Quantitative Analysis of Enterprise Architectures Maria-Eugenia Iacob and Henk Jonkers Telematica Instituut, P.O. Box 589, 7500 AN Enschede, the Netherlands E-mail: {MariaEugenia.Iacob, Henk.Jonkers}@telin.nl Abstract. Enterprise architecture is concerned with a description of all the relevant elements that make up an enterprise and how these elements inter-relate. It covers aspects ranging from the technical infrastructure, through software applications, to business processes and products. The relations between these layers play a central role. Also from a quanti- tative analysis perspective, the layers are interrelated: the higher layers impose a workload on the lower layers, while the performance charac- teristics of the lower layers directly influence the performance of the higher layers. This paper presents an approach for quantitative analysis of layered, service-based enterprise architecture models, which consists of two phases: a ‘top-down’ propagation of workload parameters, and a ‘bottom-up’ propagation of performance or cost measures. By means of an example we demonstrate the application of the approach, and show that a seamless integration with other performance analysis methods (e.g., queueing analysis) can be achieved. 1 Introduction An enterprise can be viewed as a complex ‘system’ consisting of multiple domains that influence each other. Architectures are used to describe components, their relations and underlying design principles of a system [10]. Constructing archi- tectures for an enterprise may help to, among others, increase the insight and overview required to successfully align the business and ICT. Although the value of architecture has been recognised by many organisations, mostly architectures for various organisational domains, such as business processes, applications, in- formation and technical infrastructure, are developed in isolation. The relations between these architectures often remain unspecified. Enterprise architecture is a discipline that focuses on making these relations explicit. The term refers to a description of all the relevant elements that make up an enterprise and how those elements interrelate. Models play an important role in all approaches to enterprise architecture. Models are well suited to express the interrelations among the different elements of an enterprise and, especially when visualised in different ways, they can help to reduce the language barriers between domains. However, currently they strongly focus on functional aspects. In contrast to detailed design models within domains, the quantitative as- pects of such enterprise architecture models have hardly received any attention