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="#pnpproject">Mono and the Portable.NET Project</a><br>
7 <a href="#webservices">Web Services</a><br>
8 <a href="#asp">Mono and ASP.NET</a><br>
9 <a href="#ado">Mono and ADO.NET</a><br>
10 <a href="#monodoc">MonoDoc</a><br>
11 <a href="#devel">Development Tools and Issues</a><br>
12 <a href="#java">Mono and Java</a><br>
13 <a href="#extending">Extending Mono</a><br>
14 <a href="#portability">Portability</a><br>
15 <a href="#reuse">Reusing Existing Code</a><br>
16 <a href="#gcc">Mono and GCC</a><br>
17 <a href="#performance">Performance</a><br>
18 <a href="#licensing">Licensing</a><br>
19 <a href="#patents">Patents</a><br>
20 <a href="#etc">Miscellaneous Questions</a><br>
21 <a href="#problems">Mono Common Problems</a><br>
24 href="http://www.es.gnome.org/documentacion/articulos/mono-puf/mono-puf/">Spanish
25 translation</a> is also available
30 Q: What is Mono exactly?
32 A: The Mono Project is an open development initiative sponsored by
33 Ximian that is working to develop an open source, Unix
34 version of the Microsoft .NET development platform. Its objective
35 is to enable Unix developers to build and
36 deploy cross-platform .NET Applications. The project will
37 implement various technologies developed by Microsoft that have now
38 been submitted to the ECMA for standardization.
40 Q: What is the difference between Mono and the .NET Initiative?
42 A: The ".NET Initiative" is a somewhat nebulous company-wide effort by
43 Microsoft, one part of which is a cross-platform development
44 framework. Mono is an implementation of the development framework,
45 but not an implementation of anything else related to the .NET
46 Initiative, such as Passport, software-as-a-service, or
47 corporate re-branding.
49 Q: What technologies are included in Mono?
51 A: Mono contains a number of components useful for building new
55 * A Common Language Infrastructure (CLI) virtual
56 machine that contains a class loader, Just-in-time
57 compiler, and a garbage collecting runtime.
59 * A class library that can work with any language
60 which works on the CLR.
62 * A compiler for the C# language. In the future we
63 might work on other compilers that target the Common
68 Windows has compilers that target the virtual machine from <a
69 href="http://msdn.microsoft.com/net/thirdparty/default.asp#lang">a
70 number of languages:</a> Managed C++, Java Script, Eiffel,
71 Component Pascal, APL, Cobol, Perl, Python, Scheme,
72 Smalltalk, Standard ML, Haskell, Mercury and Oberon.
74 The CLR and the Common Type System (CTS) enables applications and
75 libraries to be written in a collection of different languages that
78 This means for example that if you define a class to do algebraic
79 manipulation in C#, that class can be reused from any other
80 language that supports the CLI. You could create a class in C#,
81 subclass it in C++ and instantiate it in an Eiffel program.
83 A single object system, threading system, class libraries, and
84 garbage collection system can be shared across all these languages.
86 Q: Where can I find the specification for these technologies?
88 A: You can find the information here:
91 C# <a href="http://www.ecma.ch/ecma1/STAND/ecma-334.htm">http://www.ecma.ch/ecma1/STAND/ecma-334.htm</a>
93 CLI <a href="http://www.ecma.ch/ecma1/STAND/ecma-335.htm">http://www.ecma.ch/ecma1/STAND/ecma-335.htm</a>
95 Q: Will you implement the .NET Framework SDK class libraries?
97 A: Yes, we will be implementing the APIs of the .NET Framework SDK
100 Q: Will you offer an ECMA-compliant set of class libraries?
102 A: Eventually we will. Our current focus is on inter-operating
103 with the Microsoft SDK, but we will also offer an ECMA compliant
106 Q: What does the name "Mono" mean?
108 A: Mono is the word for `monkey' in Spanish. We like monkeys.
112 A: The JIT engine is usable on Intel x86 machines. An interpreter
113 can be used on other non-Intel x86 machines.
115 The class libraries are mature enough to run some real applications
116 (the compiler for instance, and every day more and more applications
117 are natively developed with Mono).
119 Q: When will you ship it?
121 A: Different parts of Mono will achieve usability at different stages,
122 once we are comfortable with the compiler, we will release "Mono Core",
123 which contains everything needed to develop applications with the base
124 class libraries. This should be available at some point during 2002.
126 Other higher level class libraries (ASP.NET, ADO.NET) will
127 be released when they become stable.
129 Q: What major components will you include in Mono?
131 A: Hopefully everything that Microsoft ships on their Framework
132 (ADO.NET, ASP.NET), and
133 we encourage third party developers to create reusable components that
134 work on both Mono and Windows.
136 Q: How can I contribute?
138 A: Check the <a href="contributing.html">contributing</a> section.
140 Q: Aren't you just copying someone else's work?
142 A: We are interested in providing the best tools for programmers to
143 develop applications for Free Operating Systems. We also want to help
144 provide the interoperability that will allow those systems to fit in
145 with other standards.
