Circles and Diamonds

and Squares, Oh My!

Demystifying the BPMN Standard

BPMN standards can be confusing, but once you understand their purpose and how to
use them, they can be lifesavers. This paper, based on a webinar by Justin Brunt, provides
a walk-through of the BPMN 1.0 standard, shows how it is implemented within TIBCO
Business Studio™ 2.0 (available as a free download) and how the combination of BPMN and
Business Studio can help you be successful with BPM.
 What is a Process?
About the Presenter/
There are many descriptions of business processes, but I particularly like this one in
Author
the context of BPMN. The Workflow Management Coalition defines a process as the
Justin Brunt is Senior Product representation of a business process in a form that supports automated manipulation,
Manager for TIBCO’s BPM such as modeling or enactment by a workflow management system. The process definition
product suite, TIBCO consists of a network of activities and their relationships.
iProcess™ Suite. He’s been
involved with business
process management for
over thirteen years, initially
What is BPMN?
as Director of Development Simply put, Business Process Management Modeling Notation (BPMN) is a graphical way
for Staffware PLC and of describing a business process. It’s flowchart-based, so looking at the process definition
as Director of Research. you should immediately be able to see what the process is all about. It’s basically an
Following the acquisition of
activity network combining various flow objects to describe the process. It’s targeted at
Staffware by TIBCO, Justin
different sorts of people. It’s aimed at the business analyst on one side and the technical
took on his current product
management role. Prior to person, who may have to implement a business process, on the other side. The process
joining Staffware, Justin held language was put together so that it would be applicable and understandable to people in
senior software development different roles.
roles with Logica and
Siemens. During his BPM and
workflow career, Justin’s been
involved in the development
Origins of BPMN
of BPMN-related standards. BPMN came from an organization called Business Process Management Initiative (BPMI)
Throughout this time he’s that set about putting together specifications and standards for business process
been involved with the management. They initially put together a specification called Business Process Modeling
Workflow Management
Language (BPML). Associated with that, they wanted a visualization of a business process.
Coalition or WFMC and
That’s where BPMN came in. It was originally put together by a number of people from
held the position of Vice
Chair Europe of the WFMC’s different organizations including BPM vendors, academics, and end users. The language
technical committee itself was derived from different modeling notations – UML, high def, activity decision flow.
between 2002 and 2006, But the key thing about BPMN is that it really is targeted at describing a business process,
prior to his current position whereas some of the other modeling notations have a wider scope.
as Vice Chair Europe of the
Steering Committee. He’s BPMN is very specific to business process management. To date, we’re aware of at
also a fellow of the Workflow least 44 implementations of BPMN, of which TIBCO Business Studio is one. The original
Management Coalition.
specification came out in 2004 and the BPMI organization was eventually merged into the
Justin also represents TIBCO
in the OMG’s BPM-related Object Management Group standards group. They adopted BPMN as one of their formal

initiatives. specifications last year.

CIRCLES AND DIAMONDS AND SQUARES, OH MY! 2

 Scope of BPMN
The goal of BPMN was to describe business processes and the full range of business
process types – from workflow that may be very human-centric to the integration-
centric processes you would see in EAI systems – and to unify the different people in an
organization that were interested in the business process – from the high-level business
user to the technical user who may be involved in implementing the process.

BPMN Limitations
In terms of the language itself, there are some limitations to it.

• It doesn’t describe organizational structures and resources. That is covered by a

separate specification. In fact, the Object Management Group (OMG) works on
those kinds of specifications.

• It doesn’t define the data model for the process.

• It doesn’t describe business rules.

• And one of the key things the notation doesn’t include is a specification for
persisting the process definition. There are a number of initiatives that satisfy
that requirement. One of them is the Workflow Management Coalition’s XDPL
specification. Another one is a new standard defined by the OMG: Business Process
Definition Metamodel (BPDM).

• And, although it can show the flow of data, BPMN is not a data flow diagram.

Uses of BPMN
So what can you use BPMN for? There are three main types of business processes.

• private process: All of the activities within the process are completely within a
department or an organization, with no communication from that process to the
outside world. The process definition would include all of the activities that you see
being performed within that process.

• public process: Represents an interaction between a private business process and

another participant. In this case, only activities used to communicate outside the
private business process are included.

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 • collaboration or global process: A process you would find in a business-to-
business scenario. For example, in a supplier-customer relationship, you might only
want to define the interactions between those organizations.

