The complex business applications are increasingly offered as services over the Internet, so-called software-as-a-Service (SaaS) applications. The SAP Netweaver Cloud offers an OSGI-based open platform, which enables multi-tenant SaaS applications to run in the cloud. A multi-tenant SaaS application is designed so that an application instance is used by several customers and their users. As different customers have different requirements for functionality and quality of the application, the application instance must be configurable. Therefore, it must be able to add new configurations into a multi-tenant SaaS application at run-time. In this thesis, we proposed concepts of a configuration management, which are used for managing and creating client configurations of cloud applications. The concepts are implemented in a tool that is based on Eclipse and extended feature models. In addition, we evaluate our concepts and the applicability of the developed solution in the SAP Netwaver Cloud by using a cloud application as a concrete case example.

The complex business applications are increasingly offered as services over the Internet, so-called software-as-a-Service (SaaS) applications. The SAP Netweaver Cloud offers an OSGI-based open platform, which enables multi-tenant SaaS applications to run in the cloud. A multi-tenant SaaS application is designed so that an application instance is used by several customers and their users. As different customers have different requirements for functionality and quality of the application, the application instance must be configurable. Therefore, it must be able to add new configurations into a multi-tenant SaaS application at run-time. In this thesis, we proposed concepts of a configuration management, which are used for managing and creating client configurations of cloud applications. The concepts are implemented in a tool that is based on Eclipse and extended feature models. In addition, we evaluate our concepts and the applicability of the developed solution in the SAP Netwaver Cloud by using a cloud application as a concrete case example.:List of Figures i List of Tables iii 1 Introduction 1 1.1 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2 The Structure of This Document . . . . . . . . . . . . . . . . . 2 2 Background 5 2.1 Cloud Computing . . . . . . . . . . . . . . . . . . . . . . . . . . 5 2.2 Software Product Line Engineering . . . . . . . . . . . . . . . . 7 2.3 Role Based Access Control . . . . . . . . . . . . . . . . . . . . . 10 2.4 Staged Con guration . . . . . . . . . . . . . . . . . . . . . . . . 12 2.5 Work ow Modeling . . . . . . . . . . . . . . . . . . . . . . . . . 14 2.5.1 Concept . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 2.5.2 Work ow Modeling Languages . . . . . . . . . . . . . . . 16 2.5.3 Adaptive Work ow . . . . . . . . . . . . . . . . . . . . . 17 2.5.4 Adaptation Patterns . . . . . . . . . . . . . . . . . . . . 17 2.6 Graph Transformation . . . . . . . . . . . . . . . . . . . . . . . 18 2.7 Related Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 3 Analysis 23 3.1 Illustrative Example . . . . . . . . . . . . . . . . . . . . . . . . 23 3.1.1 Domain and Exiting Platform . . . . . . . . . . . . . . . 24 3.1.2 Yard Management System as a SaaS Application . . . . 28 3.2 Requirements Identi cation . . . . . . . . . . . . . . . . . . . . 28 4 Concept 31 4.1 Con guration Management Speci cation . . . . . . . . . . . . . 31 4.1.1 Variability Modeling . . . . . . . . . . . . . . . . . . . . 32 4.1.2 Stakeholder Views Modeling . . . . . . . . . . . . . . . . 34 4.1.3 Con guration Work ow Modeling . . . . . . . . . . . . . 36 4.2 Con guration Work ow Adaptations . . . . . . . . . . . . . . . 41 4.3 Mapping between Problem Space and Solution Space . . . . . . 47 4.4 Con guration Process Simulation . . . . . . . . . . . . . . . . . 50 5 Implementation 53 5.1 Con guration Speci cation . . . . . . . . . . . . . . . . . . . . . 54 5.1.1 Extended Feature Model Speci cation . . . . . . . . . . 55 5.1.2 View Model Speci cation . . . . . . . . . . . . . . . . . . 56 5.1.3 Con guration Work ow Model Speci cation . . . . . . . 57 5.2 Graph Transformation Rules . . . . . . . . . . . . . . . . . . . . 62 5.3 Mapping Realization . . . . . . . . . . . . . . . . . . . . . . . . 65 5.4 Con guration Management Tooling . . . . . . . . . . . . . . . . 67 5.5 Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 6 Conclusions and Future Work 77 6.1 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 6.2 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78 Bibliography i

