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="#compatibility">Compatibility</a></br>
8 <a href="#pnpproject">Mono and the Portable.NET Project</a><br>
9 <a href="#webservices">Web Services</a><br>
10 <a href="#asp">Mono and ASP.NET</a><br>
11 <a href="#ado">Mono and ADO.NET</a><br>
12 <a href="#monodoc">MonoDoc</a><br>
13 <a href="#devel">Development Tools and Issues</a><br>
14 <a href="#java">Mono and Java</a><br>
15 <a href="#extending">Extending Mono</a><br>
16 <a href="#portability">Portability</a><br>
17 <a href="#reuse">Reusing Existing Code</a><br>
18 <a href="#gcc">Mono and GCC</a><br>
19 <a href="#performance">Performance</a><br>
20 <a href="#licensing">Licensing</a><br>
21 <a href="#patents">Patents</a><br>
22 <a href="#etc">Miscellaneous Questions</a><br>
23 <a href="#problems">Mono Common Problems</a><br>
26 href="http://www.es.gnome.org/documentacion/articulos/mono-puf/mono-puf/">Spanish
27 translation</a> is also available
32 Q: What is Mono exactly?
34 A: The Mono Project is an open development initiative sponsored by
35 Ximian that is working to develop an open source, Unix
36 version of the Microsoft .NET development platform. Its objective
37 is to enable Unix developers to build and
38 deploy cross-platform .NET Applications. The project will
39 implement various technologies developed by Microsoft that have now
40 been submitted to the ECMA for standardization.
42 Q: What is the difference between Mono and the .NET Initiative?
44 A: The ".NET Initiative" is a somewhat nebulous company-wide effort by
45 Microsoft, one part of which is a cross-platform development
46 framework. Mono is an implementation of the development framework,
47 but not an implementation of anything else related to the .NET
48 Initiative, such as Passport, software-as-a-service, or
49 corporate re-branding.
51 Q: What technologies are included in Mono?
53 A: Mono contains a number of components useful for building new
57 * A Common Language Infrastructure (CLI) virtual
58 machine that contains a class loader, Just-in-time
59 compiler, and a garbage collecting runtime.
61 * A class library that can work with any language
62 which works on the CLR.
64 * A compiler for the C# language. In the future we
65 might work on other compilers that target the Common
70 Windows has compilers that target the virtual machine from <a
71 href="http://msdn.microsoft.com/net/thirdparty/default.asp#lang">a
72 number of languages:</a> Managed C++, Java Script, Eiffel,
73 Component Pascal, APL, Cobol, Perl, Python, Scheme,
74 Smalltalk, Standard ML, Haskell, Mercury and Oberon.
76 The CLR and the Common Type System (CTS) enables applications and
77 libraries to be written in a collection of different languages that
80 This means for example that if you define a class to do algebraic
81 manipulation in C#, that class can be reused from any other
82 language that supports the CLI. You could create a class in C#,
83 subclass it in C++ and instantiate it in an Eiffel program.
85 A single object system, threading system, class libraries, and
86 garbage collection system can be shared across all these languages.
88 Q: Where can I find the specification for these technologies?
90 A: You can find the information here:
93 C# <a href="http://www.ecma.ch/ecma1/STAND/ecma-334.htm">http://www.ecma.ch/ecma1/STAND/ecma-334.htm</a>
95 CLI <a href="http://www.ecma.ch/ecma1/STAND/ecma-335.htm">http://www.ecma.ch/ecma1/STAND/ecma-335.htm</a>
97 Q: Will you implement the .NET Framework SDK class libraries?
99 A: Yes, we will be implementing the APIs of the .NET Framework SDK
102 Q: Will you offer an ECMA-compliant set of class libraries?
104 A: Eventually we will. Our current focus is on inter-operating
105 with the Microsoft SDK, but we will also offer an ECMA compliant
108 Q: What does the name "Mono" mean?
110 A: Mono is the word for `monkey' in Spanish. We like monkeys.
114 A: The JIT engine is usable on Intel x86 machines. An interpreter
115 can be used on other non-Intel x86 machines.
117 The class libraries are mature enough to run some real applications
118 (the compiler for instance, and every day more and more applications
119 are natively developed with Mono).
121 Q: When will you ship it?
123 A: Different parts of Mono will achieve usability at different stages,
124 once we are comfortable with the compiler, we will release "Mono Core",
125 which contains everything needed to develop applications with the base
126 class libraries, this will happen soon and in the meantime you can
127 download daily snapshots of our work. Also the full ASP.NET support is
130 Other higher level class libraries (ASP.NET, ADO.NET, WinForms) will
131 be released when they become stable.
133 Q: What major components will you include in Mono?
135 A: Hopefully everything that Microsoft ships on their Framework
136 (ADO.NET, ASP.NET, WinForms), and we encourage third party developers to
137 create reusable components that work on both Mono and Windows.
139 Q: How can I contribute?
141 A: Check the <a href="contributing.html">contributing</a> section.
143 Q: Aren't you just copying someone else's work?
145 A: We are interested in providing the best tools for programmers to
146 develop applications for Free Operating Systems. We also want to help
147 provide the interoperability that will allow those systems to fit in
148 with other standards.
150 For more background, read the <a href="http://www.go-mono.com/rationale.html">Mono
151 Project white paper</a>.
154 Q: Miguel said once that Mono was being implemented in COBOL. Is that true?.
156 A: No. It was a joke.
159 <a name="ximian"></a>
161 ** The Ximian Role in the Mono Project
163 Q: Why is Ximian working on .NET?
165 A: Ximian is interested in providing the best tools for programmers to
166 develop applications for Free Operating Systems.
168 For more information, read the project <a
169 href="rationale.html">rationale</a> page.
171 Q: Will Ximian be able to take on a project of this size?
173 A: Of course not. Ximian a supporter of the Mono project, but the only way
174 to implement something of this size is for the entire free software
175 community to get involved. Visit the <a href="contributing.html">contributing</a>
176 page if you'd like to help out.
178 Q: What pieces will Ximian be working on?
180 A: We will devote most of our resources to work on the pieces which are
181 on the critical path to release a development and execution
182 environment. Once the project is at a stage where it is useful in
183 the real world, it will achieve a critical mass of developers to
186 Q: Will Ximian offer Mono commercially?
188 A: When Mono is ready to be shipped Ximian will offer a commercial
189 support and services for Mono.
