icu overview: the open source unicode library
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Agenda Background Information What is ICU? Architecture Overview ICU Overview Agenda Background Information What is ICU? Architecture Overview Significant New ICU Features References Q and A 28th Internationalization and Unicode Conference 28th Internationalization and Unicode Conference Orlando, Florida, September, 2005TRANSCRIPT
28th Internationalization and Unicode Conference © 2005 IBM Corporation
ICU Overview:The Open Source Unicode Library
George RhotenIBM Globalization Center of Competency
ICU Overview: The Open Source Unicode Library
Orlando, Florida, September, 2005228th Internationalization and Unicode Conference
Agenda
Background Information What is ICU? Architecture Overview
– Significant New ICU Features
References Q and A
ICU Overview: The Open Source Unicode Library
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Why Globalization?
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Unicode
Handles all modern world languages Efficient and effective processing Lossless data exchange Enables single-binary global software But… all languages large, complex standard⇒
– 1,400 pages + Annexes + additional standards
– 96,000+ characters
– Major update every 3 years
– Minor update about once a year
– 70 character properties, many multi-valued
– Affects many processes: display, line-break, regular expressions, …
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Internationalization, Localization & Locales
Requirements vary widely across languages & countries– Sorting
– Text searching
– Line breaks
– Date/time/number/currency formatting
– Codepage conversion
– …and so on
Performance is key– It is easy to do the right thing
– It is hard to do it fast
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What is ICU?
International Components for Unicode Globalization / Unicode / Locales Mature, widely used set of C/C++ and Java libraries
– Basis for Java 1.1 internationalization, but goes far beyond Java 1.1 Very portable – identical results on all platforms / programming
languages– C/C++: 30+ platforms/compilers– Java: IBM & Sun JDK– You can use: C/C++ (ICU4C), Java (ICU4J), C/C++ with Java (ICU4JNI)
Full threading model Customizable Modular Open source – but non-restrictive
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Who uses ICU?
Products Within IBM– All 5 major software brands– Many other related software applications– Used on all IBM operating systems
Other Companies and Organizations– Adobe, Apple (Mac OS X), Avaya, BEA, BroadJump, Business
Objects, Caris, CERN, Cognos, Debian Linux, Gentoo Linux, HP, Home Depot, Inktomi, JD Edwards, Macromedia, Mathworks, MKS, Mozilla, NCR, OpenOffice, Parrot, PayPal, Python, QNX, Rogue Wave, SAP, Siebel, SIL, Software AG, Sun Microsystems (Solaris, Java), SuSE Linux, Sybase, Virage, webMethods, Wine, Leica Geosystems GIS & Mapping LLC., Xerox, Yahoo!...and many more
ICU Overview: The Open Source Unicode Library
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ICU Features
Unicode text handling Charset conversions (700+) Collation & Searching Locales from CLDR (250+) Resource Bundles Calendar & Time zones Complex-text layout engine Unicode Regular Expressions
Breaks: word, line, … Formatting
– Date & time– Messages– Numbers & currencies
Transforms– Normalization– Casing– Transliterations
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Architecture Overview 1
Locale Based Services– Locale is an identifier, not a container– Keywords for variants: de@collation=phonebook
Resource inheritance: shared resources
root
en
US IE
de
DE CH
zh
Hant Hans
TW CN TWCN
Language
Script
Region
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Architecture Overview 2
Open and Close Service Model
– Open a service object, use it many times, close it when done
– Better performance by avoiding setup costs per operation
ICU Threading Model
– Multiple service objects in use simultaneouslywith same or different attributes
– Large resources shared in read-only cache
– Compatible with Java threading model
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Architecture Overview 3
Data Driven Services– Customize at build-time or run-time
– Interchange with other platforms;• same results on each
– Rule-based• Collation, Word-breaks, Transforms
– Pattern-based• Date/Time/Number/Message formatting
– Table-based• Character Conversion
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Architecture Overview – ICU4C
Simple Error Handling– Thread safe– Works in C and C++
C/C++ subset for portability Version Management
– Multiple versions of ICU4C in the same process memory space– Data and library versioning
String Buffer Management– Preflighting and overflow protection
Flexible– Allows Loading and Unloading ICU4C libraries– Runtime settable memory allocation and mutex functions
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Architecture Overview – ICU4J
Supplement for Java Core globalization (no character conversion or
regular expressions)– We do supply complex text support for Sun
Modularized: products may add just needed functionality
Usually drop-in replacement for JDK functionality– Changing the import statements is usually all that is
needed
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ICU4J: Supplement for Java
CLDR (Common Locale Data Repository)– More fully supported locales than Java
Up-to-date globalization: standards-compliant; latest Unicode– Supplementary character (GB 18030, JIS X 213, HKSCS)
• Java 5 adds handling of supplementary characters
– Full properties – JDK has only a fraction
– Unicode Collation Algorithm
– Local calendars (Islamic, Japan,…); more time zone localizations
– Currencies, String Search, Internationalized Domain Names
– Transforms: Case, Scripts, Normalization
Much shorter release cycle and quicker support for Unicode standard
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Unicode Text Handling
C (UTF-16)– UChar*: null-terminated or with length
C++ (UTF-16)– UnicodeString: full featured string class
Java (UTF-16BE)– Uses java.lang.String and adds utilities
All handle supplementary characters– Required for GB 18030 and JIS 213 repertoire
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Unicode Text Handling 2
All Unicode 4.1 properties– direct API
• values, names, enumerations– UnicodeSet
• Fast, compact set operations (union, intersection, …)• Pattern-based (both Perl & POSIX syntax for properties)
– \p{greek} vs. [:greek:]• All properties:
– [\p{lowercase}-[a-z]]– [\p{greek} & \p{uppercase}]
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Recent Additions
Conforms to CLDR 1.3– Adds many translated terms for languages, scripts, regions,
currencies, and time zones.
