#2848 Requested changes implemented

Ehspresso · Ehspresso · commit 00a7d1312c02 · 2024-04-10T16:09:47.000-04:00
diff --git a/server-session/README.md b/server-session/README.md
@@ -1,7 +1,11 @@
 ---
 title: Server Session
-category: Architectural
+category: Behavioral
 language: en
+tag:
+    - Session Management 
+    - Session Tracking
+    - Cookies
 ---
 
 ## Also known as
@@ -52,25 +56,32 @@ public class LoginHandler implements HttpHandler {
     }
 
     @Override
-    public void handle(HttpExchange exchange) throws IOException {
+    public void handle(HttpExchange exchange) {
         // Generate session ID
         String sessionID = UUID.randomUUID().toString();
 
         // Store session data (simulated)
         int newUser = sessions.size() + 1;
         sessions.put(sessionID, newUser);
         sessionCreationTimes.put(sessionID, Instant.now());
+        LOGGER.info("User " + newUser + " created at time " + sessionCreationTimes.get(sessionID));
 
         // Set session ID as cookie
         exchange.getResponseHeaders().add("Set-Cookie", "sessionID=" + sessionID);
 
         // Send response
         String response = "Login successful!\n" +
                 "Session ID: " + sessionID;
-        exchange.sendResponseHeaders(200, response.length());
-        OutputStream os = exchange.getResponseBody();
-        os.write(response.getBytes());
-        os.close();
+        try {
+            exchange.sendResponseHeaders(200, response.length());
+        } catch (IOException e) {
+            LOGGER.error("An error occurred: ", e);
+        }
+        try(OutputStream os = exchange.getResponseBody()) {
+            os.write(response.getBytes());
+        } catch(IOException e) {
+            LOGGER.error("An error occurred: ", e);
+        }
     }
 }
 ```
@@ -96,7 +107,7 @@ public class LogoutHandler implements HttpHandler {
     }
 
     @Override
-    public void handle(HttpExchange exchange) throws IOException {
+    public void handle(HttpExchange exchange) {
         // Get session ID from cookie
         String sessionID = exchange.getRequestHeaders().getFirst("Cookie").replace("sessionID=", "");
         String currentSessionID = sessions.get(sessionID) == null ? null : sessionID;
@@ -112,24 +123,36 @@ public class LogoutHandler implements HttpHandler {
         }
 
         //Remove session
+        if(currentSessionID != null)
+            LOGGER.info("User " + sessions.get(currentSessionID) + " deleted!");
+        else
+            LOGGER.info("User already deleted!");
         sessions.remove(sessionID);
         sessionCreationTimes.remove(sessionID);
-        exchange.sendResponseHeaders(200, response.length());
-        OutputStream os = exchange.getResponseBody();
-        os.write(response.getBytes());
-        os.close();
+
+        try {
+            exchange.sendResponseHeaders(200, response.length());
+        } catch(IOException e) {
+            LOGGER.error("An error has occurred: ", e);
+        }
+
+        try(OutputStream os = exchange.getResponseBody()) {
+            os.write(response.getBytes());
+        } catch(IOException e) {
+            LOGGER.error("An error has occurred: ", e);
+        }
     }
 }
 ```
 
