A Software Engineering Framework for Context-Aware Service-Based Processes in Pervasive Environments - Advanced Design Approaches to Emerging Software Systems - page 115

Figure 6. Apto architecture

ent EF must be applied first. As one EF might
insert an activity whose attributes are changed by
a second one, the execution order of these EFs
becomes crucial. Therefore, the Follow relation-
ship enables the order in which EFs are applied
to the basic process to be specified.

request for the process service is intercepted by
the Process Proxy service which in turn trig-
gers the Context Analysis module. The Context
Analysis module evaluates all context constraints
of the context model. Using the constraints ele-
ments evaluated to “true” and the linkage model
we are able to determine the relevant EFs and
the order in which they should be applied to the
basic process model. We consider that the context
model is acquired from the context-management
infrastructure described in “Context Management
Framework.”
These relevant EFs are used by the Model
Composer module which supports context-aware
process configuration; i.e., it allows for the con-
figuration of a process variant by applying only
those EFs relevant in the process context. The
result is the CAAP Model. This model is auto-
matically transformed, using a set of transforma-
tion rules, to generate the executable specification
of the target platform. At this time, the proxy
service creates a new virtual end point which will
be bound to the resulting deployed process. Then
it invokes the service deployment of the corre-
sponding execution engine to deploy the gener-

Apto Architecture

The selection of a process variant in a particular
context should be done automatically. Therefore
the process context in which this selection takes
place has to be considered. To this end, the basic
process model, the defined EFs, the context and the
linkage models are used to configure the models
of the different variants. A single process variant
is created by applying a number of EFs and their
related evolution primitives to the basic process.
As a proof-of-concept we implemented a
Java application prototype for the process variant
generation. The Eclipse Modeling Framework
(EMF) was used to model the aforementioned
models. Having specified these models, the Apto
framework is able to deliver CAAP on a basis of
user request as follows (See Figure 6). The user