Embedding Mono

The Mono runtime can be embedded into C and C++ applications. Your C/C++ code can invoke managed code running in the Mono/.NET world and you can also surface your internal application APIs to Mono and .NET.

For an overview of how to embed Mono into your application and the strategies that you can use to embed Mono, check the Mono website's Embedding Mono page.

This page is the companion API reference for the above guide.

The simplest way of embedding Mono is illustrated here:

int main (int argc, char *argv)
{
	/*
	 * Load the default Mono configuration file, this is needed
	 * if you are planning on using the dllmaps defined on the
	 * system configuration
	 */
	mono_config_parse (NULL);

	/*
	 * mono_jit_init() creates a domain: each assembly is
	 * loaded and run in a MonoDomain.
	 */
	MonoDomain *domain = mono_jit_init ("startup.exe");

	/*
	 * Optionally, add an internal call that your startup.exe
	 * code can call, this will bridge startup.exe to Mono
	 */
	mono_add_internal_call ("Sample::GetMessage", getMessage);

	/*
	 * Open the executable, and run the Main method declared
	 * in the executable
	 */
	MonoAssembly *assembly = mono_domain_assembly_open (domain, "startup.exe");

	if (!assembly)
		exit (2);
	/*
	 * mono_jit_exec() will run the Main() method in the assembly.
	 * The return value needs to be looked up from
	 * System.Environment.ExitCode.
	 */
	mono_jit_exec (domain, assembly, argc, argv);
}

/* The C# signature for this method is: string GetMessage () in class Sample */
MonoString*
getMessage ()
{
	return mono_string_new (mono_domain_get (), "Hello, world");
}

mono_jit_init

mono_jit_parse_options

mono_jit_exec

mono_set_dirs

mono_parse_default_optimizations

mono_runtime_set_main_args

mono_jit_cleanup

mono_jit_set_trace_options

Internal Calls

The Mono runtime provides two mechanisms to expose C code to the CIL universe: internal calls and native C code. Internal calls are tightly integrated with the runtime, and have the least overhead, as they use the same data types that the runtime uses.

The other option is to use the Platform Invoke (P/Invoke) to call C code from the CIL universe, using the standard P/Invoke mechanisms.

To register an internal call, use this call you use the mono_add_internal_call routine.

mono_add_internal_call

P/Invoke with embedded applications

Unlike internal calls, Platform/Invoke is easier to use and more portable. It allows you to share code with Windows and .NET that have a different setup for internal calls to their own runtime.

Usually P/Invoke declarations reference external libraries like:

	[DllImport ("opengl")]
	void glBegin (GLEnum mode)
	

Mono extends P/Invoke to support looking up symbols not in an external library, but looking up those symbols into the same address space as your program, to do this, use the special library name "__Internal". This will direct Mono to lookup the method in your own process.

There are situations where the host operating system does not support looking up symbols on the process address space. For situations like this you can use the mono_dl_register_library.

mono_dl_register_library

mono_config_cleanup

mono_config_is_server_mode

mono_config_parse

mono_config_parse_memory

mono_config_set_server_mode

mono_config_string_for_assembly_file

mono_get_config_dir

mono_get_machine_config

mono_register_machine_config

mono_set_config_dir

Advanced Execution Setups

These are not recommended ways of initializing Mono, they are done internally by mono_jit_init, but are here to explain what happens internally.

mono_runtime_exec_managed_code

mono_runtime_exec_main

mono_init

mono_init_from_assembly

mono_init_version

mono_jit_exec

mono_jit_set_aot_mode

mono_set_break_policy

mono_get_runtime_build_info

Signal Chaining

mono_set_signal_chaining

mono_set_crash_chaining