1 <a href="#basics">Basics</a><br>
2 <a href="#ximian">The Ximian Role in the Mono project</a><br>
3 <a href="#gnome">Mono and GNOME</a><br>
4 <a href="#gui">Building GUI applications with Mono</a><br>
5 <a href="#msft">Mono and Microsoft</a><br>
6 <a href="#platforms">Mono platforms</a><br>
7 <a href="#pnpproject">Mono and the Portable.NET Project</a><br>
8 <a href="#webservices">Web Services</a><br>
9 <a href="#asp">Mono and ASP.NET</a><br>
10 <a href="#ado">Mono and ADO.NET</a><br>
11 <a href="#monodoc">MonoDoc</a><br>
12 <a href="#devel">Development Tools and Issues</a><br>
13 <a href="#java">Mono and Java</a><br>
14 <a href="#extending">Extending Mono</a><br>
15 <a href="#portability">Portability</a><br>
16 <a href="#reuse">Reusing Existing Code</a><br>
17 <a href="#gcc">Mono and GCC</a><br>
18 <a href="#performance">Performance</a><br>
19 <a href="#licensing">Licensing</a><br>
20 <a href="#patents">Patents</a><br>
21 <a href="#etc">Miscellaneous Questions</a><br>
22 <a href="#problems">Mono Common Problems</a><br>
25 href="http://www.es.gnome.org/documentacion/articulos/mono-puf/mono-puf/">Spanish
26 translation</a> is also available
31 Q: What is Mono exactly?
33 A: The Mono Project is an open development initiative sponsored by
34 Ximian that is working to develop an open source, Unix
35 version of the Microsoft .NET development platform. Its objective
36 is to enable Unix developers to build and
37 deploy cross-platform .NET Applications. The project will
38 implement various technologies developed by Microsoft that have now
39 been submitted to the ECMA for standardization.
41 Q: What is the difference between Mono and the .NET Initiative?
43 A: The ".NET Initiative" is a somewhat nebulous company-wide effort by
44 Microsoft, one part of which is a cross-platform development
45 framework. Mono is an implementation of the development framework,
46 but not an implementation of anything else related to the .NET
47 Initiative, such as Passport, software-as-a-service, or
48 corporate re-branding.
50 Q: What technologies are included in Mono?
52 A: Mono contains a number of components useful for building new
56 * A Common Language Infrastructure (CLI) virtual
57 machine that contains a class loader, Just-in-time
58 compiler, and a garbage collecting runtime.
60 * A class library that can work with any language
61 which works on the CLR.
63 * A compiler for the C# language. In the future we
64 might work on other compilers that target the Common
69 Windows has compilers that target the virtual machine from <a
70 href="http://msdn.microsoft.com/net/thirdparty/default.asp#lang">a
71 number of languages:</a> Managed C++, Java Script, Eiffel,
72 Component Pascal, APL, Cobol, Perl, Python, Scheme,
73 Smalltalk, Standard ML, Haskell, Mercury and Oberon.
75 The CLR and the Common Type System (CTS) enables applications and
76 libraries to be written in a collection of different languages that
79 This means for example that if you define a class to do algebraic
80 manipulation in C#, that class can be reused from any other
81 language that supports the CLI. You could create a class in C#,
82 subclass it in C++ and instantiate it in an Eiffel program.
84 A single object system, threading system, class libraries, and
85 garbage collection system can be shared across all these languages.
87 Q: Where can I find the specification for these technologies?
89 A: You can find the information here:
92 C# <a href="http://www.ecma.ch/ecma1/STAND/ecma-334.htm">http://www.ecma.ch/ecma1/STAND/ecma-334.htm</a>
94 CLI <a href="http://www.ecma.ch/ecma1/STAND/ecma-335.htm">http://www.ecma.ch/ecma1/STAND/ecma-335.htm</a>
96 Q: Will you implement the .NET Framework SDK class libraries?
98 A: Yes, we will be implementing the APIs of the .NET Framework SDK
101 Q: Will you offer an ECMA-compliant set of class libraries?
103 A: Eventually we will. Our current focus is on inter-operating
104 with the Microsoft SDK, but we will also offer an ECMA compliant
107 Q: What does the name "Mono" mean?
109 A: Mono is the word for `monkey' in Spanish. We like monkeys.
113 A: The JIT engine is usable on Intel x86 machines. An interpreter
114 can be used on other non-Intel x86 machines.
116 The class libraries are mature enough to run some real applications
117 (the compiler for instance, and every day more and more applications
118 are natively developed with Mono).
120 Q: When will you ship it?
122 A: Different parts of Mono will achieve usability at different stages,
123 once we are comfortable with the compiler, we will release "Mono Core",
124 which contains everything needed to develop applications with the base
125 class libraries, this will happen soon and in the meantime you can
126 download daily snapshots of our work. Also the full ASP.NET support is
129 Other higher level class libraries (ASP.NET, ADO.NET, WinForms) will
130 be released when they become stable.
132 Q: What major components will you include in Mono?
134 A: Hopefully everything that Microsoft ships on their Framework
135 (ADO.NET, ASP.NET, WinForms), and we encourage third party developers to
136 create reusable components that work on both Mono and Windows.
138 Q: How can I contribute?
140 A: Check the <a href="contributing.html">contributing</a> section.
142 Q: Aren't you just copying someone else's work?
144 A: We are interested in providing the best tools for programmers to
145 develop applications for Free Operating Systems. We also want to help
146 provide the interoperability that will allow those systems to fit in
147 with other standards.
149 For more background, read the <a href="http://www.go-mono.com/rationale.html">Mono
150 Project white paper</a>.
153 Q: Miguel said once that Mono was being implemented in COBOL. Is that true?.
155 A: No. It was a joke.
158 <a name="ximian"></a>
160 ** The Ximian Role in the Mono Project
162 Q: Why is Ximian working on .NET?
164 A: Ximian is interested in providing the best tools for programmers to
165 develop applications for Free Operating Systems.
167 For more information, read the project <a
168 href="rationale.html">rationale</a> page.
