You can use the SureConnect feature of the Citrix NetScaler appliance to service all incoming connections with either the requested content or a custom Web page that displays information about a delay in the request being serviced.
When servers are overloaded with the requests, the servers might either respond slowly or not at all. The SureConnect feature enables the NetScaler appliance to detect and compensate such conditions by ensuring that every client request gets serviced in some way, such as either a custom Web page or actual content is sent to the client.
You can configure whether the SureConnect progress bar alone is displayed or both the progress bar and the alternate page are displayed.
When the server becomes responsive again, the original request for content is served. If the user chooses, the alternate content window can remain in focus.
Subsequent requests from the same user within the same session are served immediately. This can be configured using the settings described later in this section.
SureConnect can be activated when a response is delayed, and when the number of user connections to a given URL exceeds a specified threshold.
SureConnect works with all standard browsers, including Microsoft Internet Explorer, Netscape Navigator, and Mozilla Firefox.
Full server queue
The server can respond fast, but there are too many users. This results in the server’s queue being full and unable to process additional client requests.
SureConnect Solution: In this situation, the SureConnect window is displayed, showing the time left until the content will be available. The alternate page is displayed under the progress bar, if an alternate page has been configured.
Large response delay
The server response is slow. Typically, if a Web server does not respond to a client request quickly, the user will leave the site.
SureConnect Solution: When the predicted delay reaches a configured time threshold, the SureConnect window displays the progress bar and the optional alternate page in the client browser.
When the client requests content from a very slow Web site, a time-out message displays in the client browser, and the content is not delivered. The user may leave the site.
SureConnect Solution: The appliance stores the request until the server is no longer busy and delivers the requested content to the client.
Server experiencing a traffic surge
The server typically responds quickly, but the current load of open connections is greater than the server capacity to serve them. Therefore, the server response is delayed.
SureConnect Solution: A SureConnect window is displayed in the client browser, showing the time left. The alternate page from the server is also displayed if it has been configured.