147 For more background, read the <a href="http://www.go-mono.com/rationale.html">Mono
148 Project white paper</a>.
151 Q: Miguel said once that Mono was being implemented in COBOL. Is that true?.
153 A: No. It was a joke.
156 <a name="ximian"></a>
158 ** The Ximian Role in the Mono Project
160 Q: Why is Ximian working on .NET?
162 A: Ximian is interested in providing the best tools for programmers to
163 develop applications for Free Operating Systems.
165 For more information, read the project <a
166 href="rationale.html">rationale</a> page.
168 Q: Will Ximian be able to take on a project of this size?
170 A: Of course not. Ximian a supporter of the Mono project, but the only way
171 to implement something of this size is for the entire free software
172 community to get involved. Visit the <a href="contributing.html">contributing</a>
173 page if you'd like to help out.
175 Q: What pieces will Ximian be working on?
177 A: We will devote most of our resources to work on the pieces which are
178 on the critical path to release a development and execution
179 environment. Once the project is at a stage where it is useful in
180 the real world, it will achieve a critical mass of developers to
183 Q: Will Ximian offer Mono commercially?
185 A: When Mono is ready to be shipped Ximian will offer a commercial
186 support and services for Mono.
188 Q: Does Ximian provide consulting services around Mono?
190 A: Yes, Ximian does provide consulting services around Mono to
191 make it suitable to your needs. Porting the runtime engine,
192 customizing it, working on specific classes or tuning the code
193 for your particular needs.
195 Q: Will you wait until Mono is finished?
197 A: Mono will ship on various stages as they mature. Some people
198 require only a subset of the technologies, those will ship first.
200 More advanced features will take more time to develop. A support
201 time line will be available in June 2002.
206 Q: How is Mono related to GNOME?
208 A: In a number of ways. This project was born out of the need of
209 providing improved tools for the GNOME community, and will use
210 existing components that have been developed for GNOME when they
211 are available. For example, we plan to use Gtk+ and Libart to
212 implement Winforms and the Drawing2D API and are considering
215 Q: Has the GNOME Foundation or the GNOME team adopted Mono?
217 A: Mono is too new to be adopted by those groups. We hope that the
218 tools that we will provide will be adopted by free software
219 programmers including the GNOME Foundation members and the GNOME
222 Q: Should GNOME programmers switch over to Mono now?
224 A: It is still far to early for discussions of "switching over." No
225 pieces of Mono will be ready within the next six months, and a
226 complete implementation is roughly one year away.
228 We encourage GNOME developers to continue using the existing tools,
229 libraries and components. Improvements made to GNOME will have an
230 impact on Mono, as they would be the "back-end" for various classes.
232 Q: Will Mono include compatibility with Bonobo components? What is the
233 relationship between Mono and Bonobo?
235 A: Yes, we will provide a set of classes for implementing and using
236 Bonobo components from within Mono. Mono should allow you to write
237 Bonobo components more easily, just like .NET on Windows allows you
238 to export .NET components to COM.
240 Q: Does Mono depend on GNOME?
242 A: No, Mono does not depend on GNOME. We use a few packages produced by
243 the GNOME team like the `glib' library.
245 Q: But will I be able to build GNOME applications?
247 A: Yes, we will enable people to write GNOME applications using Mono.
249 Q: Do you have C# bindings for GNOME?.
251 A: Yes, we currently bind libgnome, libgnomecanvas, and libgnomeui --
252 although I dare say I have no idea how functional the bindings are
253 outside of what I tested in the sample app. I imagine other libraries
254 under the GNOME framework will be added on an as-needed (and as-requested)
255 basis...although a truly good bonobo binding will have to wait on the CORBA
256 remoting support which has been started recently.
261 Q: Will Mono enable GUI applications to be authored?
263 A: Yes, you will be able to build GUI applications. Indeed, that is our
264 main focus. We will provide both the Windows.Forms API and the Gtk# API.
266 Q: What is the difference between Gtk# and System.Windows.Forms?
268 A: Gtk# is a set of bindings for the Gtk+ toolkit for C# (and other
269 CIL-enabled languages). System.Windows.Forms is an API defined
270 by Microsoft to build GUI applications.
272 Q: Will I be able to run my smart clients on systems powered by Mono?
274 A: As long as your applications are 100% .NET and do not make use
275 of P/Invoke to call Win32 functions, your smart client applications
276 will run on Mono platforms.
278 Q: Where can I learn more about Gtk#?
280 A: The following <a href="http://gtk-sharp.sourceforge.net>link</a> sends you to the page of the project.
282 Q: What can I do with Gtk#?.
284 A: Gtk# is becoming very usable and you can create applications and
285 applets like those you see in a GNOME desktop environment. It's
286 easy to install so it's worth a try.
