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A brief introduction to Weblogic Cluster

2025-01-21 Update From: SLTechnology News&Howtos shulou NAV: SLTechnology News&Howtos > Servers >

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This article mainly explains "A brief introduction to Weblogic Cluster". The content of the explanation is simple and clear, and it is easy to learn and understand. Please follow the editor's train of thought to study and learn "A brief introduction to Weblogic Cluster".

Introduction to Weblogic Cluster

Before introducing weblogic clusters, let's take a look at the traditional dual-machine architecture, as shown in the following figure: this architecture has the following shortcomings: more introduction to Weblogic

1) the standby mode of the host is adopted, and the general host is used more frequently, which leads to more idle and unbalanced utilization of resources.

2) when one Server breaks down, the user must be informed to use another Server, which is troublesome to manage and maintain.

3) when users switch applications, they need to log in again, and there is some delay.

Brief introduction of weblogic Cluster

What is a WebLogic Server Cluster Weblogic more about a WebLogic Server cluster consists of multiple WebLogic Server server instances that run simultaneously and work together to improve scalability and reliability. For clients, the cluster is an instance of WebLogic Server. The server instances that make up the cluster can run on the same computer or on different computers. You can increase the capacity of the cluster by adding more server instances to the cluster on existing computers, or you can add computers to the cluster to host incremental server instances. Each server instance in the cluster must be running the same version of WebLogic Server

How clusters are related to domains

A cluster is part of a specific WebLogic Server domain. More introduction to Weblogic

A domain is a set of related WebLogic Server resources that are managed as units. A domain contains one or more WebLogic Server instances, which can be clustered, non-clustered, or a combination of clustered and non-clustered instances. A domain can contain multiple clusters. The domain also contains the application components deployed in the domain, the resources and services required by the application components in this domain, and the server instance. Examples of resources and services used by applications and server instances include computer definitions, optional network channels, connectors, and startup classes. You can use various conditions to organize WebLogic Server instances into domains. For example, you can choose to allocate resources to multiple domains based on the logical partition of the hosted application, geographical considerations, or the number or complexity of resources managed.

In each domain, an WebLogic Server instance can act as a management server-this server instance can configure, manage, and monitor all other server instances and resources in the domain. Each management server manages only one domain. If there are multiple clusters in a domain, each cluster in the domain has the same management server.

All server instances in the cluster must reside in the same domain; the cluster cannot be "split" into multiple domains. Similarly, configured resources or subsystems cannot be shared between domains. For example, if a JDBC connection buffer pool is created in one domain, it cannot be used for server instances or clusters in another domain. (instead, a similar connection buffer pool must be created in another domain. )

Clustered WebLogic Server instances behave similarly to non-clustered instances, except for providing failover and load balancing. The procedures and tools used to configure clustered WebLogic Server instances are the same as those used to configure non-clustered WebLogic Server instances. However, in order to achieve the cluster-enabled load balancing and failover benefits, some guidelines for cluster configuration must be met. The following figure describes the relationship between the cluster and the domain:

What are the advantages of clustering

More introduction to scalability Weblogic

You can dynamically increase the capacity of applications deployed in a WebLogic Server cluster to meet your needs. Server instances can be added to the cluster without disrupting the service, and the application will continue to run without affecting clients and end users.

High availability is in the WebLogic Server cluster, and the application can continue to process when the server instance fails. You can "cluster" application components by deploying them to multiple server instances in the cluster, so that if the server instance on which a component runs fails, other server instances to which this component is deployed can continue application processing.

The selection of clustered WebLogic Server instances is transparent to application developers and clients. However, understanding the cluster-enabled technical infrastructure will help programmers and administrators maximize the scalability and availability of their applications.

What are the key functions of the cluster

Application failover Weblogic to put it more simply, failover is when some part of the processing task becomes unavailable for any reason when the application component (commonly referred to as "object" in the following sections) is processing a particular job, and a copy of the failed object ends the job. WebLogic Server supports automatic or manual migration of clustered server instances from one computer to another. A managed server that can be migrated is called a "portable server". This feature is suitable for environments that require high availability.

Load balancing is the average distribution of jobs and associated communications across computing resources and network resources in the environment.

Which types of objects can be clustered

Applications or application components of a cluster are available on multiple WebLogic Server instances in the cluster. If an object has been clustered, failover and load balancing for that object are available. Evenly deploying objects to each server instance in the cluster simplifies cluster management, maintenance, and troubleshooting. More introduction to Weblogic

Web applications can consist of different types of objects, including enterprise Java Bean (EJB), servlet, and Java Server Pages (JSP). Each object type has a unique set of behaviors related to control, invocation, and how it works within the application. For this reason, the methods used by WebLogic Server to support clustering and to provide load balancing and failover vary from type to type of object. The following types of objects can be clustered in a WebLogic Server deployment:

1) Servlet 2) JSP 3) EJB 4) remote method invocation (Remote Method Invocation, RMI) object 5) Java message Service (JMS) Target 6) Java Database connection (JDBC) connection

What types of objects cannot be clustered the following API and external services cannot be clustered within WebLogic Server: 1) File services containing file sharing 2) time services

These services are still available in individual WebLogic Server instances of the cluster. However, these services cannot use load balancing or failover capabilities.

What are the limitations of the cluster?

1) WebLogic hosts in the cluster must use permanent static IP addresses. Dynamic IP address allocation cannot be used in a clustered environment. If the server is behind the firewall and the client is outside the firewall, the server must have a public static IP address so that the client can access the server.

2) all WebLogic servers in the cluster must be on the same local area network and must be reachable by IP broadcasts.

3) all WebLogic servers in the cluster must use the same version. Configure the servers in the cluster to support the services provided. For EJB with JDBC connections, all servers that deploy a certain EJB must have the same deployment and persistence configuration. This means that all servers should have the same JDBC configuration. All hosts that deploy servlet must maintain a set of servlet with the same ACL.

Thank you for your reading. The above is the content of "A brief introduction to Weblogic Cluster". After the study of this article, I believe you have a deeper understanding of the brief introduction of Weblogic Cluster, and the specific use needs to be verified in practice. Here is, the editor will push for you more related knowledge points of the article, welcome to follow!

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