cloud SOA A Cloud interoperability framework and platform for user-centric, semantically-enhanced, service-oriented application design, deployment and distributed execution Research Guide www.cloud4soa.eu
Content PaaS and its Interoperable Potential 2 Cloud4SOA Project Overview 4 Cloud4SOA Reference Architecture 6 Core Capabilities 8 Matchmaking 8 Management 8 Monitoring 9 Migration 9 Scientific and Technological Achievements 10 Intelligent Dashboard Interface 10 SOA Principles 11 Cloud4SOA Semantic Model 12 Business Application Governance and SLA Management 13 Harmonized API and Platform Adapters 14 How to Join the Cloud4SOA Ecosystem 15 Contact Info 16 PaaS and its Interoperable Potential Cloud Platform as a Service (PaaS) is a novel, rapidly growing segment in the Cloud computing market, that enables software developers to create (develop or integrate), deploy, execute, and manage business applications, using a service provided by a third party. However, the diversity and heterogeneity of today s existing PaaS offerings raises several interoperability challenges and makes it difficult for software developers to identify the platform that best fits their needs. Furthermore, the actual PaaS market segment is still quite young, chaotic and highly fragmented, dominated by a few providers which use and promote incompatible standards and formats. This introduces adoption barriers due to the lock-in issues that prevent the portability of data and software from one PaaS to another, locking software developers to the first provider they use. Developers indeed require more flexibility. They do not only need to deploy applications into a specific Cloud platform, but also to migrate applications from one platform to another, as well as to distribute related applications across multiple PaaS. Even on the vendor side, the very same lock-in is greatly limiting the entry of new PaaS providers with innovative offerings, due to the high switching costs that their competition s customers have before them. The current state of the PaaS landscape is therefore far from a global arena open to every player. Reducing the interoperability and portability barriers between different vendors constitutes an important step for realizing the potential of an open market global vision for Cloud computing and their platforms. This is the target of the Cloud4SOA European research project.
An opportunity for European software developers and PaaS providers Cloud4SOA s objectives helps stimulate a Cloud application development market that brings significant opportunity to European software companies with their own internal development, as well as Independent Software Vendors (ISV) interested in selling SaaS services on top of a hosted PaaS. Innovative interoperable Cloud4SOAenabled PaaS offerings open up the Cloud market to new customers that were previously reluctant to adopt the Cloud paradigm because of a greater need of flexibility. Likewise, such a solution can strengthen the market position of rising European PaaS providers by leveraging accessibility and portability to their customers as a competitive advantage, while still keeping their platform-specific innovative features that makes the PaaS segment an attractive alternative to their IaaS counterparts. 3
Cloud4SOA Project Overview Cloud4SOA is providing an open semantic interoperable framework for PaaS developers and providers, capitalizing on Service Oriented Architecture (SOA), lightweight semantics and user-centric design and development principles. What do we mean by semantic interoperability? It is the ability of applications and their data to seamlessly be managed and migrated between Cloud PaaS offerings that are using the same technological background but different data models and Application Programming Interfaces (APIs). This concept is a key enabler of Cloud4SOA s capabilities. The Cloud4SOA system supports Cloudbased application developers with multiplatform matchmaking, management, monitoring and migration by semantically interconnecting heterogeneous PaaS offerings across different providers that share the same technology. All this is done using an adaptable, intelligent, user-centric web interface. These are value-added capabilities for the developer that facilitate the access and lifecycle management to the PaaS offering that best matches their computational needs, as well as empowering them with application portability in contrast to vendor lock-in. The results push towards a more open, competitive and dynamic market segment for rising PaaS providers and their potential developers.
