Prefetching techniques for client server object-oriented database systems

The performance of many object-oriented database applications suffers from the page fetch latency which is determined by the expense of disk access. In this work we suggest several prefetching techniques to avoid, or at least to reduce, page fetch latency. In practice no prediction technique is perfect and no prefetching technique can entirely eliminate delay due to page fetch latency. Therefore we are interested in the trade-off between the level of accuracy required for obtaining good results in terms of elapsed time reduction and the processing overhead needed to achieve this level of accuracy. If prefetching accuracy is high then the total elapsed time of an application can be reduced significantly otherwise if the prefetching accuracy is low, many incorrect pages are prefetched and the extra load on the client, network, server and disks decreases the whole system performance. Access pattern of object-oriented databases are often complex and usually hard to predict accurately. The ..

Chinese window system with distributed fonts.

Cheang Sio Man.Thesis (M.Phil.)--Chinese University of Hong Kong, 1990.Bibliography: leaves [103-106]Chapter 1. --- THE EMERGENCE OF WINDOW SYSTEMS --- p.1-1Chapter 2. --- THE NEED OF A CHINESE WINDOW SYSTEM --- p.2-1Chapter 3. --- REQUIREMENTS AND DIFFICULTIES OF DEVELOPING A CHINESE WINDOW SYSTEM --- p.3-1Chapter 3.1. --- Input Method and Character Encoding --- p.3-1Chapter 3.2. --- Layout Direction and Formatting Mechanism --- p.3-3Chapter 3.3. --- Fonts --- p.3-3Chapter 3.3.1. --- Bitmap font --- p.3-4Chapter 3.3.2. --- Outline font --- p.3-6Chapter 4. --- A TRIAL TO OVERCOME THE DIFFICULTIES IN SUPPORTING CHINESE FONTS - OVERVIEW OF A CHINESE FONT SERVER SYSTEM --- p.4-1Chapter 4.1. --- Network Font Server --- p.4-3Chapter 4.2. --- Local Font Server --- p.4-4Chapter 4.3. --- Fonts --- p.4-5Chapter 4.3.1. --- Bitmap font --- p.4-5Chapter 4.3.1. --- Outline font --- p.4-5Chapter 4.4. --- Caching --- p.4-6Chapter 5. --- ORGANIZATION OF THE CHINESE FONT SERVER SYSTEM --- p.5-1Chapter 5.1. --- Communication Module --- p.5-2Chapter 5.1.1. --- Client connection request channel --- p.5-3Chapter 5.1.2. --- Client communication channels --- p.5-3Chapter 5.1.3. --- Network server connection channel --- p.5-4Chapter 5.2. --- Client Service Module --- p.5-7Chapter 5.2.1. --- Font manipulation module --- p.5-7Chapter 5.2.1.1. --- Request to open a new font --- p.5-8Chapter 5.2.1.2. --- Request to close an opened font --- p.5-8Chapter 5.2.1.3. --- Request to load a font character --- p.5-9Chapter 5.2.2. --- Cache module --- p.5-10Chapter 6. --- FROM THE CHINESE FONT SERVER SYSTEM TO A CHINESE WINDOW SYSTEM --- p.6-4Chapter 7. --- SCREEN FONTS --- p.7-1Chapter 7.1. --- Hand-edit --- p.7-3Chapter 7.2. --- Bitmap Scaling --- p.7-3Chapter 7.3. --- Outline Scaling --- p.7-5Chapter 7.4. --- Manual Refinement --- p.7-16Chapter 8. --- FONT CACHING --- p.8-1Chapter 8.1. --- Font Caching Strategies --- p.8-1Chapter 8.1.1. --- Pre-loading --- p.8-1Chapter 8.1.2. --- Fix-loading --- p.8-4Chapter 8.1.3. --- Demand loading --- p.8-6Chapter 8.1.3.1. --- Least Recently Used (LRU) replacement --- p.8-9Chapter 8.1.3.2. --- Least Frequently Used (LFU) replacement --- p.8-9Chapter 8.1.4. --- Hybrid loading --- p.8-16Chapter 8.2. --- Retrieval Method --- p.8-22Chapter 8.2.1. --- Binary searching --- p.8-22Chapter 8.2.2. --- Tree searching --- p.8-24Chapter 8.2.3. --- Hash searching --- p.8 26Chapter 8.3. --- Cache Expansion and Retraction --- p.8-33Chapter 9. --- AN EXPERIMENTAL CHINESE FONT SERVER SYSTEM - CAPABILITIES AND RESTRICTIONS --- p.9-1Chapter 9.1. --- Experimental Servers --- p.9-1Chapter 9.2. --- Programming Interfaces --- p.9-3Chapter 9.2.1. --- Connection request --- p.9-3Chapter 9.2.2. --- Open and close fonts --- p.9-4Chapter 9.2.3. --- Request to load cache --- p.9-5Chapter 9.2.4. --- Change the current font --- p.9-5Chapter 9.2.5. --- Request a font character --- p.9-5Chapter 9.3. --- Testing Applications --- p.9-6Chapter 9.4. --- Statistics --- p.9-8Chapter 9.4.1. --- Cache performance --- p.9-8Chapter 9.4.1.1. --- Tests --- p.9-8Chapter 9.4.1.2. --- Results --- p.9-10Chapter 9.4.1.3. --- Discussion --- p.9-10Chapter 9.4.2. --- Local Server Vs. Network Server --- p.9-12Chapter 9.4.2.1. --- Tests --- p.9-12Chapter 9.4.2.2. --- Results --- p.9-13Chapter 9.4.2.3. --- Discussion --- p.9-13Chapter 9.4.3. --- Outline Font --- p.9-14Chapter 9.4.3.1. --- Tests --- p.9-14Chapter 9.4.3.2. --- Results --- p.9-14Chapter 9.4.3.3. --- Discussion --- p.9-15Chapter 10. --- EPILOGUE --- p.10-1Chapter 10.1. --- Conclusion --- p.10-1Chapter 10.2. --- Future Extension --- p.10-

