Cognos BI Gateway

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The IBM® Cognos® BI Web server tier can contain one or more IBM Cognos BI Gateways that handle the web communication. The SUT includes a single Cognos BI Gateway deployed in its own virtual machine.

The Cognos BI Gateway is an extension of a web server (for example, IBM HTTP Server) and knows the location of a dispatcher service running in a Cognos BI application tier (for example, a report server). The dispatcher is a multithreaded service that uses one or more threads per request.

When an IBM Cognos BI Gateway receives a request, it

  • encrypts passwords to ensure security
  • extracts information needed to submit the request to an IBM Cognos BI server
  • attaches environment variables for the web server
  • adds a default name space to the request to ensure that the server authenticates the user in the correct name space
  • passes requests to an IBM Cognos BI dispatcher for processing

For more information on Cognos BI Gateways and the Dispatcher, refer to the IBM Cognos Business Intelligence - Architecture and Deployment Guide

  • The Multitiered Architecture > Tier 1. Web Server: IBM Cognos BI Gateways
  • The Multitiered Architecture > Tier 2. Applications: IBM Cognos BI Servers > Dispatcher

Gateway tuning

Apache modules on IBM HTTP Server (IHS)

For enhanced performance and throughput, the default CGI gateway is replaced by an Apache module (apache_mod) gateway that can be used with the IBM HTTP Server.

This change applies to the IHS configuration file (httpd.conf).

The Apache module is added at the end of the IHS load module list: 

LoadModule cognos_module <cognos10_location>/cgi-bin/mod2_2_cognos.so

The complete procedure is described under the following IBM Knowledge Center navigator:

Cognos Business Intelligence 10.2.1 > Install > Business Intelligence Installation and Configuration Guide 10.2.1 > Installing and Configuring Product Components one One Computer > Configuring the web server > Use compiled gateways for production systems > Use Apache modules on Apache Server or IBM HTTP Server

Provide enough virtual CPUs

The Cognos BI Gateway performance depends on the number of available CPUs. Figure 1 shows that the different Cognos BI loads (increasing number of users) perform better with four virtual CPUs instead of only two. The gateway benefits from the higher degree of parallelism with four virtual CPUs.

Figure 1. Cognos BI transaction throughput - two compared to four gateway CPUs

Cognos BI transaction throughput - two compared to four gateway CPUs

If the Cognos BI Gateway does not have enough CPUs, it quickly becomes a bottleneck. This is obvious when looking at the CPU utilization for the Cognos BI load with 10 users in Figure 2, for example.

Figure 2. Cognos Gateway – CPU load 2 versus 4 Gateway CPUs

Cognos Gateway – CPU load 2 versus 4 Gateway CPUs

The workload level can be covered with two virtual CPUs at first sight. The CPU load is high but not yet constrained. When the same workload runs with four virtual gateway CPUs, the transaction throughput and the CPU load increase at the same workload level.