近年來網際網路日益的蓬勃發展與深入影響人們的生活。由於對於網路的需求性日益增長，因此人們需要一個既快速又便捷並可信賴的方法去獲得他們想要的資訊。LDAP是一個提供目錄服務的伺服器，它主要是提供一個快速且方便的服務讓人們搜尋他們所想要的資訊。通常我們會用許多的LDAP伺服器來管理大量的資料。並且使用LDAP代理人伺服器處理這些LDAP伺服器之間的溝通。LDAP代理人伺服器提供許多有用的機制，例如聰明的權限管理、額外的權限認證、與資料屬性的轉換等等。而現今的LDAP代理人伺服器並沒有特別對於它與後端目錄服務伺服器之間溝通上花費的時間做最佳化的處理。在這篇論文中，我們提出一個名稱為LDAP快取代理伺服器的系統，它的主要功能為將經常被搜尋的資料儲存在靠近使用者端的LDAP代理伺服器中。當使用者所搜尋的資料已經存在LDAP代理伺服器中則能迅速的取得所需的資料。
在這篇論文中，首先說明我們的LDAP快取代裡人伺服器的組織架構。接者介紹我們針對這個快取代裡人伺服器的表現所設計的實驗環境。然後比較LDAP快取代裡人伺服器與LDAP代理人伺服器在搜尋效能上的表現；包括快取誤差比率與LDAP代理伺服器的基本功能。我們的實驗結果指出當有足夠快取誤差比率時，透過使用我們所提出的LDAP快取代裡人伺服器會提升整體LDAP伺服器在搜尋上的表現。

Today, the Internet is penetrating into and affecting people’s life. As more people are on the network, the need for a quick, convenient and reliable way to obtaining information of one’s desire is soaring. LDAP is a directory server which allows people to look up information quickly and easily. Usually, groups of LDAP servers are used for storing magnitude data. To facilitate the communication and conversion between them, a mediator called LDAP Proxy is often used. LDAP Proxies provide many attractive functions, such as smart access control, external authentication, attribute conversion, etc. Unfortunately, current LDAP Proxies do not tackle the latency problem in accessing the backend directories. In this thesis, we propose a system called LDAP Cache Proxy, which incorporates caches into LDAP Proxies to store the most frequently accessed directory information closer to the clients.
We first describe our LDAP Cache Proxy architecture. We then introduce the experimental environment that we used to evaluate the performance of our proxy. The performance of LDAP Proxy and LDAP Cache Proxy is compared from different aspects, including cache hit ratios and LDAP Proxy server functions. Our experimental results show that when cache ratio is high enough, the overall LDAP performance will be improved using our LDAP Cache Proxy.

[1] Howes, T., Kille, S., and Yeong, W., “Lightweight Directory Access Protocol”, RFC 1777, March 1995
[2] Howes, T., Kille, S., and Yeong, W., “The String Representation of Standard Attribute Syntaxes”, RFC 1778, March 1995
[3] Howes, T., Kille, S., and Yeong, W., “Lightweight Directory Access Protocol (v3)”, RFC 2251, December 1997
[4] Bradner, S. “OSI connectionless transport services on top of UDP Applicability Statement for Historic Status”, RFC 2556, March 1999
[5] “Innosoft's LDAP World Implementation Survey”, http://www.innosoft.com/ldap_survey/lico.html
[6] Vesna Hassler, “X.500 and LDAP Security: A Comparative Overview”, IEEE Network, November/December 1999, page 54-64
[7] “Innosoft LDAP Proxy Server (ILPS)”, http://www.innosoft.com/directory_solutions/ids-products.html
[8] “MaXware Virtual Directory”, http://www.maxware.no/DataSheets/MVD-short.htm
[9] “NEXOR Directory Boundary Agent”, http://www.nexor.com/products/dba.htm
[10] Vesna Hassler, “X.500 and LDAP Security: A Comparative Overview”, IEEE Network, November/December 1999, page 54-64
[11] Netscape Directory Server, http://home.netscape.com/directory/v4.0/index.html
[12] The OpenLDAP Project, http://www.openldap.org/
[13] Novell Directory Service, http:// www.novell.com/products/nds/index.html
[14] LDBM overview, http://www.pyrenet.fr:457/NET_ldap/ldapC.db_ldbm_overview.html