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Title
Error: "invalid jquery function Modal.draggable" when using load balancers -
Description
Load balancers which do not support "sticky sessions" or are not configured correctly, can throw errors to end users in the Web Portal regarding JQuery scripts not working correctly.
The error is: "invalid jquery function Modal.draggable". -
Cause
The "invalid jquery function Modal.draggable" error can be caused when a WebDesigner WebPortal does not support sharing sessions between several load balanced webapplications. User sessions may get lost when they are redirected to a different webserver.
An error can be seen in the web logs which shows the client's session on two different servers at the same time. This causes the jQuery scripts to be loaded in an incorrect order, because the sessions are moving between two different servers.
To confirm, it is possible to enable a single load balanced link and compare the application behavior with a direct link to one of the webservers behind the load balancer.
Load balancers must be able to track sessions accordingly, and include their own cookies to track sessions. -
Resolution
WORKAROUND
Cookie based "Sticky sessions" are compulsory when using load balancers.
Other load balancing methods which do not use cookie insertion for "sticky sessions" or "session permanence" may create situations where the requests are redirected to different webservers depending on the load balancer configuration, which will create errors due to scripts not being loaded, or loaded in the incorrect order.
By default, Identity Manager Web Applications manage sessions with the in-process mode and use cookies to track the sessions. These cookies can be used by most load balancers on the market to track sessions accordingly, and include their own cookies to track sessions with more precision. More information can be found here: Session-State Modes.
For this cookie insertion to work, the https traffic has to be deciphered on the load balancer, either using "ssl offloading", or "ssl bridging", and in any case the session maintained on the load balancer has to follow the IIS provided session lifecycle.
STATUS
Enhancement Request #17722 has been submitted to improve Identity Manager documentation regarding the configuration of load balancers. This will be included in a future version of Identity Manager along with other improvements and listed in the release notes.