I am new to clustering on Weblogic and read this tutorial. Now I want to know that is that possible to cluster any java application on Weblogic? in that tutorial is discussed about Ejb-based applications. My application has no framework and is just simple JavaEE application and I want to cluster it on weblogic.
Yes, you can.
This is simply replicate your app into multiple servers and a load balancer on top of these will distribute the requests among them.
You have to only check your resource (server, database etc.) support it and there is no multithreading / concurrency issue with your code.
Related
I am looking for a better logical solution of a situation where one core Java EE (Web) application will call/execute many other Java applications/workers (which can be core Java or J2EE(web) application (don't know what will be the best)) at a certain time.
Those other Java applications/workers will basically connect (individually) with different Data sources (can be from remote DB or REST or SOAP, etc...) and populate/update local DB at a certain period of time.
I was doing research on Java Quartz Scheduler recently. Do u have any good suggestion to me for this Enterprise level architecture?
Btw, I am using Spring 4, Java 7
Thank you as always for all good and professional ideas.
Sample diagram can be as follows:
You can connect your java application with others easy with spring's httpInvoker or rmiInvoker.
More information here: http://docs.spring.io/spring/docs/current/spring-framework-reference/html/remoting.html
Not sure to understand good, but you can look at a messaging mechanism. Typically, the WebApp will send a message that will be received by all the Workers.
Have a look a JMS which it designed for this kind of use, and integrates well with both JEE (it is a part of the JEE spec) and Spring.
There are basically two parts to your question:
How do I schedule jobs on a Java EE server?
How do I invoke remote services from that scheduled job?
Job Scheduling
The trick with job scheduling in a Java EE environment is that you are typically running jobs in a cluster, or more than one server. Thus, only one of the nodes should be running that job at a time "on behalf of" the cluster, otherwise, you'll get multiple calls to those remote resources for the same thing.
There is a standard out there for this, JSR-237, which covers Timers and WorkManagers. Each Java EE vendor has its own implementation. WebLogic has one, WebSphere has one, and JBoss has one (the JBoss one isn't compliant with the JSR, but it does the same thing).
If you are running one of the servers that only runs the web tier of the Java EE spec (i.e, Tomcat or Geronimo), then Quartz is a good choice.
How to invoke remote services from timed jobs
Echoing #Alexandre Cartapanis' answer, probably what you'll want to do is create a JMS Topic in your Java EE server, and then when the job runs, post a message to the topic. The remote services (whatever Java EE servers) subscribe to this topic, and then you can run your queries.
The big advantage here is that if you ever need to add another service that needs to populate the local DB, all you have to do is have that server subscribe to the topic - no code changes needed. With JSch or remoting, you'll have to make a code change every time a new service comes online. You also have to make code changes if DNS addresses or IP addresses change, etc, where as the JMS way is just configuration on the server. There's a lot more that you can do with JMS, and the support is much better across the board.
Spring has adapters for Quartz and I think there's one out there for WorkManagers and Timers too.
You can make use of JSch - Java Secure Channel to trigger remote ssh calls which can start a JVM and run the Worker class.
Here are some examples.
My project is looking to deploy a new j2ee application to Amazon's cloud. ElasticBeanstalk supports Tomcat apps, which seems perfect. Are there any particular design considerations to keep in mind when writing said app that might differ from just a standalone tomcat on a server?
For example, I understand that the server is meant to scale automatically. Is this like a cluster? Our application framework tends to like to stick state in the HttpSession, is that a problem? Or when it says it scales automatically, does that just mean memory and CPU?
Automatic scaling on AWS is done via adding more servers, not adding more CPU/RAM. You can add more CPU/RAM manually, but it requires shutting down the server for a minute to make the change, and then configuring any software running on the server to take advantage of the added RAM, so that's not the way automatic scaling is done.