191 Q: Does Ximian provide consulting services around Mono?
193 A: Yes, Ximian does provide consulting services around Mono to
194 make it suitable to your needs. Porting the runtime engine,
195 customizing it, working on specific classes or tuning the code
196 for your particular needs.
198 Q: Will you wait until Mono is finished?
200 A: Mono will ship on various stages as they mature. Some people
201 require only a subset of the technologies, those will ship first.
203 More advanced features will take more time to develop. A support
204 time line will be available in June 2002.
209 Q: How is Mono related to GNOME?
211 A: In a number of ways. This project was born out of the need of
212 providing improved tools for the GNOME community, and will use
213 existing components that have been developed for GNOME when they
214 are available. For example, we plan to use Gtk+ and Libart to
215 implement Winforms and the Drawing2D API and are considering
218 Q: Has the GNOME Foundation or the GNOME team adopted Mono?
220 A: Mono is too new to be adopted by those groups. We hope that the
221 tools that we will provide will be adopted by free software
222 programmers including the GNOME Foundation members and the GNOME
225 Q: Should GNOME programmers switch over to Mono now?
227 A: It is still far to early for discussions of "switching over." No
228 pieces of Mono will be ready within the next six months, and a
229 complete implementation is roughly one year away.
231 We encourage GNOME developers to continue using the existing tools,
232 libraries and components. Improvements made to GNOME will have an
233 impact on Mono, as they would be the "back-end" for various classes.
235 Q: Will Mono include compatibility with Bonobo components? What is the
236 relationship between Mono and Bonobo?
238 A: Yes, we will provide a set of classes for implementing and using
239 Bonobo components from within Mono. Mono should allow you to write
240 Bonobo components more easily, just like .NET on Windows allows you
241 to export .NET components to COM.
243 Q: Does Mono depend on GNOME?
245 A: No, Mono does not depend on GNOME. We use a few packages produced by
246 the GNOME team like the `glib' library.
248 Q: But will I be able to build GNOME applications?
250 A: Yes, we will enable people to write GNOME applications using Mono.
252 Q: Do you have C# bindings for GNOME?.
254 A: Yes, we currently bind libgnome, libgnomecanvas, and libgnomeui --
255 although I dare say I have no idea how functional the bindings are
256 outside of what I tested in the sample app. I imagine other libraries
257 under the GNOME framework will be added on an as-needed (and as-requested)
258 basis...although a truly good bonobo binding will have to wait on the CORBA
259 remoting support which has been started recently.
264 Q: Will Mono enable GUI applications to be authored?
266 A: Yes, you will be able to build GUI applications. Indeed, that is our
267 main focus. We will provide both the Windows.Forms API and the Gtk# API.
269 Q: What is the difference between Gtk# and System.Windows.Forms?
271 A: Gtk# is a set of bindings for the Gtk+ toolkit for C# (and other
272 CIL-enabled languages). System.Windows.Forms is an API defined
273 by Microsoft to build GUI applications.
275 Q: Why not implement System.Windows.Forms on top of Gtk# or Qt#?
277 A: There are several reasons for this.
279 First of all, Gtk+ and Qt are standard toolkits on Linux, and their
280 proponents want to use their favorite toolkits when writing
283 Related to this is the idea that System.Windows.Forms is
284 brain-dead in certain areas, such as internationalization.
285 System.Windows.Forms uses explicit sizes for all controls, as opposed
286 to Gtk+ and Qt which use a box/packing model, which can better deal with
287 the different string lengths different languages will have.
289 Next is compatibility. It is not possible to implement
290 System.Windows.Forms on top of Gtk+/Qt and have 100% compatibility,
291 because System.Windows.Forms exposes some Win32-isms, such as the
292 Win32 message loop. In order to maintain compatibility, Wine must be used,
293 and this is being done; see the
294 <a href="/winforms.html">System.Windows.Forms effort page</a>.
296 Additionally, Wine apps don't currently fit in -- visually -- with
299 Q: Will I be able to run my smart clients on systems powered by Mono?
301 A: As long as your applications are 100% .NET and do not make use
302 of P/Invoke to call Win32 functions, your smart client applications
303 will run on Mono platforms.
305 Q: Where can I learn more about Gtk#?
307 A: The following <a href="http://gtk-sharp.sourceforge.net>link</a> sends you to the page of the project.
309 Q: What can I do with Gtk#?.
311 A: Gtk# is becoming very usable and you can create applications and
312 applets like those you see in a GNOME desktop environment. It's
313 easy to install so it's worth a try.
315 Q: How can I compile my HelloWorld.cs which uses Gtk#?.
317 A: Try: mcs --unsafe -o HelloWorld.exe -r glib-sharp -r pango-sharp -r
318 atk-sharp -r gdk-sharp -r gtk-sharp -r gdk-imaging-sharp
321 Q: Is there any way how to connect DataAdapter to some GTK# controls?
323 A: There is a sample file called `DbClient' in gtk-sharp/samples that you
324 might to look at. It is a sample program in Gtk# that adds/updates/deletes
325 information on a Postgress database. When we have the new table/tree widgets,
326 I am sure someone would write an adapter for System.Data (in Gtk2 the
327 tree/list widgets are written using a view/model, so you only need to write
328 a model that maps to the database). You can have a look at
329 gtk-sharp/sample/DbClient, where there is a GTK# application that uses
330 System.Data. It does not use DataAdapter, but DataReader though.
332 Q: Do you have an estimate for when Windows.Forms will be released?
334 A: We do not know, volunteers are working on this, but there is no set
335 date yet. The current approach is using the Wine Library to implement
339 ** Mono and Microsoft
341 Q: Is Microsoft helping Ximian with this project?
343 A: There is no high level communication between Ximian and Microsoft
344 at this point, but engineers who work on .NET or the ECMA groups
345 have been very friendly, and very nice to answer our questions, or
346 clarify part of the specification for us.
348 Microsoft is interested in other implementations of .NET and are
349 willing to help make the ECMA spec more accurate for this purpose.
351 Ximian was also invited to participate in the ECMA committee
352 meetings for C# and the CLI.
354 Q: Is Microsoft or Corel paying Ximian to do this?
358 Q: Do you fear that Microsoft will change the spec and render Mono
361 A: No. Microsoft proved with the CLI and the C# language that it was
362 possible to create a powerful foundation for many languages to
363 inter-operate. We will always have that.