170 Q: Will Ximian be able to take on a project of this size?
172 A: Of course not. Ximian a supporter of the Mono project, but the only way
173 to implement something of this size is for the entire free software
174 community to get involved. Visit the <a href="contributing.html">contributing</a>
175 page if you'd like to help out.
177 Q: What pieces will Ximian be working on?
179 A: We will devote most of our resources to work on the pieces which are
180 on the critical path to release a development and execution
181 environment. Once the project is at a stage where it is useful in
182 the real world, it will achieve a critical mass of developers to
185 Q: Will Ximian offer Mono commercially?
187 A: When Mono is ready to be shipped Ximian will offer a commercial
188 support and services for Mono.
190 Q: Does Ximian provide consulting services around Mono?
192 A: Yes, Ximian does provide consulting services around Mono to
193 make it suitable to your needs. Porting the runtime engine,
194 customizing it, working on specific classes or tuning the code
195 for your particular needs.
197 Q: Will you wait until Mono is finished?
199 A: Mono will ship on various stages as they mature. Some people
200 require only a subset of the technologies, those will ship first.
202 More advanced features will take more time to develop. A support
203 time line will be available in June 2002.
208 Q: How is Mono related to GNOME?
210 A: In a number of ways. This project was born out of the need of
211 providing improved tools for the GNOME community, and will use
212 existing components that have been developed for GNOME when they
213 are available. For example, we plan to use Gtk+ and Libart to
214 implement Winforms and the Drawing2D API and are considering
217 Q: Has the GNOME Foundation or the GNOME team adopted Mono?
219 A: Mono is too new to be adopted by those groups. We hope that the
220 tools that we will provide will be adopted by free software
221 programmers including the GNOME Foundation members and the GNOME
224 Q: Should GNOME programmers switch over to Mono now?
226 A: It is still far to early for discussions of "switching over." No
227 pieces of Mono will be ready within the next six months, and a
228 complete implementation is roughly one year away.
230 We encourage GNOME developers to continue using the existing tools,
231 libraries and components. Improvements made to GNOME will have an
232 impact on Mono, as they would be the "back-end" for various classes.
234 Q: Will Mono include compatibility with Bonobo components? What is the
235 relationship between Mono and Bonobo?
237 A: Yes, we will provide a set of classes for implementing and using
238 Bonobo components from within Mono. Mono should allow you to write
239 Bonobo components more easily, just like .NET on Windows allows you
240 to export .NET components to COM.
242 Q: Does Mono depend on GNOME?
244 A: No, Mono does not depend on GNOME. We use a few packages produced by
245 the GNOME team like the `glib' library.
247 Q: But will I be able to build GNOME applications?
249 A: Yes, we will enable people to write GNOME applications using Mono.
251 Q: Do you have C# bindings for GNOME?.
253 A: Yes, we currently bind libgnome, libgnomecanvas, and libgnomeui --
254 although I dare say I have no idea how functional the bindings are
255 outside of what I tested in the sample app. I imagine other libraries
256 under the GNOME framework will be added on an as-needed (and as-requested)
257 basis...although a truly good bonobo binding will have to wait on the CORBA
258 remoting support which has been started recently.
263 Q: Will Mono enable GUI applications to be authored?
265 A: Yes, you will be able to build GUI applications. Indeed, that is our
266 main focus. We will provide both the Windows.Forms API and the Gtk# API.
268 Q: What is the difference between Gtk# and System.Windows.Forms?
270 A: Gtk# is a set of bindings for the Gtk+ toolkit for C# (and other
271 CIL-enabled languages). System.Windows.Forms is an API defined
272 by Microsoft to build GUI applications.
274 Q: Why not implement System.Windows.Forms on top of Gtk# or Qt#?
276 A: There are several reasons for this.
278 First of all, Gtk+ and Qt are standard toolkits on Linux, and their
279 proponents want to use their favorite toolkits when writing
282 Related to this is the idea that System.Windows.Forms is
283 brain-dead in certain areas, such as internationalization.
284 System.Windows.Forms uses explicit sizes for all controls, as opposed
285 to Gtk+ and Qt which use a box/packing model, which can better deal with
286 the different string lengths different languages will have.
288 Next is compatibility. It is not possible to implement
289 System.Windows.Forms on top of Gtk+/Qt and have 100% compatibility,
290 because System.Windows.Forms exposes <i>lots</i> of Win32-isms, such as the
291 Win32 message loop. In order to maintain compatibility, Wine must be used,
292 and this is being done; see the
293 <a href="/winforms.html">System.Windows.Forms effort page</a>.
295 Additionally, Wine apps don't currently fit in -- visually -- with
298 Q: Will I be able to run my smart clients on systems powered by Mono?
300 A: As long as your applications are 100% .NET and do not make use
301 of P/Invoke to call Win32 functions, your smart client applications
302 will run on Mono platforms.
304 Q: Where can I learn more about Gtk#?
306 A: The following <a href="http://gtk-sharp.sourceforge.net>link</a> sends you to the page of the project.
308 Q: What can I do with Gtk#?.
310 A: Gtk# is becoming very usable and you can create applications and
311 applets like those you see in a GNOME desktop environment. It's
312 easy to install so it's worth a try.
314 Q: How can I compile my HelloWorld.cs which uses Gtk#?.
316 A: Try: mcs --unsafe -o HelloWorld.exe -r glib-sharp -r pango-sharp -r
317 atk-sharp -r gdk-sharp -r gtk-sharp -r gdk-imaging-sharp
320 Q: Is there any way how to connect DataAdapter to some GTK# controls?
322 A: There is a sample file called `DbClient' in gtk-sharp/samples that you
323 might to look at. It is a sample program in Gtk# that adds/updates/deletes
324 information on a Postgress database. When we have the new table/tree widgets,
325 I am sure someone would write an adapter for System.Data (in Gtk2 the
326 tree/list widgets are written using a view/model, so you only need to write
327 a model that maps to the database). You can have a look at
328 gtk-sharp/sample/DbClient, where there is a GTK# application that uses
329 System.Data. It does not use DataAdapter, but DataReader though.
331 Q: Do you have an estimate for when Windows.Forms will be released?
333 A: We do not know, volunteers are working on this, but there is no set
334 date yet. The current approach is using the Wine Library to implement
338 ** Mono and Microsoft
340 Q: Is Microsoft helping Ximian with this project?
342 A: There is no high level communication between Ximian and Microsoft
343 at this point, but engineers who work on .NET or the ECMA groups
344 have been very friendly, and very nice to answer our questions, or
345 clarify part of the specification for us.
