Weblogic Domain Structure
A weblogic domain is a logical group of weblogic server resources that is managed as a unit. A domain always includes a minimum of a single server instance known as Administration Server or in other words Admin Server. The Administration Server is a central point of contact for all domain resources. An Administration Server handles all administrative tasks within a weblogic server domain. You can access the domain via a web-based console that gets deployed to the Administration Server upon it`s restart. There can be only one Administration Server in a Domain. The domain can also include additional servers known as Managed servers, clunster or multiple clusters.
A managed server can be an independent server or can be part of a cluster within the weblogic server domain. A cluster is a group of weblogic servers that works as a single unit to provide high-availability. It is highly recommended to deploy all applications on managed servers in production mode. There can be multiple managed servers within a domain. Managed servers can either be clustered or non-clustered. There can be multiple servers within a cluster. When clustered, managed servers can perform their tasks as a single unit that provides high-availability and load-balancing.
Following resources are available in the domain that are required by managed servers and deployed applications
Application components: JSP, Servlets, EJB ...etc.
JDBC & JMS
Security Realm
Persistent Stores
Store and Forward Services
Monitoring Services
Startup Classes
Adapters
There are two modes in which a domain can run.
1. Development Mode: A domain running in development mode is less secure then a domain running in production mode. In development mode, an Administration Server can act as a Managed Server as well, since you can deploy applications to this single standalone Administration Server (not recommended in production mode). A domain running in development mode does not require a password when starting the Administration Server. The maximum number of connections allocated to the JDBC connection pool is 15. Demo certificates can be used in development mode. In development mode, log rotation happens during the server sartup. The auto-deployment feature is enabled in development mode.
2. Production Mode: A domain running in production mode is highly secure. The maximum number of connections allocated to the JDBC connection pool is 25. Demo certificates can be used in a production mode but a warning message is displayed in the log files. In production mode, the log rotation happens when the log size reaches to 5000k. The auto-deployment feature is disabled in production mode.
Detailed information on all components and resources of Weblogic Domain Architecture will be covered in upcoming articles.
