Inter-Application Memory Sharing: A Guide to Memory Mapped Files

When working with multiple applications on a Windows system, it often becomes necessary to share data between them. One common approach to this is memory mapping, which allows different processes to access shared regions of memory.

Implementing Memory Mapped Files

To implement memory mapping between two applications, you can utilize Memory Mapped Files (MMF). MMF is a shared memory object that resides in the system's physical memory and can be accessed by multiple processes. Here's how to use it:

Create a Memory Mapped File:

• In C , use the CreateFileMapping() function to create a new MMF. Specify the initial size of the file and the desired access permissions.
• In C#, use the MemoryMappedFile.Create() method to achieve the same result. Here, you can specify the name of the MMF as well as its size and access permissions.

Map the Memory Mapped File:

• Use the MapViewOfFile() function in C or the MapViewOfFile() method in C# to map the MMF into the address space of your process.
• This returns a pointer to the mapped memory region, which can be used to read or write data.

Write and Read Data:

• The application that writes data can directly access the shared memory region using the pointer obtained from MapViewOfFile().
• The other application can read the written data by accessing the same shared memory region using its pointer.

Closing the Memory Mapped File:

• To release the mapped memory, call the UnmapViewOfFile() function in C or the Dispose() method in C#.
• Once all mappings have been released, the underlying MMF can be closed using CloseHandle() in C or Dispose() in C#.

Conclusion

Memory Mapped Files provide an efficient and fast way to share data between applications in Windows. By following the steps outlined above, you can easily implement memory mapping in your C and C# applications. Refer to the provided article for further details and code examples.