Chapter 7: Network Access Using java.net

Saving text out of Adaptive Server

This example describes how to set up a client application in Adaptive Server. Adaptive Server version12.5 and later does not support direct access to a file; this example is a workaround for this limitation.

You can write your own external server, which performs file operations, and connect to this new server from the Adaptive Server, using a socket created from a Socket class.

In the basic roles of client and server, the client connects to the server and streams the text, while the server receives the stream and streams it to a file.

This example shows how you can install a Java application in Adaptive Server, using java.net. This application acts as a client to an external server.

The client process:

Receives an InputStream.
Creates a socket using the Socket class to connect to the server.
Creates an OutputStream on the socket.

Reads the InputStream and writes it to the OutputStream:

import java.io.*;
import java.net.*;
public class TestStream2File {

		public static void writeOut(InputStream fin)throws Exception
{
			Socket socket = new Socket("localhost", 1718);
			OutputStream fout =
	newBufferedOutputStream(socket.getOutputStream());
			byte[] buffer = new byte[10];
			int bytes_read;
			while ((bytes_read = fin.read(buffer)) != -1) {
					 fout.write(buffer, 0, bytes_read);
					 }
              fout.close();
			}
}

Compile this program.

The server process:

Creates a server socket, using the SocketServer class, to listen on a port.
Uses the server socket to obtain a socket connection.
Receives an InputStream.
Reads the InputStream and writes it to a FileOutputStream.

In this example, the server does not use threads, and therefore it can receive a connection from only one client at a time.

import java.io.*;
import java.net.*;

public class FileServer {

	public static void main (string[] args) throws IOException{
 			Socket client = accept (1718);
 			try{
  					InputStream in = client.getInputStream ();
  					FileOutputStream fout = new
   					FileOutputStream("chastity.txt");
   					byte[] buffer = new byte [10];
   					int bytes_read;
   					while (bytes_read = in.read(buffer))!= -1){
    							fout.write(buffer, 0, bytes_read);
 					}
   					fout.close();
 	}
	finally {
  			 client.close ();
 	}
}

static Socket accept (int port) throwsIOException {

	System.out.prinln ("Starting on port " + port);

	ServerSocket server = new ServerSocket (port);

	System.out.println ("Waiting");

	Socket client = server.accept ();

	System.out.println ("Accepted from " + client.getInetAddress ());
	server.close ();
	return client;
	}
}

Compile this program.

To use this combination of client and server, you must install the client in Adaptive Server and start the external server:

witness% java FileServer &

[2] 28980
witness% Starting on port 1718

Waiting

Invoke the client from within Adaptive Server.

use pubs2
go
select TestStream2File.writeOut(c1) from blurbs
where au_id = “486-29-1786”

go

View this book as PDF