Research Objectives and Results: The Cloud4SOA Cloud Semantic Interoperability Framework, which provides a) a typology of semantic interoperability conflicts in the Cloud, and b) a set of recommendations and good practices on how to achieve semantic interoperability and transparent data and application portability between different Cloud platforms. The open, generic Cloud4SOA Reference Architecture, which introduces a scalable, reusable and transferable approach for facilitating the matchmaking, management, monitoring and migration of applications to platform by semantically interconnecting different Clouds. The Cloud4SOA Models for Resources and Services, which offer the necessary semantics for annotating Cloud computing resources and services. The Cloud4SOA System, which implements the Cloud4SOA Reference Architecture and comprises of a set of interlinked collaborating software components and models. Cloud4SOA BETA and Industry Showcases Cloud4SOA looks for feedback from a Cloud market that is always evolving. Are you a software developer or PaaS provider? Visit www.cloud4soa.eu for information on how you can take a test drive! In addition, Cloud4SOA runs three industry showcases internally in the project for immediate user feedback: multimedia service delivery with Portugal Telecom, network monitoring with RomTelecom, and business collaboration with Fraunhofer FIT s BSCW platform. Project Facts Cloud4SOA receives funding through the FP7 Research Programme of the European Commission (Grant Agreement #257953) Project Coordinator: Atos (ES). Partners: National University of Ireland Galway (IE), SingularLogic (GR), Centre for Research and Technology Hellas (GR), cloudcontrol (DE), Cyntelix (NL), Portugal Telecom Inovacao (PT), Fraunhofer FIT (DE), RomTelecom (RO). Duration: September 2010 August 2013. Budget: 4.13 M Euros. Maximum Community Contribution: 2.73M Euros. Research Programme: FP7-ICT-2009-5 Objective 1.2. 5
Cloud4SOA Reference Architecture Cloud4SOA Reference Architecture
The Cloud4SOA project introduces a brokerbased reference architecture consisted of five layers: The Front-end layer supports the usercentric focus of Cloud4SOA and the easy access of both Cloud-based application developers and Cloud PaaS providers to the Cloud4SOA s functionalities exposed via widgetized services which are adaptable to the user s context. The Semantic layer is the backbone of the architecture that puts in place the Cloud semantic interoperability framework (CSIF) and facilitates the formal representation of information (i.e. PaaS offerings, applications and user profiles). It spans the entire architecture resolving interoperability conflicts and providing a common basis for publishing and searching different PaaS offerings. The SOA layer implements the core functionalities offered by the Cloud4SOA system such as PaaS offering discovery and recommendation (matchmaking), PaaS offering and application publication (profile management), application deployment, monitoring and migration. The Governance layer implements the business-centric focus of Cloud4SOA where Cloud PaaS providers and consumers (Cloud-based application developers) can establish business relationships through Service Level Agreements (SLA). Specifically, it enables the lifecycle execution and management of Cloud-based applications taking into account monitoring information, SLAs and scalability issues. The Repository layer acts as an intermediary between the Cloud4SOA system and the various PaaS offerings allowing the applications to be independent from specific PaaS offering implementations. Moreover, it provides a harmonized API that enables the seamless interconnection and management of applications across different Cloud PaaS offerings, using PaaS-specific adapters deployed in each platform. Cloud4SOA provides four core capabilities implemented by the reference architecture: Matchmaking between a Cloud application and a ranking of platforms to best fit its needs. Management of applications deployed in several PaaS providers, as well as independent SLA interaction. Monitoring of applications deployed on multiple platforms, using universal metrics. Migration of an already-deployed application from a PaaS offering to a competing one. 7
Core Capabilities Matchmaking The matchmaking component allows searching among the existing PaaS offerings for those that best match the developer s needs. To succeed in this, the matchmaking algorithm heavily capitalizes on the Semantic layer and, especially, on the PaaS and Application models while it distinguishes the user s needs into application requirements and user preferences. The degree of relation is computed based on the similarity of the semantic descriptions between PaaS offerings and an application profile taking also into account the target user s preferences. In addition, the matchmaking algorithm is designed to resolve the semantic conflicts between diverse PaaS offerings and to allow matching of concepts between different PaaS providers that may use different naming or even different measurement units. The outcome of the matchmaking algorithm is a list of PaaS offerings that satisfy users needs, ranked according to the number of satisfied user preferences. Management The management component supports the efficient deployment and governance of applications on a specific PaaS offering chosen by the application developer. The module performs an analysis of the application s requirements to build a specific application deployment descriptor. This descriptor is created according to the format defined by the PaaS offering that the user has selected. It then checks if a valid SLA contract has been previously agreed between the specific PaaS offering and the application, finally initiating the deployment process using the Cloud4SOA standard API exposed by every Cloud4SOA PaaS platform adapter. Moreover, this component provides a functionality to manage the life-cycle of the application by delegating its lower level functionality to the Governance Layer.
