Architecture of the WebLogic

WebLogic Management Console The WebLogic Server provides a robust web-based tool-the management console-that is the primary tool for performing these tasks. From the admin console, you can access the WebLogic Management service. The management Service implements Sun's Java Management Extension Standard (JMX), which is the foundation of WebLogic Resource management. You can use the management console to configure properties of resources, distribute applications and components, monitor resource usage (such as server load, memory usage of Java virtual machines, and load of database connection pools), view log messages, terminate servers, and perform other administrative tasks. A set of WebLogic server resources that are managed by a domain, a Management Server, and a managed server as a unit and associated with each other is called a domain. A domain can contain one or more WebLogic servers and can also contain WebLogic server clusters. The configuration of the domain uses the Extended Markup Language (XML) definition. The CONFIG. sql file in the Install_dir/config/domain_name directory defines the configuration of the domain, and Install_dir is the installation directory for WebLogic Server software. A domain is a complete snap-in. When distributing an app to a domain, the components of the app can only be distributed to servers within the domain. If the domain contains a cluster, all servers in the cluster must belong to the same domain.

The WebLogic server that runs the management service is called the Management Server. The management service centrally manages and monitors all resources for the domain. If you want to perform administrative operations on a domain, the Management server for that domain must be running. a domain that contains multiple WebLogic servers can have only one Management server, and the other servers are called managed servers. Each WebLogic managed server will get its own property configuration from the Management Server at startup. The Weblogic.server class is run when both the Management Server and the WebLogic managed server are started. A WebLogic server that is not started as a managed server is the Management server.

The operating mechanism for the domain

Architecture of the Java EE The Java EE application is a collection of components that are organized into a deployment unit, such as an ear (an enterprise application or Web service), a WAR (Web application), or a jar (EJB) file. The various components required by the application--EJB or Web applications, servers or clusters, JDBC connection pooling, and so on are defined in a domain configuration. Combining these resources in a single, complete domain allows us to view or access these interrelated resources in a unified manner.

Common components: Servlet : A server-side Java application that has platform-and protocol-independent features that can generate dynamic Web pages. It serves as the middle tier of a customer request (a Web browser or other HTTP client program) and a server response (a database or application on an HTTP server). A servlet is a Java application located on the server side of a Web server, unlike a traditional Java application launched from the command line, which is loaded by a Web server that must contain a Java virtual machine that supports Servlets.

JSP :(Java Server pages) is a dynamic Web technology standard developed by Sun Microsystems, a company that many companies are involved in. JSP technology is a bit like ASP technology, it is in the traditional Web page HTML file (*.htm,*.html) inserted Java program segment (scriptlet) and JSP tag (tag), thereby forming a JSP file (*.jsp). Web applications developed with JSP are cross-platform and can run on Linux and other operating systems.

EJB : Sun's server-side component model, design goals and core applications is to deploy distributed applications. With the advantages of Java cross-platform, distributed systems deployed with EJB technology can be limited to specific platforms. EJB (Enterprise JavaBean) is part of the Java EE and defines a standard for developing component-based enterprise multi-application applications. Features include network service support and core development tools (SDKs). In Java EE, Enterprise Java Beans (EJB) is called Java Business Bean, which is the core code of the kernel, namely the session bean, the entity bean Bean) and the message-driven bean (Messagedriven bean).

Session Bean: Used to implement business logic, it can be stateful or stateless. Each time the client requests, the container chooses a session bean to service the client.　　 The Session bean can access the database directly, but more often, it implements data access through the entity bean. The entity bean is a domain model object that implements the O/R mapping and is responsible for mapping table records in the database to an in-memory entity object, in fact creating an entity bean object that is equivalent to a new record, deleting an entity The bean will delete the corresponding record from the database at the same time, and when modifying an entity bean, the container will automatically synchronize the state of the entity bean with the database.  

Architecture for the Java EE

In a production environment, the typical configuration of the system is that the application and business logic components are distributed across multiple managed servers, while the Management Server is responsible for configuring and monitoring the managed servers. The role of the Management Server is to configure and monitor the managed server. If the management server is down and the application deployed on the managed server is not affected, the client's request can continue to be processed, in which case, when the Management Server is restarted, you can regain control of the active domain to spread the application or application components across a set of managed servers with some benefits. Distributing EJBS and other components across a set of servers can guarantee the availability of the primary application. Different components that perform different functions can improve the performance of the system, such as the separation of database access and billing transactions on different managed servers. A component or application like EJB that can implement various functions can be isolated so that its availability does not depend on the state of other components. Multiple apps can be deployed in a domain. When the management server is started with such a configuration, we say that the domain is active (active).

During the Management Server run, only the Management Server can modify the configuration file . The management console and the command-line management tools provide access to the Management Server, which you can use to modify the configuration of the domain. Once a domain is activated, you can monitor or configure resources for the entire domain through the administrative console. The configuration Repository (config repository) also holds other inactive configuration files, which you can edit by managing the terminal. The configuration repository consists of a series of subdirectories located in the/config directory. Any domain is uniquely defined by the CONFIG. s in a subdirectory that has the same name as the domain. You can access an inactive profile by using the configuation link on the Welcome page that appears at startup on the admin console.

There are many management Beans (MBeans) objects in the run-time object and Configuration object Management Server that resemble JavaBean. Mbeans follows Sun's Java Management Extension Standard (JMX). These objects provide administrative access to domain resources. The Management Server contains the configuration Mbeans and runtime Mbeans. Management Mbeans provides set (write) and get (read) access to configuration properties. The runtime Mbeans provides a snapshot of the domain resource information, such as information about the current HTTP session and the load information for the JDBC Connection pool. If a resource for a domain, such as a web app, is instantiated, the server creates an instance of Mbeans to gather information about the resource. When you access the monitoring page of a resource from the management console, the management console performs a get operation to get the current property value.

The management service enables the properties of a domain resource to be modified dynamically, and properties can be modified even if the WebLogic server is running. Many property changes do not need to restart the server to take effect. At this point, the modified property not only represents the current property value, but is also saved to the configuration file. In addition to the Web-based management console, the WebLogic Server provides command-line tools to access domain resource configuration and monitoring properties. You can use command-line tools to create a script that automates the management of your system. Centralized access to log messages through the domain logs provided by the Management Server, you can centrally access critical system messages for all servers. With the basic functionality provided by JMX, messages can be forwarded to the entity that subscribes to the message. Subscription entities Select messages of interest by setting filters. The information that the local server sends to other network entities at startup is called a notice. The JMX announcement causes critical log messages for all servers in the domain to be forwarded to the Management Server. When the WebLogic managed server is started, the Management server registers to accept critical log messages. These messages are stored in the domain log. Management Server to each of the domains in a

Reference to: "WebLogic Administrator's Manual"

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Architecture of the WebLogic