 Sessions are often given a maximum time in which they will be maintained. The sessionExpirationTask() creates a thread which runs every 1 minute to check for sessions that have exceeded the maximum amount of time, in this case 1 minute and removes the session data from the server's storage.
 
 ```java
-    private static void startSessionExpirationTask() {
+    private static void sessionExpirationTask() {
     new Thread(() -> {
         while (true) {
             try {
-                System.out.println("Session expiration checker started...");
+                LOGGER.info("Session expiration checker started...");
                 Thread.sleep(SESSION_EXPIRATION_TIME); // Sleep for expiration time
                 Instant currentTime = Instant.now();
                 synchronized (sessions) {
@@ -144,9 +167,10 @@ Sessions are often given a maximum time in which they will be maintained. The se
                         }
                     }
                 }
-                System.out.println("Session expiration checker finished!");
+                LOGGER.info("Session expiration checker finished!");
             } catch (InterruptedException e) {
-                e.printStackTrace();
+                LOGGER.error("An error occurred: ", e);
+                Thread.currentThread().interrupt();
             }
         }
     }).start();
diff --git a/server-session/src/main/java/com/iluwatar/sessionserver/App.java b/server-session/src/main/java/com/iluwatar/sessionserver/App.java
@@ -4,17 +4,33 @@
 import java.net.InetSocketAddress;
 import java.time.Instant;
 import java.util.*;
-import java.util.logging.Logger;
-
 import com.sun.net.httpserver.HttpServer;
+import lombok.extern.slf4j.Slf4j;
+
+/**
+ * The server session pattern is a behavioral design pattern concerned with assigning the responsibility
+ * of storing session data on the server side. Within the context of stateless protocols like HTTP all
+ * requests are isolated events independent of previous requests. In order to create sessions during
+ * user-access for a particular web application various methods can be used, such as cookies. Cookies
+ * are a small piece of data that can be sent between client and server on every request and response
+ * so that the server can "remember" the previous requests. In general cookies can either store the session
+ * data or the cookie can store a session identifier and be used to access appropriate data from a persistent
+ * storage. In the latter case the session data is stored on the server-side and appropriate data is
+ * identified by the cookie sent from a client's request.
+ * This project demonstrates the latter case.
+ * In the following example the ({@link App}) class starts a server and assigns ({@link LoginHandler})
+ * class to handle login request. When a user logs in a session identifier is created and stored for future
+ * requests in a list. When a user logs out the session identifier is deleted from the list along with
+ * the appropriate user session data, which is handle by the ({@link LogoutHandler}) class.
+ */
 
+@Slf4j
 public class App {
 
   // Map to store session data (simulated using a HashMap)
   private static Map<String, Integer> sessions = new HashMap<>();
   private static Map<String, Instant> sessionCreationTimes = new HashMap<>();
   private static final long SESSION_EXPIRATION_TIME = 10000;
-  private static Logger logger = Logger.getLogger(App.class.getName());
 
     public static void main(String[] args) throws IOException {
       // Create HTTP server listening on port 8000
@@ -30,14 +46,14 @@ public static void main(String[] args) throws IOException {
       // Start background task to check for expired sessions
       sessionExpirationTask();
 
-      logger.info("Server started. Listening on port 8080...");
+      LOGGER.info("Server started. Listening on port 8080...");
     }
 
     private static void sessionExpirationTask() {
         new Thread(() -> {
             while (true) {
                 try {
-                    logger.info("Session expiration checker started...");
+                    LOGGER.info("Session expiration checker started...");
                     Thread.sleep(SESSION_EXPIRATION_TIME); // Sleep for expiration time
                     Instant currentTime = Instant.now();
                     synchronized (sessions) {
@@ -52,9 +68,9 @@ private static void sessionExpirationTask() {
                             }
                         }
                     }
-                    logger.info("Session expiration checker finished!");
+                    LOGGER.info("Session expiration checker finished!");
                 } catch (InterruptedException e) {
-                    e.printStackTrace();
+                    LOGGER.error("An error occurred: ", e);
                     Thread.currentThread().interrupt();
                 }
             }
diff --git a/server-session/src/main/java/com/iluwatar/sessionserver/LoginHandler.java b/server-session/src/main/java/com/iluwatar/sessionserver/LoginHandler.java
@@ -2,6 +2,8 @@
 
 import com.sun.net.httpserver.HttpExchange;
 import com.sun.net.httpserver.HttpHandler;
+import lombok.extern.slf4j.Slf4j;
+import org.slf4j.Logger;
 
 import java.io.IOException;
 import java.io.OutputStream;
@@ -10,6 +12,7 @@
 import java.util.Map;
 import java.util.UUID;
 
+@Slf4j
 public class LoginHandler implements HttpHandler {
 
     private Map<String, Integer> sessions;
@@ -21,24 +24,31 @@ public LoginHandler(Map<String, Integer> sessions, Map<String, Instant> sessionC
     }
 
     @Override
-    public void handle(HttpExchange exchange) throws IOException {
+    public void handle(HttpExchange exchange) {
         // Generate session ID
         String sessionID = UUID.randomUUID().toString();
 
         // Store session data (simulated)
         int newUser = sessions.size() + 1;
         sessions.put(sessionID, newUser);
         sessionCreationTimes.put(sessionID, Instant.now());
+        LOGGER.info("User " + newUser + " created at time " + sessionCreationTimes.get(sessionID));
 
         // Set session ID as cookie
         exchange.getResponseHeaders().add("Set-Cookie", "sessionID=" + sessionID);
 
         // Send response
         String response = "Login successful!\n" +
                 "Session ID: " + sessionID;
-        exchange.sendResponseHeaders(200, response.length());
-        OutputStream os = exchange.getResponseBody();
-        os.write(response.getBytes());
-        os.close();
+        try {
+          exchange.sendResponseHeaders(200, response.length());
+        } catch (IOException e) {
+          LOGGER.error("An error occurred: ", e);
+        }
+        try(OutputStream os = exchange.getResponseBody()) {
+          os.write(response.getBytes());
+        } catch(IOException e) {
+          LOGGER.error("An error occurred: ", e);
+        }
     }
 }
diff --git a/server-session/src/main/java/com/iluwatar/sessionserver/LogoutHandler.java b/server-session/src/main/java/com/iluwatar/sessionserver/LogoutHandler.java
@@ -2,12 +2,14 @@
 
 import com.sun.net.httpserver.HttpExchange;
 import com.sun.net.httpserver.HttpHandler;
+import lombok.extern.slf4j.Slf4j;
 
 import java.io.IOException;
 import java.io.OutputStream;
 import java.time.Instant;
 import java.util.Map;
 
+@Slf4j
 public class LogoutHandler implements HttpHandler {
 
     private Map<String, Integer> sessions;
@@ -19,7 +21,7 @@ public LogoutHandler(Map<String, Integer> sessions, Map<String, Instant> session
     }
 
     @Override
-    public void handle(HttpExchange exchange) throws IOException {
+    public void handle(HttpExchange exchange) {
         // Get session ID from cookie
         String sessionID = exchange.getRequestHeaders().getFirst("Cookie").replace("sessionID=", "");
         String currentSessionID = sessions.get(sessionID) == null ? null : sessionID;
@@ -35,11 +37,23 @@ public void handle(HttpExchange exchange) throws IOException {
         }
 
         //Remove session
+        if(currentSessionID != null)
+          LOGGER.info("User " + sessions.get(currentSessionID) + " deleted!");
+        else
+          LOGGER.info("User already deleted!");
         sessions.remove(sessionID);
         sessionCreationTimes.remove(sessionID);
-        exchange.sendResponseHeaders(200, response.length());
-        OutputStream os = exchange.getResponseBody();
-        os.write(response.getBytes());
-        os.close();
+
+        try {
+          exchange.sendResponseHeaders(200, response.length());
+        } catch(IOException e) {
+          LOGGER.error("An error has occurred: ", e);
+        }
+
+        try(OutputStream os = exchange.getResponseBody()) {
+          os.write(response.getBytes());
+        } catch(IOException e) {
+          LOGGER.error("An error has occurred: ", e);
+        }
     }
 }