BPMN Core Elements

Core to the BPMN specification are a number of elements that fall into two main areas:

• flow objects – things that happen during the process

• connectors – things that describe how the different flow objects relate to each
other

Under flow objects you have events, activities, and gateways. Under connectors you have
sequence flows, message flows, and associations.

Figure 1. Core set of BPMN

elements

BPMN elements look very familiar because they are drawn from the flowcharting paradigm.
The TIBCO Business Studio palette, which helps you draw the business process, includes
all of these BPMN shapes. For instance, under events you’ll see that there are start events,
intermediate events, and end events. Using those shapes and others, you can build your
business process. Figure 2 shows what is perhaps the simplest of all business processes:
start a process, do something, and complete the process.

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Figure 2. BPMN core elements

When you look at a particular shape in TIBCO Business Studio, you are able to see a
properties view for each shape.

ACTIVITIES
In the simple process described above – start, do something, end – we just had a task;
there was no specialization at all. BPMN allows us to have much more specialization than
that. For example, you can have a sub-process. An activity could be looped so it occurs
continuously. An activity could be performed in multiple instances; perhaps an activity is
delivered to more than one person or performed by more than one person. And you can
combine these different activities; so a sub-process might also behave in a looped manner
or in a multiple instance manner, going out to different instantiations.

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Figure 3. Activities

TASKS
One interesting thing about BPMN is that the specification allows you to embellish the
shapes themselves. When you look at the shape for an activity, it’s fairly bland. It’s just a
round-cornered oblong. But to convey more meaning, you can embellish it with colors or
icons. You can change the size of the icon.

In Business Studio, we allow you to define what kind of activity you want to represent.
You might have a User Task, where somebody is sitting at a computer and an activity is
delivered to them through a workflow or BPMN system. You might have a Manual Task, that
represents a point in a process where somebody needs to do something with some paper
– a manual task, but you still want to represent that within the business process. You might
have a Service Task, where some kind of automation occurs. For instance, a system may go
and do a credit check. Or you might have a Script Task, where an automated script is run to
perform some logic that helps with the execution of the process.

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Figure 4.Tasks

So you’re allowed to extend BPMN by having these colors and definitions, the only constraint
is that you not change the meaning or the semantics of the process specification.

SUB-PROCESSES
The sub-process activity provides a means to define logic that you wish to separate from
the main body of the process. For example, you may want to encapsulate this process logic
to enable reuse, so this piece of logic can be used by different processes or within different
parts of the same process. Or you want to hide the detail of one part of the process
because it detracts from the way the process can be understood by people reading it.

There are two different types of sub-processes. One is a separate sub-process where it
looks like a complete process definition. (In Business Studio, when you want to investigate
the process definition for the sub-process you can click on the object that you see on
the screen and the tool would open up a new window where you could see the detail of
the sub-process.) The other type is an embedded sub-process, where it’s not separate
from the process definition that you’re working with, but surrounds all of the logic you’re
interested in within a boundary and it appears as a single task within the process. Within
the sub-process there is some more detail, but it isn’t held in a separate place like the
other type of sub-processes.

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Figure 5. Sub-process

EVENTS
Events define something that happens during the life of a process.

• Start Events kick off the process.

• End Events define where a process or a branch of a process ends.

• Intermediate Events define things that happen during the process. These can be
part of the flow or associated with different activities.

START EVENTS
For each of the event types there are further specializations. For instance, a process
could be started by the receipt of a message from someone. A process could be started
by the receipt or triggering of a timer. For example, a process might start every Monday
or once a month. So there are different ways of starting processes, and you can use
different event types to specify how those processes will start.

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Figure 6. Start events

INTERMEDIATE EVENTS
As with Start Events, Intermediate Events can be started by a message. (In fact, a process
could send a message to another process, so you could get this interaction between
different processes.) A process could include some timer-related information. You may
need to wait until a particular time before something else needs to happen. Or you may
use it as part of an escalation capability, where if a particular action doesn’t happen by a
particular time; you can specify some behavior that will occur on the expiry of a timer. An
event could be initiated as a result of a rule or condition. Figure 7 shows how that would
appear in the Business Studio palette. So you can click on Intermediate Event and select
the particular Intermediate Event type you want to use as part of your process.

Figure 7. Intermediate events

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 END EVENTS
You have similar options with End Events. A process could end by sending a message to
something or someone. If you get to a particular point in a process, it may terminate the
process earlier than it would have done if it had gone down some other route. These are
some of the different ways you can end the process.

