This article needs to be updated.(March 2016)
|Developer(s)||.NET Foundation and Xamarin (a Microsoft subsidiary)|
|Initial release||June 30, 2004|
220.127.116.11 / 23 February 2021
18.104.22.168 / August 13, 2021
|Written in||C, C#, XML|
|Operating system||Windows, macOS, Linux, IBM AIX, IBM i|
|Platform||IA-32, x64, IA-64, ARM, MIPS, PowerPC, SPARC, S390|
Mono is a free and open-source .NET Framework-compatible software framework. Originally by Ximian, it was later acquired by Novell, and is now being led by Xamarin, a subsidiary of Microsoft and the .NET Foundation. Mono can be run on many software systems.
|2004-06-30||1.0||C# 1.0 support|
|2006-11-09||1.2||C# 2.0 support|
|2008-10-06||2.0||Mono's APIs are now in par with .NET 2.0. Introduces the C# 3.0 and Visual Basic 8 compilers. New Mono-specific APIs: Mono.Cecil, Mono.Cairo and Mono.Posix. Gtk# 2.12 is released. The Gendarme verification tool and Mono Linker are introduced.|
|2009-01-13||2.2||Mono switches its JIT engine to a new internal representation that gives it a performance boost and introduces SIMD support in the Mono.Simd Mono.Simd namespace.|
Mono introduces Full Ahead of Time compilation that allows developers to create full static applications and debuts the C# Compiler as a Service and the C# Interactive Shell (C# REPL)
|2009-03-30||2.4||This release mostly polishes all the features that shipped in 2.2 and became the foundation for the Long-Term support of Mono in SUSE Linux.|
|2009-12-15||2.6||The Mono runtime is now able to use LLVM as a code generation backend and this release introduces Mono co-routines, the Mono Soft Debugger and the CoreCLR security system required for Moonlight and other Web-based plugins.|
On the class library System.IO.Packaging, WCF client, WCF server, LINQ to SQL debut. The Interactive shell supports auto-completion and the LINQ to SQL supports multiple database backends. The xbuild build system is introduced.
|2010-09-22||2.8||Defaults to .NET 4.0 profile, C# 4.0 support, new generational garbage collector, includes Parallel Extensions, WCF Routing, CodeContracts, ASP.NET 4.0, drops the 1.0 profile support; the LLVM engine tuned to support 99.9% of all generated code, runtime selectable llvm and gc; incorporates Dynamic Language Runtime, MEF, ASP.NET MVC2, OData Client open-source code from Microsoft;. Will become release 3.0|
|2012-10-18||3.0||C# 5.0 support, async support, Async Base Class Library Upgrade and MVC4 - Partial, no async features support.|
|2013-07-24||3.2||Default Garbage Collector is now the SGEN, instead of Boehm|
|2015-04-29||4.0||Defaults to .NET 4.5 profile and ships only .NET 4.5 assemblies, defaults to C# 6.0. First release to integrate Microsoft open-source .NET Core code|
|2017-05-10||5.0||Shipping Roslyn C# compiler to enable C#7 support; Shipping msbuild and deprecating xbuild for better compatibility; Enabling concurrent SGen garbage collector to reduce time spent in GC; Introducing the AppleTLS stack on macOS for HTTPS connections; Continued Progress on .NET Class Library convergence; Updated libjpeg in macOS package|
|2017-07-14||5.2||Support for .NET Standard 2.0, strong assembly names, and experimental default interface members.|
|2017-10-05||5.4||The JIT Runtime now supports concurrent method compilation and various other Performance Optimisations;|
|2018-02-01||5.8||Initial WebAssembly port; Modes for the SGen GC; Includes Roslyn's csi (C# interactive) REPL tool|
|2018-02-26||5.10||The Interpreter is now included in the default installation; runtime now supports Default Interface Methods; WebAssembly considered reliable now; Support for .NET 4.7.1 / C# 7.2 / F# 4.1|
|2018-05-08||5.12||Port to IBM AIX/i; now includes VB.NET compiler; option to use jemalloc|
|2018-08-07||5.14||Major Windows.Forms update to improve compatibility with .NET|
|2018-10-08||5.16||Hybrid suspend garbage collector; Client certificate support; C# 7.3 support|
|2018-12-21||5.18||.NET 4.7.2 support; more CoreFX code is used|
|2019-07-17||6.0||C# compiler defaults to version C# 8.0 RC; Various stability improvement in debugger support; Mono Interpreter is feature complete and stable|
|2019-09-23||6.4||C# compiler support for C# 8 language version; .NET Standard 2.1 support|
|2019-12-10||6.6||Added .NET 4.8 reference assemblies|
When Microsoft first announced their .NET Framework in June 2000 it was described as "a new platform based on Internet standards", and in December of that year the underlying Common Language Infrastructure was published as an open standard, "ECMA-335", opening up the potential for independent implementations. Miguel de Icaza of Ximian believed that .NET had the potential to increase programmer productivity and began investigating whether a Linux version was feasible. Recognizing that their small team could not expect to build and support a full product, they launched the Mono open-source project, on July 19, 2001 at the O'Reilly conference.
