Shulou(Shulou.com)06/01 Report--

Editor to share with you how to achieve session sharing Tomcat, I believe that most people do not know much about it, so share this article for your reference, I hope you can learn a lot after reading this article, let's go to understand it!

1. How to maintain a session session

At present, in order to enable web to adapt to large-scale access, it is necessary to implement the cluster deployment of applications. The most effective solution of the cluster is load balancing, and every request of load balancing users may be assigned to a non-fixed server, so we must first solve the unity of session to ensure the normal use of users no matter which server their requests are forwarded to, that is, we need to implement the sharing mechanism of session.

There are several solutions to achieve session unification under the cluster system:

1. Precise location of requests: session sticky, for example, the hash policy based on accessing ip, that is, all current user requests are located in one server, so that a single server stores the user's session login information. If it goes down, it is equivalent to a single point of deployment, which will be lost and the session will not be replicated.

2. Session replication sharing: session replication, for example, tomcat comes with session sharing, which mainly refers to synchronizing session among multiple application servers in a cluster environment to make session consistent and transparent. If one of the servers fails, according to the principle of load balancing, the scheduler will traverse to find available nodes and distribute requests. Because the session has been synchronized, it can ensure that the user's session information will not be lost, session replication.

Inadequacies of this scheme:

Must be done between the same kind of middleware (e.g. between tomcat-tomcat).

The performance loss caused by session replication will increase rapidly. Especially when large objects are saved in session, and the objects change rapidly, the performance degradation is more significant, which will consume the system performance. This feature limits the horizontal expansion of web applications.

Session content is synchronized to members through broadcasting, which will cause network traffic bottlenecks, even intranet bottlenecks.

The performance is not good under the big concurrency.

3. Session sharing based on cache DB cache

Session sharing based on memcache/redis caching

Even if the session information is accessed by cacheDB, the application server accepts the new request to save the session information in the cacheDB. When the application server fails, the scheduler will traverse to find the available node and distribute the request. When the application server finds that the session is not in the local memory, it looks for it in the cacheDB, and if it finds it, it copies it to the local machine, so as to achieve session sharing and high availability.

2. This configuration is based on the tomcat7 environment. Through the session replication that comes with the tomcat cluster, the session information will be automatically copied to each node.

Case environment:

Mainframe

Operating system

IP address

Main software

Tomcat-1

Centos6.5 x86_64

192.168.10.20

Jdk-7u65-linux-x64.gz

Apache-tomcat-7.0.54.tar.gz

Tomcat-2

Centos6.5 x86_64

192.168.10.21

Lab Topology:

2. Install JDK on tomcat-1 and tomcat-2 nodes

Before installing tomcat, the full name of JDK,JDK is java development kit, which is a free java language software development kit provided by sun, which includes java virtual machine (JVM). The written java source program can be compiled to form java bytecode. As long as JDK is installed, you can use JVM to interpret these bytecode files, thus ensuring the cross-platform nature of java.

Install JDK and configure the java environment:

Decompress jdk-7u65-linux-x64.gz

Move the extracted jdk1.7.0_65 directory to / usr/local/ and rename it to java

Add the following to the / etc/profile file:

Execute the profile file through the source command to make it effective.

Run the java-version command on the tomcat-1 and tomcat-2 nodes respectively to see if the java version is the same as previously installed.

So far, the java environment has been configured

3. Install and configure tomcat on tomcat-1 and tomcat-2 nodes

Extract the apache-tomcat-7.0.54.tar.gz package

Move the extracted folder to / usr/local/ and rename it to tomcat7

Configure tomcat environment variables

The content of / etc/profile file is as follows:

Execute the profile file through the source command to make it effective.

Start tomcat

Tomcat runs on port 8080 by default. Run the netstat command to view the listening information of port 8080.

Open the browser to test the access to tomcat-1 and tomcat-2 respectively

Run the / usr/local/tomcat7/bin/shutdown.sh command if you want to shut down tomcat

All right, you can see the success of the visit. It means that our tomcat installation is complete. Let's configure it.

4. Modify the configuration file

# vim / usr/local/tomcat7/conf/server.xml

Set the default host and add jvmRoute

Define a virtual host, point the path of the website file to / web/webapp1, and add the context segment to the host segment

Add document directory and test files

The index.jsp content is as follows:

Stop tomcat, check the configuration file, and start tomcat

The configuration of the Tomcat-2 node is basically similar to that of the tomcat-1 node, except that the jvmRoute is different, and in order to distinguish which node provides access, the test page title is also different. All other configurations are the same. Process outline

Test and visit again.

You can see that the session session is different

All right, now that we have finished all our preparations, let's configure the load balancing of tomcat and achieve session persistence through session replication.

5. Configure the session sharing cluster and complete the following operations in tomcat-1 and tomcat-2, respectively.

Configure the server.xml file

In Server.xml, locate the annotated node and add the following below:

Modify the applied web.xml file and add the tag, as shown below:

Add tags

It can be directly added before this is copied by the session that joins the tomcat. This step is required to build a tomcat cluster, otherwise the user's session cannot be used normally.

Note: you can refer to clustering/session replicationhow-to for the above content, as shown in the following figure:

Note: the tomcat host must point to the correct gateway, otherwise tomcat will fail to start with the following error

Restart the tomcat service and check the listening status of the port.

The Tomcat-2 node is similar to the tomcat-1 configuration, except that the address is written as the ip of tomcat-2.

Check the tomcat log: / usr/local/tomcat7/logs/catalina.yyyy-mm-dd.log

6. Nginx server configuration

Using nginx to realize load balancing of tomcat

Turn off the firewall

Install related software packages: # yum-y install pcre-devel zlib-devel

Extract and install nginx

Modify the nginx.conf file

The modifications are as follows:

Start the nginx service

7. let's start the test.

Use the browser to access the address of nginx on the client

Refresh the page

As you can see from the figure, no matter how you refresh the SessionID, it will not change, indicating that the DeltaManager cluster configuration of our Tomcat has been completed, and session sharing among multiple hosts has been realized.

8. Tomcat connects to mysql database

192.168.10.22 as a mysql database server

Configure mysql

Insert some data

Download mysql-connector-java-5.1.22-bin.jar and copy it to the $CATALINA_HOME/lib directory

Context configuration

Configure the JNDI datasource in tomcat by adding a declaration for your resource to your context

Save changes and exit

Web.xml configuration

Save the changes and exit, restart the tomcat service

Test code

Now create a simple test.jsp page, the content is as follows:

Test access

The above results show that the visit was successful.

Note:

Please refer to tomcat docs for the above configuration.

The above is all the content of the article "how to achieve session sharing in Tomcat". Thank you for reading! I believe we all have a certain understanding, hope to share the content to help you, if you want to learn more knowledge, welcome to follow the industry information channel!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.