How to open a Windows named pipe from Java?

Question

On our Linux system we use named pipes for interprocess communication (a producer and a consumer).

In order to test the consumer (Java) code, I would like to implement (in Java) a dummy producer which writes to a named pipe which is connected to the consumer.

Now the test should also work in the Windows development environment. Thus I would like to know how to create a named pipe in Windows from Java. In Linux I can use mkfifo (called using Runtime.exec() ), but how should I do this on Windows?

score 30 · Accepted Answer · edited Aug 06 '14 at 14:54

30

Use Named Pipes to Communicate Between Java and .Net Processes

Relevant part in the link

try {
  // Connect to the pipe
  RandomAccessFile pipe = new RandomAccessFile("\\\\.\\pipe\\testpipe", "rw");
  String echoText = "Hello word\n";
  // write to pipe
  pipe.write ( echoText.getBytes() );
  // read response
  String echoResponse = pipe.readLine();
  System.out.println("Response: " + echoResponse );
  pipe.close();
} catch (Exception e) {
  // TODO Auto-generated catch block
  e.printStackTrace();
}

edited Aug 06 '14 at 14:54

Philipp

4,659
9
48
69

answered Apr 09 '10 at 08:04

v01ver

340
3
2

4

Does the code above work for someone? I have tried it on Windows 7 x64, Java 1.7.0_45 and it resulted `java.io.FileNotFoundException: \\.\pipe\testpipe (The system cannot find the file specified) at java.io.RandomAccessFile.open(Native Method) at java.io.RandomAccessFile.(RandomAccessFile.java:122)`. Should it be created forehand like mentioned [in this post](http://answers.microsoft.com/en-us/windows/forum/windows8_1-files/windows-81-enterprise-64-bit-running-java-jdk/f67d1302-905e-4511-ba1b-0888b259258a)? – dma_k Jun 08 '16 at 17:24
9

I got the answer to my question above: in Java it is not possible to create a named pipe (unless one uses [JNA](https://github.com/java-native-access/jna/blob/master/contrib/platform/test/com/sun/jna/platform/win32/Kernel32NamedPipeTest.java)), only to open an existing one (see [this answer](http://stackoverflow.com/a/2247022/267197) and [that post](https://cdimascio.wordpress.com/2014/01/11/named-pipes-with-java/)). Many thanks to answers below as well. – dma_k Jun 08 '16 at 18:28
2

@dma_k I get the same error. It seems that it is not possible to create a named pipe with Java but the code works with an existing pipe that was created in an other process (e.g. the .Net process in the linked example). – Michael Aug 11 '16 at 07:57
Sharing this so it doesn't bite someone else: `RandomAccessFile#getChannel` will not work with this. No data will be sent either way. Create a wrapper `ByteChannel` yourself that calls `read` and `write` on the underlying `RandomAccessFile`, and don't use its `getChannel`. – Aly Jan 03 '22 at 08:07

score 11 · Answer 2 · answered Mar 11 '09 at 13:55

In windows, named pipes exist but they cannot be created as files in a writeable filesystem and there is no command line tool. They live in a special filesystem and can be created only by using the Win32 API.

Looks like you'll have to resort to native code, or switch from pipes to sockets for IPC - probably the best longterm solution, since it's much more portable.

score 7 · Answer 3 · answered Jan 08 '18 at 11:14

7

You can create named pipe using JNA library https://github.com/java-native-access/jna

It is clearly shown in the following test: https://github.com/java-native-access/jna/blob/master/contrib/platform/test/com/sun/jna/platform/win32/Kernel32NamedPipeTest.java

API of JNA wrapper is the same as Win32 hence you will be able to use all the features and power of named pipes on Windows.

answered Jan 08 '18 at 11:14

jreznot

2,694
2
35
53

Indeed, this is possible with JNA library. Here is some functionality implemented in Kotlin: https://github.com/mikhail-dvorkin/pipesKt – Mikhail Dvorkin Aug 16 '23 at 15:41

score 2 · Answer 4 · answered Mar 20 '13 at 12:13

It is very much possible to read and write to an existing named pipe in Java. You cannot, to my knowledge, create a named pipe in a Windows environment. Linux is a different story as named pipes can be created and consumed like files.

Relevant link on interacting with an existing pipe: http://v01ver-howto.blogspot.com/2010/04/howto-use-named-pipes-to-communicate.html

score 0 · Answer 5 · answered Jun 16 '11 at 16:16

0

maybe could use cygwin named pipes--if all your processes are cygwin.

answered Jun 16 '11 at 16:16

rogerdpack

62,887
36
269
388

In order to do this, you'd need Java on Cygwin. Seems pretty unlikely to me, though you might could wing it with one of the non-Sun JREs. – user314104 Feb 12 '12 at 05:55

score 0 · Answer 6 · answered Aug 16 '23 at 15:40

0

We implemented some functionality including creating named pipes in Kotlin:

https://github.com/mikhail-dvorkin/pipesKt

There are methods for creating named pipes that work both in Windows and in Unix. We use JNA library.

answered Aug 16 '23 at 15:40

Mikhail Dvorkin

51
3

How to open a Windows named pipe from Java?

6 Answers6

Linked