2010-01-20 Rolf Bjarne Kvinge <RKvinge@novell.com>

[mono.git] / web / faq

<a href="#basics">Basics</a><br>
<a href="#novell">The Novell Role in the Mono project</a><br>
<a href="#gnome">Mono and GNOME</a><br>
<a href="#gui">Building GUI applications with Mono</a><br>
<a href="#msft">Mono and Microsoft</a><br>
<a href="#platforms">Mono platforms</a><br>
<a href="#compatibility">Compatibility</a></br>
<a href="#pnpproject">Mono and the Portable.NET Project</a><br>
<a href="#webservices">Web Services</a><br>
<a href="#asp">Mono and ASP.NET</a><br>
<a href="#ado">Mono and ADO.NET</a><br>
<a href="#monodoc">MonoDoc</a><br>
<a href="#devel">Development Tools and Issues</a><br>
<a href="#java">Mono and Java</a><br>
<a href="#extending">Extending Mono</a><br>
<a href="#portability">Portability</a><br>
<a href="#reuse">Reusing Existing Code</a><br>
<a href="#gcc">Mono and GCC</a><br>
<a href="#performance">Performance</a><br>
<a href="#licensing">Licensing</a><br>
<a href="#patents">Patents</a><br>
<a href="#etc">Miscellaneous Questions</a><br>
<a href="#obfuscation">Obfuscation</a></br>
<a href="#problems">Mono Common Problems</a><br>

A <a
href="http://www.monohispano.org/tutoriales/mono-puf//">Spanish
translation</a> is also available (it is outdated though)

<a name="basics"></a>
** 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:

   <ul>
        <li><a
        href="http://remoting-corba.sourceforge.net/">Remoting.CORBA</a>: A
        CORBA implementation for Mono.

        <li>Ginzu: An implementation on top of Remoting for the <a
        href="http://www.zeroc.com">ICE</a> stack

        <li><a href="http://gtk-sharp.sf.net">Gtk#</a>: Bindings for
        the popular Gtk+ GUI toolkit for Unix and Windows systems.
        Other bindings are available: Diacanvas-Sharp and MrProject.

        <li><a
        href="http://www.icsharpcode.net/OpenSource/SharpZipLib/Default.aspx">#ZipLib</a>:
        A library to manipulate various kinds of compressed files and
        archives (Zip and tar).

        <li>GlGen (available from the Mono CVS): Bindings for OpenGL.

        <li>Mono.LDAP: LDAP access for .NET apps.

        <li>Mono.Data: We ship support for Postgress, MySql, Sybase,
        DB2, SqlLite, Tds (SQL server protocol) and Oracle databases. 

        <li>Mono.Cairo: Bindings for the <a
        href="http://www.cairographics.org">Cairo</a> rendering
        engine (Our System.Drawing is implemented on top of this).

        <li>Mono.Posix: Bindings for building POSIX applications using
        C#. 

        <li>Mono.Http: Support for creating custom, embedded HTTP
        servers and common HTTP handlers for your applications.
   </ul>

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:

        <ul>
                * A Common Language Infrastructure (CLI) virtual
                  machine that contains a class loader, Just-in-time
                  compiler, and a garbage collecting runtime.

                * A class library that can work with any language
                  which works on the CLR.  Both .NET compatible class
                  libraries as well as Mono-provided class libraries
                  are included.

                * A compiler for the C# language.  In the future we
                  might work on other compilers that target the Common
                  Language Runtime.
        </ul>


   Windows has compilers that target the virtual machine from <a
   href="http://msdn.microsoft.com/net/thirdparty/default.asp#lang">a
   number of languages:</a> 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# <a href="http://www.ecma.ch/ecma1/STAND/ecma-334.htm">http://www.ecma.ch/ecma1/STAND/ecma-334.htm</a>

   CLI <a href="http://www.ecma.ch/ecma1/STAND/ecma-335.htm">http://www.ecma.ch/ecma1/STAND/ecma-335.htm</a>

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 <a href="mono-roadmap.html">Mono Roadmap</a> for
   more details on the release plans.  