347 Microsoft is interested in other implementations of .NET and are
348 willing to help make the ECMA spec more accurate for this purpose.
350 Ximian was also invited to participate in the ECMA committee
351 meetings for C# and the CLI.
353 Q: Is Microsoft or Corel paying Ximian to do this?
357 Q: Do you fear that Microsoft will change the spec and render Mono
360 A: No. Microsoft proved with the CLI and the C# language that it was
361 possible to create a powerful foundation for many languages to
362 inter-operate. We will always have that.
364 Even if changes happened in the platform which were undocumented,
365 the existing platform would a value on its own.
367 Q: Are you writing Mono from the ECMA specs?
369 A: Yes, we are writing them from the ECMA specs and the published
370 materials in print about .NET.
372 Q: If my applications use Mono, will I have to pay a service fee?
374 A: No. Mono is not related to Microsoft's initiative of
375 software-as-a-service.
377 Q: Is the Mono Project is related to the Microsoft Hailstorm effort? Is
378 Ximian endorsing Hailstorm?
380 A: No. The Mono Project is focused on providing a compatible set of
381 tools for the Microsoft .NET development platform. It does not
382 address, require, or otherwise endorse the MS Passport-based
383 Hailstorm single sign-on system that is part of Windows XP and
386 Q: Will Mono or .NET applications depend on Microsoft Passport?
388 A: No. MS Passport is unrelated to running .NET compatible applications
389 produced with the Mono tools. The only thing you will need is a
390 just-in-time compiler (JIT).
392 Q: What is a 100% .NET application?
394 A: A `100% .NET application' is one that only uses the APIs defined
395 under the System namespace and does not use PInvoke. These
396 applications would in theory run unmodified on Windows, Linux,
397 HP-UX, Solaris, MacOS X and others.
399 Q: If Microsoft will release a port of their .NET platform under the
400 `Shared Source' license, why should I bother with anything else?
402 A: The Shared Source implementation will be expensive and its uses
403 will be tightly restricted, especially for commercial use. We are
404 working towards an implementation that will grant a number of
405 important rights to recipients: use for any purpose,
406 redistribution, modification, and redistribution of modifications.
408 This is what we call <a
409 href="http://www.gnu.org/philosophy/free-sw.html">Free Software</a>
411 Q: Is Mono a free implementation of Passport?
413 A: No. Mono is just a runtime, a compiler and a set of class
416 Q: Will the System.Web.Security.PassportIdentity class mean
417 that my software will depend on Passport?
419 A: No. Applications may use that API to contact a Passport site, but
420 are not required to do so.
422 As long as your application does not use Passport, you will not
425 Q: Will Mono running on Linux make Passport available for Linux?
427 A: No. However, the Passport toolkit for Linux-based web servers is
428 available from Microsoft.
430 Q: Will Mono allow me to run Microsoft Office on Linux?
432 A: No, it will not. Microsoft Office is a Windows application. To
433 learn more about running Windows applications on Intel Unix systems
434 refer to <a href="http://www.winehq.com">the Wine Project</a>.
436 Q: Will I be able to compile a Microsoft VB.NET application and execute
437 the resultant MSIL file under MONO on Linux without converting to C#
440 A: Once we have a complete VisualBasic runtime, yes.
442 Q: Can mono run the WebMatrix?
444 A: No. That requires System.Windows.Forms support which is not
445 currently implemented.
447 Q: Does mono have something like Passport?
448 Will mono have a server side Passport/Similar framework for XSP as well as client classes?
450 A: Not yet, but the client side API for authentication is not the problem.
451 We will likely have a lot of other authentication APIs, like the Liberty
452 Alliance APIs. The problem is people on the web provider end that might use
453 this for authentication.
455 <a name="platforms"></a>
458 Q: What operating systems does Mono run on?
460 A: Mono is known to run on Linux, Unix and Windows systems.
462 Q: What architectures does Mono support?
464 A: Mono today ships with a Just-in-Time compiler for x86-based
465 systems. It is tested regularly on Linux, FreeBSD and Windows
466 (with the XP/NT core).
468 There is also an interpreter, which is slower that runs on the
469 s390, SPARC and PowerPC architectures.
471 Q: Can Mono run on Windows 9x, or ME editions?
473 A: Mono requires Unicode versions of Win32 APIs to run,
474 and only a handful of *W functions is supported under Win9x.
476 There is Microsoft Layer for Unicode that provides implementation
477 of these APIs on 9x systems.
479 Unfortunately it uses linker trick for delayed load that is not
480 supported by ld, so some sort of adapter is necessary.
482 You will need MSLU and one of the following libs to link Mono to
484 href="http://mono.eurosoft.od.ua/files/unimono.zip">http://mono.eurosoft.od.ua/files/unimono.zip</a>
485 or alternatively search the net for "libunicows".
487 No changes to Mono source code required, the only thing is to make
488 sure that linker will resolve imports to adapter library instead of
489 Win32 libs. This is achieved by inserting -lunimono before
490 -lkerner32/user32 in the linker's specs file.
493 <a name="pnpproject"></a>
494 ** Mono and Portable.NET
496 Q: What are the differences between Mono and Portable.NET?
498 A: Most of Mono is being written using C#, with only
499 a few parts written in C (The JIT engine, the runtime, the
500 interfaces to the garbage collection system).
502 It is easier to describe what is unique about Mono:
504 <li> An advanced native-code compilation engine: Both
505 just-in-time compilation (JIT) and pre-compilation of CIL
506 bytecodes into native code are supported.
508 <li> A foundation for code optimization: The new code generator in
509 Mono builds on the experience of our first JIT engine, and enables
510 us to implement various advanced compiler optimization
511 tricks. With an SSA-framework, plenty of new optimizations are possible.
