关于osworkflow的关注点

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Generally pre functions are for simple, quick executions, and post are where the "meat" goes.

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Functions can be specified in two separate locations; steps and actions

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Trigger functions are just like any other function, except that they aren't associated with only one action. They are also identified with a unique ID that is used at a later time (when a trigger is fired) to be executed by the Quartz job scheduler (or any other job scheduler). These functions usually run under the context of a system user and not a regular user working in the workflow. Trigger functions are invoked by using the OSWorkflow API from an outside source, such as a job scheduler like Quartz.

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A validator is nothing more than some code that validates the input that can be paired with an action. If the input is deemed to be valid, according to the validator, the action will be executed. If the input is invalid, the InvalidInputException will be thrown back to the calling client - usually a JSP or servlet.

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A register is a helper function that returns an object that can be used in Functions for easy access to common objects, especially entities that revolve around the workflow. The object being registered can be any kind of object. Typical examples of objects being registered are: Document, Metadata, Issue, and Task. This is strictly for convenience and does not add any extra benefit to OSWorkflow besides making the developer's life much simpler.

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Conditions, just like validators, registers, and functions, can be implemented in a variety of languages and technologies. Conditions can be grouped together using AND or OR logic. Any other kind of complex login must be implemented by the workflow developer. Conditions usually associated with conditional results, where a result is executed based on the conditions imposed on it being satisfied

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Sometimes it is desirable to have an action performed automatically, based on specific conditions. This is useful for example when trying to add automation to a workflow. In order to achieve this, an attribute of auto="true" will have to be added to the specific action. The workflow engine will then evaluate the conditions and restrictions on the action, and if they are matched and the workflow could perform the action, then it automatically does so. The auto action executes with the current caller, so the permissions checks and so on are performed against the user who called the action that initiated the auto action.

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Each condition must be defined as a child of the conditions element. This element has one attribute called type, which can either be AND or OR. When using the type AND all the condition elements must evaluate to true or the overall condition will return as false. When using the type OR only one condition element must evaluate to true for the overall condition to pass. If you require more complex conditional logic, then consider implementing it yourself using the Condition or ConditionRemote interfaces, BeanShell, or BSF. Note that the type can be omitted if the conditions element contains only one condition.

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OSWorkflow provides a pluggable persistence mechanism that can be used to allow for many choices of ways for workflow content to be stored. Included with OSWorkflow are the following WorkflowStore implementations: MemoryStore (default), SerializableStore, JDBCStore, OfbizStore, and EJBStore. If one of these does not fit your requirements, you can implement your own workflow store by implementing the interface com.opensymphony.workflow.spi.WorkflowStore. See the javadocs for more information.