Oracle WebLogic Server 12c Advanced Administration Cookbook: If you want to extend your capabilities in administering Oracle WebLogic Server, this is the helping hand you've been looking for. With 70 recipes covering both basic and advanced topics, it will provide a new level of expertise.

WebLogic clustering is a highly recommended configuration for production environments. The WebLogic cluster provides reliability and high availability by distributing the requests and the load to the WebLogic Server instance members of the cluster.

Using WebLogic cluster also facilitates the administration tasks because WebLogic Server automatically distributes the configuration and deployment changes to all WebLogic Server instances, including the distribution of the deploy file to all machines.

Clustering can also avoid a single point of failure. If a machine crashes, the system can still operate with the WebLogic Manager Servers of the other machines. The architecture can grow and scale horizontally by adding more WebLogic Server instances to the cluster and distributing them to new machines.

A WebLogic cluster is normally created with the domain using the Configuration Wizard tool. The cluster can also be created and added to an existing domain by using the Administration Console. This recipe will cover adding a new cluster to the existing PROD_DOMAIN domain.

A WebLogic cluster was previously created using Configuration Wizard earlier in this book. The same cluster will be created this time, but with four Manager Server instances instead of two. So remove the original cluster before creating the new cluster.

The new cluster will be called PROD_Cluster with four WebLogic Server instances PROD_Server01, PROD_Server02, PROD_Server03, and PROD_Server04. Machine prod01 will host the instances PROD_Server01 and PROD_Server02 and machine prod02 will host the instances PROD_Server03 and PROD_Server04.

PROD_DOMAIN Topology:

PROD_DOMAIN
 |___ PROD_AdminServer
 |
 |___ PROD_Cluster
     |___ PROD_Server01
     |___ PROD_Server02
     |___ PROD_Server03
     |___...

The WebLogic Managed Server instances of the cluster were created in the previous recipe but a Listen Address value was not assigned to any of it.

The objective of this recipe is to assign a unique hostname or alias as the Listen Address value for each of the Managed Servers instead of assigning the prod01, prod02 hostnames or the IP address.

This recipe will cover other WebLogic cluster adjustments needed for high availability in production. The parameters are Failure Action, Panic Action, Cluster Address, and Number of Servers in Cluster Address for the cluster, and CrashRecoveryEnabled for Node Manager.

The Oracle WebLogic Server 12c can use either Multicast or Unicast for cluster communications. Since WebLogic version 10, the default cluster communication is the Unicast.

To improve Unicast reliability it's recommended to enable two extra configurations.

WebLogic can also use Multicast for cluster communications.

When configured for using Multicast, the Managed Servers of the cluster subscribe to a Multicast address and port and listen for heartbeats and cluster messages. Unlike Unicast, Multicast communication uses UDP and broadcasts the message through the network and therefore does not guarantee that the message is received.

This recipe will describe a quick installation of the Apache HTTP Server because a Web tier is needed to illustrate the use of WebLogic Web Server plug-in.

The plug-in is used for load balancing and the failover of HTTP requests to WebLogic Server, and the next recipe will cover its configuration and usage.

The WebLogic cluster itself does not distribute the incoming HTTP requests across the Managed Servers, so the architecture design should foresee a load balance mechanism.

WebLogic can use either an external load balancer appliance/hardware such as the BIG-IP F5 (http://www.f5.com/products/big-ip), a Web Server such as the Apache HTTP Server configured with the WebLogic Web Server plug-in, or the embedded WebLogic HttpClusterServlet configuration.

Load balancing options:

For production environments, it is recommended to use a mixed architecture that includes an external load balancer and a Web Server with the proxy plug-in. The HTTP requests will be received and distributed by the external load balancer to the Web Servers, and the Web Servers will then proxy the requests through the plug-in across the WebLogic Managed Servers of...

When configuring the Listen Address value with a hostname as in the previous recipes, WebLogic Server instances use the specific network interface card (NIC) bound to the hostname's IP address for network traffic. The traffic includes all inbound and outbound requests and the Unicast cluster communications.

In a production environment with high network traffic, it is possible to improve network utilization by adding an additional NIC to be used by the Unicast cluster communications, segregating the application traffic, and the cluster communication traffic.

This recipe will create a new channel named clusterChannel and configure the PROD_Cluster cluster to use it.

The Administration Server is a single WebLogic Server instance responsible for the configuration and management of the WebLogic domain. By default, the Administration Server runs on the machine that the domain was created.

Unlike WebLogic clustering, WebLogic Server does not provide out of the box high availability options for the Administration Server, if this machine fails.

This recipe will provide the steps to prepare the environment in case the machine that hosts the Administration Server fails.