513 The current list of optimizations are: Peephole postpass,
514 Branch optimizations, Inline method calls, Constant folding, Constant
515 propagation, Copy propagation, Dead code elimination, Linear scan
516 global reg allocation, Conditional moves, Emit per-domain code,
517 Instruction scheduling, Intrinsic method implementations, Tail
518 recursion and tail calls, Loop related optimizations, Fast x86 FP
519 compares, Leaf procedures optimizations
521 <li> A self-hosting C# compiler written in C#, which is clean, easy
524 <li> Focus on the .NET Framework: we are tracking down the .NET
525 Framework API definition, as we believe it is the API people
526 will be most familiar with.
528 <li> A multi-platform runtime engine: both a JIT engine and an
529 interpreter exist. The JIT engine runs currently on x86
530 systems, while the interpreter works on SPARC, StrongARM,
531 s390 and PowerPC systems.
533 Our new compilation engine is being ported to the PowerPC.
535 <li> Supports Linux, BSD, Windows and Solaris at this point.
537 <li> The JIT engine is written using a portable instruction
538 selector which not only generates good code but
539 is also the foundation to re-target the JIT engine to other
542 <li> Full support for remoting in the runtime.
544 <li> The C# compiler, the JIT engine and the class libraries are
545 mature enough that the whole system has been self-hosting
546 since April 2002. This means that we develop Mono
547 completely with itself at this point.
549 By forcing ourselves to use our own code to develop our
550 tools, we bug fix problems rapidly, and the system is
551 overall more robust and tested than if we did not.
553 <li> We have a great community of developers, without which Mono
554 would not be possible.
557 <a name="webservices"></a>
560 Q: How is Mono related to Web Services?
562 A: Mono is only related to Web Services in that it will implement the
563 same set of classes that have been authored in the .NET Framework
564 to simplify and streamline the process of building Web Services.
566 But most importantly, Mono is an Open Source implementation of the
569 Q: Can I author Web Services with Mono?
571 A: You will be able to write Web Services on .NET that run on Mono and
574 Q: If Mono implements the SDK classes, will I be able to write and
575 execute .NET Web Services with it?
577 A: Yes. When the project is finished, you will be able to use the
578 same technologies that are available through the .NET Framework SDK
579 on Windows to write Web Services.
581 Q: What about Soup? Can I use Soup without Mono?
583 A: Soup is a library for GNOME applications to create SOAP servers and
584 SOAP clients, and can be used without Mono. You can browse the
585 source code for soup using <a
586 href="http://cvs.gnome.org/bonsai">GNOME's Bonsai</a>.
590 A: Yes. The CLI contains enough information about a class that
591 exposing it to other RPC systems (like CORBA) is really simple, and
592 does not even require support from an object.
594 <a href="http://remoting-corba.sourceforge.net/">Remoting.CORBA</a> is
595 a CORBA implementation that is gaining momentum.
597 Building an implementation of the Bonobo interfaces once this is ready
598 should be relatively simple.
600 Q: Can I serialize my objects to other things other than XML?
602 A: Yes, although the serializing tools have not yet been planned, and
603 you would probably have to implement them yourself.
605 Q: Will Mono use ORBit?
607 A: There are a few advantages in using ORBit, like reusing existing code
608 and leveraging all the work done on it. Michael Meeks has posted
609 a few <a href="http://lists.ximian.com/archives/public/mono-list/2002-September/008592.html">reasons</a>,
610 as well as some <a href="http://lists.ximian.com/archives/public/mono-list/2002-September/008657.html">ideas</a>
611 that could be used to reuse ORBit.
613 Most users are likely to choose a native .NET solution, like <a href="http://cvs.gnome.org/bonsai">Remoting.CORBA</a>
616 <a name="monodoc"></a>
621 A: MonoDoc is a graphical documentation browser for the Mono class
622 libraries. Currently, monodoc consists of a Gtk# application and is
623 in heavy development.
626 ** Development Tools and Issues
628 Q: I am having trouble compiling a new version of Mono from CVS, it
629 complains about my runtime being out of sync.
631 A: Jonathan Pryor has provided the following answer:
633 To upgrade your class libraries and compiler, see the See
634 README.building in the MCS directory.
636 The single biggest source of confusion seems to be the "Your
637 runtime is out of sync" messages. Realize that this is *normal*
638 while BUILDING. Think about it: you're building a new class
639 library with the old runtime. If the new class library references
640 a function that the old runtime knows nothing about, the runtime
641 system issues this warning.
643 Basically what needs to happen is for a new mono runtime to be
644 compiled, then the corlib class library be compiled, and once this
645 is done, install the new runtime, followed by corlib.
647 Once this is done, you can continue building your entire
650 Q: Will it be possible to use the CLI features without using byte codes
653 A: Yes. The CLI engine will be made available as a shared library.
654 The garbage collection engine, the threading abstraction, the
655 object system, the dynamic type code system and the JIT will be
656 available for C developers to integrate with their applications if
659 Q: Will you have new development tools?
661 A: With any luck, Free Software enthusiasts will contribute tools to
662 improve the developer environment. These tools could be developed
663 initially using the Microsoft implementation of the CLI and then
664 executed later with Mono.
666 Q: What kind of rules make the Common Intermediate Language useful for
669 A: The main rule is that the stack in the CLI is not a general purpose
670 stack. You are not allowed to use it for other purposes than
671 computing values and passing arguments to functions or return
674 At any given call or return instruction, the types on the stack
675 have to be the same independently of the flow of execution of your
678 Q: Is it true that the CIL is ideal for JITing and not efficient for
681 A: The CIL is better suited to be JITed than JVM byte codes, but you
682 can interpret them as trivially as you can interpret JVM byte
685 Q: Isn't it a little bit confusing to have the name of "XSP" (the same
686 as in the Apache Project) for the ASP.NET support in Mono?.
688 A: In Mono, xsp is just the name of the C# code generator for ASP.NET
689 pages. In the Apache Project, it is a term for the "eXtensible Server
690 Pages" technology so as they are very different things, they don't
693 Q: What about using something like Jabber instead of the System.Messaging
696 A: In short, MSMQ is not something like Jabber, but asynchronous messaging
697 through queues. Useful queues do more than serialize messages, they are
698 also platform bridges.
