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Re: Interplatform (interprocess, interlanguage) communication

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On 02/03/2012 08:52 PM, Stefan Ram wrote:
>    »X« below is another language than Java, for example,
>    VBA, C#, or C.
>
>    When an X process and a Java process have to exchange
>    information on the same computer, what possibilites are
>    there? The Java process should act as a client, sending
>    commands to the X process and also wants to read answers
>    from the X process. So, the X process is a kind of server.
>
>    My criteria are: reliability and it should not be extremely
>    slow (say exchanging a string should not take more than
>    about 10 ms). The main criterion is reliability.
>
>    »Reliability« means little risk of creating problems, little
>    risk of failure at run-time. (It might help when the client
>    [=Java process] can reset the communication to a known and
>    sane start state in case of problems detected at run-time.)
>
>    The host OS is Windows, but a portable solution won't hurt.
>
>    A list of possibilities I am aware of now:
>
>    Pipes
>
>    I have no experience with this. I heard one can establish
>    a new process »proc« with »exec« and then use
>
> BufferedWriter out = new BufferedWriter(new
>    OutputStreamWriter(proc.getOutputStream()));
> BufferedReader in = new BufferedReader(new
>    InputStreamReader(proc.getInputStream()));

A pipes is just 1:1 communication and only in 1 direction.

>    Files
>
>    One process writes to the end of a file, the other reads
>    from the end of the file? - I never tried this, don't know
>    if it is guaranteed to work that one process can detect and
>    read, whether the other has just appended something to a file.

You can, but what do you do with the ever increasing file?  This is not 
reliable since the filesystem will fill up at some point.

>    What if the processes run very long and the files get too
>    large? But OTOH this is very transparent, which makes it easy
>    to debug, since one can open the files and directly inspect
>    them, or even append commands manually with »copy con file«.
>
>    Sockets
>
>    This is slightly less transparent than files, but has the
>    advantage that it becomes very easy to have the two
>    processes running on different computers later, if this
>    should ever be required. Debugging should be possible
>    by a man-in-the-middle proxy that prints all information
>    it sees or by connecting to the server with a terminal.

You can as well use a packet sniffer (Wireshark for example).  If you 
use a standard protocol you'll typically have encoding functionality in 
the tool.

>    JNI
>
>    JNI might be used to access code written in C or
>    ABI-compatible languages. This should be fast, but I heard
>    that it is error prone to write JNI code and needs some
>    learning (code less maintainable)?

That would be a clumsy approach IMHO.

I'd pick a higher level protocol such as

- SOAP (XML based, ubiquitous)
- CORBA (a little out of fashion but quite efficient in terms of network 
transport)

Advantage: you can focus on definition of the API and need not take care 
of all the nifty details.  Choice should also depend on the availability 
for language X, of course.

Kind regards

	robert

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Re: Interplatform (interprocess, interlanguage) communication Robert Klemme <shortcutter@googlemail.com> - 2012-02-03 22:44 +0100
  Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-03 17:56 -0500
    Re: Interplatform (interprocess, interlanguage) communication Robert Klemme <shortcutter@googlemail.com> - 2012-02-04 13:59 +0100
      Re: Interplatform (interprocess, interlanguage) communication Arne Vajhøj <arne@vajhoej.dk> - 2012-02-04 18:35 -0500

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