Lightning Fast Business Process Simulator

Äriprotsesside juhtimine on teatud hulk järjepidevalt korratavaid tegevusi alustades äriprotsessi analüüsist, millele järgneb modelleerimine, väljaarendamine, elluviimine ning jälgimine. Korrektne äriprotsesside juhtimine on aluseks efektiivsele ning produktiivsele ettevõttele ning võimaldab kiirelt muutuvas keskkonnas kohandada vastavalt ka ettevõtte äriprotsesse. Rutakalt, läbimõtlemata või –proovimata tehtud muudatused ettevõtte töövoo korralduses võivad halvemal juhul lõppeda veel ebaefektiivsemate tulemustega, mis põhjustavad oodatud kasu asemel hoopis kahju. Seetõttu on oluline tehtavaid muudatusi enne reaalset rakendamist põhjalikult analüüsida, mida omakorda saab teha läbi virtuaalse äriprotsesside simuleerimise. Protsesside simuleerimine on laialdaselt levinud metoodika katsetamaks kavandatavaid mudeleid ning analüüsimaks mõju erinevatele ettevõtte tulemuslikkuse näitajatele, mis tuleneb tehtud muudatustest. Käesoleval ajahetkel on olemas erinevaid äriprotsesside simuleerimise rakendusi nii teadusliku kallakuga kui ka kommertslahendusi nagu näiteks IBM Websphere Business Modeler, Savvion Process Modeler ja teised. Osutub aga, et olemasolevad rakendused on tihtipeale väga aeglased, nendega ei saa modelleerida või simuleerida keerukamaid äriprotsesse või need ei tule toime suuremahulisemate simulatsioonidega. Käesoleva magistritöö esimeses osas on räägitud üldiselt äriprotsesside juhtimisest, nende simuleerimisest ning olemasolevast tarkvarast. Seejärel esitletakse täiesti uut lahendust, kuidas ehitada äriprotsesside simulaator, mis toetab ka keerukamaid konstruktsioone äriprotsesside mudelite de facto esitusstandardist BPMN ning on kordi kiirem kui olemasolevad tasuliselt pakutavad simulatsioonitarkvarad. Kolmandas osas kirjeldatakse lähemalt loodud simulaatorit ja selle arhitektuuri ning viimases peatükis võrreldakse saavutatud tulemust eelpool nimetatud olemasolevate äriprotsesside simuleerimisrakendustega ja antakse ülevaade simulaatori jõudlusest üldiselt.Business process management is a discipline to make an organization’s workflow more efficient and more capable of adapting to changes in an ever-changing global environment. Making changes in real-life business processes could lead to undesired results if potential impact of change is not completely analyzed before the changes are applied. Business process simulation is a widely used technique for analyzing business process models with respect to performance metrics such as cycle time, cost and resource utilization before putting them to production. Many commercial state of the art business process modeling tools incorporate a simulation component, e.g. IBM Websphere Business Modeler, Savvion Process Modeler and others. However, these process simulators are often slow, cannot simulate complex real-life business processes and sometimes cannot even deal with large-scale simulations. For example, it is not possible to simulate process models with sub-processes, intermediate events or inclusive merge gateways (Or-joins). The objective is to build a lightning fast business process simulator engine which could also handle advanced constructions in the process models that are used to represent real-life processes. The simulator is designed and implemented from scratch in the Java programming language and it will support the simulation of business process models defined in the BPMN 2.0 standard. This work presents a novel approach to business process simulation field by using the architecture of a scalable and high-performance business process simulation engine. The contribution of this thesis is a set of design principles, architecture supporting simulations of models containing advanced BPMN constructions like loops, sub-processes, intermediate events and Or-joins

A Process Modelling Framework Based on Point Interval Temporal Logic with an Application to Modelling Patient Flows

This thesis considers an application of a temporal theory to describe and model the patient journey in the hospital accident and emergency (A&E) department. The aim is to introduce a generic but dynamic method applied to any setting, including healthcare. Constructing a consistent process model can be instrumental in streamlining healthcare issues. Current process modelling techniques used in healthcare such as flowcharts, unified modelling language activity diagram (UML AD), and business process modelling notation (BPMN) are intuitive and imprecise. They cannot fully capture the complexities of the types of activities and the full extent of temporal constraints to an extent where one could reason about the flows. Formal approaches such as Petri have also been reviewed to investigate their applicability to the healthcare domain to model processes. Additionally, to schedule patient flows, current modelling standards do not offer any formal mechanism, so healthcare relies on critical path method (CPM) and program evaluation review technique (PERT), that also have limitations, i.e. finish-start barrier. It is imperative to specify the temporal constraints between the start and/or end of a process, e.g., the beginning of a process A precedes the start (or end) of a process B. However, these approaches failed to provide us with a mechanism for handling these temporal situations. If provided, a formal representation can assist in effective knowledge representation and quality enhancement concerning a process. Also, it would help in uncovering complexities of a system and assist in modelling it in a consistent way which is not possible with the existing modelling techniques. The above issues are addressed in this thesis by proposing a framework that would provide a knowledge base to model patient flows for accurate representation based on point interval temporal logic (PITL) that treats point and interval as primitives. These objects would constitute the knowledge base for the formal description of a system. With the aid of the inference mechanism of the temporal theory presented here, exhaustive temporal constraints derived from the proposed axiomatic system’ components serves as a knowledge base. The proposed methodological framework would adopt a model-theoretic approach in which a theory is developed and considered as a model while the corresponding instance is considered as its application. Using this approach would assist in identifying core components of the system and their precise operation representing a real-life domain deemed suitable to the process modelling issues specified in this thesis. Thus, I have evaluated the modelling standards for their most-used terminologies and constructs to identify their key components. It will also assist in the generalisation of the critical terms (of process modelling standards) based on their ontology. A set of generalised terms proposed would serve as an enumeration of the theory and subsume the core modelling elements of the process modelling standards. The catalogue presents a knowledge base for the business and healthcare domains, and its components are formally defined (semantics). Furthermore, a resolution theorem-proof is used to show the structural features of the theory (model) to establish it is sound and complete. After establishing that the theory is sound and complete, the next step is to provide the instantiation of the theory. This is achieved by mapping the core components of the theory to their corresponding instances. Additionally, a formal graphical tool termed as point graph (PG) is used to visualise the cases of the proposed axiomatic system. PG facilitates in modelling, and scheduling patient flows and enables analysing existing models for possible inaccuracies and inconsistencies supported by a reasoning mechanism based on PITL. Following that, a transformation is developed to map the core modelling components of the standards into the extended PG (PG*) based on the semantics presented by the axiomatic system. A real-life case (from the King’s College hospital accident and emergency (A&E) department’s trauma patient pathway) is considered to validate the framework. It is divided into three patient flows to depict the journey of a patient with significant trauma, arriving at A&E, undergoing a procedure and subsequently discharged. Their staff relied upon the UML-AD and BPMN to model the patient flows. An evaluation of their representation is presented to show the shortfalls of the modelling standards to model patient flows. The last step is to model these patient flows using the developed approach, which is supported by enhanced reasoning and scheduling