365 Even if changes happened in the platform which were undocumented,
366 the existing platform would a value on its own.
368 Q: Are you writing Mono from the ECMA specs?
370 A: Yes, we are writing them from the ECMA specs and the published
371 materials in print about .NET.
373 Q: If my applications use Mono, will I have to pay a service fee?
375 A: No. Mono is not related to Microsoft's initiative of
376 software-as-a-service.
378 Q: Is the Mono Project is related to the Microsoft Hailstorm effort? Is
379 Ximian endorsing Hailstorm?
381 A: No. The Mono Project is focused on providing a compatible set of
382 tools for the Microsoft .NET development platform. It does not
383 address, require, or otherwise endorse the MS Passport-based
384 Hailstorm single sign-on system that is part of Windows XP and
387 Q: Will Mono or .NET applications depend on Microsoft Passport?
389 A: No. MS Passport is unrelated to running .NET compatible applications
390 produced with the Mono tools. The only thing you will need is a
391 just-in-time compiler (JIT).
393 Q: What is a 100% .NET application?
395 A: A `100% .NET application' is one that only uses the APIs defined
396 under the System namespace and does not use PInvoke. These
397 applications would in theory run unmodified on Windows, Linux,
398 HP-UX, Solaris, MacOS X and others.
400 Q: If Microsoft will release a port of their .NET platform under the
401 `Shared Source' license, why should I bother with anything else?
403 A: The Shared Source implementation will be expensive and its uses
404 will be tightly restricted, especially for commercial use. We are
405 working towards an implementation that will grant a number of
406 important rights to recipients: use for any purpose,
407 redistribution, modification, and redistribution of modifications.
409 This is what we call <a
410 href="http://www.gnu.org/philosophy/free-sw.html">Free Software</a>
412 Q: Is Mono a free implementation of Passport?
414 A: No. Mono is just a runtime, a compiler and a set of class
417 Q: Will the System.Web.Security.PassportIdentity class mean
418 that my software will depend on Passport?
420 A: No. Applications may use that API to contact a Passport site, but
421 are not required to do so.
423 As long as your application does not use Passport, you will not
426 Q: Will Mono running on Linux make Passport available for Linux?
428 A: No. However, the Passport toolkit for Linux-based web servers is
429 available from Microsoft.
431 Q: Will Mono allow me to run Microsoft Office on Linux?
433 A: No, it will not. Microsoft Office is a Windows application. To
434 learn more about running Windows applications on Intel Unix systems
435 refer to <a href="http://www.winehq.com">the Wine Project</a>.
437 Q: Will I be able to compile a Microsoft VB.NET application and execute
438 the resultant MSIL file under MONO on Linux without converting to C#
441 A: Once we have a complete VisualBasic runtime, yes.
443 Q: Can mono run the WebMatrix?
445 A: No. That requires System.Windows.Forms support which is not
446 currently implemented.
448 Q: Does mono have something like Passport?
449 Will mono have a server side Passport/Similar framework for XSP as well as client classes?
451 A: Not yet, but the client side API for authentication is not the problem.
452 We will likely have a lot of other authentication APIs, like the Liberty
453 Alliance APIs. The problem is people on the web provider end that might use
454 this for authentication.
456 <a name="platforms"></a>
459 Q: What operating systems does Mono run on?
461 A: Mono is known to run on Linux, Unix and Windows systems.
463 Q: What architectures does Mono support?
465 A: Mono today ships with a Just-in-Time compiler for x86-based
466 systems. It is tested regularly on Linux, FreeBSD and Windows
467 (with the XP/NT core).
469 There is also an interpreter, which is slower that runs on the
470 s390, SPARC and PowerPC architectures.
472 Q: Can Mono run on Windows 9x, or ME editions?
474 A: Mono requires Unicode versions of Win32 APIs to run,
475 and only a handful of *W functions is supported under Win9x.
477 There is Microsoft Layer for Unicode that provides implementation
478 of these APIs on 9x systems.
480 Unfortunately it uses linker trick for delayed load that is not
481 supported by ld, so some sort of adapter is necessary.
483 You will need MSLU and one of the following libs to link Mono to
485 href="http://mono.eurosoft.od.ua/files/unimono.zip">http://mono.eurosoft.od.ua/files/unimono.zip</a>
486 or alternatively search the net for "libunicows".
488 No changes to Mono source code required, the only thing is to make
489 sure that linker will resolve imports to adapter library instead of
490 Win32 libs. This is achieved by inserting -lunimono before
491 -lkerner32/user32 in the linker's specs file.
493 <a name="compatibility"></a>
496 Q: Can Mono run applications developed with the Microsoft.NET fraemwork?
498 A: Yes, Mono can run applications developed with the Microsft .NET Framework
499 on Unix. There are a few caveats to keep in mind: Mono has not
500 been completed yet, so a few API calls might be missing; And in
501 some cases the Mono behavior *might* be incorrect.
503 Q: Will missing API entry points be implemented?
505 A: Yes, the goal of Mono is to implement precisely the .NET Framework
506 API (as well as compile-time selectable subsets, for those
507 interested in a lighter version of Mono).
509 Q: If the behavior of an API call is different, will you fix it?
511 A: Yes, we will. But we will need your assistance for this. If you find a bug
512 in the Mono implementation, please fill a bug report in <a
513 href="http://bugzilla.ximian.com">http://bugzilla.ximian.com</a>.
514 Do not assume we know about the problem, we might not, and using the bug tracking
515 system helps us organize the development process.
517 Q: Can I develop my applications on Windows, and deploy on a supported
518 Mono platform (like Linux)?
522 As of today, Mono is not 100% finished, so it is sometimes useful
523 to compile the code with Mono, to find out if your application
524 depends on unimplemented functionality.
526 Q: Will applications run out the box with Mono?
528 A: Sometimes they will. But sometimes a .NET application might invoke
529 Win32 API calls, or assume certain patterns that are not correct
530 for cross-platform applications.
532 <a name="pnpproject"></a>
533 ** Mono and Portable.NET
535 Q: What are the differences between Mono and Portable.NET?
537 A: Most of Mono is being written using C#, with only
538 a few parts written in C (The JIT engine, the runtime, the
539 interfaces to the garbage collection system).
