Connect to already running MATLAB with MATLAB Engine

Question

The MATLAB Engine API allows accessing MATLAB functionality from a C program. To set up a MATLAB Engine session, one calls the engOpen function. By default, this launches a new instance of MATLAB, for the exclusive use of Engine applications.

What I want is to use an already running MATLAB session from an Engine application so I can access its variables. I need to do this on Linux and OS X.

The Engine interface has very different implementations on Windows (where it uses a COM server) and Unix. On Unix we have to pass the location of the MATLAB executable to engOpen, while on Windows (where the Engine uses a COM server) we don't. On Windows it is possible to use an existing instance of MATLAB for Engine applications: just run enableservice('AutomationServer', true). Is there any solution on Unix systems?

I am hoping that there is a general solution—perhaps undocumented—because, based on the documentation, the Python interface seems to allow this. I tested this on OS X and it works. I can, for example, start up an interactive MATLAB session, set a variable a=5, then start Python, connect to the same session and be able to retrieve this variable. It is also possible to connect to an already running session from Java.

I need to do this from C however, not from Python, as it will be used in MATLink, the Mathematica-MATLink interface. How does the Python interface achieve this? How can I reproduce the same using C?

If there is an alternative C API than the "MATLAB Engine" that makes this possible (perhaps some other documented or undocumented C API that the Python interface is based on), I can accept that as an answer. I want a C program that can make use of an already running interactive MATLAB session.

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Update:

Some poking around in the Python interface reveals that it makes use of a library called libmwengine_api. This is not the same as the documented MATLAB Engine C API. We can look at the symbols in this library. On OS X,

nm -g libmwengine_api.dylib | c++filt

Then we can google for these symbols or grep the MATLAB installation directory for files containing them. There is nothing in plain text that turns up.

Based on this I believe that the Python interface uses an undocumented C++ Engine API which is distinct from the old, documented C one.

Answer 1

"On the Mac and Linux® platforms, you cannot make an engine program connect to an existing MATLAB session."

Answer 2

Here is the source of its Python Implementation , see if it helps you.

Some Searching Gave Me The Impression that libmwengine is part of a library that is used in embedded system and which was long back obsoleted.

See This link , Library libmwengine_api was Obsoleted long back.Maybe That is why it is undocumented.