ppt

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Proto-Spiral: A Hybrid SDLC Model for
Measuring Scalability Early in
Development Using a Probabilistic
Approach
Paper: 40

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Authors
 Anirban Bhar
Assistant Professor, Dept. of Information Technology
Narula Institute of Technology, Kolkata, India
e-mail: anirban.bhar1983@gmail.com
 Dr. Sabnam Sengupta
Associate Professor, Head, Dept. of Information Technology
B.P.Poddar Institute of Management & Technology, Kolkata, India
e-mail: sabnam_sg@yahoo.com

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Topic Discussed
 Abstract
 Scalability
 Related work
 Scope of the work
 Proto-Spiral: The Model
 Case Study: e-bay.com
 Conclusion
 References

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Abstract
 A probabilistic model has been introduced for
measuring one of the many Non-functional
requirements, namely, the Scalability, which is largely
unexplored till now early in software development life
cycle.
 The proposed model is a combination of Prototype and
Spiral models.
 The system’s ‘quality characteristics’ or ‘quality
attributes’ are specified in the Non functional
requirements to improve QoS.

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Scalability
 The capability of a system to accommodate overload
caused by the growth of work is called the Scalability
of the system.
 It is one of the various non functional requirement of
a system that describes the ability of the system to
work efficiently when the functionality of the system
has increased in size or volume without affecting
much the QoS of the system.

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Related Work
 Some work is done on Scalability of databases those
use SQL
 Some research work has been done on the large scale
growing e-commerce systems
 Networked systems, wireless lans
 The Internet is facing a noticeable growth on two
aspects simultaneously: Amount of data & Number of
users.

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Scope of the work
 The previous works are individually very efficient in
their respective domains and provides some good
solutions, but all of these works has been done with
some particular already developed systems.
 All these work has been done to measure scalability of
any existing system. At the end, if it is found that the
scalability result is not satisfactory, the system needs to
be re-built.
 Proto-Spiral ensures scalability of software at different
iterations of spiral model, at different levels of
development

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Proto-Spiral: The Model
 The proposed model defines a procedure to develop
a scalable software system that may be a networked
system or a distributed system or a stand alone
system.
 If the system demands high scalability, this model
can provide a feasible practical solution to the
approach or algorithm to develop the software
system

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Proto-Spiral:
Working principal
 Prototype-oriented spiral model is used
and after development of each and
every prototype (P1, P2,…Pn), the
scalability factors (SF) have been
analyzed.
 There are some pre-defined
measurements of SF (Next Slide)
depending upon the project itself and
obviously there is a satisfactory level
for each prototype.
 The satisfactory level may be assigned
after analyzing the whole project as
well as with a probability based survey
report of the Scalability Factors
 If a developed prototype satisfies the
desired scalability factors and if it
meets the customer requirements, then
the process of building the next
prototype gets started as per the Spiral
model of software development.

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Probability Based Scalability Factors
Scalability Factors Unit
Number of Users (N)
100 1,000 10,000 20,000
Probable Throughput (X) tps 100 93.66 89.2 83.54
Probable
Resource
Usage
CPU % 70 70 73 75
Memory % 76.3 82.7 89.11 93.18
Disk % 0.5 5 50 100
Bandwidth Hertz 40 48 54 60
Probable Cost per Transaction 83 86.5 91.5 98
Satisfactory Satisfactory Satisfactory Satisfactory

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Case Study: e-bay.com
 eBay is an eCommerce system where the C2B2C
 eBay is designed using distributed object technology
in a real time system.
 It requires a high scalability, better performance, high
availability, and is a highly secured system.
 It is required to have the potential to handle large
volumes of requests generated by the internet
community and must it be able to respond to all of
these requests in a timely fashion (real-time).

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Case Study: e-bay.com continued…
Selling Search View Item Bidding
MyEbay Check Out Feedback
Focused working architecture of eBay:

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Case Study: e-bay.com continued…
The most recent statistics regarding eBay state that [source: 14]
 The registered users it manages is around 248,000,000.
 Number of photos it manages is over 1 Billion.
 eBay has live applications of nearly 10,000.
 eBay currently has 30 Software Architects in its employ
 eBay averages well over 1 billion page views per day
 Every month around 4.4 billion API calls handles by the eBay
platform.
 In every two weeks around 100,000+ lines of code are added in
this system.
 There are 30,000 software builds per week
 There are more than 44 billion SQL executions per day

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Conclusion
 In the situation like this, the report of
probability based number of users for the
coming years must be managed at the
time of the development of this kind of
service.
 The Proto-Spiral model may assure this
point to the developer and it may provide
the right development approach of a high
scalable system like e-Bay.com.

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References
1. S. M. Metev and V. P. Veiko, Laser Assisted Microtechnology , 2nd ed.,
R. M. Osgood, Jr., Ed. Berlin, Germany: Springer-Verlag, 1998.
2. The Analysis of Directional Time Series: Applications to Wind Speed
and Direction, ser. Lecture Notes in Statistics, J. Breckling, Ed.,. Berlin,
Germany: Springer, 1989, vol. 61.
3. S. Zhang, C. Zhu, J. K. O. Sin, and P. K. T. Mok, A novel ultrathin
elevated channel low-temperature poly-Si TFT, IEEE Electron Device
Lett., vol. 20, pp. 569–571, Nov. 1999.
4. M. Wegmuller, J. P. von der Weid, P. Oberson, and N. Gisin, High
resolution fiber distributed measurements with coherent OFDR, in
Proc. ECOC’00, 2000, paper 11.3.4, p. 109.
5. Badrul M. Sarwar, George Karypis, Joseph Konstan and John Ried,
“Recommender Systems for Large-scale E-Commerce: Scalable
Neighborhood Formation Using Clustering”, Department of Computer
Science and Engineering, University of Minnesota, Minneapolis, MN
55455, USA.
6. (2002) The IEEE website. [Online]. Available: http://www.ieee.org/
7. M. Shell. (2002) IEEEtran homepage on CTAN. [Online]. Available:
http://www.ctan.org/tex-
archive/macros/latex/contrib/supported/IEEEtran/

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Some more References
1. FLEXChip Signal Processor (MC68175/D), Motorola, 1996.
2. PDCA12-70 data sheet, Opto Speed SA, Mezzovico, Switzerland.
3. Prasad Jogalekar, “Evaluating the Scalability of Distributed Systems” - Murray
Woodside
4. A. Karnik, Performance of TCP congestion control with rate feedback: TCP/ABR
and rate adaptive TCP/IP, M. Eng. thesis, Indian Institute of Science, Bangalore,
India, Jan. 1999.
5. A stochastic model of TCP Reno congestion avoidance and control, Univ. of
Massachusetts, Amherst, MA, CMPSCI Tech. J. Padhye, V. Firoiu, and D. Towsley,
Rep. 99-02, 1999.
6. Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY)
Specification, IEEE Std. 802.11, 1997.
7. Mohammad Usman Ahmed, ‘eBay_Architecture_Study’, e-commerce platform.
8. Barry W. Boehm, TRW Defense Systems Group , ‘A Spiral Model of Software
Development and Enhancement’
9. Laudon & Traver, 2008
10. Greg Barish, “Scalable and High-Performance Web Applications”

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Thank You…..