541 It is easier to describe what is unique about Mono:
543 <li> An advanced native-code compilation engine: Both
544 just-in-time compilation (JIT) and pre-compilation of CIL
545 bytecodes into native code are supported.
547 <li> A foundation for code optimization: The new code generator in
548 Mono builds on the experience of our first JIT engine, and enables
549 us to implement various advanced compiler optimization
550 tricks. With an SSA-framework, plenty of new optimizations are possible.
552 The current list of optimizations are: Peephole postpass,
553 Branch optimizations, Inline method calls, Constant folding, Constant
554 propagation, Copy propagation, Dead code elimination, Linear scan
555 global reg allocation, Conditional moves, Emit per-domain code,
556 Instruction scheduling, Intrinsic method implementations, Tail
557 recursion and tail calls, Loop related optimizations, Fast x86 FP
558 compares, Leaf procedures optimizations
560 <li> A self-hosting C# compiler written in C#, which is clean, easy
563 <li> Focus on the .NET Framework: we are tracking down the .NET
564 Framework API definition, as we believe it is the API people
565 will be most familiar with.
567 <li> A multi-platform runtime engine: both a JIT engine and an
568 interpreter exist. The JIT engine runs currently on x86
569 systems, while the interpreter works on SPARC, StrongARM,
570 s390 and PowerPC systems.
572 Our new compilation engine is being ported to the PowerPC.
574 <li> Supports Linux, BSD, Windows and Solaris at this point.
576 <li> The JIT engine is written using a portable instruction
577 selector which not only generates good code but
578 is also the foundation to re-target the JIT engine to other
581 <li> Full support for remoting in the runtime.
583 <li> The C# compiler, the JIT engine and the class libraries are
584 mature enough that the whole system has been self-hosting
585 since April 2002. This means that we develop Mono
586 completely with itself at this point.
588 By forcing ourselves to use our own code to develop our
589 tools, we bug fix problems rapidly, and the system is
590 overall more robust and tested than if we did not.
592 <li> We have a great community of developers, without which Mono
593 would not be possible.
596 In general, Mono is more mature and complete since it has been used
597 to develop itself, which is a big motivator for stability and
598 correctness, while Portable.NET remains pretty much an untested
601 Q: I hear Mono keeps changing the P/Invoke API, why?
603 A: We are just fixing our implementation to be compatible with the
604 Microsoft implementation. In other words, the Mono P/Invoke API is
605 more complete when compared to the Portable.NET version, hence
606 various pieces of software that depend on this extended
607 functionality fail to work properly with Portable.NET.
609 <a name="webservices"></a>
612 Q: How is Mono related to Web Services?
614 A: Mono is only related to Web Services in that it will implement the
615 same set of classes that have been authored in the .NET Framework
616 to simplify and streamline the process of building Web Services.
618 But most importantly, Mono is an Open Source implementation of the
621 Q: Can I author Web Services with Mono?
623 A: You will be able to write Web Services on .NET that run on Mono and
626 Q: If Mono implements the SDK classes, will I be able to write and
627 execute .NET Web Services with it?
629 A: Yes. When the project is finished, you will be able to use the
630 same technologies that are available through the .NET Framework SDK
631 on Windows to write Web Services.
633 Q: What about Soup? Can I use Soup without Mono?
635 A: Soup is a library for GNOME applications to create SOAP servers and
636 SOAP clients, and can be used without Mono. You can browse the
637 source code for soup using <a
638 href="http://cvs.gnome.org/bonsai">GNOME's Bonsai</a>.
642 A: Yes. The CLI contains enough information about a class that
643 exposing it to other RPC systems (like CORBA) is really simple, and
644 does not even require support from an object.
646 <a href="http://remoting-corba.sourceforge.net/">Remoting.CORBA</a> is
647 a CORBA implementation that is gaining momentum.
649 Building an implementation of the Bonobo interfaces once this is ready
650 should be relatively simple.
652 Q: Can I serialize my objects to other things other than XML?
654 A: Yes, although the serializing tools have not yet been planned, and
655 you would probably have to implement them yourself.
657 Q: Will Mono use ORBit?
659 A: There are a few advantages in using ORBit, like reusing existing code
660 and leveraging all the work done on it. Michael Meeks has posted
661 a few <a href="http://lists.ximian.com/archives/public/mono-list/2002-September/008592.html">reasons</a>,
662 as well as some <a href="http://lists.ximian.com/archives/public/mono-list/2002-September/008657.html">ideas</a>
663 that could be used to reuse ORBit.
665 Most users are likely to choose a native .NET solution, like <a href="http://cvs.gnome.org/bonsai">Remoting.CORBA</a>
668 <a name="monodoc"></a>
673 A: MonoDoc is a graphical documentation browser for the Mono class
674 libraries. Currently, monodoc consists of a Gtk# application and is
675 in heavy development.
678 ** Development Tools and Issues
680 Q: I am having trouble compiling a new version of Mono from CVS, it
681 complains about my runtime being out of sync.
683 A: Jonathan Pryor has provided the following answer:
685 To upgrade your class libraries and compiler, see the See
686 README.building in the MCS directory.
688 The single biggest source of confusion seems to be the "Your
689 runtime is out of sync" messages. Realize that this is *normal*
690 while BUILDING. Think about it: you're building a new class
691 library with the old runtime. If the new class library references
692 a function that the old runtime knows nothing about, the runtime
693 system issues this warning.
695 Basically what needs to happen is for a new mono runtime to be
696 compiled, then the corlib class library be compiled, and once this
697 is done, install the new runtime, followed by corlib.
699 Once this is done, you can continue building your entire
702 Q: Will it be possible to use the CLI features without using byte codes
705 A: Yes. The CLI engine will be made available as a shared library.
706 The garbage collection engine, the threading abstraction, the
707 object system, the dynamic type code system and the JIT will be
708 available for C developers to integrate with their applications if
711 Q: Will you have new development tools?
713 A: With any luck, Free Software enthusiasts will contribute tools to
714 improve the developer environment. These tools could be developed
715 initially using the Microsoft implementation of the CLI and then
716 executed later with Mono.
