Post on 28-Mar-2015
22 J
uly
2009
COMPSAC 2009
1
Tool Support for Design Pattern Recognition
at Model LevelHong Zhu (1), Ian Bayley (1), Lijun Shan (2) and
Richard Amphlett (1)
(1) School of Technology, Oxford Brookes University, Oxford OX33 1HX, UK
(2) Dept. of Computer Science, National University of Defense Technology, Changsha, China
22 J
uly
2009
2COMPSAC 2009
Outline
Motivation and Related works Tool support to the application of DPs Formalisation of DPs
Our Previous work Specification of DPs Semantics of UML models
The proposed approach Bridge the gaps The tool LAMBDES-DP Experiments
Conclusion and future work
22 J
uly
2009
3COMPSAC 2009
Motivation
Design Patterns (DPs) Reusable solutions to commonly occurring design pr
oblems Represented in Alexandrian form
Synopsis, Context, Forces, Solution, Consequences, Implementation, Examples, Related patterns
Proper use can improve software quality and development productivity Reduce ambiguity Automated tool support
Explained in informal English
Clarified with illustrative diagrams
Specific code examples
22 J
uly
2009
4COMPSAC 2009
Existing works 1: Tool support Instantiation of patterns widely available in modelling tools Pattern recognition tools
Code level: More than a dozen reported in the literature (Dong, Zhao and Peng, SERP 20
07) Well-known examples:
• HEDGEHOG (Blewitt, Bundy and Stark, ASE 2005)• FUJABA (Niere, et al. ICSE 2002) • PINOT (Shi and Olsson, ASE 2006)
Design/Model level (Kim and Lu, ICECCS’06): Translate RBML and UML into Prolog (Kim and Shen, SAC’07, SQJ 2008): RBMLCC
• Plug-in to IBM Rational Rose• Pattern specified by metamodel in RBML • Apply it to 7 of the 23 GoF patterns• Class diagram only
Low level of abstractionLate in development process
Hard to improve precision and recall rate
22 J
uly
2009
5COMPSAC 2009
Existing works 2: Formalisation of DPs Le Guennec et al. (UML 2000): the extension of the UML meta-
model and OCL Eden (2001): the graphical language LePUS Mapelsden et al. (CRPIT ’02): Design Pattern Modeling Langua
ge Taibi (2003, 2006) and Mikkonen (ICSE’98): the use of predicat
e logic and temporal logic Kim, France, Ghosh, and Song (COMPSAC 2003): Role-based
metamodelling language RBML Bayley and Zhu (SEFM’07, COMPSAC’08, QSIC’08): first
order logic And many other works, e.g. Lano et al. (1996), Lauder and Kent
(1998), Mak, et al. (ICSE’04), Zdun and Avgeriou (OOPLSA’05), etc.
22 J
uly
2009
6COMPSAC 2009
Previous work 1: Specification of DPs Formal meta-modelling in first order logic (Bayley and Zhu
2007, 2008) The abstract syntax of UML diagrams specified in GEBNF (Graphically
Extended BNF). A first-order predicate logic (FOL) language systematically derived from
the abstract syntax definition Specifying design patterns in the FOL as predicate on UML diagrams and
pattern instantiation is predicate satisfaction. Advantages:
Expressiveness:• Both structural feature and behavioural features in the same FOL• Variants of patterns can be specified• All 23 GoF patterns are specified
Readability: • More readable than its rivals
Facilitate reasoning, operations and transformations of DPs• to formally prove their properties and relationships• to compose patterns
22 J
uly
2009
7COMPSAC 2009
Example: Template Method pattern
=
22 J
uly
2009
8COMPSAC 2009
Previous work 2: Semantics of UML models
Descriptive semantics of modelling language (Shan and Zhu, 2008) The formal semantics of UML is resolved into two a
spects: descriptive semantics:
• defines which systems are instances of a model.• e.g. the system consists of two classes A and B, and A
is a subclass of B. functional semantics:
• defines the basic modeling concepts, • e.g. If class X is a subclass of Y, then all instances of X
are also instances of Y.
It describes the system without referring to what is meant by class and subclass.
It defines the notion of class and subclass.
Perhaps uses axioms on the dynamic behaviour of systems.
