=Paper=
{{Paper
|id=Vol-1789/bpm-demo-2016-paper6
|storemode=property
|title=Enabling Batch Processing in BPMN Processes
|pdfUrl=https://ceur-ws.org/Vol-1789/bpm-demo-2016-paper6.pdf
|volume=Vol-1789
|authors=Luise Pufahl,Mathias Weske
|dblpUrl=https://dblp.org/rec/conf/bpm/PufahlW16a
}}
==Enabling Batch Processing in BPMN Processes==
https://ceur-ws.org/Vol-1789/bpm-demo-2016-paper6.pdf
Enabling Batch Processing in BPMN Processes
Luise Pufahl and Mathias Weske
Hasso Plattner Institute at the University of Potsdam, Germany
{Luise.Pufahl,Mathias.Weske}@hpi.uni-potsdam.de
Abstract. Business process automation improves organizations’ efficiency to
perform work. Single executions of process models, called process instances, are
usually executed independently in business process management systems (BPMS).
In practice, we can observe examples in which a synchronized execution of groups
of instances for certain activities, called batch processing, can lead to an improved
performance. Batch regions is a concept to allow batch processing in business
processes. This demo presents the implementation of the batch region concept in
an open-source BPMN engine. It shows how, with a few extensions only, batch
processing is enabled and how the consolidated view of several work items in one
user form, leads to an improved work efficiency for users.
Keywords: Batch Processing, Process Enactment, BPMN
1 Introduction
Business process automation improves organizations’ efficiency to perform work. There-
fore, processes are often captured in process models, typically in BPMN (Business
Process Modeling and Notation) [2] diagrams, the industry standard. These are then exe-
cuted by a BPMS (e.g., Bizagi [1], Camunda [3], Signavio Workflow [8]). An executing
instance of a process model is called process instance. Multiple process instances might
run simultaneously in a BPMS. However, as Russell et al. [7] observe, “each of1 these
Page of 1 is
assumed to have an independent existence and they typically execute without reference
to each other.”
accepted = true
Check order Pack order Ship order Archive order
order received
accepted = false
order rejected
Fig. 1. Simplified online retailer process shown in a BPMN diagram.
In practice, we can observe different cases where the synchronized execution of
several instances is beneficial and can improve process performance. For example, Fig. 1
shows the simplified version of an online retailer process as BPMN diagram in which
Copyright c 2016 for this paper by its authors. Copying permitted for private and academic
purposes.
Enabling Batch Processing in BPMN Processes 29
customer orders are handled. Often, online retailers do not charge any transport cost with
the effect that customers place multiple orders in relatively short time frames. In such
situation, several orders of the same customer could be packed and shipped together to
save shipment costs. This approach, called batch processing, allows business processes
which usually act on a single item, to bundle the execution of a group of process instances
for certain activities in order to improve performance. Other examples which benefit from
batch processing, we can observe in health care, e.g. collecting a set of blood samples
for delivery to the laboratory, in insurance and finance, e.g. consolidating several letters
to one customer and send them as one mail, and in administration, e.g. collecting several
invoices for their approval. Usually these examples are already executed in a batch, but
manually with the risk that batch processing rules might not be clear for everyone or
might be ignored. Recent research approaches [4–6] provide means to integrate batch
processing in business processes models and its automatic execution. In contrast to the
others, the batch region concept in [6] allows an individual batch configuration based on
which instances are batched with similar data characteristics over a number of activities.
In this demo, we want to show an implementation of the batch region concept for BPMN
processes in the open-source BPM platform Camunda [3]. Next, Section 2 introduce
the batch region concept for BPMN processes; Section 3 presents the implementation
details. We conclude in Section 4.
2 Batch Region Concept in BPMN - Design and Execution
Fig. 2. Online retailer process with a batch region to save shipping costs.
