Datasheet

Like ordered workflows, event-driven workflows have rules that describe which states can transition to
other states based on some predefined events. It would not make sense for the light switch to transition
to the
on state if someone unscrewed the face plate.
Workflow Scenarios and Examples
Now that you have a good handle on what traits a workflow platform should possess and what types of
workflows exist, the following sections discuss various workflow scenarios and illustrate a few support-
ing examples.
Human-to-System Interaction
The aforementioned workflow tenets mentioned that human-to-system interaction is vital in the context
of workflow-based systems. The importance of this principle cannot be overemphasized.
System-to-System Interaction
As you now know, it is important for workflows to be able to interact with people. It is equally impor-
tant that systems are able to interact with other systems through a defined workflow. This process of
tying external systems together in one cohesive set of steps is sometimes referred to as
orchestration. If
you are familiar with Microsoft’s server product BizTalk, you have probably heard this term.
This type of workflow is commonly associated with service-oriented architecture (SOA). SOA is a large
topic that is discussed briefly later in this chapter and in subsequent chapters of the book.
Application Flow
A workflow does not have to be an interaction between entities that are external to each other. A com-
mon scenario is defining the order in which to display data entry forms or other interface to a user.
Think about a college application website. The order in which pages are presented to the applicant is
important and is probably based on the education program to which the user is applying.
Another scenario might be a system in which data is processed from a beginning state to an end, cleansed
state. Along the way, the data is placed into different buckets that represent different states of being pro-
cessed. If during a given state, the data cannot be processed because of an extraneous issue, an exception
is raised so that a human is forced to inspect and manually fix the problem. This scenario could be applied
to customer data coming in from multiple outside sources.
A Few Examples
To get you in the overall workflow mindset, the first example is not a model for a software system at all.
It is a set of instructions for an IT recruiter to follow related to an employee hiring process. Figure 1-1
illustrates what this type of process might look like.
The steps could obviously go on from here, but this should give you an idea of what an
ordered workflow
might look like. The first step is always the receipt of an application and résumé, and the next step is
always the review for job requirements. The order of the tasks is non-negotiable.
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Chapter 1: An Introduction to Workflow and Windows Workflow Foundation
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