On-Demand Router based Load Balancer

Cloud Pak System Software V2.3.5 includes a new pattern type. Load Balancer Pattern Type provides the load balancing solution to route and load balance your web applications.

The new load balancer solution has two components, an external shared service On-Demand Router (ODR) based Load Balancer Service and a virtual system pattern Load Balancer Pattern. Load Balancer Pattern provides core functions used to route and load balance web applications. The ODR based Load Balancer Service is used by the virtual system pattern instances with Routing Policy. The ODR based Load Balancer Service communicates with Load Balancer Pattern instances to create, update and delete the load balancing rules.

Load Balancer Pattern

The Load Balancer Pattern is based on the software components provided by IBM WebSphere Application Server Network Deployment Patterns V2.3.5 (and above) pattern type. This pattern contains the following software components (each in a separate operating system node):
  • Deployment Manager
  • On-Demand Router
  • IBM HTTP Server.

The IBM HTTP Server acts as the front end proxy web server for the backend web applications. End user requests to web applications is first handled by the IBM HTTP Server and then routed to one of the ODR servers in the ODR node cluster. The ODR server will then load balance the requests to the backend web application server based on the defined virtual host and context root of the backend application. This solution supports requests from both HTTP and HTTPS protocol schemas. Note that by default, the IBM HTTP Server is not configured to handle HTTPS protocol. The Load Balancer Pattern allows creation of one or more IBM HTTP Server nodes and ODR server nodes. The IBM HTTP Server nodes are to be used in active-standby mode and the ODR server nodes are to be used in active-active mode.

The following diagram shows the deployment view of the Load Balancer Pattern instance.
Deployment view of the Load Balancer Pattern instance.
The following diagram shows how requests are routed and load balanced when you implement this solution.
How requests are routed and load balanced when you implement this solution.
The Load Balancer Pattern contains the following script packages that are added to Deployment Manager and ODR nodes, respectively. The script packages are executed at pattern deployment time to perform initial setup for load balancing.
  • Configure deployment manager for load balancing
  • Configure ODR server for load balancing
The Load Balancer Pattern contains the following policies:
  • Base Scaling Policy added to IBM HTTP Server node to scale the IBM HTTP Server nodes, the CPU and memory
  • Base Scaling Policy added to On-Demand Router node to scale the CPU and memory
  • Load Balancer Server policy on Deployment Manager node that provides post-deployment operations to manage routing rules.
Important:
  1. The Load Balancer Server policy should not be used outside of Load Balancer Pattern.
  2. Since node scaling is not allowed on ODR nodes, be sure to set the initial number of nodes high enough to handle expected routing requests.
  3. On AIX for Power, use the following WebSphere Application Server versions:
    • If you are on IBM Cloud Pak System V2.3.5, use WebSphere® Application Server Server 9.0.5.20.

ODR based Load Balancer Service

ODR based Load Balancer Service is an external shared service that holds the reference to the Load Balancer Pattern instance in a cloud group. This shared service is used by the Routing Policy to communicate with the Load Balancer Pattern instance to set up the load balancing rules specified in the Routing Policy.

The following diagram shows the relationship between the Load Balancer Pattern instance, ODR based Load Balancer Service instance and the instance with Routing Policy.
Relationship between the Load Balancer Pattern instance, ODR based Load Balancer Service instance and the instance with Routing Policy.