Backend Improvements 6 22: Difference between revisions
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These simplifications to exception handling imply severe impact on existing OX6-compliant source code that need special developer’s intention: | These simplifications to exception handling imply severe impact on existing OX6-compliant source code that need special developer’s intention: | ||
* There’s no more the need to create own exception class, but only creating an enum that implements OXExceptionCode. | * There’s no more the need to create own exception class, but only creating an enum that implements OXExceptionCode. | ||
* Special handling through catch-clauses: Since there is only one exception class, there is no possibility for flow control through catch-clauses anymore. To look for a special error, the method OXExceptionCode.equals(OXException) is suggested for being used. | * Special handling through catch-clauses: Since there is only one exception class, there is no possibility for flow control through catch-clauses anymore. To look for a special error, the method OXExceptionCode.equals(OXException) is suggested for being used. | ||
* Special handling by error code numbers: Only comparing by code number may ignore equality of the associated code prefix. Using OXExceptionCode.equals(OXException) is recommended in this case, too. | * Special handling by error code numbers: Only comparing by code number may ignore equality of the associated code prefix. Using OXExceptionCode.equals(OXException) is recommended in this case, too. | ||
* Moreover the developer should be sure that the right category is selected for a certain error code. The category decides if exception is displayed to user or logged with certain log levels. | * Moreover the developer should be sure that the right category is selected for a certain error code. The category decides if exception is displayed to user or logged with certain log levels. | ||
Revision as of 06:40, 19 July 2012
Improvements Overview of 6.20.x to 6.22 Backend
New Exception Framework
Exception handling is the process of responding to the occurrence, during computation, of exceptions – anomalous or exceptional situations requiring special processing – often changing the normal flow of program execution.
With Open-Xchange Server v6.22 the exception handling has been heavily simplified. There is only a single class named OXException. As prerequisite for remodeling the exception handling, existing error code notations – e.g. APP-0015 – and uniquely identifying exception ID – exceptionID=-1272648052-227787 – need to be maintained. Newly introduced classes OXExceptionCode and OXExceptionFactory now replace formerly used classes Code, ErrorMessage, and ExceptionFactory respectively.
Moreover the new exception framework distinguishes between log and display messages. The log messages technically describe the occurred error with optional debug information (e.g. user, context, …). Whereby the display message is intended as a short, understandable and translatable message for the Open-Xchange user. The display messages are provided as public constants by a simple class implementing com.openexchange.i18n.LocalizableStrings interface.
These simplifications to exception handling imply severe impact on existing OX6-compliant source code that need special developer’s intention: * There’s no more the need to create own exception class, but only creating an enum that implements OXExceptionCode.
* Special handling through catch-clauses: Since there is only one exception class, there is no possibility for flow control through catch-clauses anymore. To look for a special error, the method OXExceptionCode.equals(OXException) is suggested for being used.
* Special handling by error code numbers: Only comparing by code number may ignore equality of the associated code prefix. Using OXExceptionCode.equals(OXException) is recommended in this case, too.
* Moreover the developer should be sure that the right category is selected for a certain error code. The category decides if exception is displayed to user or logged with certain log levels.