700 Q: Are you supporting XMLDocument and relatives?.
702 A: Currently, we aren't implementing them yet. It would require updates to
703 most of the XmlNode derivatives so it's not a trivial task. We are
704 currently focusing on getting XPath support working.
706 Q: Is there any plan to develop an aspx server for Mono?.
708 A: The web server turned out to be very simple compared to the rest of the
709 work. Gonzalo has got the page generator mostly done (a module called
710 xsp, who has nothing to do with the XSP term used in the Apache Project).
711 Patrik has done a lot of the work to get the ProcessRequest to work.
712 You can try to help in the final touches to the System.Web classes and
713 writing regression tests for the widgets we have.
715 Q: Is there any way I can develop the class libraries using Linux yet?
717 A: Yes. Some class libraries can be developed on Linux. Search for
718 Paolo's post (he lists which classes can be compiled fine now).
720 Q: Is there any way I can install a known working copy of mono in /usr,
721 and an experimental copy somewhere else, and have both copies use
722 their own libraries? (I'm still not very good at library paths in
725 A: Yes. Just use two installation prefixes.
727 Q: How should I write tests or a tests suite?
729 A: If you do a test suite for C#, you might want to keep it
730 independent of the Mono C# compiler, so that other compiler
731 implementations can later use it.
733 Q: Would it be too terrible to have another corlib signed as mscorlib?
735 A: We rename corlib to mscorlib also when saving the PE files, in fact,
736 the runtime can execute program created by mono just fine.
738 Q: Is there a relatively straightforward way to repeat the steps taken
739 by Paolo to get Mono completely self-hosted on Linux?
741 A: To build the compiler and class libraries in Linux, run:
742 <ul><li>make -f makefile.gnu. To install them, run: </li>
743 <li>make -f makefile.gnu install prefix=/opt/mono</li>
746 If you want to produce and distribute a monocharge tarball, run:
747 make -f makefile.gnu dist
748 Of course you have to run these in the top level mcs directory.
750 Q: Is it possible to build a C# file to some sort of intermediate format which
751 can linked into a final module, like the traditional .c -> .o -> .so path?
753 A: You could do: mcs /target:module file1.cs, mcs /target:module file2.cs,
754 mcs /target:exe file1.dll file2.dll /out:mybin.exe
756 Q: Is there any plans for implementing remoting in the near future?, When will
757 work in System.Runtime.Remoting.dll start?
759 A: The remoting infrastructure is in place. Some of the channels and
762 Q: I'm wondering if there are any plans to start using nant to build the
763 class lib + test lib. i think that every project need/should use an
764 automated build process and nant + a couple of tools enables this. is
765 the problem that the compiler can't run nant yet?
767 A: Maybe well be doing some sort of automated build process + testing when
770 Q: My C code uses the __stdcall which is not availble on Linux, how can I
771 make the code portable Windows/Unix across platforms?
773 A: Replace the __stdcall attribute with the STDCALL macro, and include this
774 in your C code for newer gcc versions:
777 #define STDCALL __attribute__((stdcall))
783 Q: Does Mono support ASP.NET?
787 Mono supports ASP.NET, we have shown an unmodified IBuySpy
788 installation running on Mono as well as various other programs. You can
789 try it yourself downloading the XSP server.
791 Q: Do I need install cygwin to work on ASP.NET in mono or Linux is enough since
792 it is self host right now.
796 Q: How can I run ASP.NET-based applications with Mono?
798 A: You need the Mono runtime and a hosting web server. Currently we distribute a
799 small web server called `xsp' which is used to debug applications, or you can choose
800 to use Daniel's Apache 2 module.
802 Q: Any plan to make ASP.NET in mono works with Apache in Linux?.
804 A: Daniel has authored an Apache2 Module for Mono that hosts the ASP.NET runtime
805 and is available here: <a
806 href="http://apacheworld.org/modmono/">http://apacheworld.org/modmono/</a>
808 Q: Will you support Apache 1?
810 A: Modules developed for Apache 2 are not compatible with Apache 1.3
811 Daniel plans to support Apache 1.3 in the future but the current focus is on
812 Apache 2, because of the better support for threading and Windows.
814 Q: Can I run Apache 1 and Apache 2 on the same machine?
816 You can always keep a copy of Apache 2 running in paralell with your Apache
817 1.3 (either different port or using a reverse proxy).
819 You can also bind the two servers to different IP addresses on the
820 same physical machine.
825 Q: What is the status of ADO.NET support?. Could I start migrating
826 applications from MS.NET to Mono?.
828 A: You could start right now using the ADO.NET support in mono, of course,
829 if you want to help filling the missing gaps while you develop your app
830 :-) Well, what I mean is that we're not that far to having full ADO.NET
831 support in Mono, and we've got a lot of working things, so if we could
832 get more help, we'd finish it really soon :-)
834 Q: In developing the data architecture for the application are there and
835 objects I should stay away from in order to insure the smoothest possible
836 transition (minimum code rewrite) to Mono's ADO.NET implementation? (For
837 example, strongly typed datasets versus untyped datasets, etc...)
839 A: We are implementing all the classes in Microsoft .NET's System.Data, so
840 you can be sure that things will work the same in Mono as with the Microsoft
843 Q: Does Mono can to connect to Sybase by using Mono.Data.*?
845 A: Yes. use Mono.Data.SybaseClient. First of all you have to create a
846 SybaseConnection, and then, from it, use it as any other
847 IDbConnection-based class.
852 Q: Why don't you use Java? After all, there are many languages that
855 A: You can get very good tools for doing Java development on free
856 systems right now. <a href="http://www.redhat.com">Red Hat</a> has
857 contributed a <a href="http://gcc.gnu.org">GCC</a> <a
858 href="http://gcc.gnu.org/java">front-end for Java</a> that can take
859 Java sources or Java byte codes and generate native executables; <a
860 href="http://www.transvirtual.com">Transvirtual</a> has implemented
861 <a href="http://www.kaffe.org">Kaffe</a> a JIT engine for Java;
862 Intel also has a Java VM called <a
863 href="http://www.intel.com/research/mrl/orp">ORP</a>.