A new approach to the generation of Gray scale Chinese fonts.

by Poon Chi-cheung.Thesis (M.Phil.)--Chinese University of Hong Kong, 1993.Includes bibliographical references (leaves 82-84).AbstractAcknowledgmentsPrefaceChapter Chapter 1: --- Font Systems --- p.1Representations of Character Images --- p.1Characteristics of Chinese Font System --- p.3Large Character Set --- p.3Condensed Strokes --- p.4Low Repetition Rate --- p.5WYSIWYG (What You See Is What You Get) --- p.6Chapter Chapter 2: --- Human Visual System and Gray Scale Font --- p.9Human Visual System --- p.9Physiology --- p.9Spatial Frequencies --- p.10How much resolution is enough --- p.11Screen and Printer --- p.12Raster Display Devices --- p.13Printer --- p.14Resolution --- p.15Gray Scale Font --- p.15Generation of Gray Scale Font --- p.18Chapter Chapter 3: --- Digital Filtering Method for Gray Scale Font --- p.19Filtering Process --- p.19Weighted Functions --- p.21Generation of Gray Scale Character --- p.23Results --- p.24More Experiments --- p.24Problems --- p.26Speed and Storage --- p.26Impression of Strokes --- p.27Thin strokes in the small-size character --- p.30New Approach to Generate Gray Scale Font --- p.30Chapter Chapter 4: --- Rasterization Algorithms --- p.32Outline Font --- p.32TrueType Font --- p.33Scan Conversion --- p.35Basic Outline-to-Bitmap Conversion --- p.35Scan-converting Polygon --- p.36Rasterization of a character --- p.36Intersecting Points and Ranges --- p.37Straight Lines --- p.37Quadratic Bezier Curves --- p.38Implementation Techniques --- p.39Approximation of quadratic Bezier curve by straight lines --- p.39Simplification of the Filling Process --- p.41The Rasterization Algorithm --- p.45Chapter Chapter 5: --- Direct Rasterization with Gray Scale --- p.46Rasterization with Gray Scale --- p.46Determination of Gray Value of Boundary-pixel --- p.50Preliminary Results --- p.54Hinting --- p.56Rasterization with Hinting --- p.56Strokes Migration --- p.57Hints Finding --- p.59Chapter Chapter 6: --- Results and Conclusion --- p.62Quality --- p.66Comparison with Black-and-White Character --- p.66Hinted Against Unhinted --- p.71Generation Speeds --- p.75Discussion and Comments --- p.78Practical Font System --- p.79Conclusion --- p.80Bibliography --- p.8

