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Motivation

To execute an application specified by a component assembly, components and connectors have to be allocated to different hardware and software resources, which provide the required infrastructure. Servers, clients, or any other kind of systems are set up with the required operating system and middleware. Components are installed on the systems and configured so that they can run in this environment. Computers are connected by ethernet or wireless networks enabling the communication needed by the components. The whole process of setting up the infrastructure, allocating components, and configuring the system is handled by the deployer as introduced in section 2.1.

For QoS analyses, it is required that the deployment of the software architecture is specified in advance, since it has a major influence on QoS attributes, such as performance and reliability. For example, the response times of a component's services will be shorter when it is deployed on a machine with a 3GHz processor instead of a machine with a 1GHz processor. With the specificationi of the execution environment with its hardware and software resources and connections, and the component allocation, several QoS attributes can be predicted. So, deployers are able to try different deployment scenarios to find the optimal configuration for a software architecture. In many cases, such a procedure can save a lot of work and cost, since bottlenecks can be discovered early and hardware will not be oversized.

In the context of the PCM, we currently provide a basic model for the description of resource environments and allocation of components. In the following, we describe how these concepts can be used to specify new resource types that form an execution environment. Furthermore, we introduce allocation contexts that allow us to allocate components to multiple hard and software nodes. For the future, it is most likely that the model described here will be extended to allow a higher accuracy in terms of modelling as well as prediction results.

Section 3.4.2 describes the responsibilities and duties of deployers. In section 3.4.3, we describe what kinds of resource types we model and how they can be used. Section 3.4.4 shows how the PCM in combination with a fixed set of resource types can model an execution environment. In section 3.4.5, we describe how components are allocated on resource containers and how they can access the available resources. Finally, section 3.4.6 sums up open issues and assumptions of our model.


next up previous contents index
Next: Responsibilities of the Deployer Up: System Deployer Previous: System Deployer   Contents   Index
Snowball 2007-03-16