Scalability is the ability of a system to provide throughput in proportion to, and limited only by, available hardware resources. A scalable system is one that can handle increasing numbers of requests without adversely affecting response time and throughput.

The growth of computational power within one operating environment is called vertical scaling. Horizontal scaling is leveraging multiple systems to work together on a common problem in parallel.

Oracle Fusion Middleware scales both vertically and horizontally.

Oracle Fusion Middleware provides great vertical scalability, allowing you to add more Managed Servers or components to the same host. This is known as scale up.

Horizontally, Oracle Fusion Middleware can provide failover capabilities to another host computer. That way, if one computer goes down, your environment can continue to serve the consumers of your deployed applications. This is also known as scaling out or machine scale out. See Scaling Out a Topology in the High Availability Guide.

Deploying a high availability system minimizes the time when the system is down (unavailable) and maximizes the time when it is running (available). Oracle Fusion Middleware is designed to provide a wide variety of high availability solutions, ranging from load balancing and basic clustering to providing maximum system availability during catastrophic hardware and software failures.

High availability solutions can be divided into two basic categories: local high availability and disaster recovery. See:

• Introduction to High Availability in High Availability Guide

• Overview of Oracle Fusion Middleware Disaster Recovery in Disaster Recovery Guide

1. Use RCU to add any required schemas for the component, as described in Creating Schemas in Creating Schemas with the Repository Creation Utility.
2. Install Oracle HTTP Server, as described in About the Oracle HTTP Server Installation in Installing and Configuring Oracle HTTP Server.
3. From the Oracle home, invoke the Configuration Wizard, using the following command:

   (UNIX) ORACLE_HOME/oracle_common/common/bin/config.sh
   (Windows) ORACLE_HOME\oracle_common\common\bin\config.cmd
   

   The Configuration Wizard's Welcome screen is displayed.

4. Select Update an existing domain.
5. In Domain Location, specify the location of the domain.
6. Click Next.
7. Select Update Domain Using Product Templates.
8. Select Oracle HTTP Server (colocated).
9. Click Next.
10. Select Extend my domain automatically to support the following added products, Then, select the source from which this domain is to be extended. For example, select Oracle HTTP Server.
11. Click Next.
12. Select either RCU Data or Manual Configuration. If you select RCU Data, the information is automatically populated when you then select Get RCU Configuration. If you select Manual Configuration, click Next.

    Select the schemas for the new component you added. If the values in the Component Datasources page are not correct, modify the values.

13. Click Next.

    The JDBC Component Schema Test screen is displayed.

14. If the test succeeds, click Next.

    The Advanced Configuration screen is displayed.

15. Select System Components.
16. Click Next.
17. Click Add to create a new Oracle HTTP Server instance.
18. Enter a name for the instance and select OHS as the component type.
19. Click Next.
20. The fields in the OHS Server page are prepopulated.
21. Click Next.
22. If you do not want to create a new machine, in the Machines page, click Next.
23. In the Assign System Components page, double-click the server to move it under the machine.
24. Review the information on the screen and if it is correct, click Update.
25. When the operation completes, click Done.

You can add Managed Servers to a domain to increase the capacity of your system. The Managed Servers can be added to a cluster.

1. From the WebLogic Domain menu, choose Environment, then, Servers.

   The Servers page is displayed.

2. Click Create.

   The Create a Server page is displayed.

3. For Name, enter a name for the server.

   Each server within a domain must have a name that is unique for all configuration objects in the domain. Within a domain, each server, computer, cluster, JDBC connection pool, virtual host, and any other resource type must be named uniquely and must not use the same name as the domain.

4. For Sever Listen Port, enter the port number from which you want to access the server instance.

   If you run multiple server instances on a single computer, each server must use its own listen port.

5. Specify whether this server is to be a standalone server or a member of an existing cluster:

   • If this server is to be a standalone server, select No, this is a standalone server.

   • If this server is to be part of an existing cluster, select Yes, make this server a member of an existing Cluster. Then, select the cluster.

   • If this server is to be part of a new cluster, click Create a cluster.

6. Click Next.
7. For Select a Machine, either select an existing machine or click Create new machine.
8. Click Create.
9. If the server or cluster did not have Oracle JRF applied, apply JRF, as described in Applying Oracle JRF Template to a Managed Server or Cluster.

• Applying Oracle JRF Template to a Managed Server or Cluster
  

1. From the WebLogic Domain menu, choose Environment, then, Clusters.

   The Clusters page is displayed.

