Edit Sample Guide on HTTP Session Caching.
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John Blum
@@ -4,6 +4,7 @@
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:apache-geode-version: 16
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:apache-geode-docs: https://geode.apache.org/docs/guide/{apache-geode-version}
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:apache-geode-javadoc: https://geode.apache.org/releases/latest/javadoc
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:apache-geode-website: https://geode.apache.org/
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:spring-boot-docs: https://docs.spring.io/spring-boot/docs/current/reference/html
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:spring-boot-javadoc: https://docs.spring.io/spring-boot/docs/current/api
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:spring-data-geode-docs: https://docs.spring.io/spring-data/geode/docs/current/reference/html
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@@ -15,9 +16,9 @@
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:spring-session-website: https://spring.io/projects/spring-session
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This guide walks you through building a simple Spring Boot application using {spring-session-website}[Spring Session]
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backed by Apache Geode to manage HTTP Session State.
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backed by {apache-geode-website}[Apache Geode] to manage HTTP Session state.
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It is assumed that the reader is familiar with the Spring _programming model_ as well as the Java Servlet API.
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It is assumed that the reader is familiar with the Spring _programming model_ as well as the _Java Servlet_ API.
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No prior knowledge of Spring Session or Apache Geode is required to utilize HTTP Session State Caching in your
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Spring Boot applications.
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@@ -28,16 +29,16 @@ link:../index.html#geode-samples[Back]
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[[geode-samples-caching-http-session-background]]
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== Background
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HTTP Session State Caching is probably 1 of the most useful forms of caching in an enterprise application, especially
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given the proliferation of Web applications in the enterprise.
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HTTP Session Caching is one of the most used forms of caching in enterprise applications, especially given
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the proliferation of Web applications in the enterprise.
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HTTP Sessions are used primarily to manage conversational state with users of your applications between HTTP requests
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given that HTTP is a stateless protocol. This is primarily due to the fact that HTTP connections are not persistent.
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When an HTTP client makes a request, the client opens a connection, sends an HTTP request to the server, waits for the
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server to process the request, receives a response and then closes the connection. Each time an HTTP request is sent,
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HTTP Sessions are primarily used to manage conversational state with users of your Web applications between HTTP
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requests given that HTTP is a stateless protocol. This is due to the fact that HTTP connections are not persistent.
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When an HTTP client makes a request, the client opens a connection to the server, sends an HTTP request, waits for
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the server to process the request and respond, and then closes the connection. Each time an HTTP request is sent,
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the same procedure is followed.
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Of course, there are alternatives to HTTP when making Web Service requests. For instance, if you are using
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Of course, there are alternatives to HTTP when making remote Web Service requests. For instance, if you are using
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https://en.wikipedia.org/wiki/WebSocket[WebSockets] in your applications, then you would have persistent connections
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and would most likely be using either the https://stomp.github.io/[STOMP] or https://wamp-proto.org/[WAMP] protocols.
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@@ -46,28 +47,27 @@ over the STOMP protocol.
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TIP: Spring Session additionally {spring-session-docs}/#websocket[supports] Session State Management for _WebSockets_.
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As mentioned above, it is useful to use the HTTP Session to manage conversational state with users of your application
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As mentioned above, it is useful to use the HTTP Session to manage conversational state with users of your applications
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so that they can experience continuity between separate interactions (i.e. HTTP requests). In order to maintain that
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continuity and provide a consistent, uninterrupted experience, the HTTP Session must be preserved in a reliable manner.
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1 way to do this is to employ a data management solution in your application architecture that 1) makes the HTTP Session
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highly available and 2) makes the HTTP Session resilient to failures in the system architecture.
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One way to do this is to employ a data management solution in your application architecture that 1) makes the HTTP
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Session highly available and 2) makes the HTTP Session resilient to failures in the system architecture.
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Apache Geode is ideal for managing HTTP Session state given that it can distribute data/state across a scaled-out,
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highly-available architecture by replicating data in a redundant and organized (partitioned) manner thereby making
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the data resilient to failures, such as network or hardware failures.
