Journal of Software Engineering and Applications, 2011, 4, 106-122
doi:10.4236/jsea.2011.42012 Published Online February 2011 (
Copyright © 2011 SciRes. JSEA
An Embedded Software Modeling and Process by
Using Aspect-Oriented Approach
Yong-Yi Fan Jiang1, Jong -Y ih Kuo2, Shang-Pin Ma3
1Department of Compu t e r Science and Information Engineering, Fu Jen Catholic University, Taiwan, China; 2Department of Com-
puter Science and Information Engineering, National Taipei University of Technology, Taiwan, China; 3Department of Computer
Science and Information Engineering, National Taiwan Ocean University, Taiwan, China.
Email: yyfanj@csi e .,,
Received January 6th, 2011; revised January 20th, 2011; accepted January 25th, 2011.
In recent years, mobile devices have become widespread and refined, and they have offered increased convenience in
human life. For these reasons, a variety of embedded systems have been designed. Therefore, improving methods for
developing of embedded software systematically has become an important issue. Platform-based design is one example
of an embedded-system design method that can reduce the design cost via improving a design’s abstraction level.
However, platform-based design lacks precise definitions for platforms and design processes. This paper provides an
approach that combines the aspects and platform-based design methods for developing embedded software. The ap-
proach is bu ilt on platform-based design meth odology and uses the separating of concerns (SoC) concept to define the
aspects and to reduce the crosscutting concerns in embedded system modeling. For aspect issues, we use the extended
UML notation with aspects to describe both the static structure and the dynamic structure of the embedded system. We
used an example of a digital photo frame system to demonstrate our approach.
Keywords: Platform-Based Design, Aspect-Oriented, Unified Modeling Language, Embedded Software
1. Introduction
With advances in technology, many scientific and tech-
nological products such as smart phones, home DVD
players, automobile peripherals and computer peripherals
evolved from single-chip microprocessors to operating
systems containing a small processor [1]. Because of their
potential for improving the convenience of modern life,
embedded systems are constantly being developed to
meet their strong demand by society. These increasingly
complex systems can now be regarded as a small desktop
system, and their increased complexity has also led to in-
creased problems.
Desktop software, which operates on a stable platform
and which uses a general-purpose system, has a more ma-
ture development platform. Because personal computers
have the variety of development tools, system develop-
ment can be a systematic process. In addition to being
important for the development of desktop systems, a sys-
tematic development process and a design method are
equally important for embedded systems. However, to-
day’s embedded systems involve a wide range of design
regimes ranging from the top of the applications to the
bottom of the digital circuit, and the development of em-
bedded systems also requires designers who are experts
in several areas of the system’s construction. Currently,
there is not a complete develo pment process and method;
therefore, the creation of a systematic method for embed-
ded system development is still an important area of re-
search. For the development of most embedded systems,
the system design is a combination of both software and
hardware design. As a result, the product life cycle is
limited because of the rapid change in hardware technol-
ogy. A given design may enter the market later than anti-
cipated because the original system design must be upda-
ted before it is acceptable to the market. In this regard,
embedded software is more flexible than general-purpose
software over time. Furthermore, the embedded system is
a combination of both hardware and software, and this
combination presents greater inconvenience for system
maintenance and updating. If a market is driven by pro-
duction of substandard products, correcting these design
flaws will result in increased unit costs.
The increasing size of the embedded systems is also a
major issue for their development. To satisfy the users’
convenience requirements, consideration of the embed-
An Embedded Software Modeling and Process by Using Aspect-Oriented Approach
Copyright © 2011 SciRes. JSEA
ded system’s size is an increasingly important considera-
tion. Although the trend in embedd ed system design is to
provide greater resource capacity, the system’s calcula-
tion performance is still not that of a general desk top sys-
tem. Users also cannot replace the embedded system’s
components. Furthermore, upgrading the hardware’s cal-
culation capability means greater power consumption,
which is an important issue for embedded systems. One
of the resolutions for this issue is to reduce the software
burden on the hardware.
In terms of PC hardware deployment, Vincentelli [2]
proposed a platform-based design approach that has been
used in the industrial domain and has a certain degree of
effectiveness. Platform-based design improves the system
level of the design abstraction. Through a clear definition
of the platforms, mapping of the API platform to the ar-
chitecture platform allowed for completion of the design.
The abstract levels of system development reduced errors
and improved the design’s reusability. It also redu ced the
time-to-market for embedded systems and reduced design
In recent years, considerations of the embedded sys-
tem’s security needs and its non-functional requirements
have become the focus of aspect-oriented design. Aspect-
oriented design involves the separation-of-concerns based
method [3], which is used to improve the size of inter-
connected software systems. It uses a modular approach
to solve the problems presented by crosscutting concerns
that arise in object-oriented software development.
