Guideline 2.2 Enough Time states that users should be given enough time to read and use the content.
Following the guideline, several techniques are available, geared towards letting users adjust the length of any timed connection. Depending on the application requirements this would be possible or not. You can use the Chronometer Control to manage the time elapsed for each process and re-start the timing if necessary. The remaining time for a process can also be warned to the user displaying a message on the screen.
In the case of web transactions where the events are triggered using ajax, the time and position of the messages should be controlled. The error and warning messages position and display behavior can be configured using the Client Side Validation properties. The developer can control the position of the error messages and if the validation message display will be all at a time or not.
About re-authentication and timing: When an authenticated session expires, the user should be able to continue the activity without loss of data after re-authenticating. Use the Web Session data type to store the session information while it's active, and store the data in the database associated with a cookie ID to be able to retrieve the information when the session expires. Use SetCookie function.