718 Q: What kind of rules make the Common Intermediate Language useful for
721 A: The main rule is that the stack in the CLI is not a general purpose
722 stack. You are not allowed to use it for other purposes than
723 computing values and passing arguments to functions or return
726 At any given call or return instruction, the types on the stack
727 have to be the same independently of the flow of execution of your
730 Q: Is it true that the CIL is ideal for JITing and not efficient for
733 A: The CIL is better suited to be JITed than JVM byte codes, but you
734 can interpret them as trivially as you can interpret JVM byte
737 Q: Isn't it a little bit confusing to have the name of "XSP" (the same
738 as in the Apache Project) for the ASP.NET support in Mono?.
740 A: In Mono, xsp is just the name of the C# code generator for ASP.NET
741 pages. In the Apache Project, it is a term for the "eXtensible Server
742 Pages" technology so as they are very different things, they don't
745 Q: What about using something like Jabber instead of the System.Messaging
748 A: In short, MSMQ is not something like Jabber, but asynchronous messaging
749 through queues. Useful queues do more than serialize messages, they are
750 also platform bridges.
752 Q: Are you supporting XMLDocument and relatives?.
754 A: Currently, we aren't implementing them yet. It would require updates to
755 most of the XmlNode derivatives so it's not a trivial task. We are
756 currently focusing on getting XPath support working.
758 Q: Is there any plan to develop an aspx server for Mono?.
760 A: The web server turned out to be very simple compared to the rest of the
761 work. Gonzalo has got the page generator mostly done (a module called
762 xsp, who has nothing to do with the XSP term used in the Apache Project).
763 Patrik has done a lot of the work to get the ProcessRequest to work.
764 You can try to help in the final touches to the System.Web classes and
765 writing regression tests for the widgets we have.
767 Q: Is there any way I can develop the class libraries using Linux yet?
769 A: Yes. Some class libraries can be developed on Linux. Search for
770 Paolo's post (he lists which classes can be compiled fine now).
772 Q: Is there any way I can install a known working copy of mono in /usr,
773 and an experimental copy somewhere else, and have both copies use
774 their own libraries? (I'm still not very good at library paths in
777 A: Yes. Just use two installation prefixes.
779 Q: How should I write tests or a tests suite?
781 A: If you do a test suite for C#, you might want to keep it
782 independent of the Mono C# compiler, so that other compiler
783 implementations can later use it.
785 Q: Would it be too terrible to have another corlib signed as mscorlib?
787 A: We rename corlib to mscorlib also when saving the PE files, in fact,
788 the runtime can execute program created by mono just fine.
790 Q: Is there a relatively straightforward way to repeat the steps taken
791 by Paolo to get Mono completely self-hosted on Linux?
793 A: To build the compiler and class libraries in Linux, run:
794 <ul><li>make -f makefile.gnu. To install them, run: </li>
795 <li>make -f makefile.gnu install prefix=/opt/mono</li>
798 If you want to produce and distribute a monocharge tarball, run:
799 make -f makefile.gnu dist
800 Of course you have to run these in the top level mcs directory.
802 Q: Is it possible to build a C# file to some sort of intermediate format which
803 can linked into a final module, like the traditional .c -> .o -> .so path?
805 A: You could do: mcs /target:module file1.cs, mcs /target:module file2.cs,
806 mcs /target:exe file1.dll file2.dll /out:mybin.exe
808 Q: Is there any plans for implementing remoting in the near future?, When will
809 work in System.Runtime.Remoting.dll start?
811 A: The remoting infrastructure is in place. Some of the channels and
814 Q: I'm wondering if there are any plans to start using nant to build the
815 class lib + test lib. i think that every project need/should use an
816 automated build process and nant + a couple of tools enables this. is
817 the problem that the compiler can't run nant yet?
819 A: Maybe well be doing some sort of automated build process + testing when
822 Q: My C code uses the __stdcall which is not availble on Linux, how can I
823 make the code portable Windows/Unix across platforms?
825 A: Replace the __stdcall attribute with the STDCALL macro, and include this
826 in your C code for newer gcc versions:
829 #define STDCALL __attribute__((stdcall))
835 Q: Does Mono support ASP.NET?
839 Mono supports ASP.NET, we have shown an unmodified IBuySpy
840 installation running on Mono as well as various other programs. You can
841 try it yourself downloading the XSP server.
843 Q: Do I need install cygwin to work on ASP.NET in mono or Linux is enough since
844 it is self host right now.
848 Q: How can I run ASP.NET-based applications with Mono?
850 A: You need the Mono runtime and a hosting web server. Currently we distribute a
851 small web server called `xsp' which is used to debug applications, or you can choose
852 to use Daniel's Apache 2 module.
854 Q: Any plan to make ASP.NET in mono works with Apache in Linux?.
856 A: Daniel has authored an Apache2 Module for Mono that hosts the ASP.NET runtime
857 and is available here: <a
858 href="http://apacheworld.org/modmono/">http://apacheworld.org/modmono/</a>
860 Q: Will you support Apache 1?
862 A: Modules developed for Apache 2 are not compatible with Apache 1.3
863 Daniel plans to support Apache 1.3 in the future but the current focus is on
864 Apache 2, because of the better support for threading and Windows.
866 Q: Can I run Apache 1 and Apache 2 on the same machine?
868 You can always keep a copy of Apache 2 running in paralell with your Apache
869 1.3 (either different port or using a reverse proxy).
871 You can also bind the two servers to different IP addresses on the
872 same physical machine.
877 Q: What is the status of ADO.NET support?. Could I start migrating
878 applications from MS.NET to Mono?.
880 A: You could start right now using the ADO.NET support in mono, of course,
881 if you want to help filling the missing gaps while you develop your app
882 :-) Well, what I mean is that we're not that far to having full ADO.NET
883 support in Mono, and we've got a lot of working things, so if we could
884 get more help, we'd finish it really soon :-)
886 Q: In developing the data architecture for the application are there and
887 objects I should stay away from in order to insure the smoothest possible
888 transition (minimum code rewrite) to Mono's ADO.NET implementation? (For
889 example, strongly typed datasets versus untyped datasets, etc...)