Chinese outline fonts support in X Window System.

by Raymond Cheuk-kuen Chen.Thesis (M.Phil.)--Chinese University of Hong Kong, 1994.Includes bibliographical references (leaves 157-160).Chapter 1. --- INTRODUCTION --- p.8Chapter 1.1. --- Windowing System --- p.8Chapter 1.2. --- Fonts --- p.10Chapter 1.2.1. --- Bitmap Fonts --- p.11Chapter 1.2.2. --- Outline Fonts --- p.12Chapter 1.3. --- Different font support models --- p.15Chapter 1.3.1. --- Supported by applications --- p.15Chapter 1.3.2. --- Supported by windowing system --- p.17Chapter 1.3.'3. --- Supported by a dedicated server --- p.19Chapter 1.4. --- Issues of Chinese Font Support --- p.20Chapter 2. --- OVERVIEW OF X WINDOW SYSTEM --- p.22Chapter 2.1. --- Introduction --- p.22Chapter 2.2. --- Architecture --- p.23Chapter 2.3. --- Font Management in the X Window System --- p.23Chapter 2.3.1. --- Before X Version 11 Release5 --- p.24Chapter 2.3.2. --- In X Version 11 Release5 --- p.25Chapter 2.3.3. --- Portable Compiled Format --- p.25Chapter 2.3.4. --- Font Server --- p.26Chapter 2.3.5. --- Font Management Library --- p.28Chapter 2.4. --- Internal Code --- p.29Chapter 3. --- CHINESE FONT SERVER --- p.30Chapter 3.1. --- Motivation --- p.30Chapter 3.2. --- Font Server Architecture --- p.31Chapter 3.2.1. --- Device Independent Font Server layer(DIFS) --- p.32Chapter 3.2.2. --- Operating System layer(OS) --- p.32Chapter 3.2.3. --- Font Management Library(FML) --- p.33Chapter 3.2.4. --- Font Path Element --- p.34Chapter 3.2.5. --- Font File Renderer --- p.35Chapter 3.2.6. --- Font server Renderer --- p.36Chapter 3.3. --- Implementation of Chinese Font Server --- p.36Chapter 3.3.1. --- Font data and code set --- p.36Chapter 3.3.2. --- Registering a new font reader --- p.38Chapter 3.3.3. --- Font specific functions --- p.42Chapter 3.3.4. --- Load-All Scheme --- p.43Chapter 3.3.5. --- Demand-Loading Scheme --- p.44Chapter 3.3.6. --- Embedding of font rasterizer --- p.44Chapter 3.4. --- Test Results --- p.45Chapter 3.4.1. --- X Application Tests --- p.45Chapter 3.4.2. --- Demand-Loading Test --- p.49Chapter 3.5. --- Some Remarks --- p.53Chapter 4. --- OVERVIEW OF PRINTING SYSTEM --- p.54Chapter 4.1. --- Motivation --- p.54Chapter 4.2. --- Design Considerations --- p.56Chapter 4.2.1. --- Modification of the X server --- p.56Chapter 4.2.2. --- Embed the printing system into the font server --- p.57Chapter 4.2.3. --- Distributed Architecture --- p.58Chapter 4.3. --- System Architecture --- p.60Chapter 4.4. --- Printer Server --- p.61Chapter 4.5. --- Font Server --- p.63Chapter 4.6. --- Printing Services Protocols --- p.63Chapter 4.7. --- X Window System Server --- p.65Chapter 4.8. --- Printer Server Library --- p.65Chapter 