Mapping BPMN process models to data models in ORM. H. Balsters

Transcription

1 Mapping BPMN process models to data models in ORM Process-driven database design H. Balsters September 2013

2 Integrating data and processes (1) Business data is data inside databases Business processes define the workflow dependencies inside an organization

3 Integrating data and processes (2) In organizations, operational environments are increasingly permeated with IT Requirements w.r.t. size and quality of data concerning modern products, services and control, are managed using automatic support In our case, this automatic support is offered by database-driven control systems

4 Integrating data and processes (3) IT (in our case, properly designed databases) can take care of collecting data that can guarantee data quality Business processes drive people and organizations, and use data to function properly

5 Integrating data and processes (4) The actions in processes need decisions based on input data. and (external) constraints The actions also result in output data, at the very least data describing what exactly happened It is often necessary to check that the action was executed correctly: input and output data "match". Separate processes are performed in a certain order, to realize the eventual business process: a workflow Workflow systems and database systems work together to realize the complete business process

6 Integrating processes with data Total Quality Management: Integrating data and processes, understanding, validating, and evaluating complete business processes from beginning to end Process-driven database design: How do we get data in sync with our processes?

7 Things that need fixing Common practice 1: there is a business process (e.g., some manager s flowchart), but no systematic link to a database Common practice 2: there is business data (e.g., some manager s spread sheet), but no systematic link to a business process

8 Process-driven database design Model a business process from the perspective of an end-user of the database Such a business process is called a data-use process (a DUP) Each (data-)stakeholder in the business process has its own DUP Derive a (complete and minimal) data model that fits each DUP

9 How do we synchronize the business process with the business data? BPMN, followed by ORM.. Making Business Process Models using Business Process Modelling Notation (BPMN) Making Business Data Models using Object Role Modeling (ORM) The ORM models are derived from the BPMN/DUP-models

10 ORM/SQL results in the grand finale: the full system database From ORM, we generate complete relational databases (business data) Imperative SQL (stored functions and procedures), e.g., could implement our business processes in terms of high-level database transactions This is how we eventually arrive at the big picture of what enterprise/organization data should/could look like

11 Why BPMN? International standard (OMG: Object Management Group) Process language for Business Applications Large set of process primitives Core subset is easy to read and write Good tooling widely available Maps nicely to ORM (as we shall see later)

12 Our example: The Thermostat Representative of many typical technical (but also business!) processes Airplane flight control: Homeostat Quality control in production process Quality control in administrative organizations Often, large amounts of data Data is highly structured and is heavily tied to constraints All transaction details can be logged (e.g. for auditing/troubleshooting purposes) Hence, by logging, a process trace automatically involves data!

13 Consider as the end user/stakeholder: quality controller of a heating system Consider the kind of questions such a q.c. would want to pose to a database containing information about the heating system We will model the process underlying the heating system (how the system works as far as it is relevant for the q.c.): construct a DUP for the q.c. wrt the heating system Subsequently we will derive the data relevant to that DUP

14 Heating system using a thermostat

15 BPMN-task 1: <Set Temperature> General pattern is: <Verb-phrase present tense Noun-phrase> This yields: ORM-event 1: [Temperature Setting: is logged] General pattern is: [Noun-phrase (Verb-phrase objectified): is logged]

16 We note that we use the word event as it is used in database terminology; i.e., in a CRUD sense In the event [Temperature Setting: is logged], is logged refers to the time stamping of that event A structure of an event is offered by a data model fragment capturing the occurrence of an activity at a certain instant in time

17 We are attempting to find a (minimal) set of fact types offering the data need for an activity inside some business process (cf. Tony Morgan, BBB, 2008)

18 We guide the construction of a data model fragment (in this case pertaining to the event TempSetting, by asking the following (not necessarily complete) set of general fact-type identification questions against the task in question: 1. Which entities are involved in the event as participants? 2. At what instant (timestamp) does the event happen? 3. How do we identify the event? 4. What do we have as input for the event? 5. What do we have as output of the event? (Of course, answering such a set of questions, will -in general- often need the support of domain expert knowledge.)