2. ExpandCreate. Then, select either Cluster or Dynamic Cluster.
   For this example, select Cluster.

   The Create a Static Cluster page is displayed.

3. For Name, enter a name for the cluster.
4. In the Cluster Messaging Mode section, select one of the following:

   • Unicast. Then, for Unicast Broadcast Channel, enter a channel. This channel is used to transmit messages within the cluster.

   • Multicast. Then, for Multicast Broadcast Channel, enter a channel. A multicast address is an IP address in the range from 224.0.0.0 to 239.255.255.255. For Multicast Port, enter a port number.

     Note:

     You must ensure that the multicast address is not in use.

5. Click Next.
6. In the Add Servers page, select one or more servers to be added to the cluster. In this scenario, select wls_server1 and wls_server2.
7. Click Create.

You can configure elastic scaling for dynamic clusters. Elastic scaling adds or removes dynamic server instances on demand or based on certain conditions.

Elasticity allows you to configure elastic scaling for a dynamic cluster based on either of the following:

• Manually adding or removing a running dynamic server instance from an active dynamic cluster. This is called on-demand scaling. You can perform on-demand scaling using the Fusion Middleware component of Enterprise Manager, the WebLogic Remote Console, or the WebLogic Scripting Tool (WLST).

• Establishing policies that set the conditions under which a dynamic cluster should be scaled up or down and actions that define the scaling operations themselves. When the conditions defined in the scaling policy occur, the corresponding scaling action is triggered automatically.

Dynamic clusters consist of server instances that can be dynamically scaled up to meet the resource needs of your application. A dynamic cluster uses a single server template to define configuration for a specified number of generated (dynamic) server instances. When you create a dynamic cluster, the dynamic servers are preconfigured and automatically generated for you, enabling you to easily scale up the number of server instances in your dynamic cluster when you need additional server capacity.

For more information about elasticity and dynamic clusters, see What is Elasticity? in Configuring Elasticity in Dynamic Clusters for Oracle WebLogic Server.

1. Invoke WLST from the following directory:

   cd ORACLE_HOME/oracle_common/common/bin
   ./wlst.sh
   

2. Read the standalone domain template. For example, for the Oracle HTTP Server standalone domain template:

   readTemplate('ORACLE_HOME/ohs/common/templates/wls/ohs_standalone_template.jar')

3. Configure Node Manager:

   cd('/')
   create('domainName', 'SecurityConfiguration')   
   cd('SecurityConfiguration/domain_name')
   set('NodeManagerUsername', 'username')
   set('NodeManagerPasswordEncrypted', 'password')
   setOption('NodeManagerType', 'PerDomainNodeManager')
   

4. The standalone template contains default configuration values. However, you can change those values. For example:

   cd('/OHS/ohs1')
   cmo.setAdminHost('127.0.0.1')
   cmo.setAdminPort('7779')
   cmo.setListenAddress('localhost')
   cmo.setListenPort('7777')
   cmo.setSSLListenPort('4443')
   

5. Create the domain. Note that this operation takes some time.

   writeDomain('domain_dir')
   closeTemplate()

1. Invoke WLST from the following directory:

   cd ORACLE_HOME/oracle_common/common/bin
   ./wlst.sh
   

2. Read the domain template and add the template for the system component. The following example shows the Oracle HTTP Server template:

   readDomain('DOMAIN_HOME')
   addTemplate('ORACLE_HOME/ohs/common/templates/wls/ohs_managed_template.jar')
   

3. If you have not already created a machine for the system component, create one:

   cd('/')
   create('ohs_machine', 'Machine')
   cd('/Machines/ohs_machine')
   create('ohs_machine', 'NodeManager')
   cd('NodeManager/ohs_machine')
   

   In this case, leave the Node Manager port as it is.

4. Create the system component instance, in this case, Oracle HTTP Server:

   cd('/')
   create('myohs', 'SystemComponent')
   cd('/SystemComponent/myohs')
   cmo.setComponentType('OHS')
   set('Machine', 'ohs_machine')
   

5. Configure the system component instance that you just created. Note that the properties that you set will be different for each type of system component. For example, for Oracle HTTP Server:

   cd('/OHS/myohs')
   cmo.setAdminHost('127.0.0.1')
   cmo.setAdminPort('7779')
   cmo.setListenPort('7777')
   cmo.setSSLListenPort('4443')
   

6. Update the domain:

   updateDomain()
   closeDomain()