Merge branch 'philipp-session-demo' into 'master'

adds session demo

See merge request !3

pom.xml

@@ -26,6 +26,12 @@
             <artifactId>jakarta.jakartaee-api</artifactId>
             <version>9.1.0</version>
             <scope>provided</scope>
+            <exclusions>
+                <exclusion>
+                    <groupId>javax</groupId>
+                    <artifactId>javaee-api</artifactId>
+                </exclusion>
+            </exclusions>
         </dependency>
         <dependency>
             <groupId>jakarta.ws.rs</groupId>
@@ -40,6 +46,12 @@
             <artifactId>apache-jena-libs</artifactId>
             <type>pom</type>
             <version>4.2.0</version>
+            <exclusions>
+                <exclusion>
+                    <groupId>javax.annotation</groupId>
+                    <artifactId>javax.annotation-api</artifactId>
+                </exclusion>
+            </exclusions>
         </dependency>
         <dependency>
             <groupId>org.apache.logging.log4j</groupId>

src/main/java/com/kgshape/app/rest/demo/SessionAwareEndpoint.java

+package com.kgshape.app.rest.demo;
+
+import com.kgshape.app.service.demo.DemoSessionCache;
+
+import jakarta.enterprise.context.RequestScoped;
+import jakarta.enterprise.context.SessionScoped;
+import jakarta.inject.Inject;
+import jakarta.ws.rs.GET;
+import jakarta.ws.rs.Path;
+
+/**
+ * The name of this bean is misleading, then contrary to its name, the offered endpoints
+ * (all which start with /sessionTest) don't need to know there statefulness
+ *
+ * This can also be seen with the {@link RequestScoped} annotation, meaning
+ * that this object is created again for each object
+ */
+@RequestScoped
+@Path("/sessionTest")
+public class SessionAwareEndpoint {
+
+	/**
+	 * The only thing which makes the whole endpoint session aware is the injection of this {@link SessionScoped}
+	 * bean
+	 *
+	 * But also note that the scope of the injected Bean should be irrelevant to the development of your endpoint.
+	 * Think of this principle like that: The injected object fulfills a contract, in this case a session wide cache
+	 * The technique used to achieve this contract is not the business of the endpoint, but the implementation of this object
+	 * (it could possibly be a more sophisticated service, which synchronizes sessions across multiple cluster nodes, or something
+	 * else)
+	 */
+	@Inject
+	private DemoSessionCache demoSessionCache;
+
+	/**
+	 * Upon request contains a JSESSIONID cookie used to identify the session
+	 *
+	 * As long as the cookie isnt changed this session is alive (also regard session time out)
+	 */
+	@GET
+	public String getCounter() {
+		return String.valueOf(this.demoSessionCache.getAtomicInteger().getAndIncrement());
+	}
+}

src/main/java/com/kgshape/app/service/demo/DemoSessionCache.java

+package com.kgshape.app.service.demo;
+
+import java.io.Serializable;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import jakarta.annotation.PostConstruct;
+import jakarta.enterprise.context.SessionScoped;
+
+/**
+ * This object exists once per session
+ */
+@SessionScoped
+public class DemoSessionCache implements Serializable {
+
+	private AtomicInteger atomicInteger;
+
+	/**
+	 * Always use {@link PostConstruct} to initialize the state of your bean
+	 *
+	 * Reason: Objects may be recycled, leading to inconsistencies, when initializing logic is in the constructor
+	 * (as the constructor wouldn't be called if the object would be recycled)
+	 */
+	@PostConstruct
+	protected void init() {
+		this.atomicInteger = new AtomicInteger();
+	}
+
+	public AtomicInteger getAtomicInteger() {
+		return this.atomicInteger;
+	}
+}