Data Characterisation
From a data perspective, there are a series of characteristics that occur repeatedly in different workflow modelling paradigms. These can be divided into four distinct groups:
- Data visibility - relating to the extent and manner in which data elements can be viewed by various components of a workflow process.
- Data interaction - focussing on the manner in which data is communicated between active elements within a workflow.
- Data transfer - which consider the means by which the actual transfer of data elements occurs between workflow components and describe the various mechanisms by which data elements can be passed across the interface of a workflow component.
- Data-based routing - which characterise the manner in which data elements can influence the operation of other aspects of the workflow, particularly the control flow perspective.
Each of these characteristics are examined in more detail in data patterns website. For the purpose of this discussion, we take a broad view of the potential structure and substance of workflow data. The representational capabilities of workflow systems vary widely and the more sophisticated of them enable data elements of significant complexity to be captured by including provision for composition, repetition and reference operators within the data specification language thus providing support for the construction and use of abstract data types for managing workflow data. Table 1 identifies the major structural characteristics that are relevant to the specification of data elements and indicates their applicability to individual workflow engines.
Construct |
Staffware |
Websphere |
FLOWer |
COSA |
XPDL |
BPEL4WS |
|---|---|---|---|---|---|---|
| string | - | - | - | - | - | - |
| integer | - | - | - | - | - | - |
| float | - | - | - | - | - | - |
| boolean | . | . | - | - | - | - |
| date | - | . | - | - | - | - |
| time | - | . | - | - | . | - |
| document/reference | - | . | - | - | - | - |
| enumeration | . | . | . | . | - | - |
| composition | - | - | - | . | - | - |
| array | . | - | - | . | - | . |
| set | . | . | . | . | . | - |
Table 1: Data Elements in Workflow Systems
For the purpose of this body of work, we do not examine the ability of workflow engines to describe arbitrary classes of data structures but focus rather on how these elements are utilised in the context of workflow operation.