Figure 8. End events

EXAMPLES OF EVENTS
Figure 9 shows some examples of how events could be used. For the first one, we’ve got
a process that is started by the receipt of a message. For example, you receive a purchase
order and that instantiates a process that manages the fulfillment of the order.

In the second one we’ve got a timer within the flow. Once an activity is performed, the
process needs to wait for a message to be received before it proceeds to the next activity
within the process. Perhaps it’s waiting for the receipt of a scanned contract.

In the next one we have an event on the boundary of an activity. We’re processing an
order, but we’ve got a timer trigger such that after 48 hours if something hasn’t happened,
we can escalate to the manager. The manager gets a notification that something is not
happening as it should.

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Figure 9. Example of events

GATEWAYS
Gateways help us specify the flow of the process. There may be points where you need to
decide which path to go down through the process. There may be other points where you
need to have several things happen in parallel. Different types of gateways allow you to
change the way the process flows.

The first of these is an exclusive gateway. And there are two different types of these.
One is data based, meaning that it makes a decision based on data. For example, if the
value of a purchase order is greater than $10,000, proceed down this path, otherwise,
proceed down that path. There are two different representations of this gateway in the
specification. One is shown here with the cross in the middle. (An empty diamond means
exactly the same thing, but in Business Studio we’ve chosen to use the cross symbol
for added visualization.) The other type of exclusive gateway is event based, so the
determination of which path to go down is determined by the receipt of one type of event
or another.

Another type of gateway you’ll see and may want to use yourselves is a parallel gateway.
Several paths go out from this type of gateway and all will be performed in parallel.

The other gateway is an inclusive decision/merge. In this case, you may have conditions
associated with the different routes. You may then end up with one or more paths being
followed depending on which conditions are met.

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 The final type of gateway is a multiple gateway. This is less defined by the BPMN
specification. The behavior can be defined by the people developing the tools, so it’s
completely up to the tool vendor as to how they represent that.

If none of the above mechanisms satisfies the requirement, tool vendors have the
opportunity to use the multiple type. Gateways can be used for splitting into several paths
and for joining multiple paths back together. If you have an exclusive decision gateway that
then splits into multiple paths, you will see a gateway that joins them back together again.

Figure 10. Gateways

EXCLUSIVE GATEWAY
In Figure 11 we have an example of an exclusive gateway where we’ve got conditions: If a
loan is greater than this value, go down this path to have the loan approved. If it’s a lower
value, we can have a different person approve it. Later you can see that the paths merge.
In this particular instance you will only see one of the paths followed through the process.

We also have an example of the event-based gateway, where we may be waiting for
different things to happen. One might be an acceptance message. The other might be
a cancel message. So we would follow a different path depending on the event that was
received by the process. Again, we see the joining of the different paths at the end and we
see that only one of these paths would be followed through the process.

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Figure 11. Exclusive Gateways

INCLUSIVE GATEWAY
The inclusive gateway works the other way around, where multiple paths may be followed.
In this example, we have several chapters of a book to edit, and depending on how many
of those chapters are available, we’ll define how many of those paths we go down.

Figure 12. Inclusive Gateways

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 COMPLEX GATEWAY
Here is an example of the complex gateway, where you might have more choices to make
and different behavior following from that, which can be defined by the tool vendor as to
how that is implemented and appears within a product.

Figure 13. Complex gateways

PARALLEL GATEWAY
Going on to parallel gateways, in Figure 14 we have an example where a process can split
into more than one path. In this particular case, we have two different parallel paths that
will be followed together. The process will then wait until both of those activities have been
performed before proceeding to whatever activities appear after the joining gateway.

One of the other things BPMN allows you to do is have very similar logic, but for it to be
defined in different ways. So here we have two paths within a process that have exactly
the same meaning but different ways of representing them. In the top one we’re using
a gateway to say this is how the process splits into two parallel paths. The bottom one
allows you to have multiple paths out of the first activity into the secondary activities, and
then they join back into the next activity via a parallel gateway. The behavior of those two
process fragments is exactly the same, but you can represent them in different ways. It

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 may be that an organization decides that they have a particular methodology for defining
a process and one may decide that they use gateways to define the splitting. Another
organization may decide they’re quite happy to just have multiple paths coming out of
activities to define the same thing.

Figure 14. Parallel gateways

CONNECTORS
The last set of elements within the specification are connectors – the things that join the
different parts of the process together. Connectors define how the flow objects – the
events, gateways and activities – are joined together, what sequence they appear in. And
again, there are different specializations of those elements.

