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XXXXXXXXXXXXXXXXXXXXX REVISE FOR V6.2 PROCESS MODELER XXXXXXXXXXXX A flow rule — an instance of the Rule-Obj-Flow rule
type — is a network of shapes and connectors (directed
arrows), each with associated parameters and values. Flows govern:
- How work objects
are created
- How they progress through one or more flow executions
- How they become resolved (completed)
Flows are the fundamental rule instances that represent business
processes, identifying who works on a work object in what sequence, what
decisions and processing occur automatically, and many other aspects of
the business process.
Some applications don't require users to interact with work object
forms. Flows that implement straight-through-processing operate without
user input. External portals and systems can execute flows through Active
Server Pages, JavaServer Pages, Service Portlet or Service JSR94 rules,
or other means. Informally, these are known as "headless" BPM
applications. A collection of standard activities known as the Process
Engine API simplifies building such applications.
As you build an
application
Application developers use Microsoft Visio to create, edit, and
evolve a flow. Process Commander uploads the resulting
VSD
file, including the Shape Parameters details from the
workstation. Both the diagram image (a JPG file) and the rule details
are saved with the flow rule.
Visio provides an attractive, easy-to-interpret and
easy-to-manipulate presentation of the business process.
To start Visio on your workstation, click the Flow Edit toolbar
button (). Create and evolve the flow in Visio as
needed using familiar Windows techniques such as drag-and-drop. As you
work, you can enter the names of utility shapes, decision shapes, assignment shapes, router shapes, flow actions and the rules that these shapes reference. If some of the activities and other rules for these shapes
do not yet exist, you can leave the rule in draft
mode.
As you exit from Visio, the system uploads the flow diagram (and
the extensive data structure that Visio contains), and saves it in the
flow rule.
You can't test a flow rule that has Availability set to
No/Draft. You can test the flow rule if the Availability
is set to Yes
, even if the Visio DRAFT mode () is in force,
indicating that not all the activities, properties, or other rules are
yet defined.
Runtime processing
— The simple case
At runtime, a user can start the execution of a flow by entering a
new work object. The system examines the property
pyFlowName, in the model instance for the class, to
determine which flow to start. The flow operates on the work object to
advance it through the business process that the flow implements,
performing automated steps automatically, or creating assignments for
users as appropriate.
You can think of a work object as located "on" one shape
or arrow of the flow at any one instant, until the work object becomes
resolved or the flow ends. Alternatively, you can think of the flow
operating on the data (properties) in the work object until the flow
finishes or the work object becomes resolved. Both points of view are
correct.
A flow may define many optional detours, side trips, and branches
reflecting decisions reached along the way. The path that one work
object follows through the flow depends on its own requirements,
automatic decisions in rules (such as decision tree rules and map
value rules) and on available resources. For example:
- One mortgage application that fails to meet the automatic
credit approval rules may require special research, while others
are handled automatically
- An arriving customer service call in Mary’s territory may
be routed to Tom if Mary is unavailable
- A request that is in a foreign language may be routed to a
manager who can decide who among his or her team is best qualified
to handle the request. Normal requests, not in a foreign language,
may be routed automatically based on a round-robin algorithm.
- The system can randomly select one work object out of every
hundred for a quality review.
As a flow rule executes, the following processing often occurs:
- The system generates a unique work object ID for a new
work object. (This occurs for starter flows, those for which the
Creates a new work object? box on the Flow form is
selected.)
- As needed, it creates assignments for human
users reflecting the need for more facts, judgments, and places the
assignment into an appropriate user worklist or workbasket. After a user
(or in some cases an agent or external participant) perform an
assignment, the work object progresses farther through the
flow.
- The system automatically makes decisions, urgency calculations, and
gathers data automatically from many sources including outside
systems.
- Rules promote compliance with service level goals, and
alerts management or raises the urgency value when processing does
not meet these goals. This is known as escalation.
- Processing of the flow ends when a FlowEnd shape is reached.
The work object may or may not be resolved at that
point.
Types of
flows
The Process Explorer tool presents — for the currently
selected application — starter flow rules and the subflows they
call in a graphical form. See Process and Rules category — Processes page.
- A flow rule that contains no assignments, and so can
execute from start to end without human input, is known as a
straight-through
process.
- A flow rule that consists only of assignments or
decisions and meets other criteria is known as a screen flow.
- A flow that creates a new work object is called a starter flow.
- A flow that is called by another flow is known as a subflow; the calling flow is
called parent
flow. Processing of a subflow is synchronous, meaning that the
calling flow execution pauses for the duration of the subflow. When
the subflow execution reaches an End shape, the calling flow
can continue (if additional shapes are present). See Flow
rule — Completing the Diagram tab — Call or Branch to a
Subflow.
Parallel processing
with Split-Join
In some business processes, the order of certain steps is not
important as long as all the steps get done. In other situations, a step can be
considered complete when either of two other steps finishes.
The Split/Join facility () supports such asynchronous operation, by
allowing processing of two or more subflows to proceed in parallel.
For example, a contract may need approval of both a legal reviewer and
a purchasing department reviewer, but order is not important. In the
1980's era of paper forms and in-boxes, only one of these two has
the paper — artificial sequencing. With a work-object and a flow
that uses Split-Join, each subflow can create an assignment, and the
two reviewers can proceed independently.
See Flow rule
— Completing the Diagram — Split/Join shape.
Split-Join parallel processing occurs only
when considered at the business process level. Although two
assignments exist, they both belong to a single work object. During
the minutes or seconds that either user performs the assignment (thus
updating the work object), the system locks the work object and so the
work object is not available to the other user.
Similarly, at a more atomic level, if the two users both access a
single-node Process Commander system that has a single JVM and single
CPU chip, no parallel processing occurs at the Java thread level, even
when the two users work on different work objects.
Parallel processing
with Split-forEach
Parallel processing
with Spin-off
Parallel processing
with Start a NewProcess and flow actions
Process Commander offers ways for a flow execution to be started
for an existing (open) work object. These are alternatives to calling
a subflow, using a Split-Join shape, or using a Split-forEach shape:
- Users can access an open work object in update mode, click the
Start a new
process button, and
choose a second flow to start. This button is available on most
Update work object forms. Users may be prompted to enter flow
parameters to complete the operation. The Start a new
process button lists
all the eligible flow rules with the Can be added to a work
object? box selected on the Flow form. (To include this
button on a work object form, reference the standard section rule
Work-.Flows in a harness rule.)
- Users can select the standard flow action
Work-.AddFlow, Work-.AddCovered, or
Work-.AddtoCover to start a new flow execution.
Data structure for
flow executions
Several system-maintained properties in a work object record the
current state of flow executions in process. For example, the integer
property @baseclass.pxFlowCount indicates how many flow
executions are in process for the work object.
The Page Group
property @baseclass.pxFlow
contains a page of facts about each execution:
- pyFlowType — Second key part of the flow
rule
- pxAssignmentKey — Key of the current
assignment instance for this flow execution. typically an instances
of the Assign-Workbasket or Assign-Worklist class.
- pyLastFlowStep — Internal name of the most
recent shape or connector processed
- pyNextFlowStep — Internal name of the next
shape or connector to be processed
- pyFlowParameters — A classless page
containing parameters used to start this flow
Concepts