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wilamowski-b-m-irwin-j-d-industrial-communication-systems-2011

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14-4 Industrial Communication Systems<br />

components at the lower layers provide component services to the components above them. A SOA is a<br />

way of connecting loosely coupled converged application services across a network via common interaction<br />

primitives. Services map distinct business processes that can be chained together in order to realize<br />

certain collaborative behavior.<br />

14.3.1 Service Meta Architectures<br />

The Meta data model illustrated in Figure 14.1 represents an explicit Meta specification of a single software<br />

component and its interface. This explicit model supports software reconfiguration by clearly<br />

defining application constructs and their interface. Such data is used to specify construct convergence<br />

and interaction. External entities (other applications and constructs) may access this Meta data in order<br />

to utilize service constructs and their compositions. A composition is typically formed from many<br />

interconnected components that are constructed in a layered and hierarchical manner. Connectors and<br />

adaptors provide a level of indirection that reduces dependencies among components. Interconnected<br />

compositions are coupled using operation and attribute connectors and adaptors [14].<br />

1<br />

0..*<br />

Provided<br />

operation<br />

0..*<br />

Provided<br />

interface<br />

1<br />

1<br />

0..*<br />

Provided<br />

attribute<br />

Component<br />

specification<br />

1<br />

1..*<br />

Interface<br />

specification<br />

Attribute<br />

1<br />

1..*<br />

Interface<br />

permissions<br />

1<br />

0..*<br />

1<br />

Required<br />

interface<br />

0..*<br />

Required<br />

attribute<br />

1<br />

0..*<br />

Required<br />

operation<br />

Operation<br />

specification<br />

1<br />

1<br />

1<br />

1<br />

0..*<br />

Pre<br />

condition<br />

0..*<br />

Input<br />

parameter<br />

0..*<br />

Output<br />

parameter<br />

0..*<br />

Post<br />

condition<br />

Parameter<br />

FIGURE 14.1<br />

Conceptual Meta model of a component.<br />

© <strong>2011</strong> by Taylor and Francis Group, LLC

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