891 A: We are implementing all the classes in Microsoft .NET's System.Data, so
892 you can be sure that things will work the same in Mono as with the Microsoft
895 Q: Does Mono can to connect to Sybase by using Mono.Data.*?
897 A: Yes. use Mono.Data.SybaseClient. First of all you have to create a
898 SybaseConnection, and then, from it, use it as any other
899 IDbConnection-based class.
904 Q: Why don't you use Java? After all, there are many languages that
907 A: You can get very good tools for doing Java development on free
908 systems right now. <a href="http://www.redhat.com">Red Hat</a> has
909 contributed a <a href="http://gcc.gnu.org">GCC</a> <a
910 href="http://gcc.gnu.org/java">front-end for Java</a> that can take
911 Java sources or Java byte codes and generate native executables; <a
912 href="http://www.transvirtual.com">Transvirtual</a> has implemented
913 <a href="http://www.kaffe.org">Kaffe</a> a JIT engine for Java;
914 Intel also has a Java VM called <a
915 href="http://www.intel.com/research/mrl/orp">ORP</a>.
917 The JVM is not designed to be a general purpose virtual machine.
918 The Common Intermediate Language (CIL), on the other hand, is
919 designed to be a target for a
920 wide variety of programming languages, and has a set of rules
921 designed to be optimal for JITers.
923 Q: Could Java target the CLI?
925 A: Yes, Java could target the CLI, Microsoft's J# compiler does that.
927 The <a href="http://weblog.ikvm.net/">IKVM</a> project builds a
928 Java runtime that works on top of .NET and on top of Mono. IKVM is
929 essentially a JIT compiler that translates from JVM bytecodes into
930 CIL instructions, and then lets the native JIT engine take over.
932 Q: Is it possible to write a JVM byte code to CIL converter?
934 A: Yes, it is possible. Here are a few starting point:
937 * A byte code representation is really a flattened forest of
938 trees. Look at the Mono JIT engine to see how we compute
939 the basic blocks (this is used to figure out the "trees").
941 The forest is just an array of trees.
943 Indeed, run the JIT engine with -d (mono -d prog.exe) and
944 you will see how these trees look like.
946 You will have to do something similar for Java.
948 * Each "forest of trees" has a meaning. This meaning can now
949 be translated into the equivalent "meaning" in CLR-land.
952 See also the <a href="http://weblog.ikvm.net/">IKVM project</a>
954 Q: Could mono become a hybrid CIL/java platform?
956 A: No. It is quite far from the philosophy of the project. The idea of Mono
957 is, to have only _one_ VM, on which all can run. And if there existing a
958 binary-converter from Java-.class to IL and if there existing something
959 like J-Sharp on Mono, you can write programs in Java, which than can run
960 on Mono. You do not need two bindings (like your example: GTK-Sharp _and_
961 Java-Gnome). You need only _one_ of it (GTK-Sharp). Thats the idea of Mono.
962 An other point is, that there are no people, who use Open Source-JVMs. They
963 all prefer Suns original. But for Unix there don't exist a .NET-Framework.
964 So it is possible, that in the future Mono is the standard .NET for Unixes.
966 Q: Do you plan to implement a Javascript compiler?
968 A: Yes. The beginnings of the JScript compiler can be found on CVS.
969 Cesar coordinates this effort.
971 Q: Can Mono or .NET share system classes (loaded from mscore.dll and other
972 libs) or will it behave like Sun's Java VM?
974 A: What you can do with mono is to load different applications in their own
975 application domain: this is a feature of the CLR that allows sandboxing
976 applications inside a single process space. This is usualy exploited to
977 compartmentalize different parts of the same app, but it can also be
978 effectively used to reduce the startup and memory overhead.
979 Using different appdomains the runtime representation of types and
980 methods is shared across applications.
982 <a name="extending"></a>
985 Q: Would you allow other classes other than those in the
988 A: Yes. The Microsoft class collection is very big, but it is by no
989 means complete. It would be nice to have a port of `Camel' (the
990 Mail API used by Evolution inspired by Java Mail) for Mono
993 You might also want to look into implementing CORBA for Mono. Not
994 only because it would be useful, but because it sounds like a fun
995 thing to do, given the fact that the CLI is such a type rich
998 For more information on extending Mono, see our <a
999 href="ideas.html">ideas</a> page.
1001 Q: Do you plan to Embrace and Extend .NET?
1003 A: Embracing a good technology is good. Extending technologies in
1004 incompatible ways is bad for the users, so we do not plan on
1005 extending the technologies.
1007 If you have innovative ideas, and want to create new classes, we
1008 encourage you to make those classes operate correctly well in both
1011 Today Mono ships with a number of extra libraries that were
1012 developed either by members of the Mono community, or other
1015 Q: Is there any way I can develop the class libraries using Linux yet?
1017 A: Yes. Mono has been selfhosting since March 2002.
1019 Q: Is there any way I can install a known working copy of mono in /usr,
1020 and an experimental copy somewhere else, and have both copies use
1021 their own libraries? (I'm still not very good at library paths in
1024 A: Yes. Just use two installation prefixes.
1027 <a name="portability"></a>
1030 Q: Will Mono only work on Linux?
1032 A: Currently, we are doing our work on Linux-based systems and
1033 Windows. We do not expect many Linux-isms in the code, so it
1034 should be easy to port Mono to other UNIX variants.
1036 Q: What about Mono on non Linux-based systems?
1038 A: Our main intention at Ximian is to be able to develop GNOME
1039 applications with Mono, but if you are interested in providing a
1040 port of the Winforms classes to other platforms (frame buffer or
1041 MacOS X for example), we would gladly integrate them, as long
1042 they are under an open source license.
1044 Q: What operating systems/CPUs do you support
1046 A: Mono currently runs on Linux, Windows, Solaris and FreeBSD.
1047 There is a JIT engine available for x86 processors that can
1048 generate code and optimizations tailored for a particular CPU.
1050 Interpreters exist for the SPARC, PowerPC and StrongARM CPUs.
1052 Q: Does Mono run on Windows?
1054 A: Yes. You can get pre-compiled
1055 binaries from <a href="http://www.go-mono.com/download.html">http://www.go-mono.com/download.html</a>
1057 Q: Does Mono run on Linux?
1059 A: Yes. You can get pre-compiled
1060 binaries from <a href="http://www.go-mono.com/download.html">http://www.go-mono.com/download.html</a>
1062 Q: Will I require Cygwin to run mono?
1064 A: No. Cygwin is only required to build Mono.
1066 Q: Will Mono depend on GNOME?
1068 A: It will depend only if you are using a particular assembly (for
1069 example, for doing GUI applications). If you are just interested
1070 in Mono for implementing a `Hello World Enterprise P2P Web
1071 Service', you will not need any GNOME components.
1073 Q: Is anyone working on porting Mono to IA-64?
1075 A: Nobody is working on such port.
1077 Q: If I were about to start a Mono port to IA-64,would the same lburg code
1078 generator work for IA-64 also? or anything else need to be used for code
1079 generation(as the processor architecture is totally different from IA32)
1081 A: The lburg approach can be use for any processor architecture. But you might
1082 think in another better approach.