In Figure 15, we have a normal sequence flow that says that this follows this and this
follows this. The next is a conditional connector and this has the same kind of idea that
we saw in Figure 14 whereby you can choose to use a gateway for splitting into separate
paths, or you can have multiple paths coming out of an activity. The conditional connector
provides you with much the same idea in that you can have an activity, which has multiple
paths coming out of it, and each of them has this connector which has the diamond on
which defines that there is a condition associated with each of these paths. And only if
that condition is met will it go down that particular path onto the next activity. The next
kind of connector is the association. We have a number of different elements within BPMN
that allow us to associate information with the process itself. This dotted line allows us

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 to associate things like data and information with the process itself and we’ll see some
examples of that soon. The next one is a message flow and this shows how messages go
between one part of the process and another or, indeed, between different processes
themselves. We’ll see some examples of that, too.

Figure 15. Connectors

SEQUENCE FLOW
Figure 16 shows some examples of the use of the connectors. In the first example, we’ve
got one activity following another, using the normal sequence flow connector. In the
second example we’ve got conditions and a default path where the flow will go if none of
the conditions are met.

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 Figure 16. Sequence flow

CONDITIONAL SEQUENCE FLOW

The conditional sequence flow is an alternative to using a gateway. In Figure 17 we
have three paths coming out of an activity, each with a condition on. Depending on the
evaluation of the condition, one of those paths will be followed. Indeed, you could have a
further path, which is that none of those conditions are met. In that case, you would have a
default flow.

Figure 17. Conditional

sequence flow

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 ASSOCIATIONS
We talked earlier about the associations connector. There are a number of things you can
associate with a process. The first one is an annotation, that’s basically a way that you
can comment the process. It adds no logic to the process and it doesn’t affect the way
the process behaves, but it does give you the opportunity to add information to help the
reader make sense of the process you’re defining.

You can also add a data object. For a purchase order, you could use data objects to
indicate that a purchase order has been received, approved, or completely fulfilled. For
a job application process, you may want to indicate that the state of the job application
changes as it goes through the process. It helps the readability of the process by letting
you know what kinds of thing the process is dealing with.

Figure 18. Associations

GROUPS
Groups is a way of surrounding a number of activities within a process or across multiple
processes. If you’re dealing with multiple processes within the same diagram, you can
associate them by lassoing them with the group element. This has no bearing on the
logic of the flow. It simply helps the understanding of the process, helps you categorize
and group activities that can be considered part of the same phase of a project or are
otherwise related to each other.

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Figure 19. Artifacts

The specification also allows you to add your own artifacts to the process modeling
language, while making sure that you’re not clashing with anything that is specified
as part of the core standard. So you could add artifacts to represent a database, an
organizational modeling system, things that add to the information about the process.

POOLS AND LANES

Pools and lanes (or swim lanes, as they are sometimes called) are ways of describing
how a process or processes are organized. They define how different organizations or
different people get involved with the process. By default, each process lives within a
pool, so a number of activities will live in a pool.

Figure 20. Pools and lanes

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 A pool can be split into lanes. You might have a pool that represents the organization and
within that pool you might want to subdivide it into different departments that are involved
within a particular process and show how the different departments interact with each
other. Or you might want to have a swim lane for different individuals that participate in the
process.

In Figure 21 we have an example where a process in one pool is interacting with a process
in another pool. You’ll notice that there are no sequence flows between the pools. The
interaction between processes in different pools is facilitated by the flow of messages
between the different activities in the processes. We’ve got this synchronization between
the two processes where one sends out a message to say I’ve sent this order (and you may
want to annotate that with a data object that says this is an order), and the other process
receives the order and then confirms receipt of the order by sending a message back to
the initiator of the process to say we’ve received the order, we’ll now confirm it, and go on
to fulfill the process.

Figure 21. Interaction between

pools

So it’s a powerful way of describing the interactions between different parties that may be
involved in a global or collaborative process.

LANES
In Figure 22 we’ve got a view of different lanes within the same processor. Here we’ve
got a process that’s contained within one pool and that pool is broken up into different
lanes. In this example we’ve got different groups in the organization: we’ve got the order
management organization performing their tasks and interacting with the manufacturing

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 group. So we’ve received an order, we notify manufacturing that we’ve received this
order, and we can then go and manufacture the goods, and so on. What you’ll notice
here is that the connector between the different pools is a sequence flow, a solid line.
We’re allowed to use that between different lanes within the same pool. The way that
lanes are defined is an aid to understanding the process – how the organization works
within the process, who does what – rather than it affecting the flow itself. That’s why
we’re able to use the sequence flow rather than being restricted to using the message
flow.