19 Minimal ORM model underlying this task:

20 The desired ORM-event is realized by the following SQL-instruction: Insert into TempSetting values (tempsettingnr, instant, thermostatnr, targettemperature) applied to the TempSetting table

21 BPMN-task 2: <Measure Temperature>, is associated to ORM-event 2: [Temperature Measurement: is logged] Applying the same fact-type identification method, we obtain the following ORM model fragment

22 We note that we also need a rule (written here in OLE: ORM-Logic driven English [Balsters 2012]) indicating that a temperature measurement event is preceded (in time) by a temperature setting event for each TempSetting, TempMeasurement, Instant1, and Instant2: if that TempMeasurement involves that TempSetting and that TempSetting is at that Instant1 and that TempMeasurement is at that Instant2 then that Instant1<that Instant2.

23 In SQL: Insert into TempMeasurement values (tempmeasurementnr, instant, tempsettingnr, currenttemperature)

24 BPMN-task 3: <Compare temperature>, results in ORM-event 3: [Temperature Comparison: is derived and logged] BPMN-control 1: Query-fork after <Compare Temperature>, results in ORM-event 4: [Temp(erature Comparison results in )OK]

25 Minimal ORM model

26 A temperature value will be called OK, exactly when the measured temperature is equal to or higher than the temperature value that has been set. Otherwise the temperature value is called too low In the case that the temperature value is OK, the system moves on to the next temperature measurement These derivation rules ( written in OLE) are offered by for each TempComparison: that TempComparison results in some TempOK, exactly when the Temperature of the TempMeasurement of that TempComparison is equal to or higher than the Temperature of (the TempSetting of the TempMeasurement of that TempComparison)

27 The database has evolved into:

28 Alternative: Modeling temperature comparison using derivations only* * ackn. to Terry Halpin

29 BPMN-ORM procedure: What have we been doing? 1. Create BPMN-task and specify the associated ORM event 2. Find the minimal model that realizes the desired ORM event using our fact-type identification method 3. Create next BPMN-task 4. Transform that task into a subsequent ORM event 5. Find the minimal extension to the previous ORM model fragment that defines that subsequent ORM event 6. Repeat 1-5 until all events for all data-stakeholders are finished 7. At the end you will have created the complete corporate database, associated to the original business process

30 General rules for transforming BPMN models to ORM models Consider a simple (but generally structured) process model

31 The Start event is transformed into

32 The sequence flow of activity <Do Event1> followed by <Do Event2> is transformed into

33 We note that we also need a rule to indicate that Event2 is preceded (in time) by Event1 (written here in OLE) for each Event1, Event2, Instant1, and Instant2: if that Event1 has successor that Event2 and that Event1 is at that Instant1 and that Event2 is at that Instant2 then that Instant1<that Instant2

34 Activity <Do Event2> is followed by a gateway (in this case an exclusive-or fork) resulting in a divergence of two activities followed by an exclusive gateway, which is transformed into

35 Usually, the two fact types Event2Check results in Event2CheckOK Event2Check results in Event2CheckNot-OK are derived

36 An alternative to modeling temperature comparison using derivations only

37 The exclusive-or gateway results in a divergence of two activities <Do Event3> and <Do Event4>, after which the process stops; this results in the following transformation into an ORM model

38 We also need an extra constraint stating that if Event2 is followed by Event3, then Event3 is followed by some Stop event (and an analogous rule in the case that Event2 is followed by Event4). We can state this (in OLE) as follows for each Event2 and Event3: if that Event2 is followed by that Event3 then that Event3 is followed by some Stop We note that an inclusive-or gateway in the process model (replacing the exclusive-or gateway) would result in deleting the exclusion constraint in the ORM model

39 Remaining work 1.A general mapping of the meta-model of a (yet to-be defined) core of BPMN to the meta-model of FBM 2.This core is to be database-specific Tooling (α-versions complete) 1.BPMN to OLE (interactive dialogue tool) 2.OLE to SQL (compiler)