支援行動內容分享的Upload-on-Demand方法

隨著通訊技術及行動裝置不斷演進，行動內容分享已是最受歡迎的行動應用之一。主從式的行動內容分享服務架構，可分為傳統的主從式架構及proxy 輔助的主從式架構。傳統的主從式架構，要事先將分享的內容上傳至伺服器。proxy 輔助的主從式架構，利用proxy 轉送或代收內容。我們發現這些方法都會將內容上傳至伺服器。我們也發現，如果上傳的內容沒有任何人有興趣想要下載，就會造成網路頻寬的浪費。因此，在無線/行動頻寬有限的情況下，如何有效的使用頻寬避免浪費，將是提供行動內容分享服務的重要課題。節省頻寬最有效的方法是，避免上傳沒有用的內容，也就是有需要才上傳。因此，本論文採用需要才上傳(Upload-on-Demand, UoD)的概念，設計並發展UoD 內容分享方法。在UoD 系統中，使用者只上傳分享內容的Metadata 及預覽內容，而不是全部的內容。當其他使用者要求下載內容時，才將完整的內容上傳至UoD 系統的儲存空間。如此，將可有效的使用頻寬，提供優質的內容分享服務。為了探討UoD 內容分享服務的效能，我們建構實際的網路測試環境。首先，我們探討使用UoD 策略對網路頻寬需求的影響。其次，我們探討使用者資訊更新頻率對內容下載延遲的影響。此外，我們也提出UoD 資訊更新策略來決定最佳的資訊更新頻率，以符合使用者對下載內容延遲的要求並節省網路頻寬。

關鍵字

行動內容分享；主從式架構；網路頻寬； Upload-on-Demand (UoD) ；延遲

並列摘要

As communication technologies and mobile devices keep improving, mobile content sharing has become one of the most popular mobile applications. The client-server content sharing service architecture can be divided into traditional client-server architecture and proxy-assisted client-server architecture. In the traditional client-server architecture, we need to upload the shared content to the server. In the proxy-assisted client-server architecture, we can utilize the proxy to transfer or receive the shared content. It shows that both of them should upload the whole content to the server. It also reveals that when the uploaded content is not downloaded by other users, this will result in the waste of the network bandwidth. Therefore, how to effectively utilize the network bandwidth when the wireless/ mobile bandwidth is limited will be an important task for providing the mobile content sharing service. The best way to save bandwidth is to avoid uploading unnecessary content. That is, upload the content only when it is requested. Hence, we adopt the concept of Upload-on-Demand (UoD) to create and develop a UoD content sharing method. In the UoD system, the user merely uploads the metadata and the preview of shared content, instead of uploading the whole content. We upload the whole content on the storage of UoD system only when other users request the download of such content. In this way, we can utilize effectively the bandwidth and provide a better content sharing service. In order to analyze the performance of the UoD system, we build a practical network test environment. At first, we study the impact of UoD strategy on the demand of network bandwidth. Secondly, we examine the influence of update frequency on download delay problems. Furthermore, we suggest a new strategy for UoD information update by deciding the best update frequency to satisfy the users' request of download delay and to save the bandwidth.

並列關鍵字

Mobile content sharing ； Client-server architecture ； Network bandwidth ； Upload-on-Demand (UoD) ； Delay

國際替代計量

支援行動內容分享的Upload-on-Demand方法

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