This paper focuses on the combination of aspect-ori-
ented design and platform-based design, and this metho-
dology is used to construct a digital photo frame. The
platform-based design approach is used to improve the
level of abstraction in system development. The design of
a digital photo frame is used to define a clear hierarchical
system and the mapping between platforms, and the de-
fined modules and communication logics improved soft-
ware reusability. Finally, we use AORE (aspect-oriented
requirement engineering) [4], the concept of aspect-ori-
ented design, to analyze the embedded system’s non-
functional requirements in an earlier stage of system de-
velopment, thus reducing inefficient connectivity of sys-
tem modules and enhancing system efficiency.
Section 2 describes the background knowledge for the
embedded system development process and aspects-ori-
ented design. Section 3 describes our approach, an aspe-
ct-oriented and platform-based design for embedded sys-
tem development. The described method includes a plat-
form-based design system development process with as-
pects and a meta-model for aspects. Section 4 presents a
case study for development of a digital photo frame. Se c-
tion 5 describes the implementation of the digital photo
frame system. Finally, Section 6 presents conclusions ari-
sing from the combination of aspect-oriented and plat-
form-based des i gn m e t hod ologies.
2. Background Work
2.1. Embedded System Development and Process
In recent years, a great deal of domestic and international
research has focused on embedded system development.
Embedded systems are highly coupled assemblies of soft-
ware and hardware. In contrast to general-purpose sys-
tems, the main characteristic of embedded systems is their
interaction with environment. Therefore, embedded sys-
tems often have real-time features. For special purposes
in different products, the security of embedded systems
has become considerably important [5].
Woodward [6] proposed that there are five challenges
in the development of embedded so ftware: First, compl e-
xity describes a single system that is continuously being
augmented with added features. Second, optimization re-
fers to the cycles required for design, assessment and re-
design. This becomes a difficult issue because of the
length of time allotted for system construction. Third,
interdependency conveys the idea that different parts of
the design process are dependent on one another. Fourth,
verification requires confirmation that the system’s im-
plementation is consistent with its specifications. Finally,
tools refer to the tools available for development of em-
bedded systems. The currently available tools are poor
and weak compared with those available for desktop soft-
Similarly, Urting [7] described the importance and the
challenges of non-functional requirements for embedded
systems. Embedded systems often contend with memory
limitations, time requirements and actual demand for li-
mited resources. These considerations are a major chal-
lenge for developers of embedded systems. Additionally,
the development of embedded systems takes into account
non-functional requirements, but it does not consider the
reusability of code.
The development of embedded software is a systematic
approach for integrating software and hardware co-design
and for improving system reliability in a highly reusable
context that improves the efficiency of product develop-
ment. In the face of increasing system complexity, sim-
plifying the development process to meet time-to-market
targets has become an important consideration. The fol-
lowing sections describe development methodologies of
embedded systems, including object-oriented analysis and
design, platform-based design and other design methodo-
2.1.1. Obje ct -Oriented Analysis and Design
Paltor and Lilius [8] pointed out that the UML (Unified
Modeling Language) provides standard notations to de-
An Embedded Software Modeling and Process by Using Aspect-Oriented Approach
Copyright © 2011 SciRes. JSEA
scribe the object-oriented design and analysis software,
and it can be used for modeling complex embedded soft-
ware systems. However, UML is not a software process;
it cannot express the stag es software design. Additionally,
UML can be used with various notations, but it does not
explain how to create and use the diagrams.
As system complexity increases; Zhu [9] proposed the
use of object-oriented analysis and design with UML to
avoid risk. He purposed the SLOOP (System Level De-
sign with an Object-Oriented Process) method with four
models: The concep tual model is an analysis o f the cu sto-
mer’s requirements. The functional model focuses on the
functional structure, rather than the structural entity. The
model consists of the process and the communication be-
tween processes. The architectural model describes the
entity’s architecture and its required resources. The re-
sources can be classified into process resources and com-
munications resources. Finally, the performance model
combines the functional model and th e structural model.
In the modeling language, SLOOP uses the ROOM
(Real-time Object-Oriented Modeling) [10] language with
the embedded UML. The ROOM includes four notations:
module, interface, channel and port. In the conceptual
model, one can use the case diagram to analyze system
requirements and use the class diagram to describe the
system structure. The sequence diagram can then be used
to describe the scenarios in use case.
With the same goals of reducing time-to-market and
reducing the complexity and design costs of systems-on-
chip, Green [11,12] proposed a design method, HASoC
(Hardwar e and Soft ware on Chip), to model the life cycle
of embedded systems. HASoC uses the MOOSE (Multi-
model Object Oriented Simulation Environment) method
and is based on UML-RT notations. There are four mod-
els in the HASoC paradigm: uncommitted modeling,
committed modeling, system integration, and platform
modeling. In the product concept model, natural language
is used to define software borders and should not to be
very complete.
