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Web Proxy Server

Web Proxy Server

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Web Proxy Server

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  1. Web Proxy Server

  2. Proxy Server Introduction • Returns status and error messages. • Handles http CGI requests. • For more information about CGI please refer to NCSA's CGI tutorial at http://hoohoo.ncsa.uiuc.edu/cgi/. • Determines the Class to run Dynamically no code change is needed. • Decodes the encoded parameter list. • Is multi-threaded.

  3. The Apps Class • You can retrieve the source for the abstract Apps class on cochise at http://cochise.cs.washington.edu/~maxwell/proxy/Apps.java. • The server calls setSocket for the application passing it the socket of the connection. • This function opens a BufferedReader and a PrintWriter. • These functions are convenient for sending strings back and forth. • You can still gain access to the socket and open your own readers and writers. • The parameter list. • Inherits from Thread.

  4. Creating your own Application • Extend your class from class Apps. Implement a procedure public void run(). • This is the function, which gets called to start the thread. • Send a content type back down the output stream. • Send all your information. • Close the output stream.

  5. Wrapper Class • If you want to write your application in something other the Java you will need to create a Java wrapper class. • First create a class that extends Apps and create a function public void run(). In this function you need to do the following. String arg[] = new String[ numArgs + 1]; arg[0] = "ProgramName"; arg[1] = argument1; arg[numArgs] = null; Runtime r = Runtime.getRuntime(); Process p = r.exec(arg); Buffered Reader pIn = new BufferedReader(new InputStreamReader(p.getInputStream())); PrintWriter pOut = new PrintWriter(p.getOutputStream()); pOut.println(parm); String in; while((in = pIn.readln())) dOut = in;

  6. Schedule Client

  7. Receive Send Decode Encode We are choosing to encode requests in a URL. URL is passed. It is received and Decode sends each line of information to the Controller. Network Control Web

  8. Proxy Calendar+ JDBC mySQL Web

  9. PC GUI • The control of the GUI works as follows. • The first screen that is displayed is the login screen. • The user will login and the information is sent to the Controller to be processed. • Once the login is verified, the splash screen is displayed while information needed by the schedule GUI is received from the server. • Finally, the Main GUI is displayed. • The Main GUI enables the user to look at events from a year, month, or day perspective. • If the user wants to add an event, they will enter it in the space provided. • That information is sent to the Main GUI. • The Main GUI sends it on to the Controller. • The Controller sends it to the server.

  10. Data Processing • The Network Control is running in a separate thread than the Controller. • When processing the user login, the information is bundled up into a SendEvent and passed on to the Network Control. • The Network Control sends the event to the Encode class to be encoded into a URL string. • The the Network Control sends this string to the Send class to be sent to the server. • The Server information is stored in a class called ProxyInfo.class. If the server information changed, the class can be removed and replaced with the correct information. • When the information is sent, it opens a URL connection. • This sends back the content, which is a Buffered Input Stream. • The stream is passed by the Network Control to the Receive Class. • The Receive classes parses each line of information, sends it to the Decode class to be parsed further and sent to the Network Control. • The Network Control packages it up into a ReceiveEvent and sends it to the Controller to be processed and sent to the GUI.

  11. package schedule; import java.lang.*; import java.io.*; import java.net.*; import java.util.*; public class NetworkThread extends Thread implements SendListener { private SendEvent evt; private Vector listeners; private boolean readyToSend = false; public NetworkThread() { super(); listeners = new Vector(); } public void processSend(SendEvent evt) { // System.out.println("Getting to network send..."); if (!isAlive()) this.start(); if(!readyToSend) { this.evt = evt; readyToSend = true; } }

  12. public void addReceiveListener(ReceiveListener sl) { listeners.addElement(sl); } public void removeReceiveListener(ReceiveListener sl) { listeners.removeElement(sl); } private void notifyListeners(ReceiveEvent re) { for (int i=0; i < listeners.size(); i++) { ((ReceiveListener)listeners.elementAt(i)).processReceive(re); } } public void run() { ReceiveEvent rEvent; while (true) { if(!readyToSend) try { sleep(10); } catch (InterruptedException e) { }

  13. else { String encodedString; Encode encode = new Encode(); encodedString = encode.encodeString(evt); Send sender = new Send(); Object openStream = sender.OpenStream(encodedString); if (openStream == null ) { System.out.println("Server Down....."); readyToSend = false; notifyListeners(null); continue; } Receive receiver = new Receive(openStream); String s = null; Decode decoder = new Decode(); while ((s = receiver.readLine()) != null) { decoder.decodeNextLine(s); } rEvent = decoder.getReceiveEvent(); notifyListeners(rEvent); readyToSend = false; } } } }

  14. package schedule; import java.net.*; public class Encode { public String encodeString(SendEvent e) { String CGI; String encoded; CGI = "" + e.getApplicationName() + "?username=" + e.getUserName() + "&password=" + e.getPassWord() + "&command=" + e.getCommand() + "&" + e.getInfo(); System.out.println("Encoding string = " + CGI); encoded = URLEncoder.encode(CGI); return encoded; } }

  15. JDBC Function Calls • Loading the Driver • twz1.jdbc.mysql.jdbcMysqlDriver • Getting parameters • jdbcMysqlBase.getDefaultNames() • .jdbcMysql.properties file • Connecting • DriverManager.getConnection(url) • Connection Handle • setCatalog() • Queries • execute • Result Sets