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An Evaluation of the Webdav Extensions to the HTTP Protocol

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An Evaluation of the Webdav Extensions to the HTTP Protocol 2000:138 MASTER'S THESIS An evaluation of the WebDAV extensions to the HTTP protocol Björn Nilsson Civilingenjörsprogrammet Institutionen för Systemteknik Avdelningen för Datorkommunikation 2000:138 • ISSN: 1402-1617 • ISRN: LTU-EX--00/138--SE An evaluation of the WebDAV extensions to the HTTP protocol Master’s Thesis in Computer Science Björn Nilsson January 2000 An evaluation of the WebDAV extensions to the HTTP protocol Abstract Abstract The HyperText Transfer Protocol (HTTP) is used for the most popular service on the Internet today – World Wide Web. WebDAV is a new extension to the HTTP protocol, which makes it possible to write, edit and share information across intranets and the Internet. In this Master’s Thesis, the WebDAV extensions are examined. A comparison between HTTP with WebDAV and the existing Internet protocols FTP and POP3 is done. Also a behavioral analysis of existing WebDAV applications is made. The conclusions are that HTTP with WebDAV extensions can replace both FTP and POP3. When using HTTP’s pipelining and persistent connections, better performance than with FTP is achieved. It seems like WebDAV can be used as a universal protocol for client-server solutions, gaining the advantages of HTTP such as encryption and caching. An evaluation of the WebDAV extensions to the HTTP protocol Preface Preface This Master’s Thesis has been made as the final part of my Master of Science degree in Computer Science and Engineering at Luleå University of Technology (LTU). The work has been carried out from September 1999 to January 2000 at Telia ProSoft AB in Malmö. I would like to thank my supervisor at Telia ProSoft, Anders Jönsson, for assistance and guidance throughout the work. I would also like to thank Lars-Åke Larzon at LTU who has been my examiner. Björn Nilsson Malmö, January 2000 An evaluation of the WebDAV extensions to the HTTP protocol Table of Contents Table of Contents 1 INTRODUCTION....................................................................................................................... 1 1.1 DESCRIPTION OF THE ASSIGNMENT .......................................................................................... 1 1.2 PURPOSE OF THE ASSIGNMENT ................................................................................................. 1 1.3 LIMITATIONS ............................................................................................................................. 2 1.4 STRUCTURE OF THE REPORT ..................................................................................................... 2 2 BACKGROUND ......................................................................................................................... 3 2.1 HTTP - HYPERTEXT TRANSFER PROTOCOL............................................................................ 3 2.1.1 Overview......................................................................................................................... 3 2.1.2 Methods........................................................................................................................... 3 2.1.3 Persistent connections and pipelining.......................................................................... 5 2.1.4 Byte range operations.................................................................................................... 6 2.1.5 Authentication ................................................................................................................ 6 2.1.6 Integrity.........................................................................................................................11 2.1.7 Confidentiality..............................................................................................................11 2.2 FTP – FILE TRANSFER PROTOCOL.........................................................................................12 2.2.1 Overview.......................................................................................................................12 2.2.2 Commands....................................................................................................................13 2.2.3 Authentication ..............................................................................................................14 2.2.4 Integrity.........................................................................................................................15 2.2.5 Confidentiality..............................................................................................................15 2.3 POP3 – POST OFFICE PROTOCOL...........................................................................................15 2.3.1 Overview.......................................................................................................................15 2.3.2 Commands....................................................................................................................16 2.3.3 Security issues..............................................................................................................17 3 WEBDAV...................................................................................................................................18 3.1 OVERWRITE PREVENTION.......................................................................................................18 3.2 PROPERTIES .............................................................................................................................21 3.3 NAME SPACE MANAGEMENT ..................................................................................................23 3.4 WORK IN PROGRESS ................................................................................................................25 3.4.1 Advanced Collections..................................................................................................25 3.4.2 Versioning.....................................................................................................................27 3.4.3 Searching and Locating...............................................................................................28 3.4.4 Access Control..............................................................................................................29 3.5 WEBDAV SERVERS................................................................................................................31 3.6 SECURITY CONSIDERATIONS ..................................................................................................31 4 ANALYSIS OF WEBDAV......................................................................................................33 4.1 FILE TRANSFERS......................................................................................................................33 4.1.1 Testbed setup................................................................................................................33 4.1.2 Performance.................................................................................................................33 4.1.3 Functionality................................................................................................................39 4.1.4 Security.........................................................................................................................40 4.2 MAIL READING........................................................................................................................40 4.2.1 Overview.......................................................................................................................40 4.2.2 Properties .....................................................................................................................40 4.2.3 Functionality of the client............................................................................................41 4.3 BEHAVIOR OF COMMON WEBDAV APPLICATIONS ...............................................................42 4.3.1 Web Folders.................................................................................................................42 4.3.2 Office 2000 ...................................................................................................................46 5 CONCLUSIONS .......................................................................................................................50 6 REFERENCES..........................................................................................................................51 APPENDIX A – GLOSSARY...........................................................................................................53 An evaluation of the WebDAV extensions to the HTTP protocol Introduction 1 Introduction From 1994 up until today, the World Wide Web has developed from a forum in which scientists exchanged their research reports into a center where everyone has a Web page. A large part of the television commercials today include a URL. In order for this to happen, the architecture behind Internet has expanded tremendously from its original specification. The core of the Web is the Hypertext Markup Language (HTML), a markup language to show and format text in web browsers. Originally, the language only supported linking to other pages, inclusion of pictures and text formatting like bold, italics and headlines. In several steps it expanded with functions such as frames, forms, script languages and style sheets. Now it is common to create connections between Web pages and databases to show the contents dynamically.
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