Kirk Wiseman, VP of Training for PerformanceG2
Often times companies would like the ability to offer Cognos 8 to remote clients over a Wide-Area Network (WAN), and are surprised with the performance degradation when moving from a Local-Area Network (LAN) to a WAN. A recently written article for IBM by Martin Keller lists six quick ways to limit the degradation that occurs over the lan:
1. Manage Expectations/Limit Content to What is Really Needed
Problems are partly perception. If your end-users are well informed then their perceptions can be managed, and a problem diminished. It is common-sense that you shouldn’t try to push megabytes of data down the line if you are on a thin connection. Reports and Metadata should be designed appropriately for low-bandwidth deployments (this applies to both WAN and Mobile/Blackberry users). Maximize use of Consumer and Recipient modes rather than Studios; deliver concise and necessary data only: 1. Focus on the Business Pain, not the Data 2. Reduce images [or use web-optimized images] 3. Employ data governors in the Reports and Models.
Some User Interface elements can be hidden in IBM Cognos 8 in case they are not required to be offered to the end users. There are 2 ways of hiding UI elements:
1) As an appendix in the report URL. That way UI elements can be hidden for specific reports, e.g. those accessed by low bandwidth users, only. This technique only affects the IBM Cognos Viewer. A standard report URL looks like this:
http://webserver:80/cognos8/cgi-bin/cognos.cgi?b_action=cognosViewer&ui.action=run&ui.object=%2fcontent%2ffolder%5b%40name%3d%27Samples%27%5d%2ffolder%5b%40name%3d%27Cubes%27%5d%2fpackage%5b%40name%3d%27Sales%20and%20Marketing%20(cube)%27%5d%2ffolder%5b%40name%3d%27Report%20Studio%20Report%20Samples%27%5d%2freport%5b%40name%3d%27Top%20Retailers%20by%20Country%27%5d&ui.name=Top%20Retailers%20by%20Country&run.outputFormat=&run.prompt=true
In this case, the IBM Cognos Viewer header looks like this:
(Figure 1- Report Viewer with header and toolbar enabled)
The following parameters can be appended to a report URL in order to hide UI elements for the users. These URLs can be provided to users e.g. via bookmarks or email: http://webserver:80/cognos8/cgi-bin/cognos.cgi ?…. ..&run.outputFormat=&run.prompt=true &cv.toolbar=false&cv.header=false
Using those parameters, the Cognos Viewer header becomes:
(Figure 2- Report Viewer without toolbar and header)
2) As a global setting. This way all reports system-wide will hide the UI elements, however, it can also be limited to specific groups or roles only. This technique can have effect on Cognos Connection as well as Cognos Viewer. Edit the following file: c8_location/templates/ps/portal/system.xml Example for hiding the Cognos Connection header:
< param name="ui_hide" >
< CC_HEADER/ >
< /param >
A full documentation of this technique and a list of UI elements that can be hidden can be found in the “Administration and Security Guide” which is part of the official product documentation that ships with IBM Cognos 8. If the end-users are aware that they are using a slow network connection to traverse many router hops to reach the IBM Cognos web server then they may be more tolerant of apparently poor performance. They may learn to refresh output less frequently, or to schedule execution and delivery instead of waiting for it. Negotiate Quality of Service with the End-Users. If they are prepared to trade-off performance of one Web Application for the performance of IBM Cognos then this can be implemented in Quality of Service on the Routers.
2. Monitor Network Performance
Inspect the Web Server Access Logs for HTTP-304 status responses. These indicate that content was already cached on the Browser and did not need to be re-delivered across the WAN. Inspect the HTTP traffic using client-side tools such as IBM’s Page Detailer or Fiddler http://www.fiddler2.com/fiddler2/ . These can expose how much data is being transferred to the Browser, and how long it takes to be delivered. Though performance of a connection from the remote site to an external web site may be good, and from the Data Centre to that external web site may also be good, this is no assurance that the VPN connection between the two is satisfactory. Evaluate external connection speeds using tools such as: http://www.speedtest.net/, http://www.dslreports.com/speedtest?more=1, or similar provided by your own bandwidth provider.
Evaluate point-to-point Network Performance by facilitating a timing tool such as “SpeedTest Mini” from http://www.speedtest.net/mini.php on the IBM Cognos Web Server. When accessed by a remote browser, this tool will objectively indicate the effective transfer speed between the browser and the web server irrespective of what bandwidth is actually provisioned.
(Figure 3- Screenshot from Speedtest.net MINI)
Tools like this will also help to indicate available bandwidth when “Quality of Service” (QoS) tuning is constraining utilization. Note that if both client and server are connected via Asymmetric Digital Serial Line (ADSL) then the effective transfer speeds will be further limited by the “upload” rate at the Server end of the connection. Emulate several bandwidth situations from your local PC, independent where your web server is located physically. The free tool “Network Delay Simulator” (http://www.akmalabs.com/downloads_netsim.php) provides this functionality. Once the tool is installed, the network delay parameters that are subject for testing can be defined per local network adapter:
(Figure 4- Network Delay Simulator configurations)
The traffic can then be monitored using the “Graph Stats” tab:
(Figure 5- Network Delay Simulator graphical statistics)
This tool binds itself to the network adapters, therefore tools like Microsoft Fiddler can still be used to measure the web page traffic including response times.
3. Distribute Static Content
The simplest way to improve WAN performance is to ensure that Static Content that is delivered as the Studios and other User Interfaces are delivered only over LAN. This is easily achieved by ensuring that a Web Gateway is established at/near each remote user community. Then only SOAP requests and Report Output are transmitted over the WAN between the Web Server and Application Tier components. Some IBM Cognos’ customers/partners are operating an Application Service Provider model whereby they deliver Hosted Business Intelligence over Extranet/Internet (using connection speeds varying from 256kbps through to 1mbps) to their customers using IBM Cognos 8 or Series 7. These sites do not provide Authoring Studios over the Internet, but the Consumer User Interfaces are “useable”.
4. Consider Citrix where appropriate
Consider providing thick-client applications (eg Framework Manager) over Citrix if Remote Users need to model data. Using a Browser within a Citrix session is probably more expensive on bandwidth utilization than running it locally.
5. Consider HTTP Compression
HTTP Compression is easily implemented on the Web Server, and modern Browsers support compressed delivery without further configuration.
6. Browser Patches
See Microsoft for Patches that affect client-side performance of AJAX Applications
http://support.microsoft.com/kb/942840
Read the complete article by Martin Keller here.
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