a different binary representation, because they may have a different internal data structure, so for example you won't be able to exchange a Hastable object between Mono and MS.NET. It should not be a problem if you are using primitive types, arrays or your own classes. In any case, could you post a test case? Q: My C code uses the __stdcall which is not availble on Linux, how can I make the code portable Windows/Unix across platforms? A: Replace the __stdcall attribute with the STDCALL macro, and include this in your C code for newer gcc versions: #ifndef STDCALL #define STDCALL __attribute__((stdcall)) #endif Q: I want to be able to execute Mono binaries, without having to use the "mono" command. How can I do this? A: From Carlos Perelló: I think that the best solution is the binfmt feature with the wrapper that exists with Debian packages at: http://www.debianplanet.org/mono/dists/unstable/main/source/admin/ If you want use it with Big endian machines, you should apply a patch (http://carlos.pemas.net/debian/mono/binfmt-detector-cli.c.diff) It works really good and lets you use wine also, it reads the .exe file headers and check if it's a .net executable. This way you just execute: ./my-cool-mono-application.exe and it works without the need of any wrapper. Q: I see funny characters when I run programs, what is the problem? A: (From Peter Williams and Gonzalo Paniagua): This is Red Hat 9 (probably) using UTF8 on its console; the bytes are the UTF8 endianness markers. You can do: LC_ALL=C mono myexe.exe And they wont show up. Alternatively, you can do: $ echo -e "\033%G" to enable UTF-8 on the console. ** Mono and ASP.NET Q: Does Mono support ASP.NET? A: Yes. Mono supports ASP.NET, we have shown an unmodified IBuySpy installation running on Mono as well as various other programs. You can try it yourself downloading the XSP server. Q: Do I need install cygwin to work on ASP.NET in mono or Linux is enough since it is self host right now. A: Linux is enough. Q: How can I run ASP.NET-based applications with Mono? A: You need the Mono runtime and a hosting web server. Currently we distribute a small web server called `xsp' which is used to debug applications, or you can choose to use Daniel's Apache 2 module. Q: Any plan to make ASP.NET in mono works with Apache in Linux?. A: Daniel has authored an Apache2 Module for Mono that hosts the ASP.NET runtime and is available here: http://apacheworld.org/modmono/ Q: Will you support Apache 1? A: Modules developed for Apache 2 are not compatible with Apache 1.3 Daniel plans to support Apache 1.3 in the future but the current focus is on Apache 2, because of the better support for threading and Windows. Q: Can I run Apache 1 and Apache 2 on the same machine? You can always keep a copy of Apache 2 running in parallel with your Apache 1.3 (either different port or using a reverse proxy). You can also bind the two servers to different IP addresses on the same physical machine. ** Mono and ADO.NET Q: What is the status of ADO.NET support?. Could I start migrating applications from MS.NET to Mono?. A: You could start right now using the ADO.NET support in mono, of course, if you want to help filling the missing gaps while you develop your app :-) Well, what I mean is that we're not that far to having full ADO.NET support in Mono, and we've got a lot of working things, so if we could get more help, we'd finish it really soon :-) Q: In developing the data architecture for the application are there and objects I should stay away from in order to insure the smoothest possible transition (minimum code rewrite) to Mono's ADO.NET implementation? (For example, strongly typed datasets versus untyped datasets, etc...) A: We are implementing all the classes in Microsoft .NET's System.Data, so you can be sure that things will work the same in Mono as with the Microsoft implementation. Q: Does Mono can to connect to Sybase by using Mono.Data.*? A: Yes. use Mono.Data.SybaseClient. First of all you have to create a SybaseConnection, and then, from it, use it as any other IDbConnection-based class. ** Mono and Java Q: Why don't you use Java? After all, there are many languages that target the Java VM. A: You can get very good tools for doing Java development on free systems right now. Red Hat has contributed a GCC front-end for Java that can take Java sources or Java byte codes and generate native executables; Transvirtual implemented Kaffe a JIT engine for Java; Intel also has a Java VM called ORP. The JVM is not designed to be a general purpose virtual machine. The Common Intermediate Language (CIL), on the other hand, is designed to be a target for a wide variety of programming languages, and has a set of rules designed to be optimal for JITers. Q: Could Java target the CLI? A: Yes, Java could target the CLI, Microsoft's J# compiler does that. The IKVM project builds a Java runtime that works on top of .NET and on top of Mono. IKVM is essentially a JIT compiler that translates from JVM bytecodes into CIL instructions, and then lets the native JIT engine take over. Q: Is it possible to write a JVM byte code to CIL converter? A: Yes, this is what IKVM does. Q: Could mono become a hybrid CIL/java platform? A: This can be obtained easily with IKVM. Q: Do you plan to implement a Javascript compiler? A: Yes. The beginnings of the JScript compiler can be found on CVS. Cesar coordinates this effort. Q: Can Mono or .NET share system classes (loaded from mscore.dll and other libs) or will it behave like Sun's Java VM? A: What you can do with mono is to load different applications in their own application domain: this is a feature of the CLR that allows sandboxing applications inside a single process space. This is usualy exploited to compartmentalize different