22 J
uly
2009
9COMPSAC 2009
Translation of models into First Order Logic Signature mapping: rules to derive symbols of FOL from the metamodel Axiom mapping: rules to derive statements in the FOL from the
metamodel that must be true for all valid models Translation mapping: rules to translate a graphical model into predicates
in FOL that it is true if and only if a system is an instance of the model Hypothesis mapping: rules that selected by the user to be applied in order
to characterise the context in which the model is used
22 J
uly
2009
10COMPSAC 2009
Example: The following is a subset of the
predicates generated from the diagram
22 J
uly
2009
11COMPSAC 2009
Bridging the Gap Differences between the FOL for DP spec and the FOL
for UML semantics Syntactic difference Semantic difference
Predicates in a DP specification are evaluated on UML models Predicates in the descriptive semantics of UML models are evaluated
on software systems DP specification is translated into the syntax of FOL
for descriptive semantics
22 J
uly
2009
12COMPSAC 2009
Example: The specification of Template Method can be translated
into:
22 J
uly
2009
13COMPSAC 2009
P is a pattern.Spec(P) is the formal specification of P.
The descriptive semantics of model m.
System s is an instance of model m.
System s satisfies the specification.
Recognition of a pattern at design level becomes a logic inference problem.
22 J
uly
2009
14COMPSAC 2009
The Tool LAMBDES-DP
22 J
uly
2009
15COMPSAC 2009
Experiments:
1. Use StarUML to produce design instances as UML diagrams and export them as XMI representations.
2. Use LAMBDES to convert these XMI representations to FOL;3. Use LAMBDES to check these FOL representations for consiste
ncy errors, revising them until there are no more errors;4. For each pattern, use LAMBDES-DP to determine if the model c
onforms to (i.e. implies the specification of) the pattern. Three possible outcomes:
Proof Found, meaning definitely yes, Completion Found, meaning definitely no, and Time Out, meaning that no proof was found in the maxim
um time limit that SPASS allows, which is 990 seconds.
22 J
uly
2009
16COMPSAC 2009
Subjects of the experiments
Patterns: 23 Patterns in GoF book
Design Instances:Two sets of design instances were produced manually
from the diagrams in the GoF book. Set 1 (Class Only): contains a class diagram for each
of the 23 patterns in the book. Set 2 (Class + Seq): contains class and sequence dia
grams for the only 6 patterns in the book that contain both.
22 J
uly
2009
17COMPSAC 2009
Overview of the Design Instances: ClassOnly Set
22 J
uly
2009
18COMPSAC 2009
Overview of the Design Instances: Class+Seq Set
22 J
uly
2009
19COMPSAC 2009
Experiment ResultsClassOnly Class+Seq
Recall
(False negative error rate)
0% 0%
Precision
(False positive error rate)
< 22% 0%
Conclusion: Recognition of patterns at design level can be accurate with
good precision and recall rate; Behavioural feature is crucial for accurate specification and
hence the recognition of patterns, as we have argued in (Bayley and Zhu, COMPSAC 2008);
22 J
uly
2009
20COMPSAC 2009
Future work Improvement of the efficiency of LAMBDES-DP
SPASS cannot handle the inference of large logic systems (when it has more than 1000 formulas, which is equivalent to models that have more than 10 elements.)
Enhance LAMBDES-DP functionality Pattern composition Pattern directed refactoring at design level Reasoning about patterns
Experiment with industrial real systems Integration with code level tools
Some tools extract information from code and represent the extracted information in the form of first order logic predicates
22 J
uly
2009
21COMPSAC 2009
References
I. Bayley and H. Zhu. Formalising design patterns in predicate logic. In Proc. of SEFM’07, pp 25–36.
I. Bayley and H. Zhu. On the composition of design patterns. Proc. of QSIC’08, pp27–36.
I. Bayley and H. Zhu. Specifying behavioural features of design patterns in first order logic. Proc. of COMPSAC’08, pp203–210.
L. Shan and H. Zhu. A formal descriptive semantics of UML. Proc. of ICFEM’09, pp375–396.
L. Shan and H. Zhu, Semantics of Metamodels in UML, Proc. of TASE’09. (In press)