115 lines
4.2 KiB
Plaintext
115 lines
4.2 KiB
Plaintext
Copyright (C) 1999-2001, International Business Machines Corporation
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and others. All Rights Reserved.
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Readme file for ICU time zone data (source/tools/gentz)
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Alan Liu
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Last updated 2 Feb 2001
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RAW DATA
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--------
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The time zone data in ICU is taken from the UNIX data files at
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ftp://elsie.nci.nih.gov/pub/tzdata<year>. The other input to the
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process is an alias table, described below.
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BUILD PROCESS
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-------------
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Two tools are used to process the data into a format suitable for ICU:
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tz.pl directory of raw data files + tz.alias -> tz.txt
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gentz tz.txt -> tz.dat (memory mappable binary file)
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After gentz is run, standard ICU data tools are used to incorporate
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tz.dat into the icudata module. The tz.pl script is run manually;
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everything else is automatic.
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In order to incorporate the raw data from that source into ICU, take
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the following steps.
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1. Download the archive of current zone data. This should be a file
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named something like tzdata1999j.tar.gz. Use the URL listed above.
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2. Unpack the archive into a directory, retaining the name of the
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archive. For example, unpack tzdata1999j.tar.gz into tzdata1999j/.
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Place this directory anywhere; one option is to place it within
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source/tools/gentz.
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3. Run the perl script tz.pl, passing it the directory location as a
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command-line argument. On Windows system use the batch file
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tz.bat. Also specify one or more ourput files: .txt, .htm|.html,
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and .java.
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For ICU4C specify .txt; typically
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<icu>/source/data/misc/timezone.txt
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where icu is the ICU4C root directory. Double check that this is
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the correct location and file name; they change periodically.
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It is useful to generate an html file. After it is generated,
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review it for correctness.
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As the third argument, pass in "tz.java". This will generate a
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java source file that will be used to update the ICU4J data.
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4. Do a standard build. The build scripts will automatically detect
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that a new .txt file is present and rebuild the binary data (using
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gentz) from that.
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The .txt and .htm files and typically checked into CVS, whereas
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the raw data files are not, since they are readily available from the
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URL listed above.
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Additional steps are required to update the ICU4J data. First you
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must have a current, working installation of icu4j. These instructions
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will assume it is in directory "/icu4j".
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5. Copy the tz.java file generated in step 3 to /icu4j/tz.java.
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6. Change to the /icu4j directory and compile the tz.java file, with
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/icu4j/classes on the classpath.
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7. Run the resulting java program (again with /icu4j/classes on the
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classpath) and capture the output in a file named tz.tmp.
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8. Open /icu4j/src/com/ibm/util/TimeZoneData.java. Delete the section
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that starts with the line "BEGIN GENERATED SOURCE CODE" and ends
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with the line "END GENERATED SOURCE CODE". Replace it with the
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contents of tz.tmp. If there are extraneous control-M characters
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or other similar problems, fix them.
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9. Rebuild icu4j and make sure there are no build errors. Rerun all
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the tests in /icu4j/src/com/ibm/test/timezone and make sure they
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all pass. If all is well, check the new TimeZoneData.java into
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CVS.
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ALIAS TABLE
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-----------
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For backward compatibility, we define several three-letter IDs that
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have been used since early ICU and correspond to IDs used in old JDKs.
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These IDs are listed in tz.alias. The tz.pl script processes this
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alias table and issues errors if there are problems.
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IDS
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---
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All *system* zone IDs must consist only of characters in the invariant
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set. See utypes.h for an explanation of what this means. If an ID is
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encountered that contains a non-invariant character, tz.pl complains.
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Non-system zones may use non-invariant characters.
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Etc/GMT...
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----------
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Users may be confused by the fact that various zones with names of the
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form Etc/GMT+n appear to have an offset of the wrong sign. For
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example, Etc/GMT+8 is 8 hours *behind* GMT; that is, it corresponds to
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what one typically sees displayed as "GMT-8:00". The reason for this
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inversion is explained in the UNIX zone data file "etcetera".
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Briefly, this is done intentionally in order to comply with
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POSIX-style signedness. In ICU we reproduce the UNIX zone behavior
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faithfully, including this confusing aspect.
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