parts of the same app, but it can also be effectively used to reduce the startup and memory overhead. Using different appdomains the runtime representation of types and methods is shared across applications. ** Extending Mono Q: Would you allow other classes other than those in the specification? A: Yes. The Microsoft class collection is very big, but it is by no means complete. It would be nice to have a port of `Camel' (the Mail API used by Evolution inspired by Java Mail) for Mono applications. You might also want to look into implementing CORBA for Mono. Not only because it would be useful, but because it sounds like a fun thing to do, given the fact that the CLI is such a type rich system. For more information on extending Mono, see our ideas page. Q: Do you plan to Embrace and Extend .NET? A: Embracing a good technology is good. Extending technologies in incompatible ways is bad for the users, so we do not plan on making incompatible changes to the technologies. If you have innovative ideas, and want to create new classes, we encourage you to make those classes operate correctly well in both Mono and .NET. Today Mono ships with a number of extra libraries that were developed either by members of the Mono community, or other groups. In some cases, we have found the bits from Microsoft to be incomplete, but we avoid breaking the API, instead we expose the missing functionality in new assemblies (See Mono.Security and System.Security). Q: Is there any way I can develop the class libraries using Linux yet? A: Yes. Mono has been selfhosting since March 2002. Q: Is there any way I can install a known working copy of mono in /usr, and an experimental copy somewhere else, and have both copies use their own libraries? (I'm still not very good at library paths in Linux) A: Yes. Just use two installation prefixes. ** Portability Q: Will Mono only work on Linux? A: Currently, we are doing our work on Linux-based systems and Windows. We do not expect many Linux-isms in the code, so it should be easy to port Mono to other UNIX variants. Q: What about Mono on non Linux-based systems? A: Our main intention at Ximian is to be able to develop GNOME applications with Mono, but if you are interested in providing a port of the Winforms classes to other platforms (frame buffer or MacOS X for example), we would gladly integrate them, as long they are under an open source license. Q: What operating systems/CPUs do you support A: Mono currently runs on Linux, Windows, Solaris, FreeBSD, HP-UX and MacOS X. There is a JIT engine available for x86 processors that can generate code and optimizations tailored for a particular CPU. Interpreters exist for the SPARC v8, SPARC v9, Itanium, HP-PA, PowerPC and StrongARM CPUs. Q: Does Mono run on Windows? A: Yes. You can get pre-compiled binaries from http://www.go-mono.com/download.html Q: Does Mono run on Linux? A: Yes. You can get pre-compiled binaries from http://www.go-mono.com/download.html Q: Will I require Cygwin to run mono? A: No. Cygwin is only required to build Mono. Q: Will Mono depend on GNOME? A: It will depend only if you are using a particular assembly (for example, for doing GUI applications). If you are just interested in Mono for implementing a `Hello World Enterprise P2P Web Service', you will not need any GNOME components. Q: Do you plan to port Rhino to C#?. A: Eto Demerzal has started a Rhino port to C#. Q: Has anyone succeeded in building a Mac version of the C# environment. If so can you explain how? A: Yes, Mono works on Linux/PPC and MacOS X (10.2 and 10.3) ** Reusing Existing Code Q: What projects will you reuse or build upon? A: We want to get Mono in the hands of programmers soon. We are interested in reusing existing open source software. Q: Will I be able to use Microsoft SQL Server 2000 or will I need to switch to a specific Open Source Database. Will I need to recode? A: There is no need to rewrite your code as long as you keep using Microsoft SQL Server. If you want to use an open source database, you might need to make changes to your code. Q: What do I need to watch out for when programming in VB.NET so that I'm sure to be able to run those apps on Linux? A: Not making any P/Invoke or DLL calls should and not using anything in the Microsoft.* namespaces should suffice. Also do not use any Methods/Classes marked as "This type/method supports the .NET Framework infrastructure and is not intended to be used directly from your code." even if you know what these classes/methods do. Q: Will built-in reporting be supported for crystal reports? This is a heavily used part of our system. A: . Crystal Reports are propriety. Someone may try to emulate the behavior, but no-one has yet volunteered. Q: Who about writing to the registry? As I understand it, Linux does not have a counterpart to the registry. Should I avoid relying on that feature? A: Try to avoid it. Although there would be a emulation for registry in Mono too. GNOME does have a registry like mechanism for configuration. But Even if gnome has a configuration system similar to the registry, the keys will not be equal, so you will probably end up having to do some runtime detection, and depending on this load an assembly that has your platform-specific hacks. Q: System.Data.SqlClient with FreeTDS, will you port parts of these to C# and use them? A: This has been done. ** Mono and GCC Q: Are you working on a GCC front-end to C#? A: We are not working on a GCC front-end for C# Q: Will you support C/C++ on the Mono VM? A:The open64 compiler effort from SGI helps a lot in this direction. The Open64 compiler is a modified version of GCC that generates a new intermediate language instead of RTL. This could be the foundation to generate CIL code, and to implement the upcoming