WebSphere Application Server Terminology

 

                          WebSphere Application Server Terminology


The following terms describe elements in WebSphere Application Server configurations:





1) Cell :

A cell is a logical grouping of WebSphere Application server Process

or 

A cell is a logical grouping of one or mode nodes

or 

Cell is a basic WebSphere administrative unit 

or

The administrative domain that a Deployment Manager manages. A cell is a logical grouping of nodes that enables common administrative activities in a WebSphere Application Server distributed environment. 


Note : A cell must have one DMGR  and one or  many Nodes 

2) Node:

The place where we install the Application server process is called as Node.

or

The Machine where we install the Application server called as Node.

or 

A node is a logical group of one or more application servers on a physical computer. The node name is unique within the cell. A node name usually is identical to the host name for the computer. That is, a node usually corresponds to a physical computer system with a distinct IP address.


3) Application Server :

The application server is the primary component of WebSphere. The server runs a Java virtual machine, providing the runtime environment for the application's code. The application server provides containers that specialize in enabling the execution of specific Java application components.


4)DMGR (Deployment Manager):


The administrative process used to provide a centralized management view and control for all elements in a WebSphere Application Server distributed cell, including the management of clusters. The Network Deployment Manager is responsible for the contents of the repositories on each of the nodes. The Network Deployment Manager manages this through communication with node agent processes on each node of the cell.


5)Nodeagent:


A node agent manages all managed processes on a WebSphere Application Server on a node by communicating with the Network Deployment Manager to coordinate and synchronize the configuration. A node agent performs management operations on behalf of the Network Deployment Manager. The node agent represents the node in the management cell. Node agents are installed with WebSphere Application Server base, but are not required until the node is added to a cell in a Network Deployment environment.


6) Cluster :

A logical grouping of one or more functionally identical application server processes. A cluster provides ease of deployment, configuration, workload balancing, and fallback redundancy. A cluster is a collection of servers working together as a single system to ensure that mission-critical applications and resources remain available to clients.
Clusters provide scalability. For more information, refer to additional documentation that customer support may provide that describes vertical and horizontal clustering in the WebSphere Application Server distributed environment.

Clusters mainly provide 

  • Load balancing 
  • Failover
  • Provide scalability & high availability




Horizontal Clustering : The servers that are members of a cluster can be located in different host computers called as Horizontal Clustering .

Advantage: In case of hardware failure  the other server can process the request. It has better performance as the system used is different
Disadvantage: Maintaining two different server is difficult & expensive.





Vertical Clustering : The servers that are members of a cluster can be located in same host computers called as Vertical Clustering .

Advantage: Monitoring & central administration is easy & cost effective as fewer servers are needed.
Disadvantage: In case of hardware failure all the application server would fail.


Hybrid Cluster / Mixed Cluster :

Its combination of horizontal cluster and vertical cluster .








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