2.1.2. Platf orm-Based Design
Platform-based design [2,13,14], based on the design
concept of personal computers, is a paradigm for the de-
velopment of system-on-chip embedded systems, and this
methodology is used to add increasing complexity to em-
bedded systems to meet demands for decreased time-to-
Vincentelli proposed the platform-based design as an
abstract expression that includes many low-level refine-
ments. Each platform, from the high-level map to the
low-level abstraction, can be an abstract class. Figure 1
presents a platform-based design model that includes two
parts, the upper half of an API platform and the lower
half of an architecture platform. The intersection point,
the system platform layer, is a combination of the API
platform and the architecture platform, which can be me-
thods or tools. The API platform includes a RTOS (Real-
Time Operating System), an I/O driver and network fea-
tures, and the platform is an interface between the appli-
cation and the hardware platform. The architecture plat-
form uses a meet-in-the-middle process to choose the
system’s hardware. The meet-in-the-middle approach is
not a top-down process, in which software is designed
first and hardware is developed second. Finally, the ab-
stract System Platform Layer and Architecture Platform
should confirm each other until an Architecture Platform
appropriated with applications. In addition, system plat-
form layer can change in response to changes in require-
ments, so the meet-in-the-middle process can help the
system more closely to achieve the design objectives. The
top layer, the application space, is defined as a set of ap-
plications; the bottom layer, the architecture space, repre-
sents a collection of hardware components. The top-down
arrow in the upper half of the model represents a map-
ping relationship between an application and an abstract
design. The top-down arrow in the lower half indicates a
mapping relationship between the abstract design and the
actual platform.
The platform-based design approach can provide a
more flexible development method, an d the use of abstra-
ction can reduce development costs. However, the accu-
racy and performance of these methods is not enough
to outperform traditional methods for embedded system
design. Additionally, Sangiovanni et al also mention that
platform-based design lacks a clear definition of the rela-
tionships between platforms and a systematic develop-
ment process [15].
Based on Vincentelli’s platform-based design, Lee [16]
proposes another kind of platform-based design. Figure 2
represents Lee’s proposal for a platform-based design
model. In their definition, the components on platform are
system’s designs and the platform is a set that includes the
Figure 1. Vincentelli’s platform-based design model [14].
An Embedded Software Modeling and Process by Using Aspect-Oriented Approach
Copyright © 2011 SciRes. JSEA
components (designs). Such as: a set of java programs, a
set of standard ASIC design which used the core library
designed, and a set o f dig ital CMOS integrated circuit d e-
sign. Additionally, he considered that there are two issues
for each platform. The first problem is definition of the
design set. The second problem is determining how to re-
present elements in the design set. Lee replaced the inter-
section point with a platform, the middle layer, which re-
presents all possible designs that use a specification lan-
guage. The arrows are as same as those in Figure 1, but
the relationship is replaced with the relationship between
the design sets. For example, the two lower arrows may
indicate different compilers that produce different sets of
binary code from different C-language programs, and the
surrounded region in the architecture space is used to run
all C-language programs with x86 binary code. The big-
gest difference between the two designs is that Lee’s de-
sign does not focus on the number of sets. Instead, it fo-
cuses on the proper use of the relationship between the
general representations of the platforms, and it tries to
more closely represent system entities.
Riccobene [17] used a platform-based design process
combined with the unified process, an d proposed the uni-
fied process for embedded systems (UPES). UPES is an
MDA (model-driven architecture) style-Y development
process. UPES focuses on software and hardware, and it
is divided into an application model and platform model.
The deployment of the platform model is the same as the
general platform-based design. In the application model,
the unified process is used for development. UML is used
to model the embedded system, and MDA tools were
develope d for system coding.
To aid integration engineers and core suppliers who
are developing embedded software in a short time, Wehr-
meister [19-21] proposed a complete and integrated de-
velopment methodology SEEP (Sistemas Eletrônicos
Figure 2. Lee’s platform-based design model [18].
Embarcados baseados em Plataformas), for system-on-
chip ASIP (Application-Specific Instruction Set Proces-
sor) design. SEEP is an RT-UML object-oriented model
that provides a smooth conversion to implementation. The
SEEP process is divided into the following steps: First,
the engineer defines and confirms a high-level, pure-fun-
ction model. This model does not consider the structure
or design requirements (e.g., energy consumption and
performance). Then, in the system exploration phase, al-
gorithms are evaluated for their utility in implementing
part or all of the programs. The input of this process is
used completed algorithm and the models Library on the
platform. The predesigned components can be analyzing
using these algorithms, and the evaluation must consider
the system’s efficiency, its memory control and its cost-
effectiveness. In the architectural exploration phase, the
system design must complement its implementation in a
way that decides main system architecture. Then, prede-
signed platforms and components are selected from the
library. This phase includes the following tasks: hardware
and software separation, definition of hardware types, d e-
finition of the number of processing units (e.g., the mi-
croprocessor, ASIP, DSP) and definition of the communi-
cation mode. During this phase, a part of macro-archite-
ctures are deployed to software, and others are deployed
to hardware blocks. Then, the remaining phases of deve-
lopment include software compilation, RTOS generation,
communication synthesis, and micro-architecture synthe-
sis for integrated of hardware and software.