1084 Q: Do you plan to port Rhino to C#?.
1086 A: Eto Demerzal has started a Rhino port to C#.
1088 Q: Has anyone succeeded in building a Mac version of the C# environment.
1089 If so can you explain how?
1091 A: You could try to check with the Darwin people, or the Fink people.
1092 Mono/C# is self hosting on Linux/PPC which is the hard part, so it
1093 should be relatively simple to get it to work on MacOS
1095 <a name="reuse"></a>
1096 ** Reusing Existing Code
1098 Q: What projects will you reuse or build upon?
1100 A: We want to get Mono in the hands of programmers soon. We are
1101 interested in reusing existing open source software.
1103 Q: What about Intel's research JIT framework, ORP?
1105 A: At this time, we are investigating whether we can use elements of
1106 ORP for Mono. ORP is a research JIT engine that has a clearly
1107 defined API that splits the JIT from the GC system and the actual
1108 byte code implementation.
1110 We are using some pieces of ORP (Their code generation interface)
1111 and we use it as a source of inspiration for optimizations. Paolo
1112 and Dietmar consider ORP as being one of the best JIT engines out
1113 there (and their research work and papers are very useful if you are
1114 interested in JIT technology).
1116 Q: What about using GNU Lightning?
1118 A: We are not using GNU Lightning. Our JIT is using an instruction
1119 selector based on tree-pattern matching, and a code generation
1120 interface that is very tied to the current architecture.
1122 Q: Will I be able to use Microsoft SQL Server 2000 or will I need to switch
1123 to a specific Open Source Database. Will I need to recode?
1125 A: There should not be any need to recode.
1127 Q: What do I need to watch out for when programming in VB.NET so that I'm
1128 sure to be able to run those apps on Linux?
1130 A: Not making any PInvoke or DLL calls should and not using anything in
1131 the Microsoft.* namespaces should suffice. Also do not use any
1132 Methods/Classes marked as "This type/method supports the .NET Framework
1133 infrastructure and is not intended to be used directly from your code."
1134 even if you know what these classes/methods do.
1136 Q: Will built-in reporting be supported for crystal reports? This is a
1137 heavily used part of our system.
1139 A: Probably not. Crystal Reports are propriety. Someone may try to emulate
1140 the behavior, but no-one has yet volunteered.
1142 Q: Who about writing to the registry? As I understand it, Linux does not have
1143 a counterpart to the registry. Should I avoid relying on that feature?
1145 A: Try to avoid it. Although there would be a emulation for registry in
1146 Mono too. GNOME does have a registry like mechanism for configuration. But
1147 Even if gnome has a configuration system similar to the registry, the keys
1148 will not be equal, so you will probably end up having to do some runtime
1149 detection, and depending on this load an assembly that has your
1150 platform-specific hacks.
1152 Q: System.Data.SqlClient with FreeTDS, will you port parts of these to C# and
1155 A: if their license is compatible with mono's, yes, we'd think about porting
1156 them. If not, we'll continue with the plan of using FreeTDS.
1161 Q: Are you working on a GCC front-end to C#? A GCC back-end that will
1162 generate CIL images? What about making a front-end to GCC that
1163 takes CIL images and generates native code?
1165 A: We are currently seeking volunteers for those projects.
1166 Visit the <a href="contributing.html">contributing</a> section if
1169 Q: But would this work around the GPL in the GCC compiler and allow
1170 people to work on non-free front-ends?
1172 A: People can already do this by targeting the JVM byte codes (there
1173 are about 130 compilers for various languages that target the JVM).
1175 Q: Why are you writing a JIT engine instead of a front-end to GCC?
1177 A: We want the JIT engine and runtime engine because they will be able
1178 to execute CIL executables generated on Windows, and so no recompilation
1181 <a name="performance"></a>
1184 Q: How fast will Mono be?
1186 A: We can not predict the future, but a conservative estimate is that
1187 it would be at least `as fast as other JIT engines'.
1189 We would like to ship various JIT engines with Mono, just like
1190 Microsoft has done with their .NET development platform. We could
1191 provide a faster, JIT for fast load times but lower performance,
1192 and an and an optimizing JIT that would be slower at generating
1193 code but produce more optimal output.
1195 The CIL has some advantages over the Java byte code: it is really
1196 an intermediate representation and there are a number of
1197 restrictions on how you can emit CIL code that simplify creating
1200 For example, on the CIL, the stack is not really an abstraction
1201 available for the code generator to use at will. Rather, it is a
1202 way of creating a postfix representation of the parsed tree. At
1203 any given call point or return point, the contents of the stack are
1204 expected to contain the same object types independently of how the
1205 instruction was reached.
1207 <a name="licensing"></a>
1210 Q: Will I be able to write proprietary applications that run with
1213 A: Yes. The licensing scheme is planned to allow proprietary
1214 developers to write applications with Mono.
1216 Q: What license or licenses are you using for the Mono Project?
1218 A: The C# Compiler is released under the terms of the <a
1219 href="http://www.opensource.org/licenses/gpl-license.html">GNU GPL</a>. The runtime
1220 libraries are under the <a
1221 href="http://www.opensource.org/licenses/lgpl-license.html">GNU
1222 Library GPL</a>. And the class libraries are released
1223 under the terms of the <a
1224 href="http://www.opensource.org/licenses/mit-license.html">MIT X11</a>
1227 The Mono runtime and the Mono C# Compiler are also available under
1228 a proprietary license for those who can not use the LGPL and the
1231 For licensing details, contact <a
1232 href="mailto:mono-licensing@ximian.com">mono-licensing@ximian.com</a>
1235 Q: I would like to contribute code to Mono under a particular
1236 license. What licenses will you accept?
1238 A: We will have to evaluate the licenses for compatibility first,
1239 but as a general rule, we will accept the code under the same
1240 terms of the "container" module.
1242 <a name="patents"></a>
1245 Q: Could patents be used to completely disable Mono (either submarine
1246 patents filed now, or changes made by Microsoft specifically to
1247 create patent problems)?
