//******************************************************************************
//
// File:    JobFrontendRef.java
// Package: edu.rit.pj.cluster
// Unit:    Interface edu.rit.pj.cluster.JobFrontendRef
//
// This Java source file is copyright (C) 2012 by Alan Kaminsky. All rights
// reserved. For further information, contact the author, Alan Kaminsky, at
// ark@cs.rit.edu.
//
// This Java source file is part of the Parallel Java Library ("PJ"). PJ is free
// software; you can redistribute it and/or modify it under the terms of the GNU
// General Public License as published by the Free Software Foundation; either
// version 3 of the License, or (at your option) any later version.
//
// PJ is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
// A PARTICULAR PURPOSE. See the GNU General Public License for more details.
//
// Linking this library statically or dynamically with other modules is making a
// combined work based on this library. Thus, the terms and conditions of the
// GNU General Public License cover the whole combination.
//
// As a special exception, the copyright holders of this library give you
// permission to link this library with independent modules to produce an
// executable, regardless of the license terms of these independent modules, and
// to copy and distribute the resulting executable under terms of your choice,
// provided that you also meet, for each linked independent module, the terms
// and conditions of the license of that module. An independent module is a
// module which is not derived from or based on this library. If you modify this
// library, you may extend this exception to your version of the library, but
// you are not obligated to do so. If you do not wish to do so, delete this
// exception statement from your version.
//
// A copy of the GNU General Public License is provided in the file gpl.txt. You
// may also obtain a copy of the GNU General Public License on the World Wide
// Web at http://www.gnu.org/licenses/gpl.html.
//
//******************************************************************************

package edu.rit.pj.cluster;

import java.io.File;
import java.io.IOException;

import java.net.InetSocketAddress;

/**
 * Interface JobFrontendRef specifies the interface for the PJ job frontend
 * process.
 *
 * @author  Alan Kaminsky
 * @version 20-Jun-2012
 */
public interface JobFrontendRef
	{

// Exported operations.

	/**
	 * Assign a backend process to the job.
	 *
	 * @param  theJobScheduler  Job Scheduler that is calling this method.
	 * @param  name             Backend node name.
	 * @param  host             Host name for SSH remote login.
	 * @param  jvm              Full pathname of Java Virtual Machine.
	 * @param  classpath        Java class path for PJ Library.
	 * @param  jvmflags         Array of JVM command line flags.
	 * @param  shellCommand     Shell command string.
	 * @param  Nt               Number of CPUs assigned to the process.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public void assignBackend
		(JobSchedulerRef theJobScheduler,
		 String name,
		 String host,
		 String jvm,
		 String classpath,
		 String[] jvmflags,
		 String shellCommand,
		 int Nt)
		throws IOException;

	/**
	 * Assign a job number to the job. The host name for the job frontend's
	 * middleware channel group is also specified.
	 *
	 * @param  theJobScheduler  Job Scheduler that is calling this method.
	 * @param  jobnum           Job number.
	 * @param  pjhost           Host name for middleware channel group.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public void assignJobNumber
		(JobSchedulerRef theJobScheduler,
		 int jobnum,
		 String pjhost)
		throws IOException;

	/**
	 * Cancel the job.
	 *
	 * @param  theJobScheduler  Job Scheduler that is calling this method.
	 * @param  errmsg           Error message string.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public void cancelJob
		(JobSchedulerRef theJobScheduler,
		 String errmsg)
		throws IOException;

	/**
	 * Renew the lease on the job.
	 *
	 * @param  theJobScheduler  Job Scheduler that is calling this method.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public void renewLease
		(JobSchedulerRef theJobScheduler)
		throws IOException;

	/**
	 * Report that a backend process has finished executing the job.
	 *
	 * @param  theJobBackend  Job Backend that is calling this method.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public void backendFinished
		(JobBackendRef theJobBackend)
		throws IOException;

	/**
	 * Report that a backend process is ready to commence executing the job.
	 *
	 * @param  theJobBackend
	 *     Job Backend that is calling this method.
	 * @param  rank
	 *     Rank of the job backend process.
	 * @param  middlewareAddress
	 *     Host/port to which the job backend process is listening for
	 *     middleware messages.
	 * @param  worldAddress
	 *     Host/port to which the job backend process is listening for the world
	 *     communicator.
	 * @param  frontendAddress
	 *     Host/port to which the job backend process is listening for the
	 *     frontend communicator, or null if the frontend communicator does not
	 *     exist.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public void backendReady
		(JobBackendRef theJobBackend,
		 int rank,
		 InetSocketAddress middlewareAddress,
		 InetSocketAddress worldAddress,
		 InetSocketAddress frontendAddress)
		throws IOException;

