 Cloud computing  Workflow  Workflow lifecycle  Workflow design  Workflow tools : xcp, eucalyptus, open nebula

A Cloud is a type of parallel and distributed system consisting of a collection of inter-connected and virtualized computers that are dynamically provisioned and presented as one or more unified computing resources based on service-level agreements established through negotiation between the service provider and consumers.” FEATURES :  Hundreds of thousands of users / applications  Systems should be fast, secure and available  Intelligent infrastructure:  Transparency  Monitoring  scalability

The aim of application of cloud computing is to combine all the resources, and let anyone can use it.

“The automation of a business process, in whole or parts, where documents, information or tasks are passed from one participant to another to be processed, according to a set of procedural rules “

Operational aspect of a work procedure:  how tasks are structured,  who performs them,  what their relative order is,  how they are synchronized,  how information flows to support the tasks and  how tasks are being tracked.

 Design  Typical workflow is graph oriented  Language: how expressive is workflow  GUI: Visual Service Composition Environment  Deployment  Workflow Description is sent to Workflow Engine  Possibly validated and compiled  Execution  Workflow Engine enacts Workflow Description  Monitoring  Events reflecting from workflow and services execution Refinement

 All person are given unique position & work.  All have to perform their own job & on the basis of their response, next step is exeuted.  All people involved perform according to given role, power & then give their suggestion to people at higher level.  Every position is regarded as an agent, using the key elements, person, to accomplish and control of design.

1. XEN Cloud Platform 2. Eucalytpus 3. Open Nebula

The Xen Cloud Platform (XCP) manages storage, VMs and the network in a cloud. XCP does not provide the overall cloud architecture, but rather focuses on configuration and maintenance of clouds. It also enables external tools, including Eucalyptus and OpenNebula.

Its basic component is the XCP Host, which is a Xen hypervisor enabled to communicate with other XCP hosts. Several XCP Hosts can be bound together into a XCP Resource Pool. A single XCP Host from this pool must be setup as the Master XCP Host, which offers an administration interface and commands others XCP hosts. Optionally, a Resource Pool may have a Shared Storage whose objective is to store and export VM images mainly for VM migration, which allows administrators to place and replace VMs on any XCP host.

XCP is an open source infrastructure manager tool for clouds that does not provide the overall architecture for cloud computing, since it does not provide interfaces to end users to interact with the cloud. However XCP provides a useful environment for administrators and an API for developers of cloud management systems.

the Eucalyptus architecture foresees two different user classes: administrators and client.  The former are the users that manage the entire cloud, having access to all features of Eucalyptus.  The latter are the final users that can request and make use of VM instances directly from Eucalyptus, without the need for administrators’ intervention Eucalptus arhitecture : it has four components.

1. VMs on a node are managed by a Node Controller (NC) running on this same node, allowing support of different hypervisors. 2. NCs are grouped in clusters managed by the Cluster Controller (CC), which gathers state information from each NC, schedules client requests to individual NCs and manages configuration of public and private networks. 3. top of the architecture there is the Cloud Controller (CLC). It processes client requests and makes VM placement decisions. 4. The Storage controller (Walrus) is a data storage service compatible with Amazon´s Simple Storage Service which is responsible to manipulate VM images delivering them to NCs when a client instantiates a VM.

 Advantage : is a natural fit for existing enterprise processing environments resulting from the hierarchical design. SUMMARY : Eucalyptus provides an open source solution to manage the virtual infrastructure of a cloud. The use of interfaces based on Web Services is one of their key characteristics, allowing native integration with Amazon services. Moreover, the hierarchical architecture is designed to reduce human intervention.

 A flexible tool that orchestrate storage,network and virtualization technologies to enable the dynamic placement of services on distributed infrastructures.  A number of communities are actively using OpenNebula. Some of these are: the European Space Astronomy Centre and the European Organization for Nuclear Research. COMPONENTS OF OPEN NEBULA :

Open Nebula is designed with three layers in mind: 1. Tools : contains modules providing functionalities for administrators and clients. a.) One component is the Command Line Interface(CLI) that can be used by administrators to manipulate the infrastructure through intuitive commands. b.)The Schedulermodule, responsible for VM placement, is implemented in this layer. c.) Other tools can be created using the OpenNebula Cloud API which is based on a XML-RPC interface. Administrators access OpenNebula through CLI, while clients launch and manage VMs using web services interfaces.

2. Core : consists of components responsible for handling client requests and control resources. a.) The main component of this layer is the Request Manager, which handles client requests through an XML-RPC interface calling internal components according to the invoked method. b.) Hosts and VMs are managed and monitored by the Host Manager and the VM Manager, respectively. c.) The Virtual Network Manager (VN Manager) manages virtual networks by keeping track of IP and MAC addresses and their association with VMs. d.) The SQL Database stores internal data structures.

3. Drivers : supports different underlying platforms. a.) Drivers run on separated processes that communicate with the Core module through a simple text messaging protocol. b.) there are drivers to deal with file transfers that are implemented by network protocols like NFS and SSH. c.) Also, there are drivers to manage VMs that are dependent on each hypervisor running on the host. d.) Finally, there are drivers to request services from external clouds like Amazon EC2 or ElasticHosts.