This expression is used to define top-level process definitions as well as subprocess definitions. Top-level process definition require the 'revision' attribute to be set. The 'name' attribute is mandatory for top-level and sub process definitions. http://www.openwfe.org/docbook/build/ch06s02.html#expression_process_definition The 'sequence' expression defines a list of children expressions that have to be evaluated sequentially. http://www.openwfe.org/docbook/build/ch06s02.html#expression_sequence The children of this expression will be executed in parallel. Concurrence has various attributes for determining how the synchronization at the end of the parallel executions has to happen. http://www.openwfe.org/docbook/build/ch07s03.html An iterator takes care of executing its children one or more item. It's the equivalent of the 'for' loop in classical programmation. 'concurrent-iterator' will execute all its iterations concurrently whereas 'iterator' will execute them sequentially. http://www.openwfe.org/docbook/build/ch07s14.html#pat_expression_iterator The 'concurrent-iterator' executes all of its iteration concurrently, it's like a concurrent 'for' loop. http://www.openwfe.org/docbook/build/ch07s13.html A participant is anyone/anything taking part in a process. Participants are usually defined in the file etc/engine/participant-map.xml The main attribute of a participant expression is 'ref' which refers to a participant name in the participant map. Engines are participant too. http://www.openwfe.org/docbook/build/ch06s02.html#expression_participant An absolute reference to a participant (by its name in the participant map). The name of the participant that will receive the workitem is the value of the given field. The given variable should hold the name of the participant that will receive the workitem. If 'ref' isn't present and if neither 'field-ref' nor 'variable-ref' holds a value for the participant name, this attribute holds the 'default' participant name. A comma separated list of participant names that are tried one after the other until delivery succeeds to one of them. This list is tried only if other references yielded failed deliveries to their participant. This attribute helps define 'fail-over participants'. A filter determines which permissions are set on the fields of a workitem emitted to the participant. The attribute filter should contain the name of a filter defined by a 'filter-definition' expression. As engines deliver workitem to participants, they lose control over the workitem. The participant may never reply. This attribute sets locally after how much time the engine shall consider the workitem as 'lost' and resume the flow. If the timeout is set to '-1', 'no' or 'none', the engine will never consider the workitem as lost. The flow will resume with a copy of the workitem as it was just before being sent to the participant. The flow will not be considered as failed and 'else-ref' participants won't get triggered. A small help attribute. Its value is set as the content of the field named '__description__' just before being sent to the engine. When the workitem comes back, the field is cleaned (removed). This attribute is useful for setting task descriptions for the participant (could be useful for a human participant as well as for an 'automatic' participant). If this attribute is present and set to 'true', the engine will resume the flow and 'forget' about having sent a workitem to the participant. Can be useful for implementing advanced notification mechanisms. The 'cancel-process' expression will cancel the whole workflow instance upon being evaluated. Use it with care : it's explicit termination of a flow. http://www.openwfe.org/docbook/build/ch06s09.html#expression_cancel_process The 'forget' expression simply applies its child expression (in a separate execution thread) and immediately replies. It may be seen as a way of forking an independent process branch. http://www.openwfe.org/docbook/build/ch06s09.html#expression_forget 'lose' will apply its child expression but will never reply, it may still get cancelled (whereas a 'forget' branch having immediately replied, cannot get cancelled). 'lose' makes sense within a concurrence to tag a branch as 'we don't care about its reply and we'll cancel it when the non-lost branch will have replied. http://www.openwfe.org/docbook/build/ch06s09.html#expression_lose The 'rotate' expression turns a vertical workitem field into an horizontal one and vice-versa. A typical horizontal workitem field is a list of strings stored with comma separators. The typical vertical workitem field is an instance of ListAttribute. http://www.openwfe.org/docbook/build/ch06s09.html#expression_rotate This attribute is mandatory, it points to the field whose value should get rotated. If the attribute 'to-field' is not present. The field named here will be the source and the target of the rotation operation. If this attribute is present, the rotation operation will store its result in the field named here. If this field is set to 'yes' or 'true', the rotated strings will be trimmed. The default separator is the comma ",". This attribute may be used to specify another one. Do not use a regular expression here. The 'eval' expression may extract OpenWFE 'code' from a workitem field (see the 'field' attribute) or from a nested OpenWFE constuct and evaluate it on the fly. http://www.openwfe.org/docbook/build/ch06s09.html#expression_eval When the field attribute is set, the 'eval' expression will read the code to evaluate from the field named here. Any nested content will be ignored.