How to model with EPC

What is EPC

EPC is a process modeling method, the full name is Event-driven process Chain. In the early 90 's only by Keller and other people proposed. For EPC, domestic developers are unfamiliar, and many people may have heard of EPC "01" and have only been contacted in the framework of ARIS (architecture of integrated information System). EPC may be unfamiliar to many people, but SAP R3 may be more or less heard by many people, and SAP R3 is based on EPC process modeling.

A period of time ago, the company received a logistics project, which has a subsystem is to do WMS (Warehouse management System), mainly processing items in storage, out of the library, inventory process management. After I look at the requirements of this WMS subsystem, the first idea in my mind is that EPC should be used to model abstractions for business scenarios such as process and document status that need to be handled internally. Unfortunately, this is just a thought in mind, in reality, it is impossible to implement this project. (This is distressing, but the implementation of many projects in the country is very manageable and it is difficult to listen to the views of developers). When he returned home, he turned over the information about EPC that he had previously plundered. Here are two documents to mention here:

The first one is the SAP sap Business blueprint:understanding Enterprise Supply Chain Management "02", which contains a section devoted to the elements of EPC modeling, and in subsequent chapters, A lot of illustrations explain how to build business processes with EPC process.

The book focuses on four main elements of EPC: events, Functions (function), organizational units (orgnization unit), Information (data) (in fact, the two elements of OUs and data are in the Aris System framework). Because the purpose of this book is mainly in business interpretation, so for these elements to explain the lack of conceptualization, formalization. But after reading, use the EPC legend to draw the business process diagram, it is not much difficulty to estimate.

Let's take a look at an example that will deepen the understanding of the process model built by EPC: The following illustration shows a process for receiving and processing goods.

The second is the "formalization and verification of Event-driven Process chains" written by master Alast "04". Alast is an expert in the field of Petri net, and this document is still not out of the PN perspective. This document explains several elements of EPC from the "process" perspective:

functions:a function corresponds to a activity (task, process Step) abound needs to be executed. Events:events describe the situation unreported and/or after a function is executed. Functions are linked by events. An event may correspond to the postcondition of one function and act as a precondition of another function. Logical connectors:connectors can be used to connect activities and events. This way the ' control ' is specified. There are three types of Connectors:and, XOR (exclusive OR) and OR

Another important part of this article is the alast of EPC to Petrinet, but not the mapping of or logical connectors because the semantics of or are not very clear, as explained in the Alast document.

An EPC event can be mapped to a library (place) in PN, and a function can be mapped to a change in pn (transitions). As for the mapping of logical connectors and and XOR with place control, it is easy to say:

Lack of domestic EPC application

See here, we estimate that the EPC process model can have a basic understanding. Because this article is not about EPC, but just want to explain: EPC in business modeling for us to provide a good reference, but the domestic currently based on the EPC model of the process products or business products almost no. There are only a few of the information on the Web searching for Chinese EPC, and it is mainly due to the explanation of the Aris framework.

It's not that EPC is a panacea, in fact EPC is only one of the process modeling. Several process models such as petrinet, EPC, Activity Diagram, FSM, etc., and if possible, the XPDL definition meta model.

However, the domestic work flow related products and application development, affected by the WfMC XPDL deeply.

On the one hand because the domestic theoretical research is too weak and pale, some researchers may have noticed the above process modeling methods, but because these process modeling methods do not form a complete formal description language support (in fact, there are some, such as based on PN PNML, based on EPC EPML, etc. , but these XML descriptive languages are too theoretical and not as biased as XPDL, so it's hard to be directly understood by some developers.

On the other hand, the main areas of domestic workflow applications in recent years are still OA and related approval process. In such a "user-oriented autonomous behavior control" process Application field, XPDL elaborated process meta Model objects: process, activity, transitions, participant has been basically able to describe a complete process. After a complete description of a process, most vendors focus on: (1) Enriching the process definition by extending the attributes, and (2) supporting some user actions such as return, free flow, etc. by perfecting the engine's function.

But few manufacturers really reflect on it, XPDL process modeling must be perfect? Is it appropriate? One of the biggest drawbacks for XPDL is the lack of a description of State and event (which has been partially incorporated into the event concept in XPDL2.0).

For other process modeling petrinet, EPC, Activity Diagram and FSM, state is a core element:

In these process modeling methods, EPC is the most emphasis on the business process. But domestic applications are blank.

As far as I know, there are already two or three domestic manufacturers have adopted petrinet as a process description model, Osworkflow and jbpm the application of the two open Source engine, has also made some manufacturers unknowingly adopted the FSM and activity diagram model. Only EPC is not applied (except, of course, those with SAP R3).

I remember in 2001, I also developed a RiseOffice5.0 document process system in a broad company that used task and action objects, some like FSM state and action. However, now has a broad new version of the Riseoffice Workflow system, has adopted a XPDL model. In fact, this is also a development trend of many domestic manufacturers: Although not understand "process modeling", but know that XPDL can describe the process.

In fact, the abstract model of EPC is suitable for commercial business processes such as business-to-business, supply chain process management, warehousing and logistics management. This kind of business process has a very common characteristics, for "activity processing before and after state" very care. Once the state is grasped, the life cycle control and business rule control of the business object can be enriched according to the state, which is more important in the business system of two points.

In comparison, the XPDL model only describes the "connection between activities and activities", it is difficult to see clearly the state and change relationship between activities in the model angle.

But few developers or developers are thinking about the problem: activity and status. XPDL, while shielding the idea of "state", but because it is currently the most "perfect XML descriptive Process language" (of course, we do not talk about BPEL, BPML, such as specifications), for developers, only to consider following the specification and extension, you can basically clearly describe a "process", While it is not possible to express the state problems of various sections of the process, it is possible to clearly show the "relationship between activities".

More, the domestic process development, these years mainly rely on office automation and approval flow, plus the domestic application emphasis on the "discrete activity point of the combination of relations", that is, in many customers eyes: The process is a discrete task, these tasks in different situations can be very arbitrary combination. And such demand is the basic description of the activity and transitions that XPDL relies on. Plus WFMC is a more than 10-year international Standards Organization, for customers, developers, such organizations and standards, are relatively easy to accept.

And epc,petrinet,fsm,activity diagram is very fragile, there is no international organization support, not perfect description language support. Most of all, in the XPDL model, there is almost no shadow of any of these four models, and it seems that WfMC are deliberately avoiding these modeling ideas.

The domestic business modeling process should absorb the EPC modeling method, especially in the business system, such as business-to-business, supply chain process management, warehousing logistics management and other commercial process systems. Of course, such a cost is relatively high, the need to base on these model elements and ideas, independent exploration of a complete set of descriptive language. In fact, the success of SAP R3 is worthy of reference.

The following warehouse management system in a warehousing process in the "Warehousing order Processing" with the EPC model, as follows: