中文摘要 主計處每年必需編製中央政府總預算書至立法院審議，而目前總預算書的編製是由八百餘家單位預算及分預算機關使用主從式架構的預算編製系統執行編製作業，然後逐層由上級機關彙編而成。本研究欲探討的是若此一主從式架構的系統改採多層式架構時，在其眾多效能的問題之中，討論應用伺服器叢集上的派工法則在工作平均等待時間的表現情況。 使用預算編製作業系統的機關及使用者幾乎是固定而且範圍容易掌握。所以，本研究在此前提下，從部份使用者的作業習慣及資料庫中，估算出模擬模型所需之數據、機率分配及公式。在選擇派工法則的部份，則除了一般常用之「輪流法(Round-robin, RR)、最少連線數法(Least Connections, LC)及最小負載法(Least Load, LL)」之外，本研究另提出「估計負載法(Estimated Load, EL)」。即是因為在瞭解使用者端特性的前提下，事先計算影響負載的數據，便可以估算負載情況並運用在派工法則上。 本研究的結果顯示EL法在各項工作的服務時間估算誤差愈小時，其表現的結果愈好，其各項工作的平均等待時間相當接近做為測試基準的最小負載法。 / Abstract The Directorate-General of Budget, Accounting and Statistics (DGBAS) of the Executive Yuan (EY) is responsible to compile the General Budget for Central Government and submit to Legislative Yuan every year. The sources of General Budget are processed by 832 government agencies and subordinate agencies by using the same software that is based on client/server architecture. This paper discusses about performance of dispatching rules on cluster-based application servers when this software architecture transferring to n-tiered architecture. We carry out the comparative studies using four dispatching rules, namely, Round-robin (RR), Least Connections (LC), Estimated Load (EL), and Least Load (LL). The LL rule is used as the baseline in our analysis and the performance metric is average waiting time. Unlike general web-based software, we know clients who use this software. So we can estimate job arrival rate, job size, and even service time. In view of this, we proposed the EL rule in this paper. Our analyses indicate that the EL rule performs very well. As long as accuracy in estimating service time getting better, the EL rule is a good choice.

在服務經濟的時代，人們為了提升生活品質越來越重視心靈需求而非過往所重視的物質需求。文化創意產業提供的原創性以及內容扮演越來越重要的角色，文化創意產業近年來在世界各國之經濟地位也漸趨重要；本篇論文提出一個透過網際網路提供台灣國立故宮博物院動態展覽的嶄新影音廣播服務--「故宮影音頻道」。故宮影音頻道意圖透過影音多媒體展示，更全方位且完整地呈現中華文物的精緻特質和內涵，以帶給瀏覽者更清晰具體的文物觀賞體驗，以及激發瀏覽者之創意靈感。 故宮影音頻道為了符合高標準的服務品質以及處理來自世界各地使用者的潛在高峰需求而特別設計負載平衡的機制。本篇論文更進一步地探討故宮影音頻道平台後端作業流程的技術挑戰以及展示提供線上影音廣播服務的具備彈性、靈活、分散特性的雲端平台。首先，我們在雲端平台上建立具有處理大量使用者的負載平衡機制的故宮影音頻道。接著我們讓故宮影音頻道上線進行實驗、收集資料及分析。根據實驗的結果，我們為了維持高標準的服務品質應用排隊理論設計了兩階段的服務系統，最後探討在不同電腦及網路環境下，如何利用該服務系統計算出符合服務品質的設定。 / The iPalace Video Channel is a video-based website and provide people around the world a brand new video-broadcasting service on the Internet which introduces relics in National Palace Museum in Taiwan. The iPalace Video Channel is designed to meet the high standard of service quality which users can watch videos without delay and be capable of coping with potential high peak demands from worldwide. In this paper, first, we establish the iPalace Video Channel and an elastic and reliable mechanism via load balancing that is capable of handling potential huge peak-demand of video services. Second, we conduct an experiment by sampling the video-based service in practice and evaluating the presented approach online. Third, from the finding of evaluation, we establish the two phase service system for delivering video services with high standard of service quality. Finally, we discuss the formal queuing model of video services from which the settings of the queuing system that satisfy acceptable service quality could be calculated under various computer and network environments

