Server Smalltalk Guide
When dealing with higher-level abstractions, such as object spaces and
remote object models, passing error objects becomes unmanageable. SST
defines five exceptions to deal with these broad cases. The
parent-child relationship is as follows:
(ExAll)
ExSstFatalError
(ExError)
ExSstInvocationError
ExSstNonFatalError
ExSstSetupError
ExSstUnknownException
These exceptions are raised in different situations, and have different
meanings. Each will have a string describing the cause of the exception
as the first element of the arguments to the signal. Any further
arguments may contain objects related to the error. The exceptions are
as follows:
- ExSstFatalError
- Raised when a situation occurs that cannot be handled or fixed in any way
by the SST system. It is usually raised from extremely low levels
within the system.It indicates that the system has become unstable, and
results may be suspect. This exception is a child of ExAll,
so that it will not be caught by normal exception handlers. This
exception may occur in Communications activities.
- ExSstInvocationError
- Raised by spaces when a message invocation returns an
SstError. It is raised only if the space's
configuration has raiseExceptions set to true.
This exception will only occur when dealing with object spaces.
- ExSstNonFatalError
- Indicates that some error condition occurred that affected the current
operation, although the overall system integrity remains unaffected.
This usually occurs if some internals are incorrectly adjusted, such as
wrongly setting the logical process on requests.
- ExSstSetupError
- Raised only during system start up. It indicates that the system
description is either flawed, or some resource is not available. For
example, a space which was setup as the local space does not match the actual
local machine. This exception may occur in Communications
activities.
- ExSstUnknownException
- Thrown when processing remote exceptions, as described in Logical process invocation. Non-system exceptions destined for remote spaces are
converted to an ExSstUnknownException.
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