288 Q: How can I compile my HelloWorld.cs which uses Gtk#?.
290 A: Try: mcs --unsafe -o HelloWorld.exe -r glib-sharp -r pango-sharp -r
291 atk-sharp -r gdk-sharp -r gtk-sharp -r gdk-imaging-sharp
294 Q: Is there any way how to connect DataAdapter to some GTK# controls?
296 A: There is a sample file called `DbClient' in gtk-sharp/samples that you
297 might to look at. It is a sample program in Gtk# that adds/updates/deletes
298 information on a Postgress database. When we have the new table/tree widgets,
299 I am sure someone would write an adapter for System.Data (in Gtk2 the
300 tree/list widgets are written using a view/model, so you only need to write
301 a model that maps to the database). You can have a look at
302 gtk-sharp/sample/DbClient, where there is a GTK# application that uses
303 System.Data. It does not use DataAdapter, but DataReader though.
305 Q: Do you have an estimate for when Windows.Forms will be released?
307 A: We do not know, volunteers are working on this, but there is no set
308 date yet. The current approach is using the Wine Library to implement
312 ** Mono and Microsoft
314 Q: Is Microsoft helping Ximian with this project?
316 A: No. Ximian CTO Miguel de Icaza had a friendly conversation with
317 Microsoft software architect David Stutz, but that's about the
318 extent of the contact. Microsoft is interested in other
319 implementations of .NET and are willing to help make the ECMA spec
320 more accurate for this purpose.
322 Ximian representatives have also spoken with Sam Ruby at the ECMA
323 TG3 committee to discuss the same issues.
325 Q: Is Microsoft or Corel paying Ximian to do this?
329 Q: Do you fear that Microsoft will change the spec and render Mono
332 A: No. Microsoft proved with the CLI and the C# language that it was
333 possible to create a powerful foundation for many languages to
334 inter-operate. We will always have that.
336 Even if changes happened in the platform which were undocumented,
337 the existing platform would a value on its own.
339 Q: Are you writing Mono from the ECMA specs?
341 A: Yes, we are writing them from the ECMA specs and the published
342 materials in print about .NET.
344 Q: If my applications use Mono, will I have to pay a service fee?
346 A: No. Mono is not related to Microsoft's initiative of
347 software-as-a-service.
349 Q: Is the Mono Project is related to the Microsoft Hailstorm effort? Is
350 Ximian endorsing Hailstorm?
352 A: No. The Mono Project is focused on providing a compatible set of
353 tools for the Microsoft .NET development platform. It does not
354 address, require, or otherwise endorse the MS Passport-based
355 Hailstorm single sign-on system that is part of Windows XP and
358 Q: Will Mono or .NET applications depend on Microsoft Passport?
360 A: No. MS Passport is unrelated to running .NET compatible applications
361 produced with the Mono tools. The only thing you will need is a
362 just-in-time compiler (JIT).
364 Q: What is a 100% .NET application?
366 A: A `100% .NET application' is one that only uses the APIs defined
367 under the System namespace and does not use PInvoke. These
368 applications would in theory run unmodified on Windows, Linux,
369 HP-UX, Solaris, MacOS X and others.
371 Q: If Microsoft will release a port of their .NET platform under the
372 `Shared Source' license, why should I bother with anything else?
374 A: The Shared Source implementation will be expensive and its uses
375 will be tightly restricted, especially for commercial use. We are
376 working towards an implementation that will grant a number of
377 important rights to recipients: use for any purpose,
378 redistribution, modification, and redistribution of modifications.
380 This is what we call <a
381 href="http://www.gnu.org/philosophy/free-sw.html">Free Software</a>
383 Q: Is Mono a free implementation of Passport?
385 A: No. Mono is just a runtime, a compiler and a set of class
388 Q: Will the System.Web.Security.PassportIdentity class mean
389 that my software will depend on Passport?
391 A: No. Applications may use that API to contact a Passport site, but
392 are not required to do so.
394 As long as your application does not use Passport, you will not
397 Q: Will Mono running on Linux make Passport available for Linux?
399 A: No. However, the Passport toolkit for Linux-based web servers is
400 available from Microsoft.
402 Q: Will Mono allow me to run Microsoft Office on Linux?
404 A: No, it will not. Microsoft Office is a Windows application. To
405 learn more about running Windows applications on Intel Unix systems
406 refer to <a href="http://www.winehq.com">the Wine Project</a>.
408 Q: Will I be able to compile a Microsoft VB.NET application and execute
409 the resultant MSIL file under MONO on Linux without converting to C#
412 A: Once we have a complete VisualBasic runtime, yes.
414 Q: Can mono run the WebMatrix?
416 A: No. That requires System.Windows.Forms support which is not
417 currently implemented.
419 Q: Does mono have something like Passport?
420 Will mono have a server side Passport/Similar framework for XSP as well as client classes?
422 A: Not yet, but the client side API for authentication is not the problem.
423 We will likely have a lot of other authentication APIs, like the Liberty
424 Alliance APIs. The problem is people on the web provider end that might use
425 this for authentication.
427 <a name="pnpproject"></a>
428 ** Mono and Portable.NET
430 Q: What are the differences between Mono and Portable.NET?
432 A: Most of Mono is being written using C#, with only
433 a few parts written in C (The JIT engine, the runtime, the
434 interfaces to the garbage collection system).
