웹 커넥션 관리

package sample.config;

import jakarta.servlet.*;
import jakarta.servlet.http.*;
import jeus.servlet.tcp.*;

/*
  This class extends the abstract class jeus.servlet.tcp.
  TCPDispatcherConfig class. This implementation provides
  routing and handling information to the TCP listener
  according to our defined communications protocol.
*/
public class SampleConfig extends TCPDispatcherConfig {
    /*
      Any init code goes into this method. This method will be
      Called once after starting the TCP listener.
      We leave this method empty for our simple example.
    */
    public void init() {}

    /*
      This method returns the fixed-length of the header so
      that the TCP listener knows when to stop
      reading the header. The header length for
      our example is 41 (bytes): 4 (magic) + 1
      (type) + 4 (body length) + 32 (service name).
    */
    public int getHeaderLength() {
        return 41;
    }

    /*
      This method must return the length of the body.
      For our example, this length is represented as an
      “int” in the header, starting at position “5”
      (see the protocol definition above).
    */
    public int getBodyLength(byte[] header) {
        return getInt(header, 5);
    }

    /**)
     * Returns the long-size length of request body of
     * incoming request packet.
     * If you don't need to support long, you may map to
     * {@link #getBodyLength(byte[])}.
     */
    public long getBodyLengthLong(byte[] header) {
        return getBodyLength(header);
    }

    /*
      This method must return the context path so that the
      request can be routed by the TCP listener to the context
      that contains the TCP handler (TCPServlet implementation).
      For our example, we always use the context path “/tcptest”.
    */
    public String getContextPath(byte[] header) {
        return "/tcptest";
    }

    /*
      This method must return the name (path) of the TCP
      handler(TCPServlet) relative to the context path.
      For our example, we fetch this name from the 9th position
      in the header.
    */
    public String getServletPath(byte[] header) {
        return "/" + getString(header, 9, 32);
    }

    /*
      This method returns some path info from the header.
      It is not used in our example and thus returns “null”.
    */
    public String getPathInfo(byte[] header) {
        return null;
    }

    /*
      This method returns any session ID embedded in the header.
      It is not used in our example and thus returns “null”.
    */
    public String getSessionId(byte[] header) {
        return null;
    }

    /*
      This method determines whether the TCP listener
      should keep the socket connection open after the TCP handler
      has delivered its response. If it returns “false”, the
      connection will be dropped like in HTTP communications.
      If it returns “true” the connection will be kept open
      like in the Telnet or FTP protocols. For our example,
      we choose to make it persistent (connection not closed
      by the TCP listener).
    */
    public boolean isPersistentConnection() {
        return true;
    }
}

package sample.servlet;

import java.io.*;
import jakarta.servlet.*;
import jakarta.servlet.http.*;
import jeus.servlet.tcp.*;

/**
 * Sample TCPServlet implementation
 *
 * Protocol scheme:
 *
 * common header (for request and response) : total 41 byte
 *
 *   magic field: length = 4 byte, value = 7777
 *   type field : length = 1 byte, 0 : request, 1:response
 *   body length field : length = 4, value = 128
 *   service name field : length = 32
 *
 * request and response body
 *
 *   message1 field : length = 64
 *   message2 field : length = 64
 *
 */

public class SampleTCPServlet extends TCPServlet {

    public void init(ServletConfig config) throws ServletException {
    }

    public void service(TCPServletRequest req, TCPServletResponse res)
        throws ServletException, IOException {
        ServletContext context = req.getServletContext();
        byte[] header = req.getHeader();
        byte[] body = new byte[req.getContentLength()];
        int read = req.getInputStream().read(body);
        if (read < body.length) {
            throw new IOException("The client sent the wrong content.");
        }

        String encoding = res.getCharacterEncoding();
        if (encoding == null)
            encoding = "euc-kr";

        DataInputStream in = new DataInputStream(new ByteArrayInputStream(header));
        int magic = in.readInt();
        context.log("[SampleTCPServlet] received magic = " + magic);

        byte type = (byte)in.read();
        context.log("[SampleTCPServlet] received type = " + type);

        int len = in.readInt();
        context.log("[SampleTCPServlet] received body length = " + len);

        byte[] svcname = new byte[32];
        in.readFully(svcname);
        context.log("[SampleTCPServlet] received service name = "
                     + (new String(svcname)).trim());

