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From: Arun Ramakrishnan <aramakrishnan@languageweaver.com>
To: "user@commons.apache.org" <user@commons.apache.org>
Date: Wed, 23 Sep 2009 18:06:06 -0500
Subject: [exec] Piping to Input Stream using PipedInputStream
Thread-Topic: [exec] Piping to Input Stream using PipedInputStream
Thread-Index: Aco8om4Nmu8zoYPrRTiKXWjg/ZFSlA==
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I am trying to build java wrapper around a binary. The idea is that I can s=
tream in and out of this binary that has heavy startup time.

1)      I used to be able to achieve this using ProcessBuilder ( refer to c=
ode snippet 1 )

2)      I trying to use Apache Commons Exec instead to start the binaries (=
 it see from the code that it has separate threads to deal with the various=
 streams so that the binary dosent block due to full output or error buffer=
s ). But, it  seems extremely complicated to open a stream/pipe to the inpu=
t of the binary. I am not sure if Code snippert 2 is the right approach to =
it using Piped Streams classes.

3)      One of the problems I am having is that I don't understand why the =
pipe seems to close prematurely after only one write to it. Please refer to=
 code snippet 3 for a concise code that demonstrates the problem I am havin=
g.

Any suggestions would be appreciated.

######################## Code Snippet 1 ##############################

Process p =3D "tool.exe".execute()  // uses processBuilder
BufferedOutputStream pout =3D new BufferedOutputStream( p.getOutputStream()=
 )

// then use pout to send input to the tool.exe's input stream

########################  Code Snippet 3 ##############################

PipedOutputStream ps =3D new PipedOutputStream();
PipedInputStream is =3D new PipedInputStream(ps);
BufferedWriter os =3D new BufferedWriter(new OutputStreamWriter(ps));
String s =3D "hi there \n hi \n";
[1..1000].each{
println it
os.write(s);
}
os.close();
println is.getText();

######################## Code Snippet 2 ################################
import org.apache.commons.exec.*;

String line =3D "F:\\Suggester\\bin\\langid.bat" ;
String infile =3D "F:\\Suggester\\bin\\in.txt" ;
CommandLine commandLine =3D CommandLine.parse(line);


commandLine.addArgument("engita")
DefaultExecutor executor =3D new DefaultExecutor();
FileInputStream fis =3D new FileInputStream( infile )
PipedOutputStream ps =3D new PipedOutputStream();
PipedInputStream is =3D new PipedInputStream(ps);
PrintStream os =3D new PrintStream(ps);
String s =3D "hi there \n--#--\nwhatup";
[1..1000].each{
println it
os.append(s);
os.flush();
}
os.close();
println is.getText()
PumpStreamHandler ioh =3D new PumpStreamHandler(System.out,System.err,is);
//ioh.setProcessInputStream(System.out) his will not work
ioh.start()
executor.setStreamHandler(ioh)
//pis.write( s.getBytes() );
int exitValue =3D executor.execute(commandLine);
println " execution started"
println exitValue;

####################### End ##########################################

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