2.1.3. Other Design Metho dologies
Duc [22] observed that in software development, if a re-
usable mechanism is adopted and components are desi-
gned carefully, a system can be developed in the shortest
time-to-market. However, to meet a variety of system re-
quirements, components must be designed using a unified
format across different domains. In his argument, an ob-
ject not only represents software, but it can also represent
For many state-based behavior designs, Jeon [23]
pointed out that the interaction-based design methodolo-
gy is more intuitive. Interaction-based design uses the
combination of a sequence diagram and a state machine
diagram. The behavior of each component is described by
a state machine, but this kind of description canno t antic-
ipate the overall behavior of the system. Therefore, inte-
raction-based modeling mainly focuses on the role and
interactions of system components. The design process
encompasses the following steps: The structural- mod-
eling phase utilizes the contents of use cases and then
indicates the system structure in the class diagram. In the
behavior-modeling phase, external events are first identi-
fied and then mapped to a use case to illustrate the initial
interaction overview diagrams. The next phase completes
An Embedded Software Modeling and Process by Using Aspect-Oriented Approach
Copyright © 2011 SciRes. JSEA
the system modeling by combining the incorporated al-
ternative scenario with the interaction overview diagram,
according to the system interaction node of the interac-
tion overview diagram and with the construct sequence
2.2. Aspect-Oriented Design in Embedded
Aspect-orientation is a software development technology
concept that is based on the separating of concerns. This
technology addresses the weaknesses of object-oriented
design. In recent years, the development of object-orien-
ted programming and new hardware has driven year-by-
year changes in the scale of software development, and it
has also created systems that are difficult to maintain.
Freitas [24] proposed a fault-tolerant FRIDA (From
Requirements to Design using Aspects) method. FRIDA
uses an early-aspect concept to deal with the system’s as-
pect during the analysis and requirements phase. This
method is based on the use of aspects and RT-UML mo-
deling in the desig n phase. The goal of this approach is to
define the non-functional requirements, and it uses six
stages and tools to separate non-functional requirements
form functional requirements. In this approach, aspects
are used to reso lve orthogonal p roperties, conditions, and
restrictions that are non-functional requirement characte-
Based on this concept, Wehrmeister [25] uses a distri-
buted embedded real-time aspects framework (DERTS)
and proposes an extended high-level framework to ad-
dress the non-functional requirements in DERTS. DE-
RAF is an aspect set which is independent from the im-
plementation. It is used to address non-functional require-
ments while building a RT-UML model. By using DE-
RAF to address aspects, a programmer can understand, in
high-level semantics, how and where aspects affect sys-
tem components. The system is not custom-made, so the
use of reusable code can be achieved. Furthermore, by
using an established aspect library to store aspects, the
decrease in the system’s design difficulty can also be
3. An Aspect-Oriented Platform-Based
Design for Embedded System
This paper mainly uses platform-based design to address
aspects and to integrate the system’s hardware and soft-
ware. We focus on the aspects only in relation to applica-
tion analysis and design. In the architecture platform, the
planning of hardware components and the components’
intercommunication is not used. Modeling of the system
uses the UML 2.0 notation and the extended UML 2.0
notation to comply with the asp ect-o rien ted techno log y in
the system description. We also use the metamodel to de-
scribe the modeling of aspects. The following section ex-
plains the design process and system modeling.
3.1. An Aspect-Oriented Platform-Based Design
The definition and sep aration o f the hardware interconne-
ction between architecture platform components permits
reusability of the architecture platform. However, only
focusing on the architecture platform is not sufficient to
achieve reusable applications. Therefore, platform-based
design defines the API platform between the application
space and the architecture platform definition. The API
platform is an abstraction layer; it can be seen as the in-
terface between applications and the architecture platform.
Figure 3 shows that the software includes the RTOS, the
I/O drivers and the network connection to make up the
API Platform [2]. In addition, because our approach is
designed to address a system’s speed and energy consum-
ption in aspects, this information is defined between ap-
plications and software.
When the API platform is decided, correct selection of
the architecture platform requires a lower-level execution
model of the API platform to estimate the effectiveness
of the architecture platform model. This model can de-
scribe the system’s size, power consumption and timing.
We use aspects to define the platforms, which are classi-
Figure 3. Aspect API platform structure [2].
An Embedded Software Modeling and Process by Using Aspect-Oriented Approach
Copyright © 2011 SciRes. JSEA
fied according to the various aspects on different plat-
forms. This model describes the performance of embed-
ded system platforms and is called the aspect platform.
The nature of the system-defined aspects can influence
the number of aspect platforms. In Figure 4, the top of
the application space and the bottom of the architecture
space are defined in the same way as those for platform-
based design; they are a group of applications. They are
mapped to each other by the system platform layer. The
relationship between the application space to and the as-
pect platform with the system platform layer is the same
as that used in platform-based design; it is a relationship
between application and design. The relationship among
the aspect platforms is what joins the two layers. In Fig-
ure 5, the two down-arrows from the application space to
the aspect platform indicate the system base (which does
not include crosscutting modules in the system) and the
aspects. The two platforms map to the hardware via the
system platform layer, which can be seen as a set of me-
thods or tools.