436 It is easier to describe what is unique about Mono:
438 <li> A self-hosting C# compiler written in C#, which is clean, easy
441 <li> A multi-platform runtime engine: both a JIT engine and an
442 interpreter exist. The JIT engine runs currently on x86
443 systems, while the interpreter works on SPARC, StrongARM and
446 <li> Supports Linux, Windows and Solaris at this point.
448 <li> The JIT engine is written using a portable instruction
449 selector which not only generates good code (we are told
450 that we are faster than Rotor, but it is hard to tell) but
451 is also the foundation to re-target the JIT engine to other
454 The system employed is described in various compiler
455 books and it is very similar to what is described in the
456 book that covers LCC, the ANSI C retargetable C compiler.
458 <li> The JIT engine supports in-lining, constant folding and propagation,
460 <li> Full support for remoting in the runtime, but the class
461 libraries are still behind.
463 <li> The C# compiler, the JIT engine and the class libraries are
464 mature enough that the whole system is self-hosting. This means that
465 we develop Mono completely with itself at this point.
467 <li> We are not yet done, and there is a lot of work left to be
470 <li> We have a great community of developers, without which Mono
471 would not be possible.
473 <li> We will provide an ahead of time compilation mode in the
477 <a name="webservices"></a>
480 Q: How is Mono related to Web Services?
482 A: Mono is only related to Web Services in that it will implement the
483 same set of classes that have been authored in the .NET Framework
484 to simplify and streamline the process of building Web Services.
486 But most importantly, Mono is an Open Source implementation of the
489 Q: Can I author Web Services with Mono?
491 A: You will be able to write Web Services on .NET that run on Mono and
494 Q: If Mono implements the SDK classes, will I be able to write and
495 execute .NET Web Services with it?
497 A: Yes. When the project is finished, you will be able to use the
498 same technologies that are available through the .NET Framework SDK
499 on Windows to write Web Services.
501 Q: What about Soup? Can I use Soup without Mono?
503 A: Soup is a library for GNOME applications to create SOAP servers and
504 SOAP clients, and can be used without Mono. You can browse the
505 source code for soup using <a
506 href="http://cvs.gnome.org/bonsai">GNOME's Bonsai</a>.
510 A: Yes. The CLI contains enough information about a class that
511 exposing it to other RPC systems (like CORBA) is really simple, and
512 does not even require support from an object.
514 We will be implementing CORBA inter-operation as an extension to the
515 Mono classes so that we can integrate with Bonobo, just like
516 Microsoft provides COM inter-operation classes and support
519 Q: Can I serialize my objects to other things other than XML?
521 A: Yes, although the serializing tools have not yet been planned, and
522 you would probably have to implement them yourself.
524 Q: Will Mono use ORBit?
526 A: No. Mono will be using a new implementation of CORBA that isn't still started.
528 <a name="monodoc"></a>
533 A: MonoDoc is a graphical documentation editor and viewer. Currently, MonoDoc
534 consists of a Gtk# application and is in heavy development. There is also a
539 ** Development Tools and Issues
541 Q: Will it be possible to use the CLI features without using byte codes
544 A: Yes. The CLI engine will be made available as a shared library.
545 The garbage collection engine, the threading abstraction, the
546 object system, the dynamic type code system and the JIT will be
547 available for C developers to integrate with their applications if
550 Q: Will you have new development tools?
552 A: With any luck, Free Software enthusiasts will contribute tools to
553 improve the developer environment. These tools could be developed
554 initially using the Microsoft implementation of the CLI and then
555 executed later with Mono.
557 Q: What kind of rules make the Common Intermediate Language useful for
560 A: The main rule is that the stack in the CLI is not a general purpose
561 stack. You are not allowed to use it for other purposes than
562 computing values and passing arguments to functions or return
565 At any given call or return instruction, the types on the stack
566 have to be the same independently of the flow of execution of your
569 Q: Is it true that the CIL is ideal for JITing and not efficient for
572 A: The CIL is better suited to be JITed than JVM byte codes, but you
573 can interpret them as trivially as you can interpret JVM byte
576 Q: Isn't it a little bit confusing to have the name of "XSP" (the same
577 as in the Apache Project) for the ASP.NET support in Mono?.
579 A: In Mono, xsp is just the name of the C# code generator for ASP.NET
580 pages. In the Apache Project, it is a term for the "eXtensible Server
581 Pages" technology so as they are very different things, they don't
584 Q: What about using something like Jabber instead of the System.Messaging
587 A: In short, MSMQ is not something like Jabber, but asynchronous messaging
588 through queues. Useful queues do more than serialize messages, they are
589 also platform bridges.
591 Q: Are you supporting XMLDocument and relatives?.
593 A: Currently, we aren't implementing them yet. It would require updates to
594 most of the XmlNode derivatives so it's not a trivial task. We are
595 currently focusing on getting XPath support working.
597 Q: Is there any plan to develop an aspx server for Mono?.
599 A: The web server turned out to be very simple compared to the rest of the
600 work. Gonzalo has got the page generator mostly done (a module called
601 xsp, who has nothing to do with the XSP term used in the Apache Project).