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highly-available architecture by replicating data in a redundant and organized (partitioned) manner, thereby making
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the data resilient to network and hardware failures.
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This is an ideal arrangement in a cloud environment given that you most likely will be running multiple instances
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of your application in order to serve the demand, especially during peak loads. In these cases, you will undoubtedly
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face failures and each application will need to be prepared to take over in a moments notice to provide the consistent,
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uninterrupted experience to which we alluded to above. These applications instances will need access to
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the same HTTP Session.
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This is ideal in a cloud environment given that you will most likely be running multiple instances of your application
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in order to serve the demand, especially during peak loads. In these cases, you will undoubtedly face failures and each
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application instance will need to be prepared to take over in a moments notice to provide the consistent, uninterrupted
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experience to which we alluded to above. These applications instances will need access to the same HTTP Session state.
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An application architecture with HTTP Session State Caching appears as follows:
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image::../images/HTTP-Session-Caching.png[]
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Essentially, anytime an `HttpSession` is requested by your Spring Boot Web Application, the Servlet Container
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Essentially, anytime an HTTP Session is requested by your Spring Boot, Web Application, the Servlet Container
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(e.g. Apache Tomcat) delegates to Spring Session to provide the implementation of `javax.servlet.http.HttpSession`.
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After all, `javax.servlet.http.HttpServlet` is an interface that can have many implementations.
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@@ -76,14 +76,14 @@ a Servlet `Filter` that gets registered by Spring Session programmatically when
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classpath.
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Spring Session's implementation of the `javax.servlet.http.HttpSession` interface can backed by many different providers
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that implement the Spring Session framework's `SessionRepository` interface:
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that implement the Spring Session framework's `SessionRepository` interface.
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The Spring Session framework architecture can be depicted as follows:
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Spring Session's architecture can be depicted as follows:
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image::../images/Spring-Session-Framework-Architecture.png[]
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Again, the `SessionRepository` interface is the central component of the framework for adapting any backend data store
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provider for managing the HTTP Session.
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Again, the `SessionRepository` interface is the central component of the framework enabling any backend data store
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to be adapted and serve as a provider for managing the HTTP Sessions.
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This is effectively how https://github.com/spring-projects/spring-session-data-geode[Spring Session for Apache Geode
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& Pivotal GemFire] works.
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@@ -92,7 +92,7 @@ This is effectively how https://github.com/spring-projects/spring-session-data-g
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== Example
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For our example, we are going to keep the Web application relatively simple. Essentially, we just want to show you
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how easy it is to use Spring Session in your Spring Boot, Web applications, without a lot of ceremony and fuss.
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how easy it is to use Spring Session in your Spring Boot, Web applications, to manage the HTTP Session state.
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So, we are going to switch from Servlet Container (e.g. Apache Tomcat) to Spring Session managed HTTP Sessions with a
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single-line configuration change.
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@@ -100,7 +100,7 @@ single-line configuration change.
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First, let's introduce the Spring Web MVC `Controller` in our Spring Boot, Web application.
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[[geode-samples-caching-http-session-example-controller]]
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== Controller
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=== Controller
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Our Spring Web MVC `Controller` class is implemented as follows:
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@@ -111,16 +111,16 @@ include::{samples-dir}/caching/http-session/src/main/java/example/app/caching/se
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----
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The main Web Service endpoint in our Spring Boot, Web application is the `/session` endpoint, which is accessible from
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http//:localhost:8080/session.
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http//:localhost:8080/session[].
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The `/session` endpoint outputs 3 bits of information:
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1) The `javax.servlet.http.HttpSession` class type.
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2) Current HTTP Session count.
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3) Current HTTP Request count.
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1. The `javax.servlet.http.HttpSession` class type.
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2. Current HTTP Session count.
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3. Current HTTP Request count.
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The `HttpSession` class type lets us know the strategy (e.g. Servlet Container vs. Spring Session) is being used to
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manage the HTTP Session state.
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The `HttpSession` class type lets us know which implementation (e.g. Servlet Container vs. Spring Session) is being used
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to manage the HTTP Session state.