After three years of development, Mono 1.0 was released on June 30, 2004. Mono evolved from its initial focus of a developer platform for Linux desktop applications to supporting a wide range of architectures and operating systems - including embedded systems.
Novell acquired Ximian in 2003. After Novell was acquired by Attachmate in April 2011, Attachmate announced hundreds of layoffs for the Novell workforce, putting in question the future of Mono.
On May 16, Miguel de Icaza announced in his blog that Mono would continue to be supported by Xamarin, a company he founded after being laid off from Novell. The original Mono team had also moved to the new company. Xamarin planned to keep working on Mono and had planned to rewrite the proprietary .NET stacks for iOS and Android from scratch, because Novell still owned MonoTouch and Mono for Android at the time. After this announcement, the future of the project was questioned, MonoTouch and Mono for Android being in direct competition with the existing commercial offerings now owned by Attachmate, and considering that the Xamarin team would have difficulties proving that they did not use technologies they formerly developed when they were employed by Novell for the same work. However, in July 2011, Novell, now a subsidiary of Attachmate, and Xamarin, announced that it granted a perpetual license to Xamarin for Mono, MonoTouch and Mono for Android, which officially took stewardship of the project.
Mono's current version is 6.0.0 (as of August 2019[update]). This version provides the core API of the .NET Framework and support for Visual Basic.NET and C# 7.0. LINQ to Objects, XML, and SQL are part of the distribution. Windows Forms 2.0 is also supported, but not actively developed, and as such its support on Mono is incomplete. Version 4.0 was the first version that incorporates Microsoft original source code that was released by Microsoft as part of the .NET Core project.
As of January 14, 2021, Mono has full support for all the features in .NET 4.7 except Windows Presentation Foundation (WPF) (which the Mono team do not plan to support due to the amount of work it would need) and Windows Workflow Foundation (WF), and with only limited support for Windows Communication Foundation (WCF) and the ASP.NET async stack. However, System.Web and WCF are candidates for 'almost immediate' porting from the .NET reference source back to Mono. Some missing parts of the .NET Framework are under development in an experimental Mono subproject called Olive.
The Mono project has also created a Visual Basic .NET compiler and a runtime designed for running VB.NET applications. It is currently being developed by Rolf Bjarne Kvinge.
An open-source implementation of Microsoft Silverlight, called Moonlight, has been included since Mono 1.9. Moonlight 1.0, which supports the Silverlight 1.0 APIs, was released January 20, 2009. Moonlight 2.0 supports Silverlight 2.0 and some features of Silverlight 3.0. A preview release of Moonlight 3.0 was announced in February 2010 and contains updates to Silverlight 3 support.
The Moonlight project was abandoned on May 29, 2012. According to Miguel, two factors sealed the fate of the project: Microsoft added "artificial restrictions" that "made it useless for desktop programming", and the technology had not gained enough traction on the Web. In addition, Silverlight itself was deprecated by Microsoft by 2012.
Mono consists of three groups of components:
The core components include the C# compiler, the virtual machine for the Common Language Infrastructure and the core class libraries. These components are based on the Ecma-334 and Ecma-335 standards, allowing Mono to provide a standards compliant, free and open-source CLI virtual machine. Microsoft issued a statement that covers both standards under their Community Promise license.