3.2. An Aspect-Oriented Platform-Based Develop
In response to the lack of a complete development pro-
cess which from analysis system’s requirement phasen
platform-based design; this paper proposes a process of
Figure 4. Aspect-oriented PBD development process.
Figure 5. Aspect platforms.
embedded system development. Figure 4 shows four sta-
ges for this process: aspect-oriented requirement discov-
ery and identification; function specification and com-
munication definition; platform identification and specifi-
cation; as well as mapping and system deployment. In as-
pect-oriented requirement discovery and identification,
the functional and n on-functio nal requiremen ts are exp lo-
red and the standard documents are created. Then, these
documents are used to define, validate and eliminate con-
flicts between the requirements. The products of this sta-
ge are the mapping table and the use-case diagram. The
function specification and communication definition stage
describes the application and the system platform, and it
employs the use-class diagram to describe the application.
It also uses the component diagram to describe the hard-
ware components and the communication in the architec-
ture platform. This paper only focuses on aspect-oriented
modeling for applications in an embedded system. In the
platform identification and specification stage, the struc-
ture is described by the class diagram, and the behavior
of the application and aspect platform is described by the
sequence diagram. The final step of system deployment is
the mapping and system deployment stage.
3.3. Aspect-Oriented Modeling
In embedded system modeling, we use the UML 2.0 no-
tation, and we extended the UML 2.0 notations to model
the aspects in an embedded system. It included both the
structure model and the behavior model. In addition, to
model aspects in the embedded system, we use UML ste-
reotypes to extend the UML notation for aspects. The fol-
lowing sections use a metamodel [26] to describe the re-
lation between aspects and the origin structure of UML.
In Figure 6, the metamodel includes two parts. One
part is the UML diagram for the definition of a class dia-
gram. The aspect, advice, advicebody, pointcut, pointcut-
body and jointpoint are the parts of the aspect. In the as-
pect design, the aspect is a kind of classifier, and it inclu-
des the physical advice. The advice is an important part
of the aspect and can also be seen as a behavior feature.
The joinpoint is a kind of StructureFeature that is inclu-
ded in the operation. In this paper, we define the special
attributes of non-functional requirements for the aspects,
such as the “Start and End” of the “Time” classifier. The
following are the new stereotypes:
“joinpoin” expresses the join points of the functional
components and aspects; “advice” expresses the execu-
tion code in the join point; “weaving” links the function
components to the complement system, which includes
the aspects.
Figure 7 shows the metamodel of the sequence dia-
gram. It includes the general-purpose UML and the de-
fined aspects of weaving, aspectlifeline, weavingoccur-
An Embedded Software Modeling and Process by Using Aspect-Oriented Approach
Copyright © 2011 SciRes. JSEA
rence and advicestrategy. Weaving is a kind of message
in the sequence diagram, and weavingoccurrence is a kind
of messageend. When weavingoccurrence occurs, it calls
the aspectlifeline aspect; therefore, aspectlifeline can be
seen as is a kind of lifeline. Aspectlifeline includes the
three types of advicestrategy: After is behind the time
point of aspectlifeline; Around replaces the time point of
aspectlifeline; and Before is in front of the time point of
4. System Content and Modeling
In this section, we use a digital photo frame example to
describe the combination of platform-based design with
the aspect-oriented development method.
Figure 6. Metamodel of aspect-oriented structure modeling—Class diagram.
Figure 7. Metamodel of aspect-oriented behavior modeling—Sequence diagram.
An Embedded Software Modeling and Process by Using Aspect-Oriented Approach
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4.1. Requirements of the Digital Photo Frame
Using marketed Digital Photo Frames (DPF) as examples,
a digital photo frame usually includes:
1) A color LCD screen to use as a photo player
2) A USB or network interface for use as a phototrans-
fer interface
3) An extern al AC -power supply
4) Other storage
Traditionally, evaluation of an embedded system atta-
ches great importance to speed, but because of network
interfaces developed in recent years, the accuracy of file
transfers has also become an important concern. Because
of past habits in code writing, the system’s time code is
often scattered, and the maintenance of time-related codes
is very difficult.
Based on the definition of non-functional requirement
in embedded systems [24], this paper sets out th e follow-
ing non-functional requirement classifications in the em-
bedded system, and it identifies the following classifica-
tions (Table 1):
4.2. System and Non-Functional Requirements
Based on the proposed embedded development method
presented in section 3, a developer working during the as-
Table 1. Definition of non-functional requirements.
NFR classifier NFR Description
Start and End A start and end time of a task
Period Period work
Deadline Minimum task time limit,
then the failure of the unfin-
ished work
Latency A time from task dispatched
to task started
Throughput Output in a time
ResponseTime A time from task started to
task finished
Tasks Executable task numbers in a
Multi-Users Users number of different
systems/the same system
Connection Connections between differ-
ent systems
Transmission The volume of data
Power Single/total power
memory Single/total memory
pect-oriented requirement discovery and identification
stage can use natural language to define the DPF system.
