# Enabling Role-Based Orchestration for Cloud Applications
## 4 Experimental Evaluation
### TOSCA Model Conversion Cost
To the best knowledge of the authors, we are the first to explore the possibility of the integration of two prominent orchestration technologies of TOSCA and OAM. Another noteworthy effort is a layering approach where cloud management solutions at the bottom like CAMP and OCCI are exploited to deploy and orchestrate TOSCA application models at the top [29; 30; 22; 31]. CAMP is a standardization effort at Platform-as-a-Service(PaaS) layer [32], while OCCI can be viewed as an IaaS-layer equivalent. A framework proposed by [PERSON] et al. [30] introduced a model-driven cloud orchestration scheme based on TOSCA and OCCI. OCCI provides the standardization of common APIs for Infrastructure-as-a-Service (IaaS) providers, while TOSCA focuses on defining application topology and their orchestrations. TOSCAMP architecture was also proposed by [PERSON] et al. [31], which explored the possibility for orchestrating cloud applications through an integration of TOSCA and CAMP. Trans-cloud system [22] is similar to TOSCAMP in that it supports cross-cloud management and orchestration by combining two OASIS standards of TOSCA and CAMP. However, a difference lies in the fact that Trans-cloud proposal provides unified orchestration support for both IaaS and PaaS services. It is also noted that the Trans-cloud system is extended to a fault-aware orchestration scheme [29] by which failures of application components can be automatically recovered thanks to the knowledge of the application topology and inter-dependencies among the components. After transforming TOSCA Service Templates into either OCCI or CAMP deployment configurations by a model translator, OCCI- or CAMP-compatible runtime fulfills the deployment and management of the applications. However, without support for orchestration modeling at a proper abstraction level, it would be too complicated and time-consuming for application builders to perform their orchestration tasks. Our proposed method introduces a capability layer over IaaS or PaaS resources to enable a role-aware orchestration framework that hides irrelevant details of capability configurations. As an open-source cloud orchestration framework, Cloudify introduces a domain-specific language based on TOSCA [33]. Cloudify aims to define and deploy application templates that declare the configuration and interaction of cloud services, regardless of cloud infrastructure providers. In addition, Cloudify provides a Kubernetes plugin to interact with the Kubernetes cluster. It describes the configuration and the entire life cycle of containerized applications in the form of Kubernetes API at a low-level infrastructure layer [34]. By contrast, to save users from a burden of repetitive configuration specifics, our approach allows for model applications based on platform capabilities instead of infrastructure or underlying platform resources. KubeVela is an emerging cloud platform engine based on Kubernetes and Open Application Model [35]. As a runtime implementation conforming to the OAM specification, it is designed to pursue consistent application delivery across clouds and on-premise infrastructures using Kubernetes as a common abstraction layer. KubeVela serves as an application platform that assists platform builders in constructing DevOps platforms rather than a cloud application orchestration system. It is different from our approach in that we leverage the capability of TOSCA to build an orchestration framework equipped with several features that are not supported by KubeVela, such as application topology, component interface, and workflow definition. Different container platforms are also considered for TOSCA-based orchestration of cloud applications. For instance, a TOSCA orchestration system is built over container clusters running on Mesos [36]. An orchestration system can be built up by augmenting native container runtimes and/or by exploiting accompanying container orchestration features.