The Mono/Linux/GNOME development stack provide tools for application development while using the existing GNOME and free and open-source libraries. These include: Gtk# for graphical user interface (GUI) development, Mozilla libraries for working with the Gecko rendering engine, Unix integration libraries (Mono.Posix), database connectivity libraries, a security stack, and the XML schema language RelaxNG. Gtk# allows Mono applications to integrate into the Gnome desktop as native applications. The database libraries provide connectivity to the object-relational database db4o, Firebird, Microsoft SQL Server (MSSQL), MySQL, Open Database Connectivity (ODBC), Oracle, PostgreSQL, SQLite, and many others. The Mono project tracks developing database components at its website.
The Microsoft compatibility stack provides a pathway for porting Windows .NET applications to Linux. This group of components include ADO.NET, ASP.NET, and Windows Forms, among others. As these components are not covered by Ecma standards, some of them remain subject to patent fears and concerns.
The major components of Mono include:
The Mono runtime contains a code execution engine that translates ECMA CIL byte codes into native code and supports a number of processors: ARM, MIPS (in 32-bit mode only), SPARC, PowerPC, S390 (in 64-bit mode), x86, x86-64 and IA-64 for 64-bit modes.
The code generator is exposed in three modes:
Starting with Mono 2.6, it is possible to configure Mono to use the LLVM as the code generation engine instead of Mono's own code generation engine. This is useful for high performance computing loads and other situations where the execution performance is more important than the startup performance.
Starting with the Mono 2.7 preview, it is no longer necessary to pick one engine over the other at configuration time. The code generation engine can be selected at startup by using the
--nollvm command line arguments, and it defaults to the fast-starting Mono code generation engine.
Starting with Mono 5.18, support for LLVM is a default configuration option. Previous versions required a special LLVM fork, but now mono can fall back to its own code generator when it encounters something not handled by LLVM.
As of Mono 2.8, the Mono runtime ships with two garbage collectors: a generational collector and the Boehm-Demers-Weiser Conservative Garbage Collector. The Boehm garbage collector could exhibit memory leaks on certain classes of applications, making it unsuitable for some long-running server applications. Mono switched to Simple Generational GC (SGen-GC) as the default collector in version 3.1.1.
The SGen garbage collector has many advantages over a traditional conservative scanner. It uses generational garbage collection where new objects are allocated from a nursery, during the garbage collection cycle, all objects that survived are migrated to an older generation memory pool. The idea being that many objects are transient and can quickly be collected and only a handful of objects are long-term objects that live for the entire life of the application. To improve performance this collector assigns memory pools to each thread to let threads allocate new memory blocks without having to coordinate with other threads. Migration of objects from the nursery to the old generation is done by copying the data from the nursery to the old generation pool and updating any live pointers that point to the data to point to the new location. This can be expensive for large objects, so Mono's SGen uses a separate pool of memory for large objects (Large Object Section) and uses a mark-and-sweep algorithm for those objects.
The class library provides a comprehensive set of facilities for application development. They are primarily written in C#, but due to the Common Language Specification they can be used by any .NET language. The class library is structured into namespaces, and deployed in shared libraries known as assemblies. Speaking of the .NET Framework is primarily referring to this class library.
Namespaces are a mechanism for logically grouping similar classes into a hierarchical structure. This prevents naming conflicts. The structure is implemented using dot-separated words, where the most common top-level namespace is System, such as System.IO and System.Net. There are other top-level namespaces as well, such as Accessibility and Windows. A user can define a namespace by placing elements inside a namespace block.
Assemblies are the physical packaging of the class libraries. These are .dll files, just like (but not to be confused with) Win32 shared libraries. Examples of assemblies are mscorlib.dll, System.dll, System.Data.dll and Accessibility.dll. Namespaces are often distributed among several assemblies and one assembly can be composed of several files.
The Common Language Infrastructure (CLI) as implemented by the Common Language Runtime (CLR), is implemented by the Mono executable. The runtime compiles and executes .NET applications. The common language infrastructure is defined by the ECMA standard. To run an application, you must invoke the runtime with the relevant parameters.
The Common Language Specification (CLS) is specified in chapter 6 of ECMA-335 and defines the interface to the CLI, such as conventions like the underlying types for Enum. The Mono compiler generates an image that conforms to the CLS. This is the Common Intermediate Language. The Mono runtime takes this image and runs it. The ECMA standard formally defines a library that conforms to the CLS as a framework.
