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The
AADL meta model defines the structure of AADL models, i.e., an object representation of
AADL specifications that corresponds to a semantically decorated abstract syntax tree. The
object representation of AADL models can be manipulated programmatically through an API.
The object representation of AADL models can also be persistently stored as XML documents
in an interchangeable manner by different tools that support AADL by adhering to an XML
schema or XMI meta model specification. Both of these are derived from the AADL meta
model.
Three
model representations and persistent XML formats of AADL models have been
identified:
Figure
17 shows the three model representations and their relationship to the textual and
graphical AADL representation as well as to tools that process and analyze AADL models.
The
declarative AADL model reflects AADL specifications and supports translation from and
to the textual AADL representation. A parser translates text into a declarative AADL model.
Name resolution, semantic checking and other static analysis can be performed on this in-core
object model of the declarative AADL model. Results of such analysis can be recorded in the
declarative AADL model as property values. This makes analysis results available in a standard
format for other analysis and for generation tools as illustrated in Figure 17. An XML-to-Text
converter can reproduce textual AADL from the declarative AADL model.
The
graphical AADL model is supported by graphical editing tools operating on the declarative
AADL model and using the graphical layout model to maintain relevant layout information
about the AADL model. Graphical presentation of AADL instances is supported in a similar
manner.
The
declarative AADL model contains information that is relevant to assure the semantic
consistency of AADL models. However, this information is often not relevant to backend
analyses and runtime system generation. Therefore, a more compact AADL instance model is
desirable that is tailored to such processing. This AADL instance model is derived from the
declarative AADL model. It is used by analyses of system instances, in many cases analyses
that require a system model in which application components are bound to execution platform
components. Such analysis tools may operate on an in-core object representation of the
AADL instance model directly, or filters convert this representation into an analysis tool specific
representation. Results from such analysis can be recorded as properties in the AADL instance
model and mapped back into the declarative AADL model as necessary.
Figure 17 AADL Models and Tools
A
full discussion of the AADL Meta Model and the interchange format can be found in Annex
D of the SAE AADL Standard [SAE AADL 2005]. In the context of this note we will refer to
the meta model class AObject that is the common super class of all AADL model objects and
to InstanceObject as the common super class of all instance model objects. |
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