臺灣博碩士論文加值系統

雲端運算的使用，在技術及商業界已經司空見慣。雲端服務供應商的數量一直不斷增長，因此有一系列給遠端用戶的選擇。也有一些優秀的應用，如Dropbox的發明，檔案託管服務，提供雲端儲存以及文件同步等等。
藉由一些課程，我學習到與雲端運算相關的大量的知識，我參加了一些課程並做一個敏銳的觀察者，我意識到，這樣的系統如選課系統（例如，在交大的選課系統）或在我的國家，越南的鐵路銷售系統，像這樣的系統有時不太穩定。
當網站流量激增、流量過量時，將造成伺服器負載急劇增加而影響伺服器上的網路連接。比方說針對選課系統來說在學校讓學生選課時有時候會有超多學生同時一起來跟系統連結，這會造成伺服器當機或是反應很慢。另外一個系統像鐵路銷售系統在過年時有許多人為了工作而離開家裡從北部移到南部，然後過年時要回家團圓，因為他們同時跟系統連結，所以這也會造成一個系統像上面提到一樣的。
針對類似上面提到的系統我們會有什麼辦法又簡單又便宜能夠解決短時間迫切需求之系統呢？
亞馬遜Web服務(AWS)是一家雲端運算供應商，他們提供許多服務又便宜又有大彈性。所以我認為這就是我們的選擇之一。在我的研究，我建好一個簡單的系統跟選課系統差不多，然後把這個系統移轉到遠端去，接下來是針對這兩個系統做評估看它們的效率如何。最後我建議在雲端可以建一個系統，它的架構包含一個域名系統Web服務、三個負載平衡器、三到十八台虛擬Web伺服器、和一台資料庫伺服器。Web伺服器的數量會變動是因為靠使用者的數量同時供用讓整個系統做自動縮放。假設我們本來的系統頻寬大概1Gbps，然後跟新的系統做一個比較，新的系統能力最大可以比本來的系統能力高三倍。而且新的系統也不算貴，每學期大概要花美金600元。
完成這個研究，我有一個結論是上面類似之系統可以改善它的情況如果有應用雲端運算。

Cloud computing has been a commonplace and widely used in both technological and business world. The number of cloud providers has been constantly growing and so has the set of options for end users. There have also been some outstanding applications such as the invention of Dropbox, a file hosting service that offers cloud storage and file synchronization.
With a great deal of knowledge on cloud computing from some courses that I took in the master program and as a keen observer, I realized that such systems as the course selection system (for example the one that operates at NCTU) or the railway ticket system back in my country, Vietnam, do not work well sometimes.
There are times that websites are overloaded to a point when their services are degraded or disrupted entirely. This web traffic overload happens when there is a large surge in traffic to a particular website causing a dramatic increase in server load and putting severe strain on the network links leading to the server. For example many students access the course selection system at the time the school lets the students select their courses on it. Also, many people want to buy railway tickets on railway ticket system at the time closing to New Year vacation when they want to go home.
For those systems, is there any practical way to improve them with low cost but high degree of effectiveness?
Amazon Web Services (AWS), a cloud computing provider, provides a number of services with low cost and rapid elasticity. Therefore, this should be considered as a choice for us. In this research, I am going to conduct several experiments with an aim to migrate a sample system like a course selection system to AWS and evaluate the effects of the new system. Furthermore, I expect to propose a model for the new system on the cloud which includes one domain name system web services, three load balancers, three to eighteen web servers, and one database server. The number of web servers might be changed depending on how many users access the new system at the same time. It’s assumed that the original system has the capacity bandwidth of 1Gbps. As well as that if we compare the new system with the original one, the capacity of the new system is approximately 3 times as big as that of the original system. Furthermore, the cost of new system is relatively low estimated at $600 for every semester.
After doing this research, I have reached the conclusion that the overload system may be improved by applying cloud computing technology.

TABLE OF CONTENTS
摘要 i
ABSTRACT iii
ACKNOWLEDGEMENTS v
TABLE OF CONTENTS vi
LIST OF FIGURES viii
1 Chapter 1: Introduction 1
1.1 Motivation 1
1.2 Objective 1
1.3 Research Contribution 2
1.4 Thesis Organization 2
2 Chapter 2: Theoretical Background 3
2.1 Cloud Computing 3
2.1.1 Essential Characteristics of Cloud Computing 4
2.1.2 Service models 5
2.1.3 Cloud Deployment Models 6
2.2 Amazon Web Services (AWS) 7
2.2.1 Why AWS 7
2.2.2 Services 8
3 Chapter 3: Architecture 14
3.1 Website Overload Reasons 14
3.2 Website Overload Solutions 17
3.2.1 Expanded the Original System 17
3.2.2 Applying AWS to the Original System 20
3.3 Doing Migrations 22
3.3.1 Database Migration 24
3.3.2 Web server Migration 26
3.4 Security problems 28
4 Chapter 4: Implementation 31
4.1 Experiments 31
4.1.1 Choice software for simulation 32
4.1.2 Test link speed 100Mbps 33
4.1.3 Test link speed 1Gbps 34
4.1.4 Test with Amazon Web Services 35
4.2 Monitoring System Scaling 38
4.2.1 Requirements 38
4.2.2 Structure 39
4.2.3 Result 42
4.3 Cost of using Amazon Web Services for Course Selection System 43
5 Chapter 5: Conclusion and Future Works 45
6 REFERENCES 46
Appendix 1: AWS Scaling 48
Appendix 2: Database migration 51
Appendix 3: Web migration 54

[1] Microsoft TechNet “Understanding Database and Log Performance Factors”, April 2013
[2] White paper of EMC Corporation, “Deploying Oracle Database on EMC VNX Unified Storage”, May 2011
[3] Bianca Schroeder, Mor Harchol-Balter, “Web servers under overload: How scheduling can help”, May 2002
[4] Marshall, P.; Tufo, H.; Keahey, K. "Provisioning Policies for Elastic Computing Environments", Parallel and Distributed Processing Symposium Workshops &; PhD Forum (IPDPSW), 2012 IEEE 26th International, On page(s): 1085 - 1094
[5] Wikipedia - Cloud Computing
http://en.wikipedia.org/wiki/Cloud_computing
[6] Peter Mell, Timothy Grance, “The NIST Definition of Cloud Computing”, September 2011
[7] Database Replication
http://en.wikipedia.org/wiki/Replication_(computing)
[8] Database Journal, “Very Large Databases and High Availability Evaluating Replication Options”, Nov 8, 2006
[9] A. Sousa L. Soares A. Correia Jr. F. Moura R. Oliveira, “Development and evaluation of database replication in ESCADA”
http://citeseerx.ist.psu.edu/viewdoc/similar?doi=10.1.1.160.3801&;type=sc
[10] Webopedia – Cloud Computing
http://www.webopedia.com/TERM/C/cloud_computing.html
[11] Amazon Documentation
http://aws.amazon.com/documentation/
[12] AWS SDK for Python
http://aws.amazon.com/sdkforpython/
[13] Amazon Relational Database Service Command Line
http://docs.aws.amazon.com/AmazonRDS/latest/CommandLineReference/StartCLI.html
[14] Paramiko
http://docs.paramiko.org/
[15] Abhijit’s World of .Net
http://abhijitjana.net/2010/10/01/what-is-the-difference-between-web-farm-and-web-garden/
[16] Performance test tools
http://www.opensourcetesting.org/performance.php