He can then determine the functio nal requirements of the
DPF. A normal digital photo frame can be used to play
photos. The user can choose to play the photos automati-
cally and can also choose to play them manually. The
user can communicate with the system through the hard-
ware components and also can be linked through the USB
port. The key features of the digital photo frame are as
1) Manual play and automatic play
2) Capturing of photos by a camera
3) Support a keypad device for control
4) USB storage
Through the standard document form, the four main
functions are documented. The following tables (Table 2,
Table 3, Ta ble 4, and Ta ble 5) represent the manual use
cases. The document form includes the serial number of
the case, the use-case name, a brief description of the case
and the main flow of the use case. In the manual use case,
the system response time when the user depresses a but-
ton is seen as a non-functional requirement, and the ac-
tion here represents a joinpoint for which the follow-up
steps must be confirmed:
For the user of a digital photo frame, timing is an im-
portant issue. For playing photos, the user wants to have
a smooth response and feedback time. Therefore, the ti-
ming requirement of the user is used to define the follo-
Table 2. Use case—Manual photo display.
No. UC-1
Use Case Name: Manual Ph oto Display
Brief of Use Case: Users can manually play photos.
Main Flow : 1. U ser choos e to play photos
2. User choose “forward” to pla y photo forward
3. User choose “backward” to play photo backward
Table 3. Use case—Automatic photo display.
No. UC-2
Use Case Name: Automatic Photo Display
Brief of Use Case: Users can automatically play photos.
Mai n Flo w : 1. U ser choose to play photos
2. User choose “Automatic”
3. System start to play photos on the target system
4. User clic ks the stop button to stop3. User choose
“backward” to play photo backward
Table 4. Use case—Take photo.
No. UC-3
Use Case Name: TakePhoto
Brief of Use Case: Users can take photos through the CCD.
Main Flow: 1. User clicks the take photo button to work
2. User click s the capture button to take phot os
3. User clicks the quit button to stop3. System start to
play photos on the target system
An Embedded Software Modeling and Process by Using Aspect-Oriented Approach
Copyright © 2011 SciRes. JSEA
wing non-functional requiremen ts (see Table 6, Tabl e 7,
Table 8, and Table 9):
1) Manual and automatic play must occur within one
second of pressing the play button.
2) Automatically switching of photos should occur in
less than three seconds.
3) After pressing the camera button, the photo capture
Table 5. Use case—File transmission.
No. UC-4
Use Case Name: File Transmission
Brief of Use Case: User sends files directly form USB to target
Main Flow: 1. User press the send button
2. Display the message after the transfer is complete
Table 6. Non-functional requirement—Play in one second.
No. NFR-1
NF R Name: P l ay in o ne se cond
Brief of NFR: Manual and automatic play must press the button
wit h i n o ne se cond afte r the play
External Aspect: T ime
Main Flow: 1. Inserted into the main flow
2 of UC-1 (UC-2)
2. 1 second countdown
3. Continue the main flow 2 of UC-1
Table 7. Non-functional requirement—Switch photos.
No. NFR-2
NFR Name: Switch photos
Brief of NFR: A utomatically switch photos shall be less than 3
External Aspect: Time
Main Flow: 1. Inserted into the main flow 2 of UC-2
2. 3 seconds countdown
3. Continue the main flow 2 of UC-2
Table 8. Non-functional requireme nt—Complete photo cap-
ture in three seconds.
No. NFR-3
NFR Name: Complete to take photo in 3 seconds
Brief of NFR: Press the camera button to complete may not be
more than 3 seconds
External Aspect: Time
Main Flow: 1. Inserted into the main flow 2 of UC-3
2. 3 seconds countdown
3. Continue the main flow 2 of UC-3
Table 9. Non-functional requirement—Starting file trans-
No. NFR-4
NFR Name: Start to transmission
Brief of NFR: After pressing the transmit button, the file
transmission must start in the second
External Aspect: Time
Main Flow: 1. Inserted into the main flow 1 of UC-4
2. 1 second countdown
3. Continue the main flow 1 of UC-4
should be completed in less than three seconds.
4) After pressing the transmit button, th e file transmis-
sion must start within one second.
Through the descriptions, the non-functional require-
ments in the original system are separated using SoC.
Then, through refinement of the non-functional require-
ments in the classifications, the orthogonal concerns in
the system (e.g., the timing concerns) are separated from
the nonfunctional requirements to classify them as an
aspect. In this system, we use the time non-functional
requirements that are defined in Table 1. The priority of
aspects is of major importance to the system designer. If
the aspects are in conflict, the system designer must to
resolve the conflict.
The Table 10 classifies non-functional requirements
into aspects and describes their relationship with func-
tional requirements. In this system we used the latency
and the responsetime aspects of the non-functional re-
quirements classification, time. The NFR column repre-
sents non-functional requirements, and the FR column
represents functional requirements that are related to the
aspects and the non-functional requirements. Through the
documents and the aspect mapping table, one can clearly
understand the relationship between the functional re-
quirements and an aspect, and this information helps to
modify or to track the aspects.
