How to use C lib in .NET Core 2.0?

[LGinC]

system: Ubuntu 14.04 x64
I have a Header file(.h) and a share object(.so), how can I use it in my .net core app.

[LGinC]

or How to complete Inter-Process Communication

[Petermarcu]

@yizhang82 to point to docs on interop with native binaries and IPC.

[mellinoe]

I have a Header file(.h) and a share object(.so), how can I use it in my .net core app.

.NET Core supports PInvoke, just like the .NET Framework. Define "static extern" functions with a compatible signature in your C# code.

Native function:

extern "C" int32_t MyNativeFunction(int32_t x, int32_t y, int32_t z)
{
    return x + y + z;
}

C#:

[DllImport("mysharedobject")]
public static extern int MyNativeFunction(int x, int y, int z);

(for example)

or How to complete Inter-Process Communication

There are a variety of ways to do IPC; the same options exist in .NET as in other programming languages. Pipes or Sockets are two main options.

[LGinC]

@mellinoe oh....struct, for example, I define a struct named "struct CameraInfo" in server.h, how can I use it,
and I communicate with another process by shared memory....how to do it

[LGinC]

Only serialize to JSON or XML？

[mellinoe]

If you want to directly share objects in memory, you need to be very careful about the physical layout of your structures. This means that you should use the appropriate fixed-size types, packing directives, etc. on the native side to ensure that their shape is well-defined and predictable. On the C# side, you need to match the structure shape exactly, using the same-sized shapes, as well as LayoutKind.Sequential or LayoutKind.Explicit in a StructLayoutAttribute.

Sharing memory like this is pretty fragile, though. Usually you would want to create a well-defined interface between your managed and native layers, and perform explicit calls between them:

C#:

[DllImport("mysharedobject")]
public static extern void GetCameraInfo(out CameraInfo cameraInfo);

Native:

extern "C" void GetCameraInfo(CameraInfo* pCameraInfo) { return whatever; }

With the above, you still need to match the shape of the CameraInfo structure.

This is all very hand-wavy. This is a broad topic, and there are many approaches that can be taken. Given that you are talking about a "CameraInfo" structure, I'm going to say that you should avoid serializing and deserializing large amounts of state through JSON or XML.