Server Load Balancing Oracle Fusion Middleware High Availability Technologies

Oracle Fusion Middleware High Availability Framework 2-11 Oracle WebLogic Server allows for rolling patching where a minor maintenance patch can be applied to the product binaries in a rolling fashion without having to shut down the entire cluster. During the rolling patching of a cluster, each server in the cluster is individually patched and restarted while the other servers in the cluster continue to host your application. You can also uninstall a patch, maintenance pack, or minor release in a rolling fashion. ■ Configuration Management Most of the Oracle Fusion Middleware component configuration can done at the cluster level. Oracle Fusion Middleware uses WebLogic Server’s cluster wide configuration capabilities for server configuration, such as data sources, EJBs, and JMS, as well as component application artifacts, and ADF and WebCenter custom applications. A central MDS repository available to all members of the cluster stores additional application level components. This includes component level configuration for components, such as Oracle SOA, Oracle WebCenter, and application artifacts, such as SOA composites. ■ Backup and Recovery Oracle Fusion Middleware backup and recovery is a simple solution based on file system copy for Middle-tier components. RMAN is used for Oracle databases. There is also support for online backups. With Oracle Fusion Middleware, you can integrate with existing backup and recovery tools, or use scheduled backup tasks through oracle Fusion Middleware Enterprise Manager or cron jobs.

2.3.2.1 Server Load Balancing

Typically, Oracle Fusion Middleware high availability deployments are front ended by a load balancer which can be configured to distributed incoming requests using various algorithms. Oracle Fusion Middleware also has built-in load balancing capabilities for intra component interaction. For example, Web server to application server, or application server to database server. Oracle Fusion Middleware 11g does not provide external load balancers. To ensure that your external load balancer is compatible with Oracle Fusion Middleware, check that your external load balancer meets the requirements listed below: ■ Virtual servers and port configuration: The load balancer should have the ability to configure virtual server names and ports on your external load balancer. The virtual server names and ports must meet the following requirements. – The load balancer should allow configuration of multiple virtual servers. For each virtual server, the load balancer should allow configuration of traffic management on more than one port. For example, for Oracle Fusion Middleware Identity Management, the load balancer needs to be configured with a virtual server and port for HTTP HTTPS traffic, and separate virtual servers and ports for LDAP and LDAPS traffic. – The virtual server names must be associated with IP addresses and be part of your DNS. Clients must be able to access the external load balancer through the virtual server names. ■ Persistencestickiness: Some Oracle Fusion Middleware components use persistence or stickiness in an external load balancer. If your external load balancer does not allow you to set cookie persistence at the URI level, set the cookie 2-12 Oracle Fusion Middleware High Availability Guide persistence for all HTTP traffic. In either case, set the cookie to expire when the browser session expires. Refer to your external load balancer documentation for details. The recommended architecture for Oracle Fusion Middleware is a load balancer fronting Oracle HTTP Servers in the web tier, with Oracle WebLogic Server behind the Oracle HTTP Servers in the application tier. If Oracle WebLogic Server is deployed directly behind a load balancer in the web tier, then review the information in the Load Balancers and the WebLogic Session Cookie in the Oracle Fusion Middleware Using Clusters for Oracle WebLogic Server. Note that this is not a recommended deployment architecture for Oracle Fusion Middleware. ■ Resource monitoringport monitoringprocess failure detection: Configure the external load balancer to detect service and node failures through notification or some other means and to stop directing traffic to the failed node. Your external load balancer may have the ability to automatically detect failures. For example, for Oracle Fusion Middleware Identity Management, the external load balancer should monitor Oracle Internet Directory, Oracle Fusion Middleware Single Sign-On, and Oracle Delegated Administration Services. To monitor these components, set up monitors for the following protocols: – LDAP and LDAPS listen ports – HTTP and HTTPS listen ports depending on the deployment type These monitors use the respective protocols to monitor the services, meaning they use LDAP for the LDAP port, LDAP over SSL for the LDAP SSL port, and HTTPHTTPS for the Oracle HTTP Server port. If your external load balancer does not offer these monitors, consult your external load balancer documentation for the best method of configuring it to automatically stop routing incoming requests to a service that is unavailable. ■ Network Address Translation NAT: The load balancer should have the capability to perform network address translation NAT for traffic being routed from clients to the Oracle Fusion Middleware nodes. ■ Port translation configuration: The load balancer should have the ability to perform port translation, where it allows incoming requests received on one port to be routed to a server process running on a different port. For example, a request received on port 80 can be routed to port 7777. ■ Protocol translation: The load balancer should support protocol translation between systems running different protocols. It enables users on one network to access hosts on another network, despite differences in the native protocol stacks associated with the originating device and the targeted host. For example, incoming requests can be HTTPS, and outgoing requests can be HTTP. This feature is recommended but not required. ■ SSL acceleration: SSL acceleration is a method of offloading the processor-intensive public key encryption algorithms involved in SSL transactions to a hardware accelerator. This feature is recommended but not required. ■ Fault tolerant mode: Oracle highly recommends configuring the load balancer to be in fault-tolerant mode, otherwise the load balancer becomes a single point of failure for the system. This rules out most software load balancers that are based on a single processinterceptor as reliable solutions. Oracle Fusion Middleware High Availability Framework 2-13 ■ Ability to preserve the client IP addresses: The load balancer must have the capability to insert the original client IP address of a request in an X-Forwarded-For HTTP header or a similar feature to preserve the client IP address. ■ Other: Oracle highly recommends configuring the load balancer virtual server to return immediately to the calling client when the back-end services to which it forwards traffic are unavailable. This configuration is preferred over the client disconnecting on its own after a timeout, based on the TCPIP settings on the client system. You may not need to meet all of the requirements in the previous listed. The requirements for external load balancers depend on the topology you are considering, and on the Oracle Fusion Middleware components you are load balancing.

2.3.3 Active-Passive Deployment