UI Errror Handling and Logging
Currently the UI does not cope well with errors - often displaying Java errors / stack traces - and there is no logging. This document discusses how to improve the situation.
Desired user experience
Ideally there wouldn't be any errors - or at least any undefined errors. Things will go wrong - errors in coding, databases unavailable, bad input due to mangled URLs etc. The user should see a concise (localized) message with an indication of what they should do - and that someone else may have been alerted to a problem. This could include providing a ticket which they can use to follow up the error. If they do follow up on the error, they should expect that a support person should be able to use the ticket to look up details of the error.
When an error arises in the UI a ticket should be generated. Sufficient details about the error and its context should be logged against the ticket so that there is no ambiguity - particularly important in a multi-user environment. Some errors may be hard to reproduce so capturing relevant context is important. Currently the API uses several different log files which makes it difficult to know which messages may be related.
Typically production systems do not log debug information - the log files become too large and there can be IO issues. On the other hand, when a serious error occurs it would, in general, be useful to have the low-level debug information. I intend to look into whether we can capture debug (possibly tagged as info) information but only log it in the case of an error. This may well not go in 1.3.0 but may be possible using a custom log4j Appender.
Log files often have little discriminatory information e.g. grouper_error.log shows no information about the subject associated with the GrouperSession. grouper_event.log does have information, however, the API sometimes starts internal GrouperSystem sessions to complete its work so it is not always clear that events are associated. From a UI perspective - and I assume a Web services perspective, it would be best to tag each request with a ticket which unambiguously groups all relevant messages. A simple grep allows all associated messages to be viewed - even if they are interleaved with concurrent messages from another request.
Error messages shown to end users should be derived from nav.properties.
There is potentially a lot of relevant contextual information in request parameters and request/session attributtes which should be captured - and possibly emailed to an approriate account.
Edited comments from others from the 'descriptive error messages' thread
I definitely think we should review logging for 1.3.1, and look at when exceptions really are errors vs informational within the API.
I propose to provide an alternative log4j.properties which can, by configuration in grouper-ui/build.properties, be used in place of the Grouper provided default. The new configuration will log all messages to a single file, and all messages for the same request will be tagged with a unique ticket and will contain GrouperSession information where I can control that. I will use loggers directly rather than utility classes
I will go through the servlet Filters and Struts actions and add better exception handling and logging. There will probably be many new error messages