Elastic Beanstalk is basically a management interface for Amazon EC2 servers, Elastic Load Balancers and Auto Scaling Groups. It sets all that up for you and provides a convenient way of deploying new versions of your application easily. Elastic Beanstalk will create EC2 servers behind an Elastic Load Balancer and use an Auto Scaling configuration to add more servers as your application load increases. It handles adding the servers to the load balancer when they are ready to receive traffic, and removing them from the load balancer and deleting the extra servers when they are no longer needed.
For your Java application running on Tomcat you have a few options to handle horizontal scaling well. You can enable sticky sessions on the Load Balancer so that all requests from a specific user will go to the same server, thus keeping the HttpSession tied to the user. The main problem with this is that if a server is removed from the pool you may lose some HttpSessions and cause any users that were "stuck" to that server to be logged out of your application. The solution to this is to configure your Tomcat instances to store sessions in a shared location. There are Tomcat session store implementations out there that work with AWS services like ElastiCache (Redis) and DynamoDB. I would recommend using one of those, probably the Redis implementation if you aren't already familiar with DynamoDB.
Another consideration for moving a Java application to AWS is that you cannot use any tools or libraries that rely on multi-cast. You may not be using multi-cast for anything, but in my experience every Java app I've had to migrate to AWS relied on multi-cast for clustering and I had to modify it to use a different clustering method.
Also, for a successful migration to AWS I suggest you read up a bit on VPCs, private IP versus public IP, and Security Groups. A solid understanding of those topics is key to setting up your network so that your web servers can communicate with your DB and cache servers in a secure and performant manner.
How can I connect a realtime application which has a totally different life-cycle with WebApp to JBoss or GlassFish?
I need it to create a realtime reporting system. Using Sockets is not possible.
Is it possible to attach an application rather than a web applications to Java application servers so they can work together?
Yes. Java EE defines application clients, that can be any java apps.
With some full Java EE profiles, connections via CORBA should be possible and you could then also use C++ clients.
Another option to hook up any client could be messaging.
Why do we need Application Server in Java like JBoss or WebSphere. Is it possible that we develop large scale website only with Java (Apache Tomcat). Where thousand of user connect on site at a moment. An example is a website like b2b.
What is the cost of a Application Server? I will be thankful if you compare price among different application server and if there is any free version kindly highlight it.
Application Servers are mostly used if you want to use advanced features like transaction management, hot code swapping and advanced persistence.
There are application servers that are open source. E.g. GlassFish and JBoss.
I don't think you need an application server for building a popular web site, you'll also be fine with a servlet container like Tomcat or Jetty.
In short Application Servers provide you with few services like
Transaction Management
Load Balancing
Security
Threading
etc.
You have to take care of these things yourself in a Web Server.
There are few Open Source Application servers which are free of cost.
I have used Glassfish.
Apart from answers given above, App Servers are required for EJBs.
You need Application Server as follow:
It provides you useful services like automatic transaction,Authentication,Authorization,Lifecycle management.
To remember large user data across pages using ejb's pertaining to a client.
Load balance the user request and buisness logic.
To interact with different Client UI like Java Swing,Browsers.
It is possible to handle the httpheaders yourself. We have done socket servers in java for 20 years. You do not need a container for java swing.
Persistence can be done through databases or server side files unless you need real high speed stuff. I have yet to find a real requirement for an ejb
except that some systems simply require them
This may be because jboss can provide better after-sales service, and jboss, etc. can provide operation and maintenance support, etc. This may be the reason why many large companies choose commercial versions of servers.
But you must know that tomcat and netty are not bad. For example, many large B2B or C2C or B2C companies still use tomcat, such as Internet companies such as Alibaba.
Choose a server
Operation and maintenance costs
Scalable costs
Server cost
I'm looking for a simple open source, or reference application that I could use for testing some Java servers. The primary server would be Tomcat, and the database backend is MySQL. Are there some reasonable sample applications out there that are fairly easy to get up and running with?
The ideal application would be fairly stateless in nature and be accessible without authentication so that it could be easily used for stress testing.
There are spring examples, PetClinic and JPetStore. In these links you can find some more applications.