Q: How can I contribute?

A: Check the <a href="contributing.html">contributing</a> 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 <a href="http://www.go-mono.com/rationale.html">Mono
   Project white paper</a>.
   the project.

Q: Miguel said once that Mono was being implemented in COBOL. Is that true?.

A: No. It was a joke.


<a name="novell"></a> 

** 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 <a
   href="rationale.html">rationale</a> 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 <a href="contributing.html">contributing</a> 
   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 <a
   href="mailto:mono-licensing@ximian.com">mono-licensing@ximian.com</a>

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 <a
   href="mailto:mono-licensing@ximian.com">mono-licensing@ximian.com</a>
   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 <a href="mono-roadmap.html">Mono Roadmap</a> for details

<a name="gnome"></a> 
** 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 <a
   href="http://gtk-sharp.sf.net">Gtk#</a> 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 <a href="http://gtk-sharp.sf.net">Gtk# project</a>
   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.

<a name="gui"></a>
** 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 <a href="winforms.html">winforms page</a>

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 <a href="http://gtk-sharp.sourceforge.net">link</a> 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: <a
   href="http://primates.ximian.com/~miguel/toolkits.html">http://primates.ximian.com/~miguel/toolkits.html</a>.

<a name="msft"></a>
** 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 <a
   href="http://www.gnu.org/philosophy/free-sw.html">Free Software</a>

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 <a href="http://www.winehq.com">the Wine Project</a>.

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.

<a name="platforms"></a>
** 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:

<pre>
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
</pre>

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 <a
   href="http://mono.eurosoft.od.ua/files/unimono.zip">http://mono.eurosoft.od.ua/files/unimono.zip</a>
   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:

   <ul>
      <li> About half the contributors to Mono are Windows developers.
           They have many different for contributing to the effort, and
           we find it very important to let those developers run the runtime on Windows without forcing
           them to use a new operating system. 
          
      <li> Supporting Windows helps us identify the portable portions
           of Mono from the non-portable versions of it, helping Mono
           become more portable in the future.

      <li> Mono does not heavily modify the windows registry, update system DLLs,
           install DLLs to the Windows/System32 path.  Another words, I knew Mono would
           not cause any legacy enterprise applications to stop working - and it
           hasn't.  However, our CIO er is againt it because of the changes that would
           be made to Windows 2000, such as, affecting security.
   </ul>

<a name="compatibility"></a>
** 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 <a
   href="http://bugzilla.ximian.com">http://bugzilla.ximian.com</a>.
   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 
   <tt>#-</tt> 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
   <b>printf</b>(3) for example.), and you need to use
   the linker options <tt>/nodefaultlib /entry:main mscoree.lib</tt> in
   addition to the <tt>/clr</tt> compiler flag.  You can still use certain
   compiler intrinsic functions (such as <b>memcpy</b>(3)) and the STL.
   You should also see <a 
   href="http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vcmex/html/vcgrfconvertingmanagedextensionsforcprojectsfrommixed-modetopureil.asp"
   >Converting Managed Extensions for C++ Projects from Mixed Mode to Pure
   Intermediate Language</a> 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.

<a name="pnpproject"></a>
** 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:
   <ul>
     <li> An advanced native-code compilation engine: Both
          just-in-time compilation (JIT) and pre-compilation of CIL
          bytecodes into native code are supported.

     <li> A foundation for code optimization: The new code generator in
          Mono builds on the experience of our first JIT engine, and enables
          us to implement various advanced compiler optimization
          tricks.  With an SSA-framework, plenty of new optimizations are possible. 

          The current list of optimizations are: Peephole postpass,
          Branch optimizations, Inline method calls, Constant folding, Constant
          propagation, Copy propagation, Dead code elimination, Linear scan
          global reg allocation, Conditional moves, Emit per-domain code,
          Instruction scheduling, Intrinsic method implementations, Tail
          recursion and tail calls, Loop related optimizations, Fast x86 FP
          compares, Leaf procedures optimizations

     <li> A self-hosting C# compiler written in C#, which is clean, easy
          to maintain.