602 Patrik has done a lot of the work to get the ProcessRequest to work.
603 You can try to help in the final touches to the System.Web classes and
604 writing regression tests for the widgets we have.
606 Q: Is there any way I can develop the class libraries using Linux yet?
608 A: Yes. Some class libraries can be developed on Linux. Search for
609 Paolo's post (he lists which classes can be compiled fine now).
611 Q: Is there any way I can install a known working copy of mono in /usr,
612 and an experimental copy somewhere else, and have both copies use
613 their own libraries? (I'm still not very good at library paths in
616 A: Yes. Just use two installation prefixes.
618 Q: How should I write tests or a tests suite?
620 A: If you do a test suite for C#, you might want to keep it
621 independent of the Mono C# compiler, so that other compiler
622 implementations can later use it.
624 Q: Would it be too terrible to have another corlib signed as mscorlib?
626 A: We rename corlib to mscorlib also when saving the PE files, in fact,
627 the runtime can execute program created by mono just fine.
629 Q: Is there a relatively straightforward way to repeat the steps taken
630 by Paolo to get Mono completely self-hosted on Linux?
632 A: To build the compiler and class libraries in Linux, run:
633 <ul><li>make -f makefile.gnu. To install them, run: </li>
634 <li>make -f makefile.gnu install prefix=/opt/mono</li>
637 If you want to produce and distribute a monocharge tarball, run:
638 make -f makefile.gnu dist
639 Of course you have to run these in the top level mcs directory.
641 Q: Is it possible to build a C# file to some sort of intermediate format which
642 can linked into a final module, like the traditional .c -> .o -> .so path?
644 A: You could do: mcs /target:module file1.cs, mcs /target:module file2.cs,
645 mcs /target:exe file1.dll file2.dll /out:mybin.exe
647 Q: Is there any plans for implementing remoting in the near future?, When will
648 work in System.Runtime.Remoting.dll start?
650 A: The remoting infrastructure is in place. Some of the channels and
653 Q: I'm wondering if there are any plans to start using nant to build the
654 class lib + test lib. i think that every project need/should use an
655 automated build process and nant + a couple of tools enables this. is
656 the problem that the compiler can't run nant yet?
658 A: Maybe well be doing some sort of automated build process + testing when
664 Q: Is Mono supporting ASP.NET?
666 A: Yes. The development of the support for ASP.NET comes in various stages,
667 here is what Gonzalo has been working on: 1. The Parser. 2. Getting the
668 parser to generate output compatible with ASP.NET. 3. Running the sample
669 output with the real Microsoft runtime but using our generated page. 4.
670 Running the sample with our classes with the .NET runtime. 5. Running
671 our sample code with our classes with our runtime. This is the process
672 we are following. Currently Gonzalo has reached point 5.
674 Q: Do I need install cygwin to work on ASP.NET in mono or Linux is enough since
675 it is self host right now.
679 Q: Any plan to make ASP.NET in mono works with Apache in Linux?.
681 A: Yes, we have plans to do so, but we need to wait for Patrik's patches to
682 HttpRuntime. Once that is there, writing a mod_mono should be trivial
683 (look at mono/samples/embed for a sample embedded application).
688 Q: What is the status of ADO.NET support?. Could I start migrating
689 applications from MS.NET to Mono?.
691 A: You could start right now using the ADO.NET support in mono, of course,
692 if you want to help filling the missing gaps while you develop your app
693 :-) Well, what I mean is that we're not that far to having full ADO.NET
694 support in Mono, and we've got a lot of working things, so if we could
695 get more help, we'd finish it really soon :-)
697 Q: In developing the data architecture for the application are there and
698 objects I should stay away from in order to insure the smoothest possible
699 transition (minimum code rewrite) to Mono's ADO.NET implementation? (For
700 example, strongly typed datasets versus untyped datasets, etc...)
702 A: We are implementing all the classes in Microsoft .NET's System.Data, so
703 you can be sure that things will work the same in Mono as with the Microsoft
709 Q: Why don't you use Java? After all, there are many languages that
712 A: You can get very good tools for doing Java development on free
713 systems right now. <a href="http://www.redhat.com">Red Hat</a> has
714 contributed a <a href="http://gcc.gnu.org">GCC</a> <a
715 href="http://gcc.gnu.org/java">front-end for Java</a> that can take
716 Java sources or Java byte codes and generate native executables; <a
717 href="http://www.transvirtual.com">Transvirtual</a> has implemented
718 <a href="http://www.kaffe.org">Kaffe</a> a JIT engine for Java;
719 Intel also has a Java VM called <a
720 href="http://www.intel.com/research/mrl/orp">ORP</a>.
722 The JVM is not designed to be a general purpose virtual machine.
723 The Common Intermediate Language (CIL), on the other hand, is
724 designed to be a target for a
725 wide variety of programming languages, and has a set of rules
726 designed to be optimal for JITers.