Figure 8 shows the use-case diagram used to visualize
the information in Tab le 10 and to describe the use cases
in the system. In this system, there are four use cases:
Play photo is the use case for the photo playing, when the
user plays photos. It includes a manual- and an automat-
ic-play function; take photo can be used to take photos,
and this part needs the use of cameras; file transmission
permits users to receive photos from USB storage de vices.
For expressions of the non-functional requirements, the
“non-functional” stereotype is used to describe the non-
functional requirements in the use-case diagram. The re-
lationship between the functional requirement and the
non-functional requirement is described in the “crosscut-
ting” stereotype. Non-functional requirements are descri-
bed by the extension point in the use-case diagram. This
means that the non-functional requirements are separated
from the functional requirements.
Table 10. Aspect mapping table.
Aspects NFR FR
Latency NFR-2 UC-2
NFR-3 UC-3
Response Time NFR-1 UC-1, UC-2
NFR-4 UC-4
An Embedded Software Modeling and Process by Using Aspect-Oriented Approach
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Figure 8. Aspect-oriented use-case diagram.
4.3. Function Description and Communication
Definition with Aspects
In the following section, we use the platform-based de-
sign approach to develop a system. In the system struc-
ture modeling, there are three steps. The first step is to
decide the architecture platform for the domain and to
define the computation components and their intercom-
munication. The second step is to determine the initial
architecture platform and define the corresponding API
Platform. The final step is to define the software.
The initial architecture platform is an abstraction lev el,
which limited to the ISA, bus and memory PC standards
because our DPF system is constructed in the PC domain.
In our example, the DPF System Architecture Platform
(Figure 9) includes the hardware components (i.e., a
camera module and a keypad module). In the establish-
ment of the initial architecture platform, we used the
“meet-in-the-middle” process between the system plat-
form layer and the architecture platform to confirm the
hardware. The process can be used to build predefined
components and to establish the interconnection logic
between the components.
The next step is to define an interface between the
high-level API abstraction layer and the hardware and
software. This step is the same as the definition of the
original API Platform (Figure 3). In this model, we chan-
ged the RTOS to embedded Linux. This layer contains
the initial definition of the DPF system’s drivers for the
keypad module and the camera module driver.
Finally, the application space is described by the base
model, which is not involved in the system’s aspects. The
system is constructed with the DPF UI, Play Photo, Take
Photo, File Transmission and Photo connected to the
Base. Here, we used the MVC (Model-View-Controller)
[27] architecture pattern. The DPF UI is the “View” of
the MVC and represents the user interface in the system.
Playphoto, Takephoto, and File transmission are system
implementations. Photo is used to manage the informa-
tion related to the p hotos. Figure 10 shows the base class
diagram for the digital photo frame system.
4.4. Platform Identification and Specification
At this stage, this develop er combines the asp ect platfo rm
and the application space to describe the structure and
behavior of the system. The class diagram is used to
model the system structure, and the sequence diagram is
used to model the system behavior. First, we describe
static aspects of this system.
Figure 9. The initial architecture platform of the digital
photo frame system.
An Embedded Software Modeling and Process by Using Aspect-Oriented Approach
Copyright © 2011 SciRes. JSEA
Figure 10. Base class diagram for the digital photo frame system.
Figure 11 represents the static system structure ex-
pression of the application space and the aspect platform.
Solid arrows indicate the general base call in the system,
and dashed arrows indicate the weaving relationship be-
tween the base and aspects. Here, the weaving relation-
ship described in section 3 is the extension of the original
UML metamodel; the relation is defined as a combination
of the special relationship between the base and the as-
pects. Here, we add the joinpoint in the application space
class as a process join point to the base. The aspect entity,
advice, is defined as the responsetime in the aspect plat-
form (named setRcounter) as a time between a task’s start
and finish. Latency is expressed by setLcounter, and is
the time from task’s dispatching to its start. In addition,
this class diagram describes the aspects weaving from
Responsetime to Playphoto and File transmission, thus
weaving Playphoto and Takephoto in the latency aspect.
Figures 12 and 13 represent the sequence diagram for
the manual- and automatic-use case. The manual use case
allows users to play photos manually. The available func-
tions are backward, forward, auto and timestop. The au-
tomatic-use case is for automatically playing photos.
When the user enters the system and clicks the play but-
ton, the system will chang e photos every three seconds in
a loop. To ensure that the system reaction time will not
be too long, we use the Responsetime aspect, and we also
use Rcounter to check that the button receive the signal
from the user and notify system to play photos within one
second. The «weaving» stereotype represents the timing
of the weaving in this diagram. In addition, we also add-
ed an Lcounter to check that the automatic switching can
be completed within three seconds.
Figure 14 is the sequence diagram for the take photo
use case. After the user opens the system, the system will
first confirm that the device is opened, and then wait for
the user’s command and weave the latency aspect. When
the user issues a command to capture images, the system
will call the camera driver to capture photos, and it will
use an Lcounter to check that system resumes the photo-
capture mode within three seconds.
