Join Session or Remote Open fail without system message
Description Normally, if you attempt a session control operation such as "Join", "Remote Open", or "Become Master", the system is either expected to execute the operation or notify you if the requested operation cannot be executed. For instance, if you requested to join a private session, the system is expected to notify you that you cannot enter. The system is not expected to just ignore your request. Yet, under certain rare circumstances, it does.
Origin: This happens under various circumstances. To execute the operation, your Session Manager (SM) must be able to talk to the remote user's SM. If the remote SM does not respond, your request may be left hanging. An SM may fail to respond when browser is busy (for instance, trying to resolve a non-existent DNS name, contact a non-responding server, or simply waiting for a document arriving on a slow link). Such conditions are transient and often another attempt to execute the operation will work.
Note also that certain TI applications request security privileges. If a remote user receives a request to grant a privilege but fails to either grant or decline, no further action will be taken: your request will hang indefinitely with neither a "yes" or "no" from the remote user.
Workaround: None at present. It is a very difficult, general problem in distributed systems. Anomalies of this kind are almost always caused by transient or permanent failures of Internet infrastructure (servers, networks, etc.) and resulting misbehavior of the browser. We have been unable to find a set of consistent heuristics enabling collaboratory engine to reliably and automatically deal with all kinds of "remote failure" problems.
Permanent (?) fix (???): For certain type of "hanging" operations we provide a well-hidden "reset" shortcut (Alt-double-click at the session entry in SM). |