Dynamic Dependencies in Application Service Management

Abstract This paper addresses the role of dependency analysisin distributed management. It introduces the concept ofdependency lifetime that traces the flow of dependencyinformation from the design to installation to runtimestages of a service. Two categories of models, func-tional and structural, are used to represent this infor-mation as it flows from the design to the runtime stages.The paper describes how the dependency informationat each of these stages can be retrieved and evaluatedby management applications and presents an architec-ture to integrate these with existing network manage-ment platforms.Keywords: Dependency Analysis, Application ServiceManagement, Root cause Analysis, Impact Analysis,Problem Determination 1 Introduction The identification of dependencies becomes increas-ingly important in today’s networked environments be-cause applications and services rely on a variety of sup-porting services that might be outsourced to a serviceprovider. Failures occurring in lower service layers af-fect the quality of service of end-to-end services thatare offered to customers. However, service dependen-cies are not made explicit in today’s systems, thus mak-ing the task of problem determination particularly dif-ficult. Solving this problem requires the determinationand computation of dependencies between services andapplications. One, therefore, has to deal with questionssuch as: what are the important characteristics of de-pendencies? In other words, when a managed entity X,such as a service or resource, depends on another man-aged entity Y (X is then termed dependent and Y an-tecedent), what are the propertiesof such a dependencythat need to be recorded? How can we classify depen-dencies such that they can be used more efficiently todo root cause or impact analysis in fault management?The notion of dependencies can be applied at variouslevels of granularity: For example, threads within a run-ning application may be dependent on each other’s op-erational output; a stored procedure within a databasemanagement system may be dependent on a lock ad-ministrator, etc. This paper does not consider such situ-ationsbecause thereis a big differencebetweenapplica-tion management (focusing on application behavior ob-servablefrom“outside”)and application debugging(fo-cusing on the internal behavior of an application). Weconsider only dependencies of the former type, i.e., thatexist between different managed objects or componentsand, hence, are visible from outside an application.The paper is structured as follows: Section 2 analy-ses the requirements on application dependency mod-els by focusing on two typical service provider scenar-ios. It also gives an overview on related work in thisarea and identifies the deficiencies of existing standardsandspecifications. Section3 classifies dependenciesac-cording to criteria that we have identified during ourresearch. The methodology for determining and com-puting dependencies and our resulting architecture arepresented in sections 4 and 5. Section 6 concludes thepaper and presents issues for further research.