A batch region in a BPMN process diagram is a special type of sub-process enabling
batch processing for its activities. Fig. 2 shows the online retailer process with a batch
region surrounding the activities Pack order and Ship order. With its configuration
parameters (visualized in the right panel of Fig. 2), the process designer is able to
specify the conditions for the batch execution. Those are (1) a grouping characteristic
to cluster process instances to be processed in one batch based on data attributes (e.g.,
the custName and custAdress to identify similar order instances in our retailer
example), (2) an activation rule to determine when a batch is activated while balancing
30 Pufahl and Weske
between waiting time and costs savings (e.g., when at least two similar order instances
are available or a timeout of one hour is reached specified in a threshold rule), and (3)
the maximum batch size indicating the maximum number of instances in a batch (e.g.,
at maximum three orders fit in one parcel). In a batch region, XOR gateways are not
allowed because decisions are usually taken on individual items, but not on a item group.
Further, we require that only one start event in a batch region so that the activation of a
batch cluster is uniquely determined.
Each execution of the batch region is represented by a batch cluster. It collects
a number of sub-process instances for batch execution whereby these are assigned
based on their data values. For example, only instances with custName = John and
custAddress = M adrid are assigned to the cluster John Madrid. A batch cluster
has different life cycle states shown in Fig. 3. When the first batch region activity
is enabled, a sub-process instance gets assigned to an existing or new batch cluster.
It is checked whether a cluster is available with the same data characteristics that is
in the init or ready state. If not, a new cluster is created in the initial state init. If the
activation rule is fulfilled, it transitions into the ready state.In this state, a batch work item
including data of all instances is provided to
maxloaded
the task performer. In the ready state, further
instances can be still assigned to it to achieve
init ready running terminated
an optimal cluster utilization. In this state,
the cluster can transition into the maxloaded Fig. 3. Life cycle of a batch cluster
state, if its maximum batch size is reached, or into the running state, if the task performer
begins the work item execution. In these two states, no further instances can be added.
The cluster stays in the running state for all further activities in the sub-process. With
termination of the last batch work item, it changes into the terminated state. Now, the
instances are again independent from each other. After this short introduction into batch
region design and its execution semantics, the next section describes our extensions of
an open-source BPMN engine to enable batch processing.
3 Tool Architecture and Implementation
For the implementation2 of the presented batch region concept, Camunda [3] was
selected, a Java-based, open source engine specifically tailored for a subset of BPMN.
First, we integrated batch region concept in the BPMN XML specification by utilizing
extension elements, which the BPMN specification [2] explicitly supports to add new
attributes and properties to existing constructs. The extension was added to the sub-
process element describing the batch region configuration. Based on it, the Camunda
modeler bpmn.io was adapted to enable a quick design of batch regions. Specifically, the
sub-process element was extended as shown in Fig. 1.
The Camunda engine was extended by only four additional classes: The batch
region class stores the configurations of each identified batch region and manages the
assignment of process instances to a batch cluster. The batch cluster class governs the
batch execution for its assigned group of process instances. The batch behavior class
2
A link to repository of the implementation and a screen cast are available at http://bpt.
hpi.uni-potsdam.de/Public/BatchProcessing.
Enabling Batch Processing in BPMN Processes 31
includes the internal behavior of the activities in a batch region sub-process. In the
Camunda engine, every process activity gets a task behavior (e.g., user task, service
task) assigned, describing the internal activity behavior. In order to reuse these behaviors
and limit the engine extension, the batch behavior inherits the normal task behavior and
has additional methods for the batch execution defined in an interface. This is driven by
the idea that one of the cluster instances leads the batch execution by first merging the
data of all cluster instances and then executing the usual task behavior. Currently, this
is implemented only for user tasks, but can easily applied to other task types. Further,
a batch timer job class was added to enable the time-out defined in the threshold rule.
Additionally, the BPMN parser was adapted to read batch regions’ specifications and to
assign every batch region activity its batch behavior.