728 Q: Could Java target the CLI?
730 A: Yes, Java could target the CLI. We have details on a <a
731 href="ideas.html#guavac">project</a> that someone could take on to
734 Microsoft has an implementation of the Java language called J# that
735 can target the CIL execution engine.
737 Q: Is it possible to write a JVM byte code to CIL converter?
739 A: Yes, it is possible. Here are a few starting point:
742 * A byte code representation is really a flattened forest of
743 trees. Look at the Mono JIT engine to see how we compute
744 the basic blocks (this is used to figure out the "trees").
746 The forest is just an array of trees.
748 Indeed, run the JIT engine with -d (mono -d prog.exe) and
749 you will see how these trees look like.
751 You will have to do something similar for Java.
753 * Each "forest of trees" has a meaning. This meaning can now
754 be translated into the equivalent "meaning" in CLR-land.
757 Q: Could mono become a hybrid CIL/java platform?
759 A: No. It is quite far from the philosophy of the project. The idea of Mono
760 is, to have only _one_ VM, on which all can run. And if there existing a
761 binary-converter from Java-.class to IL and if there existing something
762 like J-Sharp on Mono, you can write programs in Java, which than can run
763 on Mono. You do not need two bindings (like your example: GTK-Sharp _and_
764 Java-Gnome). You need only _one_ of it (GTK-Sharp). Thats the idea of Mono.
765 An other point is, that there are no people, who use Open Source-JVMs. They
766 all prefer Suns original. But for Unix there don't exist a .NET-Framework.
767 So it is possible, that in the future Mono is the standard .NET for Unixes.
769 Q: Do you plan to implement a Javascript compiler?
771 A: Yes. Eto Demerzal has started a Rhino port to C#.
772 After this is completed, we will begin developing
773 the JavaScript compiler.
775 <a name="extending"></a>
778 Q: Would you allow other classes other than those in the
781 A: Yes. The Microsoft class collection is very big, but it is by no
782 means complete. It would be nice to have a port of `Camel' (the
783 Mail API used by Evolution inspired by Java Mail) for Mono
786 You might also want to look into implementing CORBA for Mono. Not
787 only because it would be useful, but because it sounds like a fun
788 thing to do, given the fact that the CLI is such a type rich
791 For more information on extending Mono, see our <a
792 href="ideas.html">ideas</a> page.
794 Q: Do you plan to Embrace and Extend .NET?
796 A: Embracing a good technology is good. Extending technologies in
797 incompatible ways is bad for the users, so we do not plan on
798 extending the technologies.
800 If you have innovative ideas, and want to create new classes, we
801 encourage you to make those classes operate correctly well in both
804 Q: Is there any way I can develop the class libraries using Linux yet?
806 A: Yes. Some class libraries can be developed on Linux. Search for
807 Paolo's post (he lists which classes can be compiled fine now).
809 Q: Is there any way I can install a known working copy of mono in /usr,
810 and an experimental copy somewhere else, and have both copies use
811 their own libraries? (I'm still not very good at library paths in
814 A: Yes. Just use two installation prefixes.
817 <a name="portability"></a>
820 Q: Will Mono only work on Linux?
822 A: Currently, we are doing our work on Linux-based systems and
823 Windows. We do not expect many Linux-isms in the code, so it
824 should be easy to port Mono to other UNIX variants.
826 Q: What about Mono on non Linux-based systems?
828 A: Our main intention at Ximian is to be able to develop GNOME
829 applications with Mono, but if you are interested in providing a
830 port of the Winforms classes to other platforms (frame buffer or
831 MacOS X for example), we would gladly integrate them, as long
832 they are under an open source license.
834 Q: What operating systems/CPUs do you support
836 A: Mono currently runs on Linux, Windows, Solaris and FreeBSD.
837 There is a JIT engine available for x86 processors that can
838 generate code and optimizations tailored for a particular CPU.
840 Interpreters exist for the SPARC, PowerPC and StrongARM CPUs.
842 Q: Does Mono run on Windows?
844 A: Yes. You can get pre-compiled
845 binaries from <a href="http://www.go-mono.com/download.html">http://www.go-mono.com/download.html</a>
847 Q: Does Mono run on Linux?
849 A: Yes. You can get pre-compiled
850 binaries from <a href="http://www.go-mono.com/download.html">http://www.go-mono.com/download.html</a>
852 Q: Will I require Cygwin to run mono?
854 A: No. Cygwin is only required to build Mono.
856 Q: Will Mono depend on GNOME?
858 A: It will depend only if you are using a particular assembly (for
859 example, for doing GUI applications). If you are just interested
860 in Mono for implementing a `Hello World Enterprise P2P Web
861 Service', you will not need any GNOME components.
863 Q: Is anyone working on porting Mono to IA-64?
865 A: Nobody is working on such port.
867 Q: If I were about to start a Mono port to IA-64,would the same lburg code
868 generator work for IA-64 also? or anything else need to be used for code
869 generation(as the processor architecture is totally different from IA32)
871 A: The lburg approach can be use for any processor architecture. But you might
872 think in another better approach.
