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In-Depth Information
Definition 11 (Successive Join Points).
Let
M
be a bSD and
P
be a point-
cut. Let
J
1
,J
2
,...,J
k
be
k
parts of
M
isomorphic to
P
.These
k
parts are suc-
cessive join points of
P
in
M
if:
1.
J
1
is the minimum join point of
P
in
M
;
2.
∀i ∈{
2
...,k},J
i
is the minimum join point of
P
in
M
,
M
being the bSD
which contains the events of
M
minus the events of
J
i−
1
and all the events
which precede the events of
J
i−
1
,so
M
=
M − pred
(
J
i−
1
)
.
Taking the minimum join point every time guarantees the uniqueness of the
successive join points. Roughly speaking, successive join points are detected in
sequence at the earliest position where they appear in a bSD.
However, the result
M
=
J
i−
1
) is not always a well-formed bSD.
Indeed, in Fig. 9, the minimum join point
M − pred
(
J
1
of
P
in
M
is formed by the two
first messages
a
and
b
. When we remove the events
pred
(
J
1
) (the events of
J
1
and the events which precede
J
1
), we have to remove the event corresponding to
M
=
the sending of the message
c
. Therefore, the result
M − pred
(
J
1
)isonly
formed by the two last messages
a
and
b
, and the event corresponding to the
reception of the message
. This is not really a problem because the algorithms
proposed afterwards can be applied even if a bSD is of the kind of
c
M
.
Fig. 9.
Example of a not well-formed bSD
3.4
Which Detection Stategies Should Be Chosen?
Each definition of part of a bSD presented in the previous sub-section leads to a
specific join point detection strategy. This sub-section discusses some arguments
for and against these strategies.
First, it is important to note that for the four proposed definitions of part of
a bSD (so the four strategies), the definitions are based on the semantics of the
language of scenarios used, since we take account of the message names, but also
of the partial order induced by the pointcut.
The definition of strict part is the most restrictive, because with this definition,
the wanted behavior can be presented in a bSD without being detected when,
for instance, it is surrounded by a message. On the other hand, this definition is
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