)
taskManager execution2
execution1
execution3 userTaskBatchBehavior batchRegion w( batchCluster
ne
execute(exec) assignToCluster(exec) addInstance(exec)
execute(exec) assignToCluster(exec) checkActivationRule()
addInstance(exec)
checkActRule()
composite(executions, batchExec) checkActivationRule()
executeBA(batchExec) checkActRule()
createTask(exec) super: execute(exec)
execute(exec) assignToCluster(exec) addInstance(exec)
addNewInstance(exec,batchExec)
signal()
leaveActivity() super: signal()
Fig. 4. Sequence diagram visualizing the interaction between added classes batch behavior, batch
region, and batch cluster to the Camunda engine.
For the example of the UserTaskBatchBehavior, the interaction of the batch behavior
with the batch region and the batch cluster class is shown in Fig. 4. As soon as an
Execution object representing a process instance enables an activity with a batch behavior,
it is added by the batch region to a cluster. If no batch cluster is currently available, it
is first created and then the add()-method of the cluster is called in which also the
activation rule is checked. Currently, our implementation supports the threshold rule.
With its fulfillment, the cluster calls the composite()-method of the batch behavior
merging the data of all instances. In case of the user task, a JSON variable with all
instance data is created. This can be later reused during the user form design. Then, the
executeBA()-method is called in which the batch behavior calls the execute()-
method of its super class. Now, the normal user task behavior is executed in which a
work item for the task performer is created. Fig. 5 shows the batch work item for the
Ship order activity of the retailer example. We have used the JSON variable to visualize
all orders in a table. The task performer can easily inspect all orders and has to enter the
value for the logistics provider only once, as it is valid for all orders. Instead of three
work items, the task performer has to process only one, leading to time and cost savings.
Our implementation provides also the feature to add new instances, while the first
batch region activity is not completed, yet. The corresponding addNewInstances()-
method simply adapts the JSON variable. With completion of a batch work item, the
32 Pufahl and Weske
Fig. 5. Batch work item for the Ship order activity of the online retailer example.
task manager calls the signal()-method of the batch behavior distributing new added
data (e.g., the logistics provider in Fig. 5) to all other cluster instances. Finally, with the
last batch work item, also the batch cluster is terminated. The implementation shows that
only small extensions on a BPMS are necessary, which also have no significant influence
on the engine performance, to enable batch processing.
4 Conclusion
Real-world examples show the necessity of batch processing in business processes. In
this paper, the batch region concept was implemented in an existing BPMS to realize
batch processing for BPMN processes. Only small extensions are necessary to adapt the
BPMN engine having also no significant impact on the engine performance. The demo
shows that batch processing has the advantage that task performers can handle several
items consolidated in one user form improving their work efficiency.
References
1. Bizagi: Bizagi Business Platform. http://www.bizagi.com/
2. OMG: Business Process Model and Notation (BPMN), Version 2.0 (2011)
3. Camunda: Camunda open-source BPM Platform. https://www.camunda.org/
4. Liu, J., & Hu, J.: Dynamic batch processing in workflows: Model and implementation. In:
Future Generation Computer Systems, 23(3), pp. 338-347. Elsevier (2007).
5. Natschläger, C., Bögl, A., Geist, V., & Biró, M.: Optimizing Resource Utilization by Com-
bining Activities Across Process Instances. In: Systems, Software and Services Process
Improvement, pp. 155-167. Springer (2015).
6. Pufahl, L., Meyer, A., and Weske, M.: Batch regions: process instance synchronization based
on data. In: EDOC, 2014 IEEE 18th International, pp. 150-159. IEEE, (2014).
Enabling Batch Processing in BPMN Processes 33
7. Russell, N., Ter Hofstede, A. H., Edmond, D., & van der Aalst, W. M.: Workflow data patterns:
Identification, representation and tool support. In: Conceptual Modeling-ER 2005. LNCS, vol.
3716, pp. 353-368. Springer (2005).
8. Signavio Workflow https://workflow.signavio.com/