874 Q: Do you plan to port Rhino to C#?.
876 A: Eto Demerzal has started a Rhino port to C#.
878 Q: Has anyone succeeded in building a Mac version of the C# environment.
879 If so can you explain how?
881 A: You could try to check with the Darwin people, or the Fink people.
882 Mono/C# is self hosting on Linux/PPC which is the hard part, so it
883 should be relatively simple to get it to work on MacOS
886 ** Reusing Existing Code
888 Q: What projects will you reuse or build upon?
890 A: We want to get Mono in the hands of programmers soon. We are
891 interested in reusing existing open source software.
893 Q: What about Intel's research JIT framework, ORP?
895 A: At this time, we are investigating whether we can use elements of
896 ORP for Mono. ORP is a research JIT engine that has a clearly
897 defined API that splits the JIT from the GC system and the actual
898 byte code implementation.
900 We are using some pieces of ORP (Their code generation interface)
901 and we use it as a source of inspiration for optimizations. Paolo
902 and Dietmar consider ORP as being one of the best JIT engines out
903 there (and their research work and papers are very useful if you are
904 interested in JIT technology).
906 Q: What about using GNU Lightning?
908 A: We are not using GNU Lightning. Our JIT is using an instruction
909 selector based on tree-pattern matching, and a code generation
910 interface that is very tied to the current architecture.
912 Q: Will I be able to use Microsoft SQL Server 2000 or will I need to switch
913 to a specific Open Source Database. Will I need to recode?
915 A: There should not be any need to recode.
917 Q: What do I need to watch out for when programming in VB.NET so that I'm
918 sure to be able to run those apps on Linux?
920 A: Not making any PInvoke or DLL calls should and not using anything in
921 the Microsoft.* namespaces should suffice. Also do not use any
922 Methods/Classes marked as "This type/method supports the .NET Framework
923 infrastructure and is not intended to be used directly from your code."
924 even if you know what these classes/methods do.
926 Q: Will built-in reporting be supported for crystal reports? This is a
927 heavily used part of our system.
929 A: Probably not. Crystal Reports are propriety. Someone may try to emulate
930 the behavior, but no-one has yet volunteered.
932 Q: Who about writing to the registry? As I understand it, Linux does not have
933 a counterpart to the registry. Should I avoid relying on that feature?
935 A: Try to avoid it. Although there would be a emulation for registry in
936 Mono too. GNOME does have a registry like mechanism for configuration. But
937 Even if gnome has a configuration system similar to the registry, the keys
938 will not be equal, so you will probably end up having to do some runtime
939 detection, and depending on this load an assembly that has your
940 platform-specific hacks.
942 Q: System.Data.SqlClient with FreeTDS, will you port parts of these to C# and
945 A: if their license is compatible with mono's, yes, we'd think about porting
946 them. If not, we'll continue with the plan of using FreeTDS.
951 Q: Are you working on a GCC front-end to C#? A GCC back-end that will
952 generate CIL images? What about making a front-end to GCC that
953 takes CIL images and generates native code?
955 A: We are currently seeking volunteers for those projects.
956 Visit the <a href="contributing.html">contributing</a> section if
959 Q: But would this work around the GPL in the GCC compiler and allow
960 people to work on non-free front-ends?
962 A: People can already do this by targeting the JVM byte codes (there
963 are about 130 compilers for various languages that target the JVM).
965 Q: Why are you writing a JIT engine instead of a front-end to GCC?
967 A: We want the JIT engine and runtime engine because they will be able
968 to execute CIL executables generated on Windows, and so no recompilation
971 <a name="performance"></a>
974 Q: How fast will Mono be?
976 A: We can not predict the future, but a conservative estimate is that
977 it would be at least `as fast as other JIT engines'.
979 We would like to ship various JIT engines with Mono, just like
980 Microsoft has done with their .NET development platform. We could
981 provide a faster, JIT for fast load times but lower performance,
982 and an and an optimizing JIT that would be slower at generating
983 code but produce more optimal output.
985 The CIL has some advantages over the Java byte code: it is really
986 an intermediate representation and there are a number of
987 restrictions on how you can emit CIL code that simplify creating
990 For example, on the CIL, the stack is not really an abstraction
991 available for the code generator to use at will. Rather, it is a
992 way of creating a postfix representation of the parsed tree. At
993 any given call point or return point, the contents of the stack are
994 expected to contain the same object types independently of how the
995 instruction was reached.
997 <a name="licensing"></a>
1000 Q: Will I be able to write proprietary applications that run with
1003 A: Yes. The licensing scheme is planned to allow proprietary
1004 developers to write applications with Mono.
1006 Q: What license or licenses are you using for the Mono Project?
1008 A: The C# Compiler is released under the terms of the <a
1009 href="http://www.opensource.org/licenses/gpl-license.html">GNU GPL</a>. The runtime
1010 libraries are under the <a
1011 href="http://www.opensource.org/licenses/lgpl-license.html">GNU
1012 Library GPL</a>. And the class libraries are released
1013 under the terms of the <a
1014 href="http://www.opensource.org/licenses/mit-license.html">MIT X11</a>
1017 The Mono runtime and the Mono C# Compiler are also available under
1018 a proprietary license for those who can not use the LGPL and the
1021 For licensing details, contact <a
1022 href="mailto:mono-licensing@ximian.com">mono-licensing@ximian.com</a>
1025 Q: I would like to contribute code to Mono under a particular
1026 license. What licenses will you accept?