	/**
	 * Cancel the job.
	 *
	 * @param  theJobBackend  Job Backend that is calling this method.
	 * @param  errmsg         Error message string.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public void cancelJob
		(JobBackendRef theJobBackend,
		 String errmsg)
		throws IOException;

	/**
	 * Renew the lease on the job.
	 *
	 * @param  theJobBackend  Job Backend that is calling this method.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public void renewLease
		(JobBackendRef theJobBackend)
		throws IOException;

	/**
	 * Request the given resource from this job frontend's class loader.
	 *
	 * @param  theJobBackend  Job Backend that is calling this method.
	 * @param  resourceName   Resource name.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public void requestResource
		(JobBackendRef theJobBackend,
		 String resourceName)
		throws IOException;

	/**
	 * Open the given output file for writing or appending.
	 *
	 * @param  theJobBackend  Job Backend that is calling this method.
	 * @param  bfd            Backend file descriptor.
	 * @param  file           File.
	 * @param  append         True to append, false to overwrite.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public void outputFileOpen
		(JobBackendRef theJobBackend,
		 int bfd,
		 File file,
		 boolean append)
		throws IOException;

	/**
	 * Write the given bytes to the given output file. <TT>ffd</TT> = 1 refers
	 * to the job's standard output stream; <TT>ffd</TT> = 2 refers to the job's
	 * standard error stream; other values refer to a previously opened file.
	 *
	 * @param  theJobBackend  Job Backend that is calling this method.
	 * @param  ffd            Frontend file descriptor.
	 * @param  buf            Array of bytes to write.
	 * @param  off            Index of first byte to write.
	 * @param  len            Number of bytes to write.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public void outputFileWrite
		(JobBackendRef theJobBackend,
		 int ffd,
		 byte[] buf,
		 int off,
		 int len)
		throws IOException;

	/**
	 * Flush accumulated bytes to the given output file.
	 *
	 * @param  theJobBackend  Job Backend that is calling this method.
	 * @param  ffd            Frontend file descriptor.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public void outputFileFlush
		(JobBackendRef theJobBackend,
		 int ffd)
		throws IOException;

	/**
	 * Close the given output file.
	 *
	 * @param  theJobBackend  Job Backend that is calling this method.
	 * @param  ffd            Frontend file descriptor.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public void outputFileClose
		(JobBackendRef theJobBackend,
		 int ffd)
		throws IOException;

	/**
	 * Open the given input file for reading.
	 *
	 * @param  theJobBackend  Job Backend that is calling this method.
	 * @param  bfd            Backend file descriptor.
	 * @param  file           File.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public void inputFileOpen
		(JobBackendRef theJobBackend,
		 int bfd,
		 File file)
		throws IOException;

	/**
	 * Read bytes from the given input file. <TT>ffd</TT> = 1 refers to the
	 * job's standard input stream; other values refer to a previously opened
	 * file.
	 *
	 * @param  theJobBackend  Job Backend that is calling this method.
	 * @param  ffd            Frontend file descriptor.
	 * @param  len            Number of bytes to read.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public void inputFileRead
		(JobBackendRef theJobBackend,
		 int ffd,
		 int len)
		throws IOException;

	/**
	 * Skip bytes from the given input file.
	 *
	 * @param  theJobBackend  Job Backend that is calling this method.
	 * @param  ffd            Frontend file descriptor.
	 * @param  len            Number of bytes to skip.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public void inputFileSkip
		(JobBackendRef theJobBackend,
		 int ffd,
		 long len)
		throws IOException;

	/**
	 * Close the given input file.
	 *
	 * @param  theJobBackend  Job Backend that is calling this method.
	 * @param  ffd            Frontend file descriptor.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public void inputFileClose
		(JobBackendRef theJobBackend,
		 int ffd)
		throws IOException;

	/**
	 * Report a comment for a process.
	 *
	 * @param  theJobBackend  Job backend that is calling this method.
	 * @param  rank           Process rank.
	 * @param  comment        Comment string.
	 *
	 * @exception  IOException
	 *     Thrown if an I/O error occurred.
	 */
	public void reportComment
		(JobBackendRef theJobBackend,
		 int rank,
		 String comment)
		throws IOException;

	/**
	 * Close communication with this Job Frontend.
	 */
	public void close();

	}