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ISBN 978-952-5726-09-1 (Print)
Proceedings of the Second International Symposium on Networking and Network Security (ISNNS ’10)
Jinggangshan, P. R. China, 2-4, April. 2010, pp. 157-160
Developing Mobile Input Method System Using
An Improved Design Pattern Approach
Fei Zhu 1,2 , Hongjun Diao 1,2* , and Wei Huang 1,2*
1 School of Computer Science and Technology, Soochow University
2 Provincial Key Laboratory for Computer Information Processing Technology, Soochow University
Email: zhufei@suda.edu.cn
Suzhou, Jiangsu, China, 215006
Email: { hjdiao, huangwei}@suda.edu.cn
Abstract—Popularity of operation system on mobile phone
makes it possible to develop a third party input method
system for it. However variety in mobile models and systems
makes it difficult to develop a general input method for
different models. As design pattern usually add reusability
and flexibility to software development process, we propose
an approach to develop input method for mobile using state
design pattern. With the idea of event-based finite state
machine, we design a novel event-condition-state pattern
framework. We use it develop a thirty party input method
system which contains a Windows Mobile system version
and a Symbian system version. We utilized common part of
the systems with sub pattern model and then rewrote
related interfaces to different systems, instead of carrying
out two developing activities. With the state design pattern,
the whole development process turns to simpler and clearer,
saving us much work in design and developing. It also
provides convenience for future maintenance and updating
as well.
Index Terms—software developing, design pattern, mobile
developing, mobile input method
I. INTRODUCTION
In software engineering, a design pattern is a general
reusable solution to a commonly occurring problem in
software design. It is widely used in software
development. State pattern, a behavioral software design
pattern, is often used to represent the states of an object
and is applied to develop software that has multiple states.
For example, documents in office automation system
with workflow typically have multiple states, including
editing, waiting for auditing, being audited, replying and
forwarding. Microsoft Pinyin input method system can be
in one of the states, including initial state before input,
input state, and selecting state after input. State pattern
can be applied in these two kinds of software.
However, design pattern is a description or framework
for how to solve a problem that can be used in many
different situations but not a determined design that can
be transformed directly into code. The famous state
design pattern proposed by Erich Gamma, Richard Helm,
Ralph Johnson and John Vlissides is not a determined
design that can be transformed directly into code either.
One of the common methods to implement the state
design pattern is to use IF-ELSE-IF statement provided
by most programming languages. However too many
branches of IF-ELSE-IF will make the program structure
and logic unclear, making it harder for future potential
modification and updating. Meanwhile, using eventresponse
mechanism provided by modern programming
technology, it is of benefit to refine the similar functional
structures and change IF-ELSE-IF statement to eventresponse
ones so as to promote readability and reusability
as well as relieving design efforts.
In this paper, we propose a novel event-condition-state
pattern framework, which is an event-based finite sate
machine, for software development. With the pattern
framework, we developed a third party input method
system which has a Microsoft Mobile version for
Microsoft Mobile system and a Symbian version for
Symbian system. We found it easy to fulfill development
with the help of the framework. We did not carry out two
developing activities for input method system. Instead,
we utilized common part of the systems with sub pattern
model and then rewrote related interfaces to different
systems. By this, we spared lots of redundant efforts in
developing, and gained convenience in later synchronous
updating and maintenance.
II. IMPROVING STATE DESIGN PATTERN
Erich Gamma, Richard Helm, Ralph Johnson and John
Vlissides, referred to as the GoF, described recurring
solutions to common problems in software design. As we
can see in figure 1, although GoF described a reasonable
state pattern, their framework only gave relations among
context objects and state objects in short, which is not
enough for implementation. There normally are many
response events, causing the structure of processing
method very much complex, which will lead to
inefficiency in software development.
Figure 1. State pattern class diagram which merely shows relations
among context object and state object without interpreting details of
implementation
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