Within a native .NET/Mono application, all code is managed; that is, it is governed by the CLI's style of memory management and thread safety. Other .NET or Mono applications can use legacy code, which is referred to as unmanaged, by using the System.Runtime.InteropServices libraries to create C# bindings. Many libraries which ship with Mono use this feature of the CLI, such as Gtk#.
Mono has innovated in some areas with new extensions to the core C# and CLI specifications:
In addition, Mono is available on a variety of operating systems and architectures.
Windows 7, Windows 8, Windows 8.1, Windows 10, macOS or Linux
Several projects extend Mono and allow developers to use it in their development environment. These projects include:
Microsoft has a version of .NET 2.0 now available only for Windows XP, called the Shared Source CLI (Rotor). Microsoft's shared source license may be insufficient for the needs of the community (it explicitly forbids commercial use).
MonoDevelop is a free GNOME integrated development environment primarily designed for C# and other .NET languages such as Nemerle, Boo, and Java (via IKVM.NET), although it also supports languages such as C, C++, Python, and Vala. MonoDevelop was originally a port of SharpDevelop to Gtk#, but it has since evolved to meet the needs of Mono developers. The IDE includes class management, built-in help, code completion, Stetic (a GUI designer), project support, and an integrated debugger.
The MonoDoc browser provides access to API documentation and code samples. The documentation browser uses wiki-style content management, allowing developers to and improve the documentation.
Xamarin.iOS and Xamarin.Android, both developed by Xamarin, are implementations of Mono for iPhone and Android-based smartphones. Previously available only for commercial licensing, after Microsoft's acquisition of Xamarin in 2016, the Mono runtime itself was relicensed under MIT license and both Xamarin.iOS and Xamarin.Android are being made free and open-source.
|2009-09-14||MonoTouch 1.0||Initial release|
|2010-04-05||MonoTouch 2.0||iPad support|
|2010-04-16||MonoTouch 3.0||iPhone 4 support|
|2011-04-06||MonoTouch 4.0||iOS 4 support|
|2011-10-12||MonoTouch 5.0||iOS 5 support|
|2012-09-19||MonoTouch 6.0||iOS 6 support|
|2013-02-20||Xamarin.iOS 6.2||Visual Studio support|
|2013-07-24||Xamarin.iOS 6.4||.NET 4.5 async/await support|
|2013-06-19||Xamarin.iOS 7.0||XCode 5 and iOS 7 support|
|2014-09-10||Xamarin.iOS 8.0||iOS 8 and Xcode 6 support|
|2015-09-16||Xamarin.iOS 9.0||iOS 9 and Xcode 7 support|
|2016-09-13||Xamarin.iOS 10.0||iOS 10 and Xcode 8 support|
|2017-09-19||Xamarin.iOS 11.0||iOS 11 and Xcode 9 support|
|2018-09-14||Xamarin.iOS 12.0||iOS 12 and Xcode 10 support|
|2019-09-13||Xamarin.iOS 13.0||iOS 13 and Xcode 11 support|
|2020-09-20||Xamarin.iOS 14.0||iOS 14 and Xcode 12 support|
Xamarin.iOS (previously named MonoTouch) is a library that allows developers to create C# and .NET based applications that run on the iPhone, iPod and iPad devices. It is based on the Mono framework and developed in conjunction with Novell. Unlike Mono applications, Xamarin.iOS "Apps" are compiled down to machine code targeted specifically at the Apple iPhone and iPad. This is necessary because the iOS kernel prevents just-in-time compilers from executing on the device.
The Xamarin.iOS stack is made up of:
Xamarin Studio is used as the primary IDE, however additional links to Xcode and the iOS simulator have been written.
From April to early September 2010, the future of MonoTouch was put in doubt as Apple introduced new terms for iPhone developers that apparently prohibits them from developing in languages other than C, C++ and Objective-C, and the use of a middle layer between the iOS platform and iPhone applications. This made the future of MonoTouch, and other technologies such as Unity, uncertain. Then, in September 2010, Apple rescinded this restriction, stating that they were relaxing the language restrictions that they had put in place earlier that year.
Xamarin.Android (formerly known as Mono for Android), initially developed by Novell and continued by Xamarin, is a proprietary implementation of Mono for Android-based smart-phones. It was first released on April 6, 2011. Mono for Android was developed to allow developers to more easily write cross-platform applications that will run on all mobile platforms. In an interview with H-Online, Miguel de Icaza stated, "Our vision is to allow developers to reuse their engine and business logic code across all mobile platforms and swapping out the user interface code for a platform-specific API."
