隨著網路的快速發展，有越來越多的資訊可以放在網路上與其他人一同分享，所以對於網路資源的管理也顯得越來越重要了。目錄 (directory) 提供了一些方便及有效率的方法來儲存並管理這些資訊，並且給一些應用程式使用以提供所謂的目錄服務 (directory service) 。為了統一對不同的 directory 的存取，IETF 提出了一種新的 directory 存取的協定 -- Lightweight Directory Access Protocol (LDAP)。在這篇論文中，我們研究並討論 LDAP 如何支援並提供有效率的 directory service。
我們首先討論directory及傳統資料庫的不同並且去比較 LDAP 及 SQL 的效能，包括搜尋資料、新增資料的效能以及快取記憶體 (cache) 對 LDAP 的影響。接下來我們討論 LDAP 在分散式環境下的一些議題。首先，我們討論在 LDAP 中資料一致性 (data consistency) 的問題並提出我們的解決方法。接下來，我們提出一個建造 LDAP 虛擬伺服器 (virtual server) 的方法來提升整個系統的效能。

With the vast advances of the Internet, increasing information is placed on the Internet and can be shared with others. The management of the network resources is getting more and more important. Directories can provide an efficiency and convenient way to store and manage information, and enable a new kind of applications, called directory services. To unify the access to different directories, IETF proposes the Lightweight Directory Access Protocol (LDAP). In this thesis, we study LDAP and discuss how to support efficient directory services.
We first study the differences between a directory and a database, and compare the performance of LDAP and SQL. The features compared include the search and add efficiency and cache effects. Next, we study LDAP in distributed environments. First, we examine the problem of data consistency in LDAP and propose our solution. We then discuss how to build a LDAP virtual server, which uses multiple real machines to form a cluster to balance the load and improve the performance.

[1] Bruce Markey, "A System Administrator's View of LDAP", http://people.netscape.com/bjm/whyLDAP.html
[2] Caroline Rose, "Directories and LDAP", http://developer.netscape.com/viewsource/rose_ldap.html
[3] Craig Richmond , "Setting up a basic DNS server for a domain", http://www.ludd.luth.se/~kavli/BIND-FAQ.html#[1]
[4] Ellen Stokes and Gordon Good, "The LDUP Replication Update Protocol", Internet draft draft-ietf-ldup-protocol-01.txt, March 2000
[5] Gordon Benett, "LDAP: A Next Generation Directory Protocol", http://idm.internet.com/foundation/ldap.html
[6] Howes, T., Kille, S., and Yeong, W., "Lightweight Directory Access Protocol", RFC 1777, March 1995
[7] Howes, T., Kille, S., and Yeong, W., "Lightweight Directory Access Protocol (v3)", RFC 2251, December 1997
[8] Innosoft Directory Services, http://www3.innosoft.com/index-text.html
[9] Microsoft Active Directory Service, http://www.microsoft.com/windows2000/library/technologies/activedirectory/default.asp
[10] Netscape Directory Server, http://home.netscape.com/directory/v4.0/index.html
[11] Novell Directory Service, http:// www.novell.com/products/nds/index.html
[12] Rawn Shah, "LDAP in action", http://www.windowstechedge.com/wte/wte-1999-07/wte-07-ldap_1.html, July 1999
[13] S. Legg, Telstra, and A. Payne, "LDUP Update Reconciliation Procedures", Internet draft draft-ietf-ldup-urp-02.txt, October 1999
[14] Sophie Cluet, Olga Kapitskaia, and Divesh Srivastava, "Using LDAP Directory Caches", PODS '99 Philadelphia PA, ACM, 1999
[15] Sun Microsystem, http://www.sun.com, July 1999
[16] "The Directory: Overview of Concepts, Models and Service", CCITT Recommendation X.500, 1988
[17] The Internet Engineering Task Force (IETF), http://www.ietf.org
[18] The OpenLDAP Project, http://www.openldap.org/
[19] Timothy A Howes, "An X.500 and LDAP Database: Design and Implementation", http://www.umich.edu/~dirsvcs/ldap/doc/index.html
[20] Timothy A. Howes, "The Lightweight Directory Access Protocol: X.500 Lite", Center for Information Technology Intergration, University of Michigan, July, 1995
[21] University of Michigan LDAP Repository, http://www.umich.edu/~rsug/ldap/
[22] Vesna Hassler, "X.500 and LDAP Security: A Comparative Overview", IEEE Network, November/December 1999, page 54-64
[23] Wensong Zhang, Shiyao Jin, Quanyuan Wu, "Creating Linux Virtual Servers", http://www.ntua.gr/lvsp/linuxexpo.html