在使用者較為密集的場合中，常會碰到無線網路壅塞的問題，例如在一個大型會議廳中，常會在各個IEEE 802.11頻道上部署不同的WiFi AP（Access Point），來分散使用者的連線。但是由於IEEE 802.11的連線機制是屬於使用者主導（client driven），只能透過使用者去選定AP進行連線，對於使用者裝置來說,，連線到不同AP的優先順序，是依照接收到不同AP的信號強度（RSSI）作為排序指標。這種做法會讓在空間上使用者分佈不平均的環境中，造成多數使用者UE只連線到少數AP，而其餘AP資源閒置無用的情形。 本論文提出一個IEEE 802.11的負載平衡解決方案，結合藍牙低功耗（Bluetooth Low Energy，BLE）及IEEE 802.11成為一個智慧型AP架構。我們利用藍牙低功耗通訊協定GATT （Generic Attribute Profile）分派AP給不同使用者進行連線，再結合馬可夫鏈平穩狀態分佈（Markov Chains Stationary Distribution）演算法，依照使用者在AP網路拓樸中的歷史分佈紀錄，將多個AP的分派轉化為Erlang-C模型的排隊系統以計算AP分派規則，藉此達到系統的負載平衡。 / Usually, a user crowded space encounters wireless network congestion problem. For example, a large conference hall often deploys different wireless AP (Access Point) on each IEEE 802.11 channel to separate users’ connections. However, since the connection mechanism of IEEE 802.11 is client driven, the AP connection is selected by the user and the selection is according to the received signal strength (RSSI) from different APs. This conventional approach may result in most of the user devices connect to relatively limited number of APs, and the resource of the rest of the APs left unused. This paper proposes a smart AP architecture which is able to manage load balance for IEEE 802.11 Wireless LAN using Bluetooth Low Energy (BLE) GATT (Generic Attribute Profile) protocol in order to appropriately assign AP to different user devices. The core AP assignment algorithm is based on Markov chain stationary distribution. Simulation results show that the proposed BM-MS (BLE Management with Markov-Chains Stationary Load Balance) method outperforms RSSI based method in terms of system throughput and average user data rate.

Video-on-demand streaming從90年代就在適當的科技下成為網際網路流量的龍頭，故宮教育頻道在技術上採用TCP-based video streaming，但Video streaming使得負載較一般的伺服器繁重。透過負載平衡來分散負載是可行的方式之一，但在TCP-based video streaming的技術下，還是可能遭遇服務品質之相關議題。而服務品質要求 (Quality of Service, QoS)是用來對使用者適配的服務品質表現，做具體之等級劃分的管理工具，本研究以故宮教育頻道 (iPalace Video Channel; iPalace)為標的，針對其DNS Load Balancing搭配Round Robin的運作背景，提出VM Side QoS及Client Side QoS，在VM Side設定Load rate作為指標、在Client Side則以撥放器的表現為主，設定Initial Buffering Time、Mean Rebuffering Duration以及Rebuffering Frequency共三個指標，並搭配流量的實驗操作，劃分Regular及Class情境來蒐集資料。 在分析後發現，在環境較為一致的Class情境中，Mean Rebuffering Duration與Load Rate及Rebuffering Frequency與Load Rate具有低度正相關。未來，若能在環境及客戶端的變異性有較多的控制及掌握，則可讓資料在蒐集上更為正確，讓後續的分析及探討與實際狀況更為相符。

防火牆是現今網路中的重要設備，負責區隔內部網路和公共網路，維護內部網路安全。然而防火牆也存在幾個重要的問題，首先，防火牆的規則是由網管人員設定，近年來隨著網路科技蓬勃發展、虛擬技術大量應用，此項工作已帶給網管人員龐大的負擔。其次，防火牆雖可隔離外部網路，阻擋有害流量，但對內部網路的防範卻毫無用武之地。目前市面上普遍使用入侵偵測系統(IDS)進行偵測，但僅能在發現攻擊行為後發出警告訊息，無法即時處理。最後，企業在連外網路部分，通常採用多條線路進行備援，並倚賴多路頻寬負載平衡器(Multi-WAN load balancer)增加頻寬的使用率，但在線路數量上卻受限於廠商所制定之規格，無法彈性調整。而在負載平衡演算法方面，也只能基於網路特徵(IP位置)、權重比例(weight)或是輪詢機制(round robin)，無法依據目前網路狀況做出更好判斷。 為改善上述問題，本論文在軟體定義網路(SDN)環境下，使用交換機取代傳統防火牆設備，透過封包分析與信任觀測區間達到規則學習，並整合Snort入侵偵測系統，透過特徵比對，找出危害網路環境之封包，即時阻擋該危險流量。本論文也提出基於隨需(on demand)概念，動態調整防火牆規則，降低管理人員負擔。最後利用交換機擁有多個實體通訊埠的概念 ，依需求可自由調整對外及對內線路數量，不再受限於廠商規格，取代傳統多路寬頻負載平衡器，建構更彈性的架構。並透過收集交換機上的實體埠與資料流表中的資訊，即時評估網路狀況，加強負載平衡。為驗證本論文所提出之⽅法的有效性，我們使用Linux伺服器架設KVM、OpenvSwitch以及POX控制器實際建構SDN網路環境，透過發送封包對防火牆提出請求，以驗證實驗方法的正確性。 根據實驗結果顯示，本論文所提出之概念均能正確運作，有效降低調整防火牆所需之人工作業。在多路寬頻負載平衡器部分，本研究所提出之負載平衡方法，與round robin負載平衡方法相較之下，在最佳情況下，能有效提升約25%平均頻寬使用率，並降低約17.5%封包遺失率。 / Firewall is an important device that is responsible for securing internal network by separating Internet from Intranet, but here are several existing issues about the firewall. First, the firewall rules are set by the network admistrator manually. Along with the vigorous development of Internet technologies and great amount of applications of virtual technology in recent years. This work burdens the network adminstrator with a heavy workload. Second, the firewall is able to isolate the external network from harmful traffic, however, it can do nothing to the internal network. The common situation is to use IDS to detect the harmful packet, but it can only send an alert message to the adminstrater, no more actions can be done. Finally, most companies use several ISP connections to assure fault tolerance and use Multi-WAN load balancer to integrate those connections to enhance bandwidth utilization. But the number of WAN/LAN ports is set by the manufacturer, and the load balance algorithm is also limited by the manufacturer. It offers only a few algorithms (network-based features, round-robin, etc.), and there is no other way to provide more efficient algorithms. In order to resolve the mentioned problems, we propose an automatic firewall based Software Defined Network (SDN). We use Openflow switches to replace traditional firewalls, the system is able to learn the rules automaticlly by packet analysis during an observation interval. We aslo integrate Snort Intrusion Detection System (IDS) to localize the dangerous packets and block them immediately. Next, we propose an on-demand based dynamic firewall rules adjustment mechanism which is able to reduce management workload. Finally, we implement a Multi-WAN load balancer architecture and provide a more efficient load balance algorithm by collecting port usage and firewall rule information. In order to verify the proposed methods, we implement a SDN environment by using Linux Ubuntu servers with KVM, Open vSwitch and POX controller. According to the experiment result, it proves that the proposed method is able to reduce the firewall configuration effectively. In the Multi-WAN load balancer, experiment results show that our method outperforms round-robin argrithom in terms of average bandwidth utilization and packet loss rate by 25% and 17.5%, respectively.