In August 2010, a Microsoft spokesman, Tom Hanrahan of Microsoft's Open Source Technology Centre, stated, in reference to the lawsuit filed by Oracle against Google over Android's use of Java, that "The type of action Oracle is taking against Google over Java is not going to happen. If a .NET port to Android was through Mono it would fall under the Microsoft Community Promise Agreement."
The Xamarin.Android stack consists of the following components:
Mono is dual licensed by Xamarin, similar to other products such as Qt and the Mozilla Application Suite. Mono's C# compiler and tools are released under the GNU General Public License (GPLv2 only) (starting with version 2.0 of Mono, the Mono C# compiler source code is also available under the MIT X11 License), the runtime libraries under the GNU Lesser General Public License (LGPLv2 only) and the class libraries under the MIT License. These are all free software and open-source licenses and hence Mono is free and open-source software.
The license of the C# compiler was changed from the GPL to the MIT X11 license to allow the compiler code to be reused in a few instances where the GPL would have prevented such:
On March 18, 2016, Microsoft's acquisition of Xamarin was officially closed. On March 31, 2016, Microsoft announced at Microsoft Build that they'll completely re-license Mono under the MIT License even in scenarios where previously a commercial license was necessary, and Microsoft stated that they won't assert any "applicable patents" against parties that are "using, selling, offering for sale, importing, or distributing Mono." It was also announced that Xamarin had contributed the Mono Project to the .NET Foundation.
Many programs covering a range of applications have been developed using the Mono application programming interface (API) and C#. Some programs written for the Linux Desktop include Banshee, Beagle, F-Spot, Gbrainy, Docky/GNOME Do, MonoTorrent, Pinta, and Tomboy. The program, Logos 5 Bible Study Software (OS X Version), was written for the MacOS.
A number of video games, such as The Sims 3 and Second Life (for their scripting languages), OpenSimulator virtual world server, or games built with the Unity or MonoGame game engines, also make use of Mono. OpenRA bundles its Apple Disk Image and Linux AppImages with Mono essentially removing almost all dependencies from the game.
Even if they aren't supporting it, they do own a product that is in direct competition with Xamarin's future offerings. Without some sort of legal arrangement between Attachmate and Xamarin, the latter would face the daunting prospect of proving that their new development doesn't use any the technology that the old one did. Considering that this is really just a wrapper around the native API, it would be hard to prove you had a clean-room implementation even for a team that wasn't intimately familiar with Attachmate's code.
The agreement grants Xamarin a broad, perpetual license to all intellectual property covering Mono, MonoTouch, Mono for Android and Mono Tools for Visual Studio. Xamarin will also provide technical support to SUSE customers using Mono-based products, and assume stewardship of the Mono open source community project.
We have no plans on building WPF. We just do not have the man power to build an implementation in any reasonable time-frame(...)For tools that are mostly OpenGL/DirectX based, use Windows.Forms, keeping in mind that some bug fixing or work around on their part might be needed as our Windows.Forms is not actively developed.
MonoTouch is a commercial product based on the open source Mono project and is licensed on a per-developer basis.
we are announcing today our commitment to open source the Xamarin SDKs for Android, iOS, and Mac under the MIT license in the coming months
Applications built with MonoTouch are native applications indistinguishable from other native applications.
Based on their input, today we are making some important changes to our iOS Developer Program license in sections 3.3.1, 3.3.2 and 3.3.9 to relax some restrictions we put in place earlier this year. In particular, we are relaxing all restrictions on the development tools used to create iOS apps, as long as the resulting apps do not download any code. This should give developers the flexibility they want, while preserving the security we need.
With these new terms, the ambiguity is gone and C# lovers and enthusiasts can go back to using MonoTouch. Developers that like garbage collection and their strongly typed languages can resume their work.
This will make it easier for developers to make cross platform apps as well as bring some of the existing apps that are made using MonoTouch to Android.
Our vision is to allow developers to reuse their engine and business logic code across all mobile platforms and swapping out the user interface code for a platform-specific API.
The type of action Oracle is taking against Google over Java is not going to happen. If a .NET port to Android was through Mono it would fall under the Microsoft Community Promise Agreement.
On May 14, Xamarin announced Mono for Android 4.2.
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