Create ODRs

The on demand router (ODR) is an intelligent HTTP and Session Initiation Protocol (SIP) proxy server in Intelligent Management. The ODR is the point of entry into an Intelligent Management environment and is a gateway through which HTTP requests and Session Initiation Protocol (SIP) messages flow to back-end application servers. We can configure the ODR to determine how it handles failure scenarios and how it tunes certain work requests.

SIP is not supported on the z/OS operating system.

The SIP ODR is stabilized, and is currently not recommended. Use the SIP proxy server instead.gotcha

(v8550) We now support a subset of ODR functions in an Apache or IBM HTTP web server plug-in. Read about Intelligent Management for web servers for more information.

The ODR can momentarily queue requests for less important applications to allow requests from more important applications to be handled more quickly or to protect back-end application servers from being overloaded. The ODR is aware of the current location of a dynamic cluster instance so that requests can be routed to the correct endpoint. The ODR can also dynamically adjust the amount of traffic that is sent to each individual server instance based on process utilization and response times. The ODR performs WLOR (Weighted Least Outstanding Request) load balancing for selecting a server within a cluster when there is no affinity or when affinity is broken.

By default, the ODR binds to ports 80 and 443 for listening on HTTP and HTTPs, which requires running the ODR as a root user. To run the ODR as a non-root user, you must change the PROXY listening ports to values greater then 1024.

The ODR is fully aware of the dynamic state of the cell, so that if one server in the cell fails, the requests are routed to another server. When the ODR is notified that the application has initialized on the restarted server, the ODR routes requests to that server again.

The ODR does not route any requests to the application on the application server until the application completes starting or initializing. If the application is started on other application server, then the requests are routed to them. If the application is not started on any other servers, then the ODR still does not route to the starting-in-progress application server. Instead, a 503 message is returned.

What to do next

Configure the middleware servers and dynamic clusters for your environment.


Related concepts

  • Intelligent Management for web servers overview
  • Overview of request flow prioritization

    Related tasks

  • Set up Intelligent Management for dynamic operations
  • Create ODRs
  • Configure ODRs
  • Configure a Web server as a trusted proxy server
  • Configure SSL offload for all HTTPS traffic
  • Define routing policies for generic server clusters
  • Define service policies for generic server clusters
  • Add middleware servers to configurations
  • Create dynamic clusters
  • Define a service policy
  • Proxy server settings

  • createodr.jacl script
  • Intelligent Management: on demand router system and custom properties