865 The JVM is not designed to be a general purpose virtual machine.
866 The Common Intermediate Language (CIL), on the other hand, is
867 designed to be a target for a
868 wide variety of programming languages, and has a set of rules
869 designed to be optimal for JITers.
871 Q: Could Java target the CLI?
873 A: Yes, Java could target the CLI, Microsoft's J# compiler does that.
875 The <a href="http://weblog.ikvm.net/">IKVM</a> project builds a
876 Java runtime that works on top of .NET and on top of Mono. IKVM is
877 essentially a JIT compiler that translates from JVM bytecodes into
878 CIL instructions, and then lets the native JIT engine take over.
880 Q: Is it possible to write a JVM byte code to CIL converter?
882 A: Yes, it is possible. Here are a few starting point:
885 * A byte code representation is really a flattened forest of
886 trees. Look at the Mono JIT engine to see how we compute
887 the basic blocks (this is used to figure out the "trees").
889 The forest is just an array of trees.
891 Indeed, run the JIT engine with -d (mono -d prog.exe) and
892 you will see how these trees look like.
894 You will have to do something similar for Java.
896 * Each "forest of trees" has a meaning. This meaning can now
897 be translated into the equivalent "meaning" in CLR-land.
900 See also the <a href="http://weblog.ikvm.net/">IKVM project</a>
902 Q: Could mono become a hybrid CIL/java platform?
904 A: No. It is quite far from the philosophy of the project. The idea of Mono
905 is, to have only _one_ VM, on which all can run. And if there existing a
906 binary-converter from Java-.class to IL and if there existing something
907 like J-Sharp on Mono, you can write programs in Java, which than can run
908 on Mono. You do not need two bindings (like your example: GTK-Sharp _and_
909 Java-Gnome). You need only _one_ of it (GTK-Sharp). Thats the idea of Mono.
910 An other point is, that there are no people, who use Open Source-JVMs. They
911 all prefer Suns original. But for Unix there don't exist a .NET-Framework.
912 So it is possible, that in the future Mono is the standard .NET for Unixes.
914 Q: Do you plan to implement a Javascript compiler?
916 A: Yes. The beginnings of the JScript compiler can be found on CVS.
917 Cesar coordinates this effort.
919 Q: Can Mono or .NET share system classes (loaded from mscore.dll and other
920 libs) or will it behave like Sun's Java VM?
922 A: What you can do with mono is to load different applications in their own
923 application domain: this is a feature of the CLR that allows sandboxing
924 applications inside a single process space. This is usualy exploited to
925 compartmentalize different parts of the same app, but it can also be
926 effectively used to reduce the startup and memory overhead.
927 Using different appdomains the runtime representation of types and
928 methods is shared across applications.
930 <a name="extending"></a>
933 Q: Would you allow other classes other than those in the
936 A: Yes. The Microsoft class collection is very big, but it is by no
937 means complete. It would be nice to have a port of `Camel' (the
938 Mail API used by Evolution inspired by Java Mail) for Mono
941 You might also want to look into implementing CORBA for Mono. Not
942 only because it would be useful, but because it sounds like a fun
943 thing to do, given the fact that the CLI is such a type rich
946 For more information on extending Mono, see our <a
947 href="ideas.html">ideas</a> page.
949 Q: Do you plan to Embrace and Extend .NET?
951 A: Embracing a good technology is good. Extending technologies in
952 incompatible ways is bad for the users, so we do not plan on
953 extending the technologies.
955 If you have innovative ideas, and want to create new classes, we
956 encourage you to make those classes operate correctly well in both
959 Today Mono ships with a number of extra libraries that were
960 developed either by members of the Mono community, or other
963 Q: Is there any way I can develop the class libraries using Linux yet?
965 A: Yes. Mono has been selfhosting since March 2002.
967 Q: Is there any way I can install a known working copy of mono in /usr,
968 and an experimental copy somewhere else, and have both copies use
969 their own libraries? (I'm still not very good at library paths in
972 A: Yes. Just use two installation prefixes.
975 <a name="portability"></a>
978 Q: Will Mono only work on Linux?
980 A: Currently, we are doing our work on Linux-based systems and
981 Windows. We do not expect many Linux-isms in the code, so it
982 should be easy to port Mono to other UNIX variants.
984 Q: What about Mono on non Linux-based systems?
986 A: Our main intention at Ximian is to be able to develop GNOME
987 applications with Mono, but if you are interested in providing a
988 port of the Winforms classes to other platforms (frame buffer or
989 MacOS X for example), we would gladly integrate them, as long
990 they are under an open source license.
992 Q: What operating systems/CPUs do you support
994 A: Mono currently runs on Linux, Windows, Solaris and FreeBSD.
995 There is a JIT engine available for x86 processors that can
996 generate code and optimizations tailored for a particular CPU.
998 Interpreters exist for the SPARC, PowerPC and StrongARM CPUs.
1000 Q: Does Mono run on Windows?
1002 A: Yes. You can get pre-compiled
1003 binaries from <a href="http://www.go-mono.com/download.html">http://www.go-mono.com/download.html</a>
1005 Q: Does Mono run on Linux?
1007 A: Yes. You can get pre-compiled
1008 binaries from <a href="http://www.go-mono.com/download.html">http://www.go-mono.com/download.html</a>
1010 Q: Will I require Cygwin to run mono?
1012 A: No. Cygwin is only required to build Mono.
1014 Q: Will Mono depend on GNOME?
1016 A: It will depend only if you are using a particular assembly (for
1017 example, for doing GUI applications). If you are just interested
1018 in Mono for implementing a `Hello World Enterprise P2P Web
1019 Service', you will not need any GNOME components.
1021 Q: Is anyone working on porting Mono to IA-64?
1023 A: Nobody is working on such port.
1025 Q: If I were about to start a Mono port to IA-64,would the same lburg code
1026 generator work for IA-64 also? or anything else need to be used for code
1027 generation(as the processor architecture is totally different from IA32)
1029 A: The lburg approach can be use for any processor architecture. But you might
1030 think in another better approach.