        String rcvmsg = null;
        rcvmsg = (new String(body, 0, 64)).trim();
        context.log("[SampleTCPServlet] received msg1 = " + rcvmsg);

        try {
            rcvmsg = (new String(body, 64, 64, encoding)).trim();
        } catch (Exception e) {}
        context.log("[SampleTCPServlet] received msg2 = " + rcvmsg);

        String msg1 = "test response";
        String msg2 = "test response2";

        byte[] result1 = null;
        byte[] result2 = null;
        if (encoding != null) {
            try {
                result1 = msg1.getBytes(encoding);
                result2 = msg2.getBytes(encoding);
            } catch (UnsupportedEncodingException uee) {
                result1 = msg1.getBytes();
                result2 = msg2.getBytes();
            }
        } else {
            result1 = msg1.getBytes();
            result2 = msg2.getBytes();
        }

        header[4] = (byte)1; // mark as response
        ServletOutputStream out = res.getOutputStream();
        out.write(header);

        byte[] buf1 = new byte[64];
        System.arraycopy(result1, 0, buf1, 0, result1.length);
        out.write(buf1);

        byte[] buf2 = new byte[64];
        System.arraycopy(result2, 0, buf2, 0, result2.length);
        out.write(buf2);

        out.flush();
    }

    public void destroy() {
    }
}

package sample.client;

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

public class Client {
    private String address;
    private int port;

    private int magic = 7777;
    private byte type = 0;
    private int bodyLength = 128;
    private byte[] serviceName="sample".getBytes();

    public Client(String host, int port) {
        this.address = host;
        this.port = port;
    }

    public void test()
        throws IOException, UnsupportedEncodingException {
        Socket socket = new Socket(address, port);
        DataOutputStream out = new DataOutputStream(
            new BufferedOutputStream(socket.getOutputStream()));
        DataInputStream in = new DataInputStream(
            new BufferedInputStream(socket.getInputStream()));

        out.writeInt(7777);
        out.write(type);
        out.writeInt(bodyLength);
        byte[] buf = new byte[32];
        System.arraycopy(serviceName, 0, buf, 0, serviceName.length);
        out.write(buf);
        byte[] msg1 = "test request".getBytes();
        byte[] msg2 = "test request2".getBytes();
        buf = new byte[64];
        System.arraycopy(msg1, 0, buf, 0, msg1.length);
        out.write(buf);
        buf = new byte[64];
        System.arraycopy(msg2, 0, buf, 0, msg2.length);
        out.write(buf);

        out.flush();

        // rx msg
        int magic = in.readInt();
        System.out.println("[Client] received magic = " + magic);

        byte type = (byte)in.read();
        System.out.println("[Client] received type = " + type);

        int len = in.readInt();
        System.out.println("[Client] received body length = " + len);

        byte[] svcname = new byte[32];
        in.readFully(svcname);
        System.out.println("[Client] received service name = " +
                           (new String(svcname)).trim());

        byte[] body = new byte[128];
        in.readFully(body);
        String rcvmsg = null;
        rcvmsg = (new String(body, 0, 64)).trim();
        System.out.println("[Client] received msg1 = " + rcvmsg);
        rcvmsg = (new String(body, 64, 64, "euc-kr")).trim();
        System.out.println("[Client] received msg2 = " + rcvmsg);

        out.close();
        in.close();
        socket.close();
    }

    public static void main(String[] argv) throws Exception {
        Client client = new Client("localhost", 5555);
        client.test();
    }
}

package sample.serverpush

...

@WebServlet("/ServerPush")
public class ServerPushServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        
        PushBuilder builder = req.newPushBuilder();
        String pushResourcePath = "resources/a.txt";
        
        // Push할 리소스의 패스를 넣어준 후 push()함수를 호출한다.
        builder.path(pushResourcePath);
        builder.push();

        resp.getWriter().write("main page\n");
    }
}