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Database File System

An Alternative to Hierarchy Based File Systems

O. Gorter

University of Twente

August 

Database File System — An Alternative to Hierarchy Based File Systems

Author: O. Gorter

Supervisors: H. Scholten, B. van Dijk, P.G. Jansen

Copyright C 2003, 2004 O. Gorter

University of Twente, Computer Sciences

Enschede, the Netherlands

http://ozy.student.utwente.nl

Database File System

O. Gorter III

Abstract

——

Over 30 years people worked with hierarchical file systems; file systems based on directories and files.

These file systems have proven their use, but today, with gigabytes of storage and millions of files,

managing files with directories is becoming increasingly difficult. This research presents an alternative to

hierarchy based file systems. At the basis of this system is a unified approach to all properties of a file.

Combining this approach with a drag and drop user interface creates an alternative that is as usable as

directories, while in the mean time going well beyond the expressive powers found in hierarchy based file

systems. The end result is a file system which makes working with files a lot easier on the user. Emphasis

of this systems lies at the user and not the operating system, therefor files like shared libraries do not

show up in this system, these should be stored by other means. The implementation is an abstraction

layer above a hierarchy based file system and the two work together in such a way that a high level of

backwards compatibility is achieved, not rendering current programs useless. This setup has been tested

on users and the results indicate that this system is a very valid alternative to hierarchical file systems.

Database File System

O. Gorter IV

Foreword

——

This document is my graduation report for the University of Twente and is all about the Database File System

(dbfs); my graduation project. Because this document is mainly written for the University some content might

not be relevant to all readers. For those only interested in what the dbfs is, I recommend reading chapters

“Introduction” and “Database File System – Overview”.

The document assumes the reader has a fair knowledge of current computer systems and related terms. As

a reference, most terms are explained in the chapter “List of Used Terms and Abbreviations”, related

research and documents are in chapter “References”.

All of the research in this document is done from a user and user interface point of view. This is different from

most research on file systems, and explains why compared to these writings, seemingly important information

is left out, while almost trivial points are discussed in depth.

For those who obtained this document digitally, it is available in two versions, one optimized for screen reading

and one optimized for print (dbfs-screen.pdf and dbfs-paper.pdf resp.). The screen version has a 4 : 3

layout with a slightly larger font and is definitely recommended when reading from a monitor.

Thanks

For all their advice, support, help and faith, I would like to thank Hans Scholten; Betsy van Dijk; Pierre Jansen;

all the others on the dies group; my flatmates; and my family.

Also a special thanks goes out to all the usability testers, whom I will only mention by first name, but you know

who you are.

Database File System Foreword

O. Gorter V

Albert

Bas

Coen

Edgar

Epco

Erwin

Gerben

Harry

Igor

Ivo

Janneke

Joris

Jeshua

Marc

Martin

Stefan

Tim

Rutger

Database File System

O. Gorter VI

Contents

——

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . III

Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IV

 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

. Relevance 

 Hierachy Based File Systems – Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

. Properties of Hierarchy Based File Systems 

 Database File System – Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

. Relevance 

. Categorisation 

 Database File System – Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

. User Interaction 

 Database File System – Internals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

. Server 

. Client 

. Graphical User Interface 

 Usability Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

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O. Gorter VII

. Objective 

. Method 

. Results 

 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

. Future Work and Recommendations 

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Related Work 

Related Software 

Other References 

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

List of Used Terms and Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

A Assignment – Database File System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

B Dutch Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

C Test 1 – Email . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

D Test 2 – Arrange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

E Interview 1 – Email Normal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

F Interview 1 – Email Dbfs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

G Interview 2 – Arrange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

H DBFS Source File Listing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

Database File System

O. Gorter 

Introduction

—1—

File access and file management is something we do on our pcs every day; lots of computer time is spend

browsing our directories and opening and saving files, or worse, finding files. The basis for this system was laid

down over 30 years ago, and since graphical user interfaces became main-stream not much has changed. Yet

computer hardware has become increasingly more powerful and limitations that existed are no longer there. Still

the biggest change in our file interface is preview (thumbnail) rendering in the file manager.

A new file system can introduce better metaphors on working with files and can make use of advanced gui

techniques not available when hierarchical file systems came into use. It can bring the focus of the file system

to the user, instead of the computer, and in doing so change how we think about files and the whole computer.

It can be an enabler for a new and more up-to-date user-oriented computer interface.

And this is exactly what this research is about, trying to bring file management to the user. It does so by providing

a search based file interface, based on file meta-data, and it introduces keywords in favor off directories. Being

user oriented means only storing documents and not system files like shared libraries. Where documents are all

files the user is interested in, this can be a msword document, but also images, music and more.

Because the systems searches and modifies meta-data, all meta-data can be treated equally, meaning that

security, ownership and sharing are just as easy to manipulate as the file-name or keywords. And without

directories the systems does away with locations, instead it can categorize documents in a more powerful way.

Without locations on a file system, we can have applications that just save everything you do. The save button

can be completely removed from every interface element of the computer, doing away with the dualistic nature

Database File System Introduction

O. Gorter 

of how we use a computer today; creating a system where there is no longer a difference on what you see on

your screen and what is stored on the hard disk.

. Relevance

In the “References” we see more works that try to extend the file system with searching. And it is a very

relevant idea, because lately it is sometimes easier to find things on the enormous internet, using google, then

on your own hard drive. You can always use a search, but it is slow and not very ubiquitous.

This is known by the two mayor os software vendors, Microsoft and Apple: both announced a more integrated

search using some sort of database. But we will have to wait a while until the new products are available.

But already we can see what a non-hierarchical approach to files can do when we look at specialized applications

like iPhoto or Adobe Photoshop Album for digital photo management, or iTunes for digital music.