A Rationale-based Model for Architecture Design Reasoning

More documents

Recommendations

Info

8.3. Other applications of ARM We are now certain that the Alarm Services can be supported by table insertions and the Top End calls. As such, the OCR and ICR of AR15 can also be reduced. This is reflected in the adjustments of EB, OCR and ICR in AR15 in Figure 8.2. If the outcome certainty OCR at AR15 cannot be reduced, it means that we don’t know whether the design would work or not. If the risk of AR35 is not at an acceptable level, we would not be certain that this design would need more investigation and design decomposition. Now that we are fairly certain that the design would work, i.e. the risk is low, then we do not need to go into further architecture design. The architecture design of this part of the system can be considered complete. When architects design a system, OCR and ICR risk values are assigned to the AR nodes, usually along a top-down fashion. There are usually more uncertainties in the initial stage when architecture design is at the high-level because details of whether the decisions are valid are yet to be confirmed. As architecture design progresses, and more details become available, architects are more confident about the validity of the lower-level decisions. This confirmation from having more details requires that architects readjust the OCR and ICR at the higher-level decisions. Therefore, the risk level of a high-risk decision can now be updated to a lower risk level. This re-adjustment process serves to confirm the architecture design. All requirements which involve high risk decisions, as indicated by OCR and ICR, should be part of architecture level requirements and need to be a part of the architecture design. Low risk functional requirements do not require architectural design because they do not have structural impact on architecture. Non-functional requirements usually have higher risk factors because (a) Non-functional requirements usually cut-across a large part of the system; (b) Non-functional requirements are usually competing with other nonfunctional requirements; (c) the impact of a design to satisfy a non-functional requirement requires more design attention. Therefore, all non-functional requirements should be considered in architecture modelling. This mechanism provides a way to define the scope of the architecture activities and allow measurement of completeness of the architecture outcomes. We have chosen an arbitrary guide to establish a yardstick for determining an acceptable risk. In order to get a common consensus on an acceptable risk level, we undertook a survey [158]. Architects were asked as to what is an acceptable level of risk. 23.5% said that a 30% risk level was acceptable, 18.5% said that a 40% risk level was acceptable. However, 14.8% of respondents said that a 70% risk level was acceptable and 13.6% said that a 80% risk level was acceptable. It shows that either architects genuinely believe in a high risk architectrue or they are inexperience with risk assessment in architecture design and with the impact risk may have on design quality. More research is required in this 147
8.3. Other applications of ARM area. 8.3.2 Verifiability of architecture design Architecture verification or evaluation is a quality assurance process to assess the soundness of an architecture design. A number of evaluation methods such as ATAM [78], SAAM [77] and ALMA [90] have been designed for such purposes. The need to verify architecture is recommended by IEEE standards [67]. They check different aspects of a software architecture to ensure its quality. During this process, architects are required to supply information, answer questions and justify the architecture design. A common practice of verification in the industry is through peer review of design specification. Since design rationale is not systematically captured, architects who designed the system need to be present to support the verification process. However, it was found in our survey that 74% of architects could also forget the reasons behind the design [158]. Another issue is that architecture decisions should be verifiable during or after development, with or without the presence of the original architects. Architecture rationale is therefore vital in supporting such verification process. Some of the information that are captured in the AREL model and can be used to support architecture design verification are: • Specifications of architecture drivers and motivational reasons. • Specification of the architecture design objects. • Documented architecture rationale to explain why the design can satisfy the requirement(s). • Documentation of assumptions and constraints of architecture design. • Traceable architecture rationale and elements. • Documentation of design alternatives. Architecture verification is supported by documented motivational reasons and design rationale. They can overcome the issue that architecture design cannot be verified easily because the design reasoning has not been captured. The documentation of design alternatives also support verification because it demonstrates that architects have explored different design options and assessed their appropriateness before selection. 148
Page 1 and 2:
A Rationale-based Model for Archite
Page 3 and 4:
maintenance. These techniques can h
Page 5 and 6:
Declaration This thesis contains no
Page 7 and 8:
2.2.6 DoD Architecture Framework .
Page 9 and 10:
5.4.6 Risk assessment in architectu
Page 11 and 12:
8.2 The architecture rationalisatio
Page 13 and 14:
12.2 Contributions . . . . . . . .
Page 15 and 16:
6.10 ≪AR≫ and ≪AAR≫ Stereot