最近，金融科技(FinTech)和行動金融服務，吸引越來越多的目光。新的創新金融科技服務，改變了金融服務的消費行為。行動網路的發展使人們能夠隨時隨地的享受行動銀行的服務已經是個不爭的事實。然而，由於無線網路先天的特性以及行動裝置的移動性，使行動金融的服務品質受到網路不穩定的影響。而且，隨著Bank 3.0時代的來臨，將會有大量的使用者同時使用行動金融服務，特別是在股市開盤以及重大訊息揭露的時候。因著大量使用者瞬間湧入，以及無線網路不穩定的影響，交易系統的效能很可能會時好時壞，所以無法滿足即時金融市場的需求。 本論文中，我們提出「行動銀行訊息即服務」的框架，使系統能夠很容易的水平擴充，並且能夠輕易的實現雙向通訊和雙向交易等多項行動金融服務。為了達到最少成本追求最大利益的目的，我們發展了能夠適應突發流量以及網路不穩定性的任務分配演算法，使得不用增加額外硬體成本的前提下改善系統效能。然後，為了實驗欲模擬大量行動裝置的使用者，我們觀察真實網路的特性並發明了網路延遲自相關模型來驗證我們提出的任務分配演算法。結果顯示，透過此任務分配演算法，確實能夠有效改善系統資源管理的能力。最後，本研究將系統佈署於真實網路環境當中，並且發現進行同樣實驗的結果與採用網路延遲自相關模型的實驗結果一致。因此，本研究間接驗證了網路自相關模型的正確性，以及證明本任務分配演算法，在突發流量和網路不穩定的即時行動金融服務環境下，能有效降低系統響應時間。 / FinTech (financial technology) and mobile financial services are getting more and more attention recently. New innovative FinTech services change the consumption behavior for financial services. It is an indisputable fact development of the mobile Internet allows people to enjoy mobile banking everywhere and anytime. However, due to the nature of wireless networking and the mobility of the mobile device, the quality of mobile financial service will be affected by network instability. Moreover, with the coming of Bank 3.0, a huge amount of users would be in the mobile service of finance simultaneously, especially when the instances of the stock market opening or disclosure of highly important financial message. As the result of bursty traffic and network instability, the performance of transaction system is up and down, making it tough to satisfy the demand of real-time financial markets. In this thesis, we propose a “Mobile Banking Messaging as a Service Framework” that can easily scale out and fulfill functions comprising Bilateral Communication, Bilateral Trading, and many other mobile financial services. To pursuit of the greatest benefit along with investment of the least resources, we develop the task assignment algorithm which can adapt the system to bursty traffic and unstable networks to improve performance for free. Then, in order to simulate a large number of mobile users, we observe the characteristic of real-world network delay and propose a network delay autocorrelation model to verify our task assignment algorithm. The results of experiment show that we could actually use our task assignment algorithm to improve the ability of the system to manage resource. Finally, we deploy our system in a real-world network delay environment and find that the results obtained in the real condition are the same with our simulation results. Therefore, this research can indirectly verify the correctness of the network delay autocorrelation model, and prove that our task assignment algorithm can effectively reduce the system response time for real-time mobile financial service system under bursty traffic and unstable networks.