Monitoring In a multi-cloud scenario, it is important to continually monitor business-critical applications hosted on a variety of Cloud providers to ensure that their performance consistently meets expectations and that Cloud resources are being effectively used. Cloud providers typically present very diverse architectures providing dissimilar resource-level metrics used to provide fine grain Quality of Service (QoS) guarantees. As a consequence, Cloud users are not able to compare offerings they are adopting. In order to consider the heterogeneity of different Cloud architectures, Cloud4SOA provides a PaaS monitoring functionality based on unified platformindependent metrics, such as latency and application status, to allow application developers to proactively monitor the health and performance of business-critical applications hosted on multiple Clouds environments. Migration Moving an application between PaaS offerings is a difficult operation, where several issues could arise related to the different modelling and notation of the same features across different providers. The Cloud4SOA framework aims to support a seamless migration to tackle semantic interoperability conflicts. Moving an application between PaaS offerings consists of two main steps: i) moving the application data and ii) moving the application itself. During the first step, all the application data is retrieved from the PaaS offering where the app is running and moved to the new PaaS offering; in order to avoid dirty or inconsistent states, the application is stopped before starting to move the data. After the data structures have been created and initialized, the application code is deployed on the new PaaS provider. 9
Scientific and technological achievements The Cloud4SOA project is delivering several significant scientific and technological achievements carried out in each layer of architectural structure. These innovations are the subject of the remainder of this booklet. Cloud4SOA System Cloud4SOA Reference Architecture Front-end layer Cloud4SOA CSIF Intelligent Dashboard Interface Intelligent Dashboard Interface Cloud4SOA exposes its functionalities via a web-based interface that implements a design metaphor based on the concept of a dashboard. The choice is motivated by the fact that the user needs an overview about the performance of the application(s) deployed on different Cloud providers and a centralized point for managing applications. The dashboard offers a set of widgets which allow encapsulating functionality in a self-contained application, i.e. an application with a front-end and business logic. Widgets can be modelled to correspond to the different actions the user wants to perform on the platform, e.g. search a PaaS offering or deploy an application. At the same time, they can be grouped in different ways to allow presenting the user only with the functionalities he is likely to need in the course of a certain activity. SOA layer Semantic layer Governance layer Repository layer 5-tier architecture SOA Principles Cloud4SOA Semantic Model Business Application Governance and SLA Management Harmonized API and Platform Adapters Scientific and technological achievements This allows defining macro activities (e.g. Search) that are composed by micro activities (represented by the widget). Furthermore, widgets are independent from an activity and communicate via an event bus, where widgets can subscribe (or not) to be notified about particular events. A user can add or remove widgets from a particular activity and adapt the interface to his particular needs. An event bus supports the asynchronous behaviour of the calls from the front-end to the back-end services (SOA layer), which is necessary since operations such as deployment can require some time to complete. Scientific and technologic advances implemented in the layers of the Cloud4SOA Reference Architecture
SOA Principles Finally, users can be presented with contextual information since Cloud4SOA uses semantics to model applications and Cloud offerings. The same semantics can be presented to the user to, for example, disambiguate the meaning of a term, when different communities use different terminologies. This implies that the interface is able to: interpret the models used by the semantic layer adapt to changes in these models and always display up-to-date information The SOA layer constitutes the heart of the Cloud4SOA system, translating a resource-centric architecture, like the semantic layer and its implementation and management concepts, into a highlevel architecture. Designed by following the service oriented computing paradigm and exploiting annotations and interfaces, the SOA layer provides services in a flexible manner and exposes them via the REST protocol, in line with what PaaS Cloud Providers do with their public APIs. The SOA layer implements, according to application developer use cases, a uniform and scriptable interface to PaaS services, for deploying, running, monitoring and migrating an application without specific dependencies on the developer s current PaaS system. Mapping this service model into the dynamic object/resourcecentric model implemented by the Cloud4SOA semantic layer produces a set of conceptual and technical difficulties, called impedance mismatch. The SOA layer solves it by adopting a technique of minimization. This consists in generating a new layer that partially wraps the Cloud4SOA ontology concepts in order to offer a more stable (and thus reusable as a service) representation of the Cloud4SOA business logic. Widgetized user interface for searching PaaS offerings 11
Cloud4SOA Semantic Model The objective of the Cloud4SOA semantic model is to investigate and resolve the semantic interoperability problems that exist in PaaS entities. The Cloud4SOA semantic model consists of five tiers, where each tier describes a set of fundamental PaaS entities and defines their relations: The Infrastructure tier captures knowledge related to the infrastructure utilized by the Platform and Application tiers and it models a number of concepts including hardware component, software component, programming language and QoS parameters. The Platform tier captures knowledge related to a Cloud-based platform which is based on the Infrastructure tier in order to operate. The main concept of the platform tier is the PaaS offering. The Enterprise tier captures knowledge related to the enterprises involved and their role in the Cloud. The Enterprise tier is modeled by the concepts of the PaaS provider and SLA. The Application tier captures knowledge related to a Cloud-based Application. A Cloud-based Application is developed/ deployed/managed in a Cloud Platform. The central concept of this tier is the Application. The concepts of the Cloud4SOA semantic model in 5-tiers The User tier captures knowledge related to the users (developers) of the Cloud4SOA reference architecture that create and manage the applications and Cloud PaaS providers that publish their PaaS offerings. The User tier facilitates users annotation, enabling them to create their account and semantic profiles in the system. The central entity of this tier is the Developer. The PaaS model is used to create instances that represent a programming platform