Figure 22. Lanes

TRANSACTIONS AND COMPENSATING BEHAVIOR

A transaction is a specialization of an embedded sub-process. In this case, there may be a
number of activities we wish to have performed, but only if all of them are performed and
succeed do we want the process to go to the next step. For example, in a travel planning
process we want to book a flight, but in association with that we also want to book a hotel.
We don’t really want to continue if one of them fails. So, if we can book a hotel, but we
can’t book a flight, we don’t want to continue. In fact, we want to unbook the other activity.
In some cases, the activities themselves will roll back. (If one fails, we will roll back to the
point where the transaction started.) In this case, you can’t undo them automatically,
because they involve manual activities; you have to perform some compensating activity
to undo what was done. If we book a flight, we can’t simply forget it, we have to go and
physically undo the booking of the flight.

In this example we’ve got one of these events that appears on the edge of an activity
that says, if I need to roll back, this is what I do. I associate an activity with that event. The

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 associated activity, in this case, is book a flight. If we need to roll back, because the other
activity failed, I need to cancel the flight. So that gives us a way of undoing things.

Figure 23. Transactions and

compensating behavior

Future of BPMN
What I want to do now is to describe where BPMN is now and what’s going to happen in
the future. The specification that TIBCO Business Studio satisfies is version 1.0. The Object
Management Group has just recently completed the 1.1 version of the specification, which
clarifies some of the ambiguities that may have existed in version 1.0 and adds a few
features I’ll discuss shortly.

The next major step is BPMN 2.0, which will be a combination of BPMN and BPDM, another
Object Management Group specification. As I mentioned earlier, BPMN 1.0 doesn’t have
a description of how you would save a process definition. An XPDL 2 from the WFMC
allows you to do that now, but BPDM is an initiative from the Object Management Group
to provide a mechanism whereby you could persist the process definition that you’ve
drawn within BPMN and exchange it between different product tools, so between maybe a
modeling tool and a process execution engine.

One of the other changes is to the BPMN acronym itself. Although it’s got the same letters,
the words will change to reflect the merging of these two processes. Instead of Business
Process Modeling Notation, it’s Business Processing Model and Notification.

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 This specification is at the beginning of its life and will probably take 18 to 24 months
before it comes out. In that intervening period, we will continue to use BPMN 1.0 and
you’ll see process modeling tools picking up the changes that will be published in 1.1 and
extending their capability.

BPMN 1.1
What have we got coming in BPMN 1.1? Some changes are purely descriptive. Earlier I
talked about the XOR Exclusive Gateway and the All Inclusive Gateway. We’ve dropped
the “XOR” and “All” to make it less of a technical description of the shapes and things that
appear within the process. We’ve also changed the way one of the shapes is represented.
The event-based gateway symbol had a star. Now it has a pentagon.

When we talked about the different events, I mentioned that you could either send a
message or receive a message as part of the process. In BPMN 1.1 we’re able to visually
distinguish between the types of events. If it’s a receive, it’s an empty envelope. If it’s a
send, it’s a full envelope.

We also have a new event type that appears within the specification itself called a signal.
It’s similar to the message event, but the message event, needed something to send to. A
sending message needed to send to something that was going to pick up that message.
A signal is like a broadcast. The process can send out the signal and it doesn’t know
who’s listening to it. If there is something listening to it, they will pick up the signal and
perform whatever needs to be performed following the receipt of that signal. But the
sender doesn’t rely on having a receiver ready and waiting for the signal. Another change
relating to events is that, similar to the gateway, there’s a change of shape from a star to a
pentagon.

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 Summary
BPMN has become almost the de facto standard for representing business processes.
We know of 44 implementations so far, and it’s likely there will be more yet.

BPMN is aimed at both technical and business users. If you cast your mind back to
some of the examples, you could draw a process that didn’t need to have all of the
detail about all the different types of events and activities. You could quite easily
have a very good representation of a process. But if you need the detail, all the
different elements within the language are there for you to add more meaning and
information to it.

Business Studio provides quite a few examples. There are sample processes you
can use as models. You can see how the different process elements are used
and how they relate to each other to give you a good start in defining processes.
There are also process fragments you can use to easily put together a particular
construct, such as a split and a join with some activities in between. You can just
drag those onto the pallet and get your process put together very quickly.

Here are some resources for further information about the BPMN specification.

http://www.omg.org http://bpmn.org http://www.wfmc.org

http://developer.tibco.com http://www.tibco.com/devnet/business_studio/

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