A Formal Model of Service Delivery

Abstract

We define a service delivery system as a set of interacting entities that are involved in the delivery of one or more business services. A service operating system manages the processes and resources within a service delivery system . This paper develops a formal model for these concepts, with the goal of clearly and precisely describing the delivery behavior of service systems . The model lays the groundwork for reasoning about the scenarios that occur in service delivery. We evaluate the model by capturing the structure and behavior of some realistic service delivery systems – a credit card service, a hospital, an IT problem service and a hotel reception desk — and reason about key performance indicators.

Appendix 1 Summary of Notation

A service delivery system SDS comprises the following elements:

Set of service requests SR

Service process instances $P = \{ {\textrm{p}}_{\textrm{1}} ,\;{\textrm{p}}_2 ,\; \ldots ,{\textrm{ p}}_{\textrm{n}} \}$

Set of process states ${\textrm{SS}} = \{ {\textrm{S}}_{\textrm{0}} ,\;{\textrm{S}}_{\textrm{1}} ,\; \ldots ,\;{\textrm{S}}_{\textrm{N}} \}$.

Initial states IS⊂SS , final states FS⊂SS

Capability types ${\textrm{CT}} = \{ {\textrm{C}}_{\textrm{0}} ,\;{\textrm{C}}_{\textrm{1}} ,\; \ldots ,\;{\textrm{C}}_{\textrm{M}} \}$

Minimum capability vector to process state S MCV(S)

Ideal capability vector to process state S ICV(S)

Set of all resources in SDS at time t ℜ(t)

Resource capability vector of a resource R RCV(R)

Access-credentials of an external resource ER AC(ER) = (&ER, CS(ER), OP(ER), CFT(ER)).

Reference to external resource ER &ER

Set of states which can access ER CS(ER)

Operations invokable on ER OP(ER)

Certificate providing access to ER CFT(ER)

Probability distribution function of the time to transition state S with capability vector ${\mathrm{\xi }}\,{\mathrm{\omega }}_{\textrm{T}} ({\textrm{S,}}\;{\mathrm{\xi , t}})$

Cumulative distribution function of the time to transition state S with capability vector ${\mathrm{\xi }}\,{\mathrm{\tau }}_{\textrm{T}} ({\textrm{S,}}\;{\mathrm{\xi , t}})$

Cost of using resource R for one time unit C(R)

Cumulative distribution function of the cost to transition state S with capability vector ${\mathrm{\xi }}\,{\mathrm{\tau }}_{\textrm{C}} ({\textrm{S,}}\;{\mathrm{\xi , t}})$

Client value CV, Provider value PV

Initial client value ICV, initial provider value IPV

Client value appreciation CVA, provider value appreciation PVA

Dispatcher algorithm DA

Appendix 2 Details of Hotel Example

Table 4

Table 5