Error Page
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Old Error Conventions
Dewitt-minirel: An enumerated type, Status, is used to
show what error was encountered. When errors are detected, the program
exits.
Old Minibase: It uses a layered approach, with Record, PageFile, Buffer
Manager, and System layers. An error in one layer will propogate up
to the higher layers.
Current Error Convention
Carey-minirel & Minibase: A layered approach was needed, but since the possibility
exists of different groups calling each other (DB->BufMgr->DSM), the path
that error discovery may take is slightly confusing. A global error class
will log errors as they go. Each layer (when an error is discovered)
will enter an error into a linked list of error msgs, allowing the user
to see where the error was first discovered and see how the error
caused various functions to fail.
The Status enumerated type is still used, and care must be taken
that different groups recognize that not all Status types are actual errors.
In some cases, Status is used to signal a condition. In these instances, the
different groups must be aware of the types used so that the proper
interpretation is made.
Header File
Possible Improvements
Bill Kimmel
[kimmel@cs.wisc.edu]