Application Governance and SLA Management that Cloud PaaS providers publish and application developers can use in order to implement and deploy their applications. The application model is used to create instances that represent an application created by a developer for hosting by a PaaS offering. A PaaS offering instance and a PaaS offering request constitute instances of the PaaS Offering and the Application concept, respectively. The PaaS offering request is matched with the available PaaS offerings for providing a set of platforms that best match the application developer s needs. To this end, the two entities should share a set of common characteristics that enable the easy matching between their instances. The Cloud4SOA semantic model serves as a means for the unification and the homogeneous representation of different Cloud systems. Its capabilities are made available to all Cloud stakeholders through the Semantic layer. An enhanced and distributed architecture for business application governance, monitoring and service level agreement (SLA) management is implemented through Cloud4SOA. The project tackles challenges investigating new service engineering paradigms, methods and tools supporting the decision making, criteria and policies involved in the semantic setting-up, construction, deployment, SLA negotiation & enforcement, monitoring, management and migration of Cloud Applications in the PaaS context. The Execution Management Service (EMS) is the key interface to the PaaS platform in everything related to the application lifecycle. This primarily includes deployment, un-deployment, maintenance and migration related tasks. The management of SLAs is another key aspect faced, although, in the scope of project, SLAs do not aim at representing a contractual relationship between the customers consuming virtualized Platforms and the PaaS vendors that provide them. Cloud4SOA provides a RESTful implementation of the WS-Agreement standard of the Open Grid Forum (OGF) that is a novel but well-accepted standard for creating and enforcing SLAs in distributed environments as well as monitoring their resources properties. Overview of the Governance layer components 13
Harmonized API and Platform Adapters The basis of the Repository layer of Cloud4SOA is the definition of a harmonized API that addresses most of the diversities of existing PaaS platforms. Support for functionality such as development life-cycle, monitoring, instance-handling, resourcehandling and migration-handling has been taken into consideration during the formulation of the API. Moving from the functional perspective to its realization, there are specific issues that arise. More specifically, the realization of the API implies that it is feasible for the majority of the methods to be implemented by many PaaS platforms. This wiring may be a simple or a complex task, since it can be performed by re-using an existing PaaS API-call or by implementing a feature from scratch. The implementation from scratch is only possible if a specific component is implemented and deployed in the PaaS in order to act as a Proxy between the Cloud4SOA API and the platform. Therefore a specific component has to accompany the developed API per PaaS which will be responsible for implementing all APImethods that cannot be implemented Harmonized API through proxying (i.e. re-wiring) and existing API-call. This component is called Platform Adapter or simply Adapter. The Platform Adapter is the Proxy between the Cloud4SOA central system and the various PaaS platforms. The API that a Platform Adapter exposes to the central system is unique (i.e. the one that the Cloud4SOA consortium has defined). In case of incompatibility either the missing part is hardcoded by the PaaS owner (or developer) or is intentionally left unimplemented.
From the functional perspective Adapters are used to: Push Asynchronously Information i.e. deploy/undeploy archives to a PaaS platform Push Synchronously Information i.e. stop/start application instances for maintenance purpose Pull Asynchronously Information i.e. migrate migrate applications to another PaaS provider Pull Synchronously Information (for monitoring and SLA enforcement purpose.) i.e. get status of application A that is installed at PaaS platform B Consequently, both synchronous and asynchronous communication patterns are used for the communication between the adapters and the central system. Hence a database and a queue are necessary. Platform Adapters are piggybacking deployed applications and store monitoring information locally. This information is periodically pushed to the central system. Finally, platform adapters constitute an overlay network that is used only during migration in order to avoid transfer through the central system. How to Join the Cloud4SOA Ecosystem Cloud PaaS Provider s side 1. Register Cloud4SOA system and create a user account (Cloud4SOA verifies that the PaaS provider s details are valid and activates the account) 2. Log in and create an PaaS profile defining the platform s specifications (e.g. offered programming language and supported QoS parameters) 3. Develop a PaaS Adapter compatible with the Cloud4SOA harmonized API Application Developer s side 1. Register Cloud4SOA system and create a user account 2. Create an application profile defining application s requirements (e.g. programming language) and user s needs (e.g. QoS parameters) 3. Search available PaaS offerings to identify the best matches 4. Select a PaaS offering and register the credential of it 5. Deploy the application to the PaaS offering (in case the application uses a database, the database has to be created first) 6. Monitor/Stop/Start/Migrate a deployed application PaaS providers already in the Cloud4SOA ecosystem 15
Contact Info Franceso D Andria Cloud4SOA Project Coordinator francesco.dandria@atos.net cloud SOA Follow us at the LinkedIn Cloud4SOA group! Try out the Cloud4SOA BETA! Cloud4SOA looks for feedback from a Cloud market that is always evolving. Are you a software developer or PaaS provider? Visit our website for information on how you can take a test drive! Consortium www.cloud4soa.eu