Some basic concepts of WebLogic

The basic concepts in WebLogic

Last week participated in the organization of WebLogic training, in order to facilitate their own memory, after training, sorting out some of the WebLogic information, will be issued in succession, the following are some basic concepts.

Domain:

A domain is a group of related WebLogic Server resources that are managed as a unit. A domain contains one or more WebLogic Server instances, which can be clustered instances, non-clustered instances, or a combination of clustered and non-clustered instances. A domain can contain multiple clusters. Domains also contain the application components that are deployed in the domain, the resources and services that are required for these application components and server instances in this domain. Examples of resources and services used by application and server instances include computer definitions, optional network channels, connectors, and startup classes.

Domain contains a special WebLogic server instance called Administration Server, which is the core of all the resources we configure and manage in the domain. In general, we call the addition of other instances in domain Managed server, where all Web applications, EJBS, Web services, and other resources are deployed.

We can organize domain according to some of the following criteria: The logical division of the program, such as an e-commerce website, can use the foreground as a domain, order processing as a domain, other resources as a domain, the physical region, such as a multinational company's website, Each country can create a domain, divided by size.

Administration Server:

The Management Server is the central operational node that controls the configuration of the entire domain, and the Management Server maintains the configuration of the domain domains as a whole and assigns the configuration to each managed server Managed server, which must have one administration server in each domain. We can access the Management server through three channels: admin Server console, Oracle WebLogic Scripting Tool WLST, JMX Client (implemented via WebLogic provided API), Finally, we can also monitor the state of the admin server through the SNMP protocol.

If the Admin server is hung, there is no impact on managed server in domain, and if the cluster is configured, there is no impact on the load balancing and failover mechanisms. This is because these are profile-based (config) files and are not dependent on instances with the admin server. The admin server doesn't have to run all the time, and when we need to modify the configuration or deploy the app, we'll run the admin server.

Managed Server:

The managed server is an instance of WebLogic server, where he obtains configuration information from the admin server. You typically deploy your own services, components, or apps on managed server. Based on performance considerations, Managed Server maintains a read-only domain profile that synchronizes profile information from the admin server when the service starts, and if the configuration file changes, the Admin server pushes the changes to Managed On the server.

Machine:

Machine refers to the physical machines that run WebLogic server instances, usually related to the managed server on which they are deployed. Machine is used for node Manager (a process running on a physical server that can remotely restart Admin and Managed Server) to restart the failed Managed server, as well as for the Managed of the cluster Servers select the appropriate session storage location (session to avoid storage on the same machine).

Node Manager:

A process running on a physical server that is used to remotely perform startup start, stop stop, suspend Suspend, restart Restart operations of the admin server and Managed server. This process is not associated with domain but is associated with machine, and if you want to control the server in the admin console, you must install node Manager. Node Manager provides the same functionality as the java-based and script-based two versions.

Cluster:

A cluster is a combination of a set of WebLogic servers that are designed to meet the high availability of services (avilability) and the scalability (Load balancing) requirements. It is important to note that the WebLogic server in the cluster must have the same version number. Cluster There are several issues to note: Servers that cannot cross domain, cluster must be in the same domain, and there can be multiple cluster in domain.

Java EE Standard:

Other content in the Java EE framework: JDBC, JNDI, JTA, JMS, JAAS, JMX, Rmi-iiop, and more.

Java Servlets and JavaServer Pages:

A servlet is a separate thread running within a server container, and the JSP file is eventually compiled into a servlet, so the servlet is a very important concept in Java programming.

Some basic concepts of WebLogic