Figure 15 represents the sequence diagram for the file
transmission use case. When the user opens the system
and the system confirms that the network device in the
system is opened, the system will begin weaving the Res-
ponsetime aspect. Then, it will use an Rcounter to check
when a button is pressed and start to send the file within
one second.
4.5. Mapping and System Deployment
DPF system is defined using the following platforms:
The application space is the application implementation,
which u sed the Q t Langua ge [5]. Th is syst em used the Qt
Language to construct the windows UI and contains two
aspects (i.e., Responsetime and latency) for three com-
ponents (i.e., Playphoto, Takephoto and Filetrasmission).
In the API Platform, there are drivers for the keypad, the
camera and the USB interface that were implemented
using the C++ language. Finally, the architecture space is
combined with hardware modules that contain the ARM9
processor module and the CCD modules. UML is the
system platform Layer. Figure 16 shows the DPF system
component diagram.
An Embedded Software Modeling and Process by Using Aspect-Oriented Approach
Copyright © 2011 SciRes. JSEA
Figure 11. Aspect weaving structure.
Figure 12. Sequence diagram for the manual UC.
An Embedded Software Modeling and Process by Using Aspect-Oriented Approach
Copyright © 2011 SciRes. JSEA
Figure 13. Sequence diagram for the automatic UC.
Figure 14. Sequence diagram for the take-photo UC.
An Embedded Software Modeling and Process by Using Aspect-Oriented Approach
Copyright © 2011 SciRes. JSEA
Figure 15. Sequence diagram for the file transmission UC.
5. System Implementation
This section describes implementation of the system. We
demonstrate a DPF embedded system achieved via a
combination of platform-based development methods and
early-aspect design methodologies. The system is based
on embedded Linux, and the user interface is Qtopia [5].
The development languages are QT and C++, and the
hardware consists of a DMA-2440 development board
from DMATECH [28]. We introduce the development
environment in Section 5.1, and Section 5.2 uses the in-
formation from Section 4 to describe implementation of
this system.
5.1. System Development Environment
This DPF is based on the DMATECH DMA-2440 deve-
lopment board (Figure 17). It was deployed with a
SAMSUNG S3C2440A pro cessor with a 400 MHz clock
and 64 M byte of main memory. It contained two UART
interfaces, a network interface 10 M/100 M and a USB1.1
interface. The development of the system can be divided
into three parts corresponding to the three platforms of
the system:
1) The Qt language used for communication between
user and the system’s graphical interface;
2) The C ++ language used to implement the system
drivers; and
3) The hardware.
5.2. System Implementation
Section 4 describes the AORE process used to identify
the system requirements and the system model. In this
section we use the information from section 4 to imple-
ment the DPF system.
As mentioned in Section 4.1, we derived an AOSE-
based, iterative process. The meet-in-the-middle process
can be used to document system requirements more clo-
sely to the abstraction level of the design. The use of plat-
form-based design and the meet-in-the-middle process is
then coupled with the mapping table. This can add or
remove system modules or make decision regarding
function modules. The description of aspect modules and
function modules can produce favourable results. Figure
18 shows the last configuration files for the system. The
API platform configuration contains three module drivers
and embedded Linux. The applications include the Play-
photo, Takephoto and File transmission functions. Figure
19 is the initial UI of the digital photo frame. From left to
right are the Playphoto, Takephoto and File transmission
functions. Figure 20 shows the play phot o f unct i o n.
6. Conclusions
This paper presents an embedded system software-de-
An Embedded Software Modeling and Process by Using Aspect-Oriented Approach
Copyright © 2011 SciRes. JSEA
Figure 16. Digital photo frame mapping.
Figure 17. DMA-2440 [28].
An Embedded Software Modeling and Process by Using Aspect-Oriented Approach
Copyright © 2011 SciRes. JSEA
Figure 18. DPF syste m deployment.
Figure 19. Digital photo frame—Main UI.
Figure 20. Digital photo frame—Play photo.
velopment process, and it used this development process
for design of a digital photo frame system. This process
contains two parts, a platform -based design approach and
the use of aspects for development of embedded system
software. In the platform-based development approach,
the SoC concept was used to divide the system into two
parts, computations and communications. The aspect
approach is used to capture software requirements and to
verify non-functional requirements. This approach used
the meet-in-the-middle process to confirm and establish
software components and hardware components. Finally,
we mapped software to the hardware and deployed the
system. Through the early-aspect approach, developers
can capture and analyse system non-functional require-
ments in the early stages of development. It also defines
the non-functional requirements that cannot be defined by
object-oriented design. Moreover, these definitions occur
in the early stages of requirement determinations, analy-
sis, and design—before the system’s implementation. It
also addresses the weaknesses in the design process by
integrating non-functional requirements with platform-
based designs for embedded syst ems.
7. Acknowledgements
This research is partially sponsored by National Science
Council (Taiwan) under the grant NSC97-2221-E-030-
009 and NSC98-2220-E-030-003.
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