     <li> Focus on the .NET Framework: we are tracking down the .NET
          Framework API definition, as we believe it is the API people
          will be most familiar with.

     <li> A multi-platform runtime engine: both a JIT engine and an
          interpreter exist.  The JIT engine runs currently on x86,
          PowerPC Sparc and S390 systems, while the interpreter works on
          x86, SPARC, StrongARM, s390 and PowerPC systems.  

          The JIT engine is being ported to amd64 systems as of this
          time. 

     <li> Supports Linux, BSD, MacOS, Windows and Solaris at this point.

     <li> The JIT engine is written using a portable instruction
          selector which not only generates good code but
          is also the foundation to re-target the JIT engine to other
          systems.  

     <li> Full support for remoting in the runtime.

     <li> The C# compiler, the JIT engine and the class libraries are
          mature enough that the whole system has been self-hosting
          since April 2002.  This means that we develop Mono
          completely with itself at this point.

          By forcing ourselves to use our own code to develop our
          tools, we bug fix problems rapidly, and the system is
          overall more robust and tested than if we did not.

     <li> Our class libraries are licensed under the terms of the MIT
          X11 license which is a very liberal license as opposed to
          the GNU GPL with exceptions, this means that Mono can be
          used in places where the GPL with exceptions is not
          permissible.

     <li> Mono has a complete Web Services stack: we implement ASP.NET
          web servers and web clients as well as implementing the
          Remoting-based SOAP infrastructure.

     <li> Remoting implementation: Mono has a complete remoting
          infrastructure that is used in our own codebase to provide
          added functionality and performance to our ASP.NET engine
          and more.

     <li> Mono has a complete <a href="c-sharp.html">C# 1.0</a>
          implementation and has been stress tested a lot more than
          Portable.NET's compiler.

     <li> Mono's C# compiler has strong error handling and has closer
          adherence to the specification with support for definite
          assignment (required to generate verifiable IL code) and 
          CLS conformance checking.

     <li> Mono's C# compiler is written in C# which is easier for new
          developers to come in and improve, fix and tune.  The Mono
          C# compiler in C# is faster than their C-based compiler.

     <li> Preview of C# 2.0: a work in progress for a 2.0
          implementation of our compiler is available (iterators,
          generics and anonymous methods are available in our
          "preview" compiler).

     <li> Mono has a complete Reflection and Reflection.Emit: these
          are important for advanced applications, compilers and
          dynamic code generation.

     <li> Mono has a <a href="xml-classes.html">complete managed XML
          stack</a>: XML, XPath, XML Serializer, XML Schema handling
          are fully functional, feature complete and tuned for
          performance.

     <li> Mono has a <a href="crypto.html">complete cryptography stack
          </a>: we implement the 1.0 and 1.1 APIs as well as using our
          fully managed stack to implement the SSL/TLS transports. 

     <li> <a href="ado-net.html">Extensive database support</a>: Mono
          ships with database provides for <a
          href="firebird.html">Firebird</a>, <a href="ibmdb2.html">IBM
          DB2</a>, <a href="oracle.html">Oracle</a>, <a
          href="sybase.html">Sybase</a>, Microsoft <a
          href="tdsclient.html">SQL Server</a>, <a
          href="sqlite.html">SQL Lite</a>, <a
          href="mysql.html">MySQL</a>, <a
          href="postgresql.html">PostgresSQL</A>, <a href="oledb.html">Ole
          DB</a> and <a href="odbc.html">ODBC</a>.

     <li> Mono includes full LDAP support.

     <li> We have a great community of developers, without which Mono
          would not be possible.
   </ul>

   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.

<a name="webservices"></a>
** 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 <a
   href="http://cvs.gnome.org/bonsai/">GNOME's Bonsai</a>.

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.  

   <a href="http://remoting-corba.sourceforge.net/">Remoting.CORBA</a> 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 <a href="http://lists.ximian.com/archives/public/mono-list/2002-September/008592.html">reasons</a>,
   as well as some <a href="http://lists.ximian.com/archives/public/mono-list/2002-September/008657.html">ideas</a>
   that could be used to reuse ORBit.