A recent trend in software industry is to provide enterprise applications in the cloud that are accessible everywhere and on any device. As the market is highly competitive, customer orientation plays an important role. Companies therefore start providing applications as a service, which are directly configurable by customers in an online self-service portal. However, customer configurations are usually deployed in separated application instances. Thus, each instance is provisioned manually and must be maintained separately. Due to the induced redundancy in software and hardware components, resources are not optimally utilized. A multi-tenant aware application architecture eliminates redundancy, as a single application instance serves multiple customers renting the application. The combination of a configuration self-service portal with a multi-tenant aware application architecture allows serving customers just-in-time by automating the deployment process. Furthermore, self-service portals improve application scalability in terms of functionality, as customers can adapt application configurations on themselves according to their changing demands. However, the configurability of current multi-tenant aware applications is rather limited. Solutions implementing variability are mainly developed for a single business case and cannot be directly transferred to other application scenarios. The goal of this thesis is to provide a generic framework for handling application variability, automating configuration and reconfiguration processes essential for self-service portals, while exploiting the advantages of multi-tenancy. A promising solution to achieve this goal is the application of software product line methods. In software product line research, feature models are in wide use to express variability of software intense systems on an abstract level, as features are a common notion in software engineering and prominent in matching customer requirements against product functionality. This thesis introduces a framework for feature-based configuration management of reconfigurable cloud applications. The contribution is three-fold. First, a development strategy for flexible multi-tenant aware applications is proposed, capable of integrating customer configurations at application runtime. Second, a generic method for defining concern-specific configuration perspectives is contributed. Perspectives can be tailored for certain application scopes and facilitate the handling of numerous configuration options. Third, a novel method is proposed to model and automate structured configuration processes that adapt to varying stakeholders and reduce configuration redundancies. Therefore, configuration processes are modeled as workflows and adapted by applying rewrite rules triggered by stakeholder events. The applicability of the proposed concepts is evaluated in different case studies in the industrial and academic context. Summarizing, the introduced framework for feature-based configuration management is a foundation for automating configuration and reconfiguration processes of multi-tenant aware cloud applications, while enabling application scalability in terms of functionality.

A recent trend in software industry is to provide enterprise applications in the cloud that are accessible everywhere and on any device. As the market is highly competitive, customer orientation plays an important role. Companies therefore start providing applications as a service, which are directly configurable by customers in an online self-service portal. However, customer configurations are usually deployed in separated application instances. Thus, each instance is provisioned manually and must be maintained separately. Due to the induced redundancy in software and hardware components, resources are not optimally utilized. A multi-tenant aware application architecture eliminates redundancy, as a single application instance serves multiple customers renting the application. The combination of a configuration self-service portal with a multi-tenant aware application architecture allows serving customers just-in-time by automating the deployment process. Furthermore, self-service portals improve application scalability in terms of functionality, as customers can adapt application configurations on themselves according to their changing demands. However, the configurability of current multi-tenant aware applications is rather limited. Solutions implementing variability are mainly developed for a single business case and cannot be directly transferred to other application scenarios. The goal of this thesis is to provide a generic framework for handling application variability, automating configuration and reconfiguration processes essential for self-service portals, while exploiting the advantages of multi-tenancy. A promising solution to achieve this goal is the application of software product line methods. In software product line research, feature models are in wide use to express variability of software intense systems on an abstract level, as features are a common notion in software engineering and prominent in matching customer requirements against product functionality. This thesis introduces a framework for feature-based configuration management of reconfigurable cloud applications. The contribution is three-fold. First, a development strategy for flexible multi-tenant aware applications is proposed, capable of integrating customer configurations at application runtime. Second, a generic method for defining concern-specific configuration perspectives is contributed. Perspectives can be tailored for certain application scopes and facilitate the handling of numerous configuration options. Third, a novel method is proposed to model and automate structured configuration processes that adapt to varying stakeholders and reduce configuration redundancies. Therefore, configuration processes are modeled as workflows and adapted by applying rewrite rules triggered by stakeholder events. The applicability of the proposed concepts is evaluated in different case studies in the industrial and academic context. Summarizing, the introduced framework for feature-based configuration management is a foundation for automating configuration and reconfiguration processes of multi-tenant aware cloud applications, while enabling application scalability in terms of functionality.