1032 Q: Do you plan to port Rhino to C#?.
1034 A: Eto Demerzal has started a Rhino port to C#.
1036 Q: Has anyone succeeded in building a Mac version of the C# environment.
1037 If so can you explain how?
1039 A: You could try to check with the Darwin people, or the Fink people.
1040 Mono/C# is self hosting on Linux/PPC which is the hard part, so it
1041 should be relatively simple to get it to work on MacOS
1043 <a name="reuse"></a>
1044 ** Reusing Existing Code
1046 Q: What projects will you reuse or build upon?
1048 A: We want to get Mono in the hands of programmers soon. We are
1049 interested in reusing existing open source software.
1051 Q: What about Intel's research JIT framework, ORP?
1053 A: At this time, we are investigating whether we can use elements of
1054 ORP for Mono. ORP is a research JIT engine that has a clearly
1055 defined API that splits the JIT from the GC system and the actual
1056 byte code implementation.
1058 We are using some pieces of ORP (Their code generation interface)
1059 and we use it as a source of inspiration for optimizations. Paolo
1060 and Dietmar consider ORP as being one of the best JIT engines out
1061 there (and their research work and papers are very useful if you are
1062 interested in JIT technology).
1064 Q: What about using GNU Lightning?
1066 A: We are not using GNU Lightning. Our JIT is using an instruction
1067 selector based on tree-pattern matching, and a code generation
1068 interface that is very tied to the current architecture.
1070 Q: Will I be able to use Microsoft SQL Server 2000 or will I need to switch
1071 to a specific Open Source Database. Will I need to recode?
1073 A: There should not be any need to recode.
1075 Q: What do I need to watch out for when programming in VB.NET so that I'm
1076 sure to be able to run those apps on Linux?
1078 A: Not making any PInvoke or DLL calls should and not using anything in
1079 the Microsoft.* namespaces should suffice. Also do not use any
1080 Methods/Classes marked as "This type/method supports the .NET Framework
1081 infrastructure and is not intended to be used directly from your code."
1082 even if you know what these classes/methods do.
1084 Q: Will built-in reporting be supported for crystal reports? This is a
1085 heavily used part of our system.
1087 A: Probably not. Crystal Reports are propriety. Someone may try to emulate
1088 the behavior, but no-one has yet volunteered.
1090 Q: Who about writing to the registry? As I understand it, Linux does not have
1091 a counterpart to the registry. Should I avoid relying on that feature?
1093 A: Try to avoid it. Although there would be a emulation for registry in
1094 Mono too. GNOME does have a registry like mechanism for configuration. But
1095 Even if gnome has a configuration system similar to the registry, the keys
1096 will not be equal, so you will probably end up having to do some runtime
1097 detection, and depending on this load an assembly that has your
1098 platform-specific hacks.
1100 Q: System.Data.SqlClient with FreeTDS, will you port parts of these to C# and
1103 A: if their license is compatible with mono's, yes, we'd think about porting
1104 them. If not, we'll continue with the plan of using FreeTDS.
1109 Q: Are you working on a GCC front-end to C#? A GCC back-end that will
1110 generate CIL images? What about making a front-end to GCC that
1111 takes CIL images and generates native code?
1113 A: We are currently seeking volunteers for those projects.
1114 Visit the <a href="contributing.html">contributing</a> section if
1117 Q: But would this work around the GPL in the GCC compiler and allow
1118 people to work on non-free front-ends?
1120 A: People can already do this by targeting the JVM byte codes (there
1121 are about 130 compilers for various languages that target the JVM).
1123 Q: Why are you writing a JIT engine instead of a front-end to GCC?
1125 A: We want the JIT engine and runtime engine because they will be able
1126 to execute CIL executables generated on Windows, and so no recompilation
1129 <a name="performance"></a>
1132 Q: How fast will Mono be?
1134 A: We can not predict the future, but a conservative estimate is that
1135 it would be at least `as fast as other JIT engines'.
1137 We would like to ship various JIT engines with Mono, just like
1138 Microsoft has done with their .NET development platform. We could
1139 provide a faster, JIT for fast load times but lower performance,
1140 and an and an optimizing JIT that would be slower at generating
1141 code but produce more optimal output.
1143 The CIL has some advantages over the Java byte code: it is really
1144 an intermediate representation and there are a number of
1145 restrictions on how you can emit CIL code that simplify creating
1148 For example, on the CIL, the stack is not really an abstraction
1149 available for the code generator to use at will. Rather, it is a
1150 way of creating a postfix representation of the parsed tree. At
1151 any given call point or return point, the contents of the stack are
1152 expected to contain the same object types independently of how the
1153 instruction was reached.
1155 <a name="licensing"></a>
1158 Q: Will I be able to write proprietary applications that run with
1161 A: Yes. The licensing scheme is planned to allow proprietary
1162 developers to write applications with Mono.
1164 Q: What license or licenses are you using for the Mono Project?
1166 A: The C# Compiler is released under the terms of the <a
1167 href="http://www.opensource.org/licenses/gpl-license.html">GNU GPL</a>. The runtime
1168 libraries are under the <a
1169 href="http://www.opensource.org/licenses/lgpl-license.html">GNU
1170 Library GPL</a>. And the class libraries are released
1171 under the terms of the <a
1172 href="http://www.opensource.org/licenses/mit-license.html">MIT X11</a>
1175 The Mono runtime and the Mono C# Compiler are also available under
1176 a proprietary license for those who can not use the LGPL and the
1179 For licensing details, contact <a
1180 href="mailto:mono-licensing@ximian.com">mono-licensing@ximian.com</a>
1183 Q: I would like to contribute code to Mono under a particular
1184 license. What licenses will you accept?
1186 A: We will have to evaluate the licenses for compatibility first,
1187 but as a general rule, we will accept the code under the same
1188 terms of the "container" module.
1190 <a name="patents"></a>
1193 Q: Could patents be used to completely disable Mono (either submarine
1194 patents filed now, or changes made by Microsoft specifically to
1195 create patent problems)?