1249 A: First some background information.
1251 The .NET Framework is divided in two parts: the ECMA/ISO covered
1252 technologies and the other technologies developed on top of it like
1253 ADO.NET, ASP.NET and Windows.Forms.
1255 Mono implements the ECMA/ISO covered parts, as well as being a
1256 project that aims to implement the higher level blocks like
1257 ASP.NET, ADO.NET and Windows.Forms.
1259 The Mono project has gone beyond both of those components and has
1260 developed and integrated third party class libraries, the most
1261 important being: Debugging APIs, integration with the Gnome
1262 platform (Accessibility, Pango rendering, Gdk/Gtk, Glade, GnomeUI),
1263 Mozilla, OpenGL, extensive database support (Microsoft only
1264 supports a couple of providers out of the box, while Mono has
1265 support for 11 different providers), our POSIX integration
1266 libraries and finally the embedded API (used to add scripting to
1267 applications and host the CLI, or for example as an embedded
1270 The core of the .NET Framework, and what has been patented by
1271 Microsoft falls under the ECMA/ISO submission. Jim Miller at
1272 Microsoft has made a statement on the patents covering ISO/ECMA,
1273 (he is one of the inventors listed in the patent): <a
1274 href="https://mailserver.di.unipi.it/pipermail/dotnet-sscli/msg00218.html">here</a>.
1276 Basically a grant is given to anyone who want to implement those
1277 components for free and for any purpose.
1279 The controversial elements are the ASP.NET, ADO.NET and
1280 Windows.Forms subsets. Those are convenient for people who need
1281 full compatibility with the Windows platform, but are not required
1282 for the open source Mono platform, nor integration with today's
1283 Mono's rich support of Linux.
1285 The Mono strategy for dealing with these tehcnologies is as
1286 follows: (1) work around the patent by using a different
1287 implementation techinque that retains the API, but changes the
1288 mechanism; if that is not possible, we would (2) remove the pieces
1289 of code that were covered by those patents, and also (3) find prior
1290 art that would render the patent useless.
1292 Not providing a patented capability would weaken the
1293 interoperability, but it would still provide the free software /
1294 open source software community with good development tools, which
1295 is the primary reason for developing Mono.
1297 The patents do not apply in countries where software patents are
1300 For Linux server and desktop development, we only need the ECMA
1301 components, and things that we have developed (like Gtk#) or Apache
1305 ** Miscellaneous Questions
1307 Q: You say that the CLI allows multiple languages to execute on the
1308 same environment. Isn't this the purpose of CORBA?
1310 A: The key difference between CORBA (and COM) and the CLI is that the
1311 CLI allows "data-level interoperability" because every
1312 language/component uses the same data layout and memory management.
1314 This means you can operate directly upon the data types that someone
1315 else provides, without having to go via their interfaces. It also
1316 means you don't have to "marshal" (convert) parameters (data
1317 layouts are the same, so you can just pass components directly) and
1318 you don't have to worry about memory management, because all
1319 languages/components share the same garbage collector and address
1320 space. This means much less copying and no need for reference
1323 Q: Will you support COM?
1325 A: The runtime will support XPCOM on Unix systems and COM on Windows.
1326 Most of the code for dynamic trampolines exists already.
1328 Q: Will Ximian offer certifications on Mono or related technologies?.
1330 A: It's possible. But there is no plan about this. So the short answer is no.
1332 Q: Are there any Boehm's GC binaries?
1334 A: Yes. You can find RPMs <a href="http://java.thn.htu.se/~toor/">here</a>, though
1335 if your distribution provides the correct packages, you should use those.
1336 The suggested version of the Boehm GC is 6.1.
1338 Q: How can I report a bug?
1340 A: The best thing is to track down the bug and provide a simple test to
1341 reproduce the bug. You can then add the bug to the
1342 <a href="http://bugzilla.ximian.com/enter_bug.cgi">bugtracking system</a>.
1344 Please provide information about what version of mono you're using
1345 and any relevant details to be able to reproduce the bug. Note that
1346 bugs reported on the mailing-list may be easily forgotten, so it's
1347 better to file them in the <a href="http://bugzilla.ximian.com/enter_bug.cgi">bug tracking system</a>.
1349 Q: Does mcs support the same command line options as the MS C#
1352 A: The Mono C# compiler now supports the same command line
1353 arguments as the Microsoft C# compiler does.
1355 Q: How about getting searchable archives on lists.ximian.com?
1357 A: You can perform a search on the mono-related mailing lists
1358 <a href="http://www.go-mono.com/mailing-lists.html">here</a>.
1360 Q: When using mono from cvs or from a snapshot, I get an error messaage
1361 saying that Mono and the runtime are out of sync. How do I fix that?
1363 A: If you use mono from cvs, you need to be prepared for changes in the
1364 runtime internals. This means that you should keep a working setup
1365 before blindling updating (a working setup may just be the last released
1366 tarball or a recent binary snapshot).
1367 Usually, compiling corlib with mcs before recompiling the C runtime does
1368 the right thing (but occasionally you may need to do it the other
1371 Q: Why are you going for a GtkHtml implementation?
1373 A: GtkHTML is just a lightweight HTML rendering engine that does not
1374 support CSS, so we need it to look decent for those of us that will
1375 be using the documentation in our day-to-day work on Linux. The
1376 Web-based interfaces lack the agility that you get from a native GUI
1377 tool to browse your documentation. Probably later on, we will write
1378 scripts and generate a full documentation set that is web-browsable,
1379 but we need a command-line and GUI tools that we can use natively on
1380 Linux when disconnected from the Web (and that has better
1381 interactions than a web page).
1383 Q: Is there a command-line tool that allows me to access .NET interactively?
1385 A: There are several but one that is free software and uses MCS is the one
1386 Dennis Lu from Rice University is working on; a REPL C# interpreter.
1388 Q: Is it possible to use Visual C++ with Mono?.
1390 A: It's possible to run VC++ generated apps under Mono, but we do not
1391 provide a Manager C++ compiler ourselves.
1393 <a name="problems"></a>
1394 ** Mono Common Problems
1396 If you are having problems compiling or running Mono software
1397 or if you think that you found a bug, etc. Please visit the
1398 <a href="http://geneura.ugr.es/~jaime/deploy/mono-common-problems.html">Mono Common Problems</a> document and try there.
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