– Access to more CLDR items
Support for Unicode interpretation of POSIX properties Charset detection API (ICU4J only) Better modularization for memory constrained environments
(ICU4C only)
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Character Set Conversion
Precise alias information:– When you ask for “Shift-JIS”, you can request the precise definition by
platform (e.g. Windows, IBM, Java, … ) Buffer management
– API automatically handles characters that cross buffers– Can provide offset mappings between byte buffer and UChar buffer
Runtime customizations allowed for:– illegal sequences– undefined characters
Unicode Text Compression – SCSU, BOCU-1 Consistent conversion results across platforms You can use more character sets at runtime or build time
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Collation: Sorting, Searching and Matching
Fast international comparison for string search; fully UCA compliant– Compressed sort keys, optimized string comparison, sublinear
string search– Incremental sortkeys used for radix sorting
Precise binary sortkey stability over time (library versioning) Fully data driven
– Many common rules provided Runtime and build time rule customizations
– strength, normalization, upper vs. lowercase first, ignore punctuation, numeric, …
– Only delta from UCA is needed for rule customization
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Calendar & Time Zones
International Calendars – Islamic, Buddhist, Hebrew, Japanese – Required for correct presentation of dates in some countries
Olson timezone support with localizations Recent Additions:
– Many more time zone localizations
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Formatting
Date & time: 8 formats per locale by default Messages
– Completely localizable, plural support Numbers & currencies
– Scientific Notation, Spelled-out (checks, etc.)– Full Orthogonal Currency support
• INR In Hindi:• INR In English: Rs. 1,234.57• INR In German: Rs. 1.234,57
Recent Additions– List available currencies API– Short and stand-alone month/day names
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Transforms
Unicode Normalization– Highly optimized for performance
– performance utilities: concatenation, detection, comparison
Casing (upper, lower, title, folding) General Transforms
– Script transliterations
– Half-width/Full-width, Hex, etc.
– Chain transforms together, filter source characters
– Rule-based, customizable at runtime.
String Prep: NFS, Internationalized Domain Names (IDN)
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Segmentation: word, line & sentence
Fast state-table implementation Customizable
– Rule-based – customizable at runtime
– Special customizations, e.g. Thai
Recent Additions:– Uses new UText API
• Discontinuous text• Buffering• Usable with UTF-8, UTF-16 or UTF-32
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Unicode Regular Expressions
Full Regex Implementation– C/C++ only: Java 1.4 has own package (though not as
powerful)
All Unicode 4.1 Properties– Supported through UnicodeSet
Good performance– Competitive with non-Unicode regex
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Complex-text layout engine
Glyph processing, positioning & adjustment– Ligature substitution, contextual forms, kerning, accent placement, bidi scripts,
etc. Support for:
– Information for drawing– Caret Display– Hit Testing– Selection Highlighting– Caret Movement– Layout Metrics– Line Break– Canonical Equivalence: a + ´ or á
Recent Additions:– Support for more complex scripts
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References
ICU main site:– http://www.ibm.com/software/globalization/icu/
– Links to• Download ICU• User Guide, Technical FAQ, Support, Bug Reports, Demonstrations
ICU support site:– http://icu.sourceforge.net/
Unicode Consortium– http://www.unicode.org/
• Unicode glossary, Unicode character database
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Questions and Answers