4.9. --- Client Applications --- p.65Chapter 5. --- DESIGN AND IMPLEMENTATION OF A PRINTER SERVER --- p.67Chapter 5.1. --- Objects identification --- p.67Chapter 5.1.1. --- Dispatcher (dispatcher) --- p.68Chapter 5.1.2. --- Communication Channel (ComChannel) --- p.68Chapter 5.1.3. --- Font Cache Manager (FnCache) --- p.69Chapter 5.1.4. --- PrnFont (PrnFont) --- p.69Chapter 5.1.5. --- Per-Font Cache (CacheStruct) 一- --- p.70Chapter 5.1.6. --- Font Server (FnServer) --- p.71Chapter 5.1.7. --- Client Manager (LRUList) --- p.71Chapter 5.1.8. --- Client Record (ClientRec) --- p.71Chapter 5.1.9. --- Printer Driver (PrnDriver) --- p.71Chapter 5.1.10. --- Down Loaded Font Table (DownLoadedFont) --- p.72Chapter 5.1.11. --- Request Header (reqHeader) --- p.72Chapter 5.1.12. --- Generic Reply(replyGeneric) --- p.74Chapter 5.2. --- Objects Organization --- p.74Chapter 5.2.1. --- Server Control Subsystem --- p.75Chapter 5.2.2. --- Client Management Subsystem --- p.78Chapter 5.2.3. --- Request Handling Subsystem --- p.84Chapter 5.2.4. --- Font Managing Subsystem --- p.86Chapter 6. --- SAMPLE PRINTER DRIVER --- p.94Chapter 6.1. --- Printer Control Languages --- p.94Chapter 6.1.1. --- Structure of PCL Command --- p.95Chapter 6.1.2. --- PCL Command Example --- p.97Chapter 6.2. --- Printer Font Resources --- p.98Chapter 6.3. --- Traditional Font Handling Methods in a Printer Driver --- p.99Chapter 6.4. --- Soft Font Creation in PCL Printer --- p.101Chapter 6.4.1. --- Font ID number --- p.102Chapter 6.4.2. --- Font Descriptor --- p.102Chapter 6.4.3. --- Character Code - --- p.104Chapter 6.4.4. --- Character Descriptor --- p.105Chapter 6.4.5. --- Character Bitmap Data --- p.107Chapter 6.5. --- New font downloading schemes for double-byte fonts --- p.107Chapter 6.5.1. --- Terminology --- p.108Chapter 6.5.2. --- Underlying Concepts of Algorithm One --- p.109Chapter 6.5.3. --- Algorithm One --- p.111Chapter 6.5.3.1. --- Code Mapping --- p.112Chapter 6.5.3.2. --- Example --- p.114Chapter 6.5.3.3. --- Memory Consideration --- p.115Chapter 6.5.4. --- Algorithm Two --- p.117Chapter 7. --- EXPERIMENT RESULTS AND DISCUSSIONS --- p.121Chapter 7.1. --- Cache Test --- p.121Chapter 7.2. --- Printer Driver Test --- p.125Chapter 7.2.1. --- Testing with 10 points font --- p.126Chapter 7.2.2. --- Testing with 12 points font --- p.129Chapter 7.2.3. --- Testing with 15 points font --- p.131Chapter 7.2.4. --- Testing with 18 points font --- p.134Chapter 7.3. --- Time Measurement --- p.136Chapter 7.4. --- Discussion --- p.139Chapter 7.5. --- Further Improvement --- p.143Chapter 8. --- CONCLUSIONS --- p.145APPENDIX A. PRINTER DRIVER CLASS --- p.147APPENDIX B. SAMPLE OUTPUT --- p.149REFERENCES --- p.15