WebSphere Application Server Components

Cell

• - Node 1
• -- Profile
• ---App Server 1
• ---App Server 2
• ---One Deployment Manager

• - Node 2,3,4,..
• -- Profile
• ---App Server 1
• ---APP Server 2
• ---Node Agent 

Node

Each machine/operating system instance with an IP address or hostname is a “node“. 

The list of nodes in your WebSphere environment may be seen in the ISC under “System Administration/Nodes”. On a node there may be one or multiple servers.
A server is a Java Virtual Machine (JVM) process meaning that it may be controlled individually and it may have memory assigned to it and have specific JVM parameters set if required.
Please note that having multiple servers on a single node is very common in WebSphere Application Server.

Profile

When a server is created in WebSphere Application Server it is created using a profile which basically is a template for the server. There are two main profiles to worry about – “default” which is an server to run applications and “dmgr” which is the deployment manager.

Deployment Manager
In an architecture with multiple nodes the deployment manager is the administration server that controls the nodes it knows about including making sure that the configuration is synchronized between the nodes.

Cell
The nodes belonging to a single deployment manager belongs to the same cell. In other words there is a single deployment manager per cell.

Managed vs Unmanaged Nodes
Looking back at the nodes a node may be managed or unmanaged.
A managed node is a WebSphere node that the deployment manager can talk to and send commands.
An unmanaged node is the opposite. WebSphere knows about the node but cannot communicate with it on a WebSphere protocol. 

IHS
IBM HTTP Server (IHS) is WebSphere unmanaged node.

Node Agent
If a node is managed it will have a nodeagent installed. The nodeagent is a separate Java process which is started and stopped individually and separate from any server. The nodeagent can be used to synchronize the configuration to the node and to start and stop “stuff” on the node. The nodeagent may be configured to start all the servers running on it when ever it starts. On servers the administrator may install applications which run on the server. The applications may be started and stopped individually but usually all applications start and stop with the server.

Cluster
For high availability you may choose to create a cluster of servers. Servers in a cluster runs the same applications and can take over from one another. Note that you cluster servers and not nodes so you could have a cluster of three servers on a single node.

So…

If you have an IBM Connections installation where everything is installed on the same Linux or Windows box and you chose the “small deployment” which puts all applications into the same server you will have the following:

A single cell

A single deployment manager controlling your cell

Three (3) nodes. One for the deployment manager, one for the server running the IBM Connections applications (managed node) and one for the IBM HTTP Server (IHS) (unmanaged node).

A single nodeagent

A single server running all the applications

A single cluster with the server

Three (3) JVM processes running – one for the deployment manager, one for the nodeagent and one for the server