Managed extensions to C++ from ECMA. Open64 (and other derivative forks of GCC) split the gcc front-ends from the backends by using the WHIRL intermediate representation. Kris has begun the implementation of a translator from WHIRL to CIL. So it will be possible to use the GCC compilers to target the CIL. Q: What about Managed C++? A: Once a full translator for WHIRL exists, we are interested in looking at expanding the GCC frontends to include extensions for Managed C++. Q: What about making a front-end to GCC that takes CIL images and generates native code? A: There is no active work on this area, but Mono already provides pre-compilation services (Ahead-of-Time compilation). ** Performance Q: How fast will Mono be? A: We can not predict the future, but a conservative estimate is that it would be at least `as fast as other JIT engines'. Mono's JIT engine has been recently re-architected, and it provides many new features, and layers suitable for optimization. It is relatively easy to add new optimizations to Mono. The CIL has some advantages over the Java byte code: The existance of structs in addition to classes helps a lot the performance and minimizes the memory footprint of applications. Generics in the CLI world are first-class citizens, they are not just a strong-typing addition to the language. The generic specifications are embedded into the instruction stream, the JIT uses this information to JIT a unique instances of a method that is optimized for the type arguments. The CIL is really an intermediate representation and there are a number of restrictions on how you can emit CIL code that simplify creating better JIT engines. For example, on the CIL, the stack is not really an abstraction available for the code generator to use at will. Rather, it is a way of creating a postfix representation of the parsed tree. At any given call point or return point, the contents of the stack are expected to contain the same object types independently of how the instruction was reached. ** Licensing Q: Will I be able to write proprietary applications that run with Mono? A: Yes. The licensing scheme is planned to allow proprietary developers to write applications with Mono. Q: What license or licenses are you using for the Mono Project? A: The C# Compiler is released under the terms of the GNU GPL. The runtime libraries are under the GNU Library GPL. And the class libraries are released under the terms of the MIT X11 license. The Mono runtime and the Mono C# Compiler are also available under a proprietary license for those who can not use the LGPL and the GPL in their code. For licensing details, contact mono-licensing@ximian.com Q: I would like to contribute code to Mono under a particular license. What licenses will you accept? A: We will have to evaluate the licenses for compatibility first, but as a general rule, we will accept the code under the same terms of the "container" module. ** Patents Q: Could patents be used to completely disable Mono (either submarine patents filed now, or changes made by Microsoft specifically to create patent problems)? A: First some background information. The .NET Framework is divided in two parts: the ECMA/ISO covered technologies and the other technologies developed on top of it like ADO.NET, ASP.NET and Windows.Forms. Mono implements the ECMA/ISO covered parts, as well as being a project that aims to implement the higher level blocks like ASP.NET, ADO.NET and Windows.Forms. The Mono project has gone beyond both of those components and has developed and integrated third party class libraries, the most important being: Debugging APIs, integration with the Gnome platform (Accessibility, Pango rendering, Gdk/Gtk, Glade, GnomeUI), Mozilla, OpenGL, extensive database support (Microsoft only supports a couple of providers out of the box, while Mono has support for 11 different providers), our POSIX integration libraries and finally the embedded API (used to add scripting to applications and host the CLI, or for example as an embedded runtime in Apache). The core of the .NET Framework, and what has been patented by Microsoft falls under the ECMA/ISO submission. Jim Miller at Microsoft has made a statement on the patents covering ISO/ECMA, (he is one of the inventors listed in the patent): here. Basically a grant is given to anyone who want to implement those components for free and for any purpose. The controversial elements are the ASP.NET, ADO.NET and Windows.Forms subsets. Those are convenient for people who need full compatibility with the Windows platform, but are not required for the open source Mono platform, nor integration with today's Mono's rich support of Linux. The Mono strategy for dealing with these technologies is as follows: (1) work around the patent by using a different implementation technique that retains the API, but changes the mechanism; if that is not possible, we would (2) remove the pieces of code that were covered by those patents, and also (3) find prior art that would render the patent useless. Not providing a patented capability would weaken the interoperability, but it would still provide the free software / open source software community with good development tools, which is the primary reason for developing Mono. The patents do not apply in countries where software patents are not allowed. For Linux server and desktop development, we only need the ECMA components, and things that we have developed (like Gtk#) or Apache integration. Q: Is Mono only an implementation of the .NET Framework? A: Mono implements both the .NET Framework, as well as plenty of class libraries that are either Unix specific, Gnome specific, or that are not part of the .NET Framework but people find useful. The following map shows the relationship