   Most users are likely to choose a native .NET solution, like <a href="http://cvs.gnome.org/bonsai">Remoting.CORBA</a>


<a name="monodoc"></a>
** 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.

<a name="devel"></a>
** 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 <a 
   href="http://www.go-mono.com">download</a> page.
   2.- Get the latest mono-lite tarball from the daily snapshots 
   <a href="http://www.go-mono.com/daily/">page</a>, 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>I think that the best solution is the binfmt feature with the
   wrapper that exists with Debian packages at:

   <a href="http://www.debianplanet.org/mono/dists/unstable/main/source/admin/">http://www.debianplanet.org/mono/dists/unstable/main/source/admin/</a>

   If you want use it with Big endian machines, you should apply a patch
   (<a href="http://carlos.pemas.net/debian/mono/binfmt-detector-cli.c.diff">http://carlos.pemas.net/debian/mono/binfmt-detector-cli.c.diff</a>)

   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.</i>

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.

<a name="asp">
** 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: <a
   href="http://apacheworld.org/modmono/">http://apacheworld.org/modmono/</a>

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.

<a name="ado">
** 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.

<a name="java">
** 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.  <a href="http://www.redhat.com">Red Hat</a> has
   contributed a <a href="http://gcc.gnu.org">GCC</a> <a
   href="http://gcc.gnu.org/java/">front-end for Java</a> that can take
   Java sources or Java byte codes and generate native executables; <a
   href="http://www.google.com/search?q=transvirtual">Transvirtual</a>
   implemented
   <a href="http://www.kaffe.org">Kaffe</a> a JIT engine for Java;
   Intel also has a Java VM called <a
   href="http://www.intel.com/research/mrl/orp/">ORP</a>.

   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 <a href="http://weblog.ikvm.net/">IKVM</a> 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 <a href="http://weblog.ikvm.net">IKVM</a> 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.

<a name="extending"></a>
** 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 <a
   href="ideas.html">ideas</a> 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.


<a name="portability"></a>
** 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 <a href="http://www.go-mono.com/download.html">http://www.go-mono.com/download.html</a>

Q: Does Mono run on Linux?

A: Yes.  You can get pre-compiled
   binaries from <a href="http://www.go-mono.com/download.html">http://www.go-mono.com/download.html</a>

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)

<a name="reuse"></a>
** 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.

<a name="gcc"></a>
** 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).


<a name="performance"></a>
** 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.

<a name="licensing"></a>
** 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 <a 
   href="http://www.opensource.org/licenses/gpl-license.html">GNU GPL</a>.  The runtime
   libraries are under the <a
   href="http://www.opensource.org/licenses/lgpl-license.html">GNU
   Library GPL</a>.  And the class libraries are released
   under the terms of the <a
   href="http://www.opensource.org/licenses/mit-license.html">MIT X11</a>
   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 <a
   href="mailto:mono-licensing@ximian.com">mono-licensing@ximian.com</a>


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. 

<a name="patents"></a>
** 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): <a
   href="http://web.archive.org/web/20030609164123/http://mailserver.di.unipi.it/pipermail/dotnet-sscli/msg00218.html">here</a>.

   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, <a
   href="http://www.gnome.org">Gnome</a> specific, or that are not
   part of the .NET Framework but people find useful. 

   The following map shows the relationship between the components:

   <img src="http://primates.ximian.com/~miguel/tmp/map.png">

<a name="obfuscation"></a>
** 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).

<a name="etc"></a> 
** 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 <a href="bugs.html">Bug Form</a> 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 <a href="http://bugzilla.ximian.com/enter_bug.cgi">bug tracking system</a>.

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 
   <a href="http://www.go-mono.com/mailing-lists.html">here</a>.

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.

<a name="problems"></a>
** 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
   <a href="http://monoevo.sf.net/mono-common-problems.html">Mono Common Problems</a> document and try there. 

** Credits

   The FAQ contains material contributed by Miguel de Icaza, Jaime Anguiano, Lluis Sánchez.