[Boost-users] named pipes in boost for Linux

[rohini chandra pallapothu]

Hi,

Could anyone please let me know if named pipes are implemented in boost for Linux for communication between two processes which are not child and parent.
I could not find in the documentation that named pipes are implemented so far. Is there information that they will be implemented in future versions.

Please let me know if my query is not clear.

Regards,
Rohini Chandra

[bruno romano]

Boost.Process

http://www.highscore.de/cpp/process/

[rohini chandra pallapothu]

Hi Bruno,

Thank you for the reply.

I have seen this documentation before. It says that two processes have to be related.

Boost.Process enables processes to communicate with each other only if they are related: One process must have created the other. If you want two processes which are not related to exchange data you should use Boost.Interprocess.

After reading the above sentences, I did not further read Boost.Process. And Boost.Interprocess does not offer pipes from what I understood. I had used boost message queues for my work but due to a short coming in the boost message queues, I am looking for another IPC technique to replace them. The short coming I refer to in boost message queues is being not able to wait on a message queue. I mean that it seems to be not possible to get a file descriptor of a boost message queue.

Best Regards,
Rohini Chandra

On Fri, Dec 17, 2010 at 6:47 PM, bruno romano <bro...@gmail.com> wrote:

Boost.Process

http://www.highscore.de/cpp/process/

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[Boris Schaeling]

On Sat, 18 Dec 2010 11:52:19 +0100, rohini chandra pallapothu
<rohinic...@gmail.com> wrote:

> [...]I have seen this documentation before. It says that two processes
> have to be
> related.

Rohini,

you can download the latest draft of Boost.Process from
http://www.highscore.de/boost/gsoc2010/process.zip. This version provides
stream behaviors to configure streams of a child process. Among others a
stream behavior for named pipes is provided. You could use it like this:

named_pipe np("/tmp/mypipe");
stream_ends ends = np(input_stream);
... = ends.child.native();
... = ends.parent.native();

The parameter passed to named_pipe::operator()() tells the stream behavior
if the child handle should be configured for input or output. stream_ends
is basically a std:pair<handle, handle> without requiring developers to
remember what the child and the parent handle is. And the method
handle::native() (and handle::release()) can be used to get the file
descriptor on Unix and the HANDLE on Windows.

HTH,
Boris

> [...]

[rohini chandra pallapothu]

Thank you Boris, but I need to setup IPC between two processes which are not child and parent.

I had used boost message queues as of now for the same but I am not able to wait on the boost message queue as it is not possible to get a file descriptor of a boost message queue. To my understanding, native() method cannot be used on a boost message queues.

Now, I want to use some other IPC technique other than boost message queues due to the above reason. So I thought of checking if pipe communication is possible between two unrelated processes using boost.

Could you please help me if you have more information regarding this.

Please let me know if you need more information to help me.
 
Best Regards,
Rohini Chandra

[Boris Schaeling]

On Sun, 19 Dec 2010 00:12:50 +0100, rohini chandra pallapothu
<rohinic...@gmail.com> wrote:

> [...]Now, I want to use some other IPC technique other than boost

> message queues
> due to the above reason. So I thought of checking if pipe communication
> is
> possible between two unrelated processes using boost.
>
> Could you please help me if you have more information regarding this.

I think the fastest solution for you is to copy&paste the code from the
stream behavior named_pipe in Boost.Process. One process needs to call
mkfifo() and open() and the other process only open(). If you set the
O_NONBLOCK flag with fcntl() you can even use asynchronous I/O with
Boost.Asio (see boost::asio::posix::stream_descriptor). It's not a Boost
solution but copying and adapting the code shouldn't take longer than a
few minutes. :)

[rohini chandra pallapothu]

Thank you Boris for the help. I was also thinking of using native Linux IPC(message queues or pipes) if I cannot do it in boost.

Best Regards ,
Rohini Chandra

[bruno romano]

Hi, you see this page ?

http://www.boost.org/doc/libs/1_44_0/doc/html/boost_asio/examples.html (several examples using boost.asio)
http://www.boost.org/doc/libs/1_44_0/doc/html/boost_asio/example/local/connect_pair.cpp (named_socket for linux)
http://www.boost.org/doc/libs/1_44_0/doc/html/boost_asio/example/local/stream_server.cpp (named_socket for linux)
http://www.boost.org/doc/libs/1_44_0/doc/html/boost_asio/example/local/stream_client.cpp (named_socket for linux)

Boost.Asio have asynchronous methods to read and write, and have a method native.

[rohini chandra pallapothu]

Thank you Bruno. I have not seen these examples. I'll go through them and see if I can use them in my application

Thank you once again.

Best Regards,