1197 A: First some background information.
1199 The .NET Framework is divided in two parts: the ECMA/ISO covered
1200 technologies and the other technologies developed on top of it like
1201 ADO.NET, ASP.NET and Windows.Forms.
1203 Mono implements the ECMA/ISO covered parts, as well as being a
1204 project that aims to implement the higher level blocks like
1205 ASP.NET, ADO.NET and Windows.Forms.
1207 The Mono project has gone beyond both of those components and has
1208 developed and integrated third party class libraries, the most
1209 important being: Debugging APIs, integration with the Gnome
1210 platform (Accessibility, Pango rendering, Gdk/Gtk, Glade, GnomeUI),
1211 Mozilla, OpenGL, extensive database support (Microsoft only
1212 supports a couple of providers out of the box, while Mono has
1213 support for 11 different providers), our POSIX integration
1214 libraries and finally the embedded API (used to add scripting to
1215 applications and host the CLI, or for example as an embedded
1218 The core of the .NET Framework, and what has been patented by
1219 Microsoft falls under the ECMA/ISO submission. Jim Miller at
1220 Microsoft has made a statement on the patents covering ISO/ECMA,
1221 (he is one of the inventors listed in the patent): <a
1222 href="https://mailserver.di.unipi.it/pipermail/dotnet-sscli/msg00218.html">here</a>.
1224 Basically a grant is given to anyone who want to implement those
1225 components for free and for any purpose.
1227 The controversial elements are the ASP.NET, ADO.NET and
1228 Windows.Forms subsets. Those are convenient for people who need
1229 full compatibility with the Windows platform, but are not required
1230 for the open source Mono platform, nor integration with today's
1231 Mono's rich support of Linux.
1233 The Mono strategy for dealing with these tehcnologies is as
1234 follows: (1) work around the patent by using a different
1235 implementation techinque that retains the API, but changes the
1236 mechanism; if that is not possible, we would (2) remove the pieces
1237 of code that were covered by those patents, and also (3) find prior
1238 art that would render the patent useless.
1240 Not providing a patented capability would weaken the
1241 interoperability, but it would still provide the free software /
1242 open source software community with good development tools, which
1243 is the primary reason for developing Mono.
1245 The patents do not apply in countries where software patents are
1248 For Linux server and desktop development, we only need the ECMA
1249 components, and things that we have developed (like Gtk#) or Apache
1253 ** Miscellaneous Questions
1255 Q: You say that the CLI allows multiple languages to execute on the
1256 same environment. Isn't this the purpose of CORBA?
1258 A: The key difference between CORBA (and COM) and the CLI is that the
1259 CLI allows "data-level interoperability" because every
1260 language/component uses the same data layout and memory management.
1262 This means you can operate directly upon the data types that someone
1263 else provides, without having to go via their interfaces. It also
1264 means you don't have to "marshal" (convert) parameters (data
1265 layouts are the same, so you can just pass components directly) and
1266 you don't have to worry about memory management, because all
1267 languages/components share the same garbage collector and address
1268 space. This means much less copying and no need for reference
1271 Q: Will you support COM?
1273 A: The runtime will support XPCOM on Unix systems and COM on Windows.
1274 Most of the code for dynamic trampolines exists already.
1276 Q: Will Ximian offer certifications on Mono or related technologies?.
1278 A: It's possible. But there is no plan about this. So the short answer is no.
1280 Q: Are there any Boehm's GC binaries?
1282 A: Yes. You can find RPMs <a href="http://java.thn.htu.se/~toor/">here</a>, though
1283 if your distribution provides the correct packages, you should use those.
1284 The suggested version of the Boehm GC is 6.1.
1286 Q: How can I report a bug?
1288 A: The best thing is to track down the bug and provide a simple test to
1289 reproduce the bug. You can then add the bug to the
1290 <a href="http://bugzilla.ximian.com/enter_bug.cgi">bugtracking system</a>.
1292 Please provide information about what version of mono you're using
1293 and any relevant details to be able to reproduce the bug. Note that
1294 bugs reported on the mailing-list may be easily forgotten, so it's
1295 better to file them in the <a href="http://bugzilla.ximian.com/enter_bug.cgi">bug tracking system</a>.
1297 Q: Does mcs support the same command line options as the MS C#
1300 A: The Mono C# compiler now supports the same command line
1301 arguments as the Microsoft C# compiler does.
1303 Q: How about getting searchable archives on lists.ximian.com?
1305 A: You can perform a search on the mono-related mailing lists
1306 <a href="http://www.go-mono.com/mailing-lists.html">here</a>.
1308 Q: When using mono from cvs or from a snapshot, I get an error messaage
1309 saying that Mono and the runtime are out of sync. How do I fix that?
1311 A: If you use mono from cvs, you need to be prepared for changes in the
1312 runtime internals. This means that you should keep a working setup
1313 before blindling updating (a working setup may just be the last released
1314 tarball or a recent binary snapshot).
1315 Usually, compiling corlib with mcs before recompiling the C runtime does
1316 the right thing (but occasionally you may need to do it the other
1319 Q: Why are you going for a GtkHtml implementation?
1321 A: GtkHTML is just a lightweight HTML rendering engine that does not
1322 support CSS, so we need it to look decent for those of us that will
1323 be using the documentation in our day-to-day work on Linux. The
1324 Web-based interfaces lack the agility that you get from a native GUI
1325 tool to browse your documentation. Probably later on, we will write
1326 scripts and generate a full documentation set that is web-browsable,
1327 but we need a command-line and GUI tools that we can use natively on
1328 Linux when disconnected from the Web (and that has better
1329 interactions than a web page).
1331 Q: Is there a command-line tool that allows me to access .NET interactively?
1333 A: There are several but one that is free software and uses MCS is the one
1334 Dennis Lu from Rice University is working on; a REPL C# interpreter.
1336 Q: Is it possible to use Visual C++ with Mono?.
1338 A: It's possible to run VC++ generated apps under Mono, but we do not
1339 provide a Manager C++ compiler ourselves.
1341 <a name="problems"></a>
1342 ** Mono Common Problems
1344 If you are having problems compiling or running Mono software
1345 or if you think that you found a bug, etc. Please visit the
1346 <a href="http://geneura.ugr.es/~jaime/deploy/mono-common-problems.html">Mono Common Problems</a> document and try there.
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