Node Manager

How Node Manager Works in the WebLogic Server Environment:

Node Manager in the WebLogic Server Environment:

How Node Manager Starts an Administration Server:

This section assumes that you have installed the Administration Server and created its domain directory using the Configuration Wizard.


Node Manager is running on Machine A, which hosts the Administration Server. The stand-alone Node Manager client is remote.

1.An authorized user issues the WLST offline command, nmConnect to connect to the Node Manager process on the machine that hosts the Administration Server, and issues a command to start the Administration Server. (If the Node Manager instance is the SSH version, the user can connect using the SSH client).
The start command identifies the domain and server instance to start, and in the case of the Java Node Manager, provides the Node Manager username and password.
Note:
If the user has previously connected to the Node Manager, a boot.properties file exists, and the user does not have to supply username and password.

2. Node Manager looks up the domain directory in nodemanager.domains, and authenticates the user credentials using a local file that contains the encrypted username and password.
3. Node Manager creates the Administration Server process.
4. The Administration Server obtains the domain configuration from its config directory.

How Node Manager Starts a Managed Server:

1. From the Administration Console, the user issues a start command for Managed Server 1.
   Note:
        A stand-alone client can also issue a start command for a Managed Server.

2. The Administration Server issues a start command for Managed Server 1 to the Node Manager on        the Machine B, providing the remote start properties configured for Managed Server 1. For                  information about the arguments and how to specify them.

3. Node Manager starts Managed Server 1.
   Node Manager starts the Managed Server using the same root directory where the Node Manager        process is running. To run the Managed Server in a different directory, set the Root Directory              attribute in the Server—>Configuration—>Server Start console page.

4. Managed Server 1 contacts the Administration Server to check for updates to its configuration             information.

5. If there are outstanding changes to the domain configuration, Managed Server 1 updates its local cache of configuration data.

How Node Manager Restarts an Administration Server 

Node Manager is running on the machine that hosts the Administration Server. The Administration Server, which was initially started with Node Manager, has exited. The Administration Server’s AutoRestart attribute is set to true.

Note: If a server instance’s AutoRestart attribute is set to false, Node Manager will not restart it.

1. Node Manager determine from the Administration Server process exit code that it requires restart.

2. Node Manager obtains the username and password for starting the Administration Server from the boot.properties file, and the server startup properties from the
<server_name>/data/nodemanager/startup.properties file.

3. Node Manager starts the Administration Server.

4. The Administration Server reads its configuration data and starts up.

How Node Manager Restarts a Managed Server:

Node Manager is running on Machine B, which hosts Managed Server 1, which was initially started with Node Manager, has existed. Managed Server 1's AutoRestart attribute is set to true

Note: If a server instance's AutoRestart attribute is set false, Node Manager will not restart it.

1. Node Manager determines from Managed Server 1’s last known state that it requires restarting.

2. Node Manager obtains the username and password for starting Managed Server 1 from the                   boot.properties file, and the server startup properties from the startup.properties file. These server-      specific files are located in the server directory for Managed Server 1.

3. Node Manager starts Managed Server 1.
Note: Node Manager waits RestartDelaySeconds after a server instances fails before attempting       to restart it.

4. Managed Server 1 attempts to contact the Administration Server to check for updates to its                 configuration data. If it contacts the Administration Server and obtains updated configuration data,     it updates its local cache of the config directory.

5. If Managed Server 1 fails to contact the Administration Server, and if Managed Server                         Independence mode (MSI) is enabled, Managed Server 1 uses its locally cached configuration             data.
Note: Managed Server Independence mode is enabled by default.

How Node Manager Shutdown a Server Instance:

The Communications involved in shutting down a Managed Server that is under Node Manger Control. Depending on the state and availability of the Managed Server, Node Manager might need to try alternative strategies to successful initiate the shutdown.

Node Manager is running on Machine B, which hosts Managed Server 1.

1. Through the Administration Console, an authorized user issues a shutdown command for Managed      Server 1.

2. The Administration Server issues the shutdown command directly to Managed Server 1. If it               successfully contacts Managed Server 1, Managed Server 1 performs the shutdown sequence               described in “Graceful Shutdown” in Managing Server Startup and Shutdown.

3. If, in the previous step, the Administration Server failed to contact Managed Server 1, it issues a         shutdown command for Managed Server 1 to Node Manager on Machine B.

4. Node Manager issues a request to the operating system to kill Managed Server 1.

5. The operating system ends the Managed Server 1 process.