From 6ff26adbfa8065c057a11b02c2220752c6f81cd9 Mon Sep 17 00:00:00 2001
From: Philipp <p.gritsch@student.uibk.ac.at>
Date: Thu, 25 Nov 2021 20:43:29 +0100
Subject: [PATCH] adds session demo
---
pom.xml | 12 +++++
.../app/rest/demo/SessionAwareEndpoint.java | 44 +++++++++++++++++++
.../app/service/demo/DemoSessionCache.java | 31 +++++++++++++
3 files changed, 87 insertions(+)
create mode 100644 src/main/java/com/kgshape/app/rest/demo/SessionAwareEndpoint.java
create mode 100644 src/main/java/com/kgshape/app/service/demo/DemoSessionCache.java
diff --git a/pom.xml b/pom.xml
index 13d5743..6532855 100644
--- a/pom.xml
+++ b/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>
diff --git a/src/main/java/com/kgshape/app/rest/demo/SessionAwareEndpoint.java b/src/main/java/com/kgshape/app/rest/demo/SessionAwareEndpoint.java
new file mode 100644
index 0000000..da5d0c5
--- /dev/null
+++ b/src/main/java/com/kgshape/app/rest/demo/SessionAwareEndpoint.java
@@ -0,0 +1,44 @@
+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());
+ }
+}
diff --git a/src/main/java/com/kgshape/app/service/demo/DemoSessionCache.java b/src/main/java/com/kgshape/app/service/demo/DemoSessionCache.java
new file mode 100644
index 0000000..38bf0c9
--- /dev/null
+++ b/src/main/java/com/kgshape/app/service/demo/DemoSessionCache.java
@@ -0,0 +1,31 @@
+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;
+ }
+}
--
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