between the components: ** Obfuscation Q: Are there any obfuscation programs for Mono/Linux? A: We are not aware of these, but some from Windows might work. Q: What could I do to avoid people decompiling my program? A: You can use the bundle functionality in Mono. This would bundle your binary inside a Mono runtime instance, so you distribute a single executable that contains the code inside. Notice that for this to work and be practical, you need to get a commercial license to the Mono runtime. The reason is that the bundle functionality is covered by the LGPL: so you would have to distribute your assemblies separatedly to allow developers to relink mono which would defeat the purpose of bundling for obscuring your code. It is not impossible to break, just like any other obfuscators. That being said, value these days does not lie in particular tiny routines, but lies in the large body of work, and if someone steals your code, you are likely going to find out anyways. Q: Any other option? A: You could precompile with --aot your code, then disassemble the original .exe, and remove all the code, then re-assemble and ship both the vessel .exe and the precompiled code. This is not a supported configuration of Mono, and you would be on your own in terms of dealing with bugs and problems here. Get the companies that build the obfuscation packages to read the ECMA spec and fix the bugs in their products that generate non-standard binaries (or, if they expose a bug in mono, please file a report in our bugzilla). Pay Ximian/Novell to spend the development time needed to get mono to support the broken binaries that some of the obfuscation packages generate (or contribute that support). ** Miscellaneous Questions Q: You say that the CLI allows multiple languages to execute on the same environment. Isn't this the purpose of CORBA? A: The key difference between CORBA (and COM) and the CLI is that the CLI allows "data-level interoperability" because every language/component uses the same data layout and memory management. This means you can operate directly upon the data types that someone else provides, without having to go via their interfaces. It also means you don't have to "marshal" (convert) parameters (data layouts are the same, so you can just pass components directly) and you don't have to worry about memory management, because all languages/components share the same garbage collector and address space. This means much less copying and no need for reference counting. Q: Will you support COM? A: The runtime will support XPCOM on Unix systems and COM on Windows. Most of the code for dynamic trampolines exists already. Q: Will Ximian offer certifications on Mono or related technologies?. A: It's possible. But there is no plan about this. So the short answer is no. Q: How can I report a bug? A: The best thing is to track down the bug and provide a simple test to reproduce the bug. You can then add the bug to our bug tracking system. You can use our Bug Form to enter bugs for the appropriate component. Please provide information about what version of mono you're using and any relevant details to be able to reproduce the bug. Note that bugs reported on the mailing-list may be easily forgotten, so it's better to file them in the bug tracking system. Q: Does mcs support the same command line options as the MS C# compiler? A: The Mono C# compiler now supports the same command line arguments as the Microsoft C# compiler does. Q: How about getting searchable archives on lists.ximian.com? A: You can perform a search on the mono-related mailing lists here. Q: When using mono from cvs or from a snapshot, I get an error messaage saying that Mono and the runtime are out of sync. How do I fix that? A: If you use mono from cvs, you need to be prepared for changes in the runtime internals. This means that you should keep a working setup before blindling updating (a working setup may just be the last released tarball or a recent binary snapshot). Usually, compiling corlib with mcs before recompiling the C runtime does the right thing (but occasionally you may need to do it the other way around). Q: Why are you going for a GtkHtml implementation? A: GtkHTML is just a lightweight HTML rendering engine that does not support CSS, so we need it to look decent for those of us that will be using the documentation in our day-to-day work on Linux. The Web-based interfaces lack the agility that you get from a native GUI tool to browse your documentation. Probably later on, we will write scripts and generate a full documentation set that is web-browsable, but we need a command-line and GUI tools that we can use natively on Linux when disconnected from the Web (and that has better interactions than a web page). Q: Is there a command-line tool that allows me to access .NET interactively? A: There are several but one that is free software and uses MCS is the one Dennis Lu from Rice University is working on; a REPL C# interpreter. Q: Is it possible to use Visual C++ with Mono?. A: It's possible to run VC++ generated apps under Mono, but we do not provide a Manager C++ compiler ourselves. Q: Does Mono support generics?. A: Yes, the Mono runtime now supports the new Generics extensions, and there is also support for generics in our new compiler: `gmcs'. The Mono C# 1.0 compiler (mcs) will ship with various C# 2.0 features, but generics will remain on the separate compiler (gmcs) as this code is not as tested as the main compiler. ** Mono Common Problems If you are having problems compiling or running Mono software or if you think that you found a bug, etc. Please visit the Mono Common Problems document and try there. ** Credits The FAQ contains material contributed by Miguel de Icaza, Jaime Anguiano, Lluis Sánchez.