1028 A: We will have to evaluate the licenses for compatibility first,
1029 but as a general rule, we will accept the code under the same
1030 terms of the "container" module.
1035 <a name="patents"></a>
1038 Q: Could patents be used to completely disable Mono (either submarine
1039 patents filed now, or changes made by Microsoft specifically to
1040 create patent problems)?
1042 A: No. First, its basic functional capabilities have pre-existed too
1043 long to be held up by patents. The basic components of Mono are
1044 technologically equivalent to Sun's Java technology, which has been
1047 Mono will also implement multi-language and
1048 multi-architecture support, but there are previous technologies
1049 such as UCSD p-code and ANDF that also support multiple languages
1050 using a common intermediate language. The libraries are similar
1051 to other language's libraries, so again, they're too similar to
1052 be patentable in large measure.
1054 However, if Microsoft does patent some technology, then our plan is
1055 to either (1) work around it, (2) chop out patented pieces, (3)
1056 find prior art that would render the patent useless.
1058 Not providing a patented capability would weaken the
1059 interoperability, but it would still provide the free software /
1060 open source software community with good development tools, which
1061 is the primary reason for developing Mono.
1064 ** Miscellaneous Questions
1066 Q: You say that the CLI allows multiple languages to execute on the
1067 same environment. Isn't this the purpose of CORBA?
1069 A: The key difference between CORBA (and COM) and the CLI is that the
1070 CLI allows "data-level interoperability" because every
1071 language/component uses the same data layout and memory management.
1073 This means you can operate directly upon the data types that someone
1074 else provides, without having to go via their interfaces. It also
1075 means you don't have to "marshal" (convert) parameters (data
1076 layouts are the same, so you can just pass components directly) and
1077 you don't have to worry about memory management, because all
1078 languages/components share the same garbage collector and address
1079 space. This means much less copying and no need for reference
1082 Q: Will you support COM?
1084 A: The runtime will support XPCOM on Unix systems and COM on Windows.
1085 Most of the code for dynamic trampolines exists already.
1087 Q: Will Ximian offer certifications on Mono or related technologies?.
1089 A: It's possible. But there is no plan about this. So the short answer is no.
1091 Q: Are there any Boehm's GC binaries?
1093 A: Yes. You can find RPMs <a href="http://java.thn.htu.se/~toor/">here</a>, though
1094 if your distribution provides the correct packages, you should use those.
1095 The suggested version of the Boehm GC is 6.1.
1097 Q: How can I report a bug?
1099 A: The best thing is to track down the bug and provide a simple test to
1100 reproduce the bug. You can then add the bug to the
1101 <a href="http://bugzilla.ximian.com/enter_bug.cgi">bugtracking system</a>.
1103 Please provide information about what version of mono you're using
1104 and any relevant details to be able to reproduce the bug. Note that
1105 bugs reported on the mailing-list may be easily forgotten, so it's
1106 better to file them in the <a href="http://bugzilla.ximian.com/enter_bug.cgi">bug tracking system</a>.
1108 Q: Does mcs support the same command line options as the MS C#
1111 A: The Mono C# compiler now supports the same command line
1112 arguments as the Microsoft C# compiler does.
1114 Q: How about getting searchable archives on lists.ximian.com?
1116 A: You can perform a search on the mono-related mailing lists
1117 <a href="http://www.go-mono.com/mailing-lists.html">here</a>.
1119 Q: When using mono from cvs or from a snapshot, I get an error messaage
1120 saying that Mono and the runtime are out of sync. How do I fix that?
1122 A: If you use mono from cvs, you need to be prepared for changes in the
1123 runtime internals. This means that you should keep a working setup
1124 before blindling updating (a working setup may just be the last released
1125 tarball or a recent binary snapshot).
1126 Usually, compiling corlib with mcs before recompiling the C runtime does
1127 the right thing (but occasionally you may need to do it the other
1130 Q: Why are you going for a GtkHtml implementation?
1132 A: GtkHTML is just a lightweight HTML rendering engine that does not
1133 support CSS, so we need it to look decent for those of us that will
1134 be using the documentation in our day-to-day work on Linux. The
1135 Web-based interfaces lack the agility that you get from a native GUI
1136 tool to browse your documentation. Probably later on, we will write
1137 scripts and generate a full documentation set that is web-browsable,
1138 but we need a command-line and GUI tools that we can use natively on
1139 Linux when disconnected from the Web (and that has better
1140 interactions than a web page).
1142 <a name="problems"></a>
1143 ** Mono Common Problems
1145 If you are having problems compiling or running Mono software
1146 or if you think that you found a bug, etc. Please visit the
1147 <a href="http://geneura.ugr.es/~jaime/deploy/mono-common-problems.html">Mono Common Problems</a> document and try there.