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The HTTP Request count is simply incremented every time a client HTTP Request is made to the HTTP server (e.g. Servlet
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Container) before the HTTP Session expires. If the HTTP Session expires before another client HTTP Request is made,
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@@ -136,8 +136,8 @@ include::{samples-dir}/caching/http-session/src/main/resources/application.prope
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----
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The configuration is quite simple. In this case, we have set the HTTP Session `timeout`, using the
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`server.servlet.session.timeout` property to *15 seconds*. This property is to configure the HTTP Session timeout
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whether the HTTP Session is being managed by the Servlet Container (e.g. Apache Tomcat) or by Spring Session.
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`server.servlet.session.timeout` property, to *15 seconds*. This property is used to configure the HTTP Session timeout
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regardless of whether the HTTP Session is being managed by the Servlet Container or by Spring Session.
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Additionally, we have configured the data management policy used by Apache Geode to manage the HTTP Session state
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in a `LOCAL` only cache (a.k.a. Region). This was done by setting the
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@@ -147,8 +147,9 @@ The other configuration properties in Spring Boot's `application.properties` fil
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TIP: In most production deployments, you will likely be using a client/server topology, where the HTTP Session
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is managed by a cluster of Apache Geode or Pivotal GemFire servers so that the HTTP Session can be shared across
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multiple instances of the Spring Boot, Web application, especially in a cloud environment when utilizing Microservices
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architecture. However, for example purposes, we tried to keep the sample as simple as possible.
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multiple instances of the Spring Boot, Web application. This would be especially true in a cloud environment
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when utilizing a Microservices architecture. However, for example purposes, we tried to keep the sample
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as simple as possible.
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NOTE: The default data management policy for the client cache (a.k.a. Region) used to manage HTTP Session state is a
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`PROXY`, which is the basis for the client/server topology. Therefore, the default configuration assumes you will be
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@@ -203,7 +204,7 @@ and we will see the HTTP Session count increment along with the HTTP Request cou
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image::../images/HttpSessionCachingApplication-ServletContainerSessionExpiration.png[]
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Now, we can repeat this exercise, but this time, with Spring Session.
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Now, we can repeat this same exercise, but this time, using Spring Session.
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[[geode-samples-caching-http-session-example-run-spring-session]]
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=== Run the Example with Spring Session
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@@ -234,16 +235,16 @@ When we run the example again, and access the `/session` Web service endpoint, w
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image::../images/HttpSessionCachingApplication-SpringSession.png[]
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Now we see the implementing class for the `javax.servlet.http.HttpSession` is
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Now we see that the implementing class for the `javax.servlet.http.HttpSession` is
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`org.springframework.session.web.http.SessionRepositoryFilter$SessionRepositoryRequestWrapper$HttpSessionWrapper`.
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Easy!
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Of course, the ability to scale-out and optimize the data management policies around HTTP Session management
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is very provider-specific (e.g. Apache Geode) and highly dependent on the use case and application requirements,
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Of course, the ability to scale-out and optimize the data management policies for HTTP Session management is very
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provider-specific (e.g. Apache Geode) and highly dependent on the use case as well a application requirements,
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therefore is beyond the scope of this guide.
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[[geode-samples-caching-http-session-summary]
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[[geode-samples-caching-http-session-summary]]
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== Summary
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Spring Session is a powerful framework for managing your HTTP Session state. Not only does it allow you to plugin
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@@ -264,5 +265,7 @@ Spring Session also allows you to manage different types of Sessions depending o
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Therefore, it makes it a simple matter to switch providers, or adopt additional Session management capabilities as your
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application requirements change and/or your use cases grow.
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Finally, (HTTP) Session state caching is 1 of the most effective and common ways to utilize caching in your Spring Boot,
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Web applications, and make the users experience first-class.
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HTTP Session state caching is one of the most effective and common ways to utilize caching in your Spring Boot,
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Web applications, and ensure the users experience is first-class.
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link:../index.html#geode-samples[Back]
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