Changes to Daylight Saving Time affecting IBM SDK for Java on Linux platforms
Information about the impact of the US Energy Policy Act of 2005, which changes the effective dates of US
Daylight Saving Time (DST) in 2007 for the US. Actions are required to address this issue in IBM SDKs and Java
Runtime Environments downloaded from IBM developerWorks.
Flash (Alert)
Audience
This Flash provides guidance to customers running Linux platform versions of the Java™ SDK and JRE downloaded
free of charge from the IBM developerWorks Web site, under the IBM License Agreement for Non-warranted Software.
Content
The passage of the Energy Policy Act of 2005 alters the Daylight Saving Time (DST) start and stop dates by
four weeks. Beginning in 2007, DST start and end dates will be:
Start date: Second Sunday of March
End date: First Sunday of November
As a result of this change, preventive maintenance actions will be required for the Java SDK/JRE and for Linux
operating systems.
The SDK/JRE Service Refreshes deliver the changes to the time zones in the United States, Canada,
Bermuda and the Bahamas taking effect on 11 March 2007. See
DST updates in Service Refreshes of Java SDKs and JREs
for a summary the DST-enabled Java refreshes and their DST content.
How do I know if my system could be affected?
All IBM-delivered releases of the SDK and Java Runtime Environment up to and including v5.0 will be affected
by this DST change, unless you are running with the latest Service Refreshes of the SDK/JRE delivered for Java
1.3.1, 1.4.2, and 5.0.
In addition, your Linux Operating Systems may also be affected.
What could happen if I do not update my systems?
Any US, Canada, Bermuda or Bahamas time-zone based application that uses time will be affected, in
particular during the additional weeks of extended Daylight Saving Time in March and November
starting in 2007.
In addition, systems located outside these affected North American zones which interconnect
with systems inside these zones may also be impacted. You should therefore assess them for impact,
considering, for example, the effects on end-users located in North America of time-sensitive applications
hosted in Europe or Asia which run transactions across global networks.
The following typical scenarios and operations will produce incorrect results as a consequence of using the time offset by one hour.
Time format and display.
Time zone name display.
Operations that check whether a particular date is in daylight savings.
Computations and/or business logic based on daylight savings time, etc.
Any of the above that run on a system whose time is set to a time zone
other than the affected North America time zone but does computations based on an affected North America time zone.
As an aid to assessing the impact on your applications of these DST changes in your environments, we are providing
a list of Java classes that perform date and time processing, together with some examples of what may happen
if your systems are not protected:
What do I need to do to protect my Java applications?
This Flash provides guidance to customers running Java applications on the Java 1.3.1, 1.4.2, and 5.0 SDK/JRE
releases. Appendix A contains a list of the Java SDK/JREs on Linux platforms that can be upgraded.
If you are running time-sensitive Java applications on the Java 1.2.2, 1.3.0, 1.4.0, or 1.4.1 SDK/JRE releases,
you are strongly advised to upgrade to the latest service refresh level of the Java 1.4.2 or 5.0 release.
If you have not already upgraded to the latest Service Refreshes of the 1.3.1, 1.4.2 or 5.0 releases, you should protect your
systems by upgrading them as detailed below.
We are also making available the IBM Time Zone Update Utility for Java to help customers apply the DST-related
fixes to an installed SDK/JRE in unusual situations where upgrading to the recommended Service Refresh is not a practical option.
In addition to upgrading your SDK/JRE, you may also need to apply a fixes to your Linux Operating Systems.
Service Refreshes of the SDK/JRE required
The strongly-recommended method to protect your systems is to upgrade them to the latest Java Service Refresh level,
using the downloads from the IBM developerWorks Web site.
The IBM Time Zone Update Utility for Java provides an alternative, secondary mechanism for applying the DST changes to your Java systems.
We understand that significant upgrades to installed systems may require substantial periods of planning and testing to minimise risks.
We recognise that situations may arise where these risks are high and we are offering a mitigation in the form of a utility program for
updating existing product bundles and installed binaries, including back-level service refreshes. This may be helpful in certain situations,
for example:
You need to apply the DST changes for Bermuda (and possibly other countries making late decisions to adjust their dates in step with the US)
prior to the availability of IBM Service Refreshes that contain these fixes. Changes needed for Western Austrailia or Brazil also come into this
category.
You have recently applied an i-fix or unique patch to your installed Java system, and a version of the SDK/JRE containing the both this patch
and the DST fixes is not available.
Your environment contains non-IBM products that package or prereq the SDK/JRE and your supplier is unable to upgrade them to a level that
supports a DST-enabled version of the SDK/JRE.
You are unable to accommodate an upgrade from Java 1.4.0 or Java 1.4.1, for which IBM Service Refreshes are unavailable.
You have multiple copies of the SDK/JRE installed and the Utility's "search and locate" capability would be useful, prior to upgrading
your systems by applying Java Service Refreshes.
The IBM Time Zone Update Utility for Java performs two tasks:
Searching your installation to detect and locate all the IBM-supplied Java SDKs/JREs on your systems. These may include SDKs/JREs
installed as part of IBM products, SDKs/JREs installed stand-alone, supplied as part of Linux distributions or from IBM developerWorks,
for example. For all instances discovered, it will report the JRE/SDK release/refresh level and identify the level of DST updating currently applied.
Locating the time zone information for each identified SDK/JRE and then modifying the package by replacing the current time zone data with the updated time zone data.
You can download the IBM Time Zone Update Utility for Java, at the URL here.
Further information about the Utility is contained in the README file.
Please be aware that if you have obtained your installed Java SDK/JRE free of charge from IBM developerWorks under an IBM License Agreement
for Non-warranted Software, then your usage of the IBM Time Zone Update Utility will be under similar license conditions.
The upgrades for the Operating Systems can be applied independently of the upgrades for the Java SDK/JRE.
The sequence in which they are applied is unimportant, but we recommend that you always apply both upgrades prior
to executing or testing applications that rely on continuity of correct time zone adjustments before and during the period
11 March 2007 to 1 April 2007.
Appendix: List of Java 1.3.1, 1.4.2 and 5.0 SDKs/JREs for Linux platforms
IBM 32-bit for Linux on Intel® architecture, Java 2 Technology Edition, Version 5.0
IBM 64-bit for Linux on AMD64/EM64T architecture, Java 2 Technology Edition, Version 5.0
IBM 32-bit for Linux on iSeries™ and pSeries™ architecture, Java 2 Technology Edition, Version 5.0
IBM 64-bit for Linux on iSeries and pSeries architecture, Java 2 Technology Edition, Version 5.0
IBM 31-bit for Linux on zSeries™ architecture, Java 2 Technology Edition, Version 5.0
IBM 64-bit for Linux on zSeries architecture, Java 2 Technology Edition, Version 5.0
IBM 64-bit SDK for Linux on AMD64 / EM64T architecture, Java 2 Technology Edition, Version 1.4.2
IBM 64-bit SDK for Linux on Intel Itanium® architecture, Java 2 Technology Edition, Version 1.4.2
IBM 32-bit SDK for Linux on Intel architecture, Java 2 Technology Edition, Version 1.4.2
IBM 32-bit SDK for Linux on iSeries and pSeries, Java 2 Technology Edition, Version 1.4.2
IBM 64-bit SDK for Linux on iSeