We developed a J2EE web application (.war). The application runs without problems in Glassfish, Payara and Weblogic (so far). It's supposed it should run in any J2EE compliance Application Server.
Soon the application will be on production and we expect a large number of users. We are considering implementing a cluster in the Application Server in order to properly balance service in several nodes. We have an application-scoped resource that each session must access in exclusive-mode. We achieve the exclusive-access thanks to what it could be called a MuTex via calls to serialized methods in a application-scoped singleton object. Now, with the new cluster scenario, we need to keep the exclusive-mode access between all the session in all the nodes (each node is executed on his own JVM).
I would like to know which would be the best practices regarding shared objects in distributed environments (nodes of a clustered web application server)?
How and we achieve the implementation of a singleton object accessible to all the nodes of the cluster?
Any information or help will be really appreciated.
Thanks in advance!
Related
I have coded a Spring MVC Hibernate application with RabbitMQ as a messaging server & a MySQL DB. I have also used Hazelcast an in-memory distributed cache to centralize the state of the application, moving the local tomcat session to a centralized session & implementing distributed locks.
The app right now is hosted on a single tomcat server in my local system.
I want to test my application on a multiple JVM node environment i'e app running on multiple tomcat servers.
What would be the best approach to test the app.
Few things that come to my mind
A. Install & configure a load balancer & set up a tomcat cluster in my local system. This I believe is a tedious task & requires much effort.
B. Host the application on a PAAS like OpenShift, cloudfoundry but I am not sure if I will be able to test my application on several nodes.
C. Any other way to simulate a clustered environment on my local windows system?
I would suggest first you should understand your application requirement. For the real production/live environment, are you going to use Infrastructure as a service or PAAS.
If Infrastructure as a service then
I would suggest create local cluster environment and use the tomcat and spring application sticky session concept. Persist the session in Hazelcast or redis server installed on different node. Configure load balancer for multiple nodes having tomcat server. 2-3 VMs for testing purpose would be suitable.
If requirement is PAAS then
Don't think about local environment. Test directly on OpenShift or AWS free account and trust me you would be able to test on PAAS if all setup is fine.
I am looking for a way to integrate external services (like active directory and DB access, web service calls) in a non (or incomplete) Java EE environment such as Tomcat. In a full Java EE server I would (probably) implement a resource adapter (JCA) however in the current project everything runs in a tomcat (v.7.X). This means that many apects like concurrency, transactions, state etc. are not handled by a Java EE container.
It is a stateless setting and the folks told me that there will be some kind of transaction handling (details are due, JTA?). There will be several tomcats in a clustered environment. The number of users is in 3-4 digits range.
My questions are:
How and when should I initialize external services access? (Use a singleton or a factory etc.?)
Should I use a third party connection pool for database access? (like Hikari or the tomcat internal one)
How to deal with concurrency? (synchronized blocks, using volatile?)
I am developing a spring boot application.
Since spring boot created a .jar file for an application.
I want to cluster this particular application on different server. Lets say I build a jar file and ran a project then it should run in cluster mode from number of defined servers and should be able to serve end user needs.
My jar will reside on only one server but it will be clustered across number of servers. When end user calls a web service from my spring boot app he never know from where it is getting called.
The reason behind clustering is suppose any of the server goes down in future, end user will still be able to access web services from another server. But I don't know how to make it clustered.
Can any one please give me insight on this ?
If you want to have it clustered, you just run your Spring Boot application on multiple servers (of course, the JAR must be present on those servers, otherwise you can't run it). You would then place a loadbalancer in front of the application servers to distribute the load.
If all services you are going to expose are stateless so you only need to use load balancer in front of your nodes for ex. apache or nginx, if your services are stateful "store any state [session, store data in db]" so you have to use distributed cache or in memory data grid:
for session you can use spring-session project which could used rails to store sessions.
for store data in DB you need to cluster DB it self and can use distributed cache above your DB layer like Hazelcast.
Look into spring cloud, they have used some netflix open software along with amazons to create 12 factor apps for micro services.
Ideally you would need a load balancer, service registry that can help you achieve multiple instances of spring boot. I believe you have to add a dependency called eureka.
Check the below link
Spring cloud
You can deploy it in cloud foundry and use autoscale function to increase your application instances.
I ‘m trying to create a small EJB 3.1 application in which I want to use two application servers from two different vendors. (JBoss 6.1.0 Final and Glassfish 3.1). This is just to experience the taste of distributed applications and new features of EJB3.1.
This is the problem I’m having…
I have created a simple EJB (kind of a hello world ejb) and deployed it in GlassFish server which is running in the machine A. Let’s call it GlassFishHelloWorldEjb. This one has business remote and local views.
I have created another EJB project in which I have an EJB called JBossHelloWorldEjb. I have deployed it in the Jboss server which is running in the machine B.
Now I want to inject GlassFishHelloWorldEjb to a reference in the JBossHelloWorldEjb so that I can call it within the JBossHelloWorldEjb. Then I have a web app deployed in the Jboss which calls the JBossHelloWorldEjb.
MyWebApp(Jboss, machine B)-----> JBossHelloWorldEjb (Jboss, machine B)----> GlassFishHelloWorldEjb(GlassFish, Machine A)
I tried many ways to inject the GlassFishHelloWorldEjb in to the JBossHelloWorldEjb but failed. Could some please shed some light to achieve this.
Would greatly appreciate if you could show me the way to do this through both INJECTION and Programmatic JNDI look up.
Cheers
Lekamge
one option might be to use Spring RemoteEJB Proxies
OR. import client required jars for remote and write your own wrapper
I've got a Java Enterprise Web Application which uses Tomcat6+Struts+Hibernate+MySql. at the time being it's publicly up and running on a single server. In order to performance issues we should move the application to a clustered environment. Anyhow I wanna use Tomcat6 clustering as below:
A Load Balancing machine including a web server (Apache+mod_proxy) as front-end
Some application server machines, each one running a tomcat6 instance
A session management back-end
And finally a db server
something like this
The load balancer machine receives all the requests and depending on the balancing algorithm redirects them to the respective tomacat6 machine. After doing the business part, the response is returned to the webserver and at the end to the user. In this scenario the front-end machine processes all the requests and responses so it'd be a bottleneck point in the application.
In Apache Tomcat clustering, is there a way to load balancing mechanism and web servers? I mean putting a load balancer in the front end and leave the request/response processing part to multiple web servers.
Tomcat has no support for clustering built in. What happens is that the load balancer distributes requests, so the various Tomcat instances don't need to know what is happening.
What you have to do is to make sure your application can handle it. For example, you must be aware that caches can be stale.
Say instance 1 has object X in it's cache and X is modified by a request processed on instance 2. The cache in instance 2 will be correct, the cache from instance 1 will be stale now.
The solution is to use a cache which supports clustering or disable caching for instances which can be modified. But that doesn't matter to Tomcat.