Page 17 and 18:
11.13A Process to Synchronise Chang
Page 19 and 20:
5.13 Design Rationale Helps Evaluat
Page 21 and 22:
that architecture design is highly
Page 23 and 24:
1.2. Research motivations and resea
Page 25 and 26:
1.2. Research motivations and resea
Page 27 and 28:
1.4. Structure of the thesis the ch
Page 29 and 30:
Part I Problem Analysis 10
Page 31 and 32:
2.1. Industry practice of design ra
Page 33 and 34:
2.2. Architecture frameworks and de
Page 35 and 36:
Page 37 and 38:
Page 39 and 40:
Page 41 and 42:
Page 43 and 44:
Chapter 3 Related work in design ra
Page 45 and 46:
3.2. Why do we need design rational
Page 47 and 48:
3.2. Why do we need design rational
Page 49 and 50:
3.3. Existing methods for capturing
Page 51 and 52:
Page 53 and 54:
Page 55 and 56:
Page 57 and 58:
3.4. Other related studies 3.3.7 Qu
Page 59 and 60:
3.4. Other related studies evolutio
Page 61 and 62:
3.5. How well design rationale meth
Page 63 and 64:
3.5. How well design rationale meth
Page 65 and 66:
Chapter 4 Research methodology and
Page 67 and 68:
4.1. Software engineering research
Page 69 and 70:
4.2. The chosen research and valida
Page 71 and 72:
Part II Architecture Design Rationa
Page 73 and 74:
on a regular basis. Their inputs ha
Page 75 and 76:
5.1. Architecture rationale in the
Page 77 and 78:
5.2. Survey methodology data collec
Page 79 and 80:
5.3. Survey findings experience). I
Page 81 and 82:
5.3. Survey findings Table 5.1: Fre
Page 83 and 84:
5.3. Survey findings Business Goals
Page 85 and 86:
5.3. Survey findings 5.3.5 Document
Page 87 and 88:
5.3. Survey findings Table 5.8 summ
Page 89 and 90:
5.3. Survey findings We used Spearm
Page 91 and 92:
5.3. Survey findings previous desig
Page 93 and 94:
5.4. Discussion of findings Since t
Page 95 and 96:
5.4. Discussion of findings or cons
Page 97 and 98:
5.5. Limitations and use design rat
Page 99 and 100:
Part III The Representation and App
Page 101 and 102:
6.1. A conceptual model for design
Page 103 and 104:
6.2. Architecture Rationale and Ele
Page 105 and 106:
6.2. Architecture Rationale and Ele
Page 107 and 108:
6.3. Architecture elements Figure 6
Page 109 and 110:
6.4. Architecture rationale Figure
Page 111 and 112:
6.4. Architecture rationale • ris
Page 113 and 114:
6.4. Architecture rationale depicts
Page 115 and 116: 6.5. The extended AREL To prevent c
Page 117 and 118: 6.6. A UML representation of AREL a
Page 119 and 120: 6.6. A UML representation of AREL a
Page 121 and 122: 6.7. AREL usability AE by ≪AEsupe
Page 123 and 124: 6.8. Summary The AREL model is exte
Page 125 and 126: 7.1. The EFT system reasoning, a co
Page 127 and 128: 7.1. The EFT system The processing
Page 129 and 130: 7.1. The EFT system not chosen beca
Page 131 and 132: 7.1. The EFT system Figure 7.5: Int
Page 133 and 134: 7.1. The EFT system sequence checki
Page 135 and 136: 7.1. The EFT system Figure 7.7: Dec
Page 137 and 138: 7.1. The EFT system Therefore, in a
Page 139 and 140: 7.1. The EFT system Figure 7.10: De
Page 141 and 142: 7.2. An empirical study to validate
Page 151 and 152: 7.3. Summary The case study is spec
Page 153 and 154: 8.1. Background Based on these assu
Page 155 and 156: 8.2. The architecture rationalisati
Page 163 and 164: 8.3. Other applications of ARM As d
Page 165: 8.3. Other applications of ARM Figu
Page 169 and 170: Chapter 9 Architecture rationale an
Page 171 and 172: 9.1. Background 9.1 Background In t
Page 173 and 174: 9.2. Traceability of architecture r
Page 175 and 176: 9.4. AREL and eAREL traceability ap
Page 185 and 186: Chapter 10 Architecture decision de
Page 187 and 188: 10.1. Background 10.1.2 Introductio
Page 189 and 190: 10.2. Building a BBN to represent a
Page 197 and 198: 10.3. Reasoning about change impact
Page 209 and 210: 10.5. Summary design object may cau
Page 211 and 212: 11.1. Capturing architecture design
Page 213 and 214: 11.1. Capturing architecture design
Page 215 and 216: 11.2. Checking AREL models Figure 1
Page 217 and 218:
11.3. Tracing AREL models Figure 11
Page 219 and 220:
11.4. Analysing AREL with BBN • S
Page 221 and 222:
11.5. Limitations Figure 11.13: A P
Page 223 and 224:
Chapter 12 Conclusions 12.1 Summary
Page 225 and 226:
12.2. Contributions reasoning metho
Page 227 and 228:
12.2. Contributions implementations
Page 229 and 230:
12.3. Future work architecture deci
Page 231 and 232:
12.3. Future work to examine the co
Page 233 and 234:
BIBLIOGRAPHY [10] B. W. Boehm, Soft
Page 235 and 236:
BIBLIOGRAPHY [37] A. Eden and R. Ka
Page 237 and 238:
BIBLIOGRAPHY [62] J. D. Herbsleb an
Page 239 and 240:
BIBLIOGRAPHY [89] N. Lassing, D. Ri
Page 241 and 242:
BIBLIOGRAPHY [115] D. L. Parnas,
Page 243 and 244:
BIBLIOGRAPHY [142] Z. Simsek and J.
Page 245 and 246:
BIBLIOGRAPHY [167] W. F. Tichy, N.
Page 247 and 248:
Appendix A AREL Tool User Manual 1
Page 249 and 250:
4.1 AREL Check Model When the Check
Page 251 and 252:
4.2 AREL Model Tracing AREL model t
Page 253 and 254:
Figure 9 - result of downward trace
Page 255 and 256:
To initiate the graph’s creation,
Page 257 and 258:
onto the diagram 14 Assign values t
Page 259 and 260:
Useful Definitions The following ar
Page 261 and 262:
) Some projects only c) Not at all
Page 263 and 264:
19. I revisit architecture design d
Page 265 and 266:
Complaint Procedure If you have any
Page 267 and 268:
Privacy Protection Only investigato
Page 269 and 270:
B. Exploring design reasoning. 1. W
Page 271 and 272:
3. Why does the system use asynchro
Page 273 and 274:
C. General Comments on AREL Modelli
Page 275:
IEEE Computer Society Press. A. Tan
show all

A Rationale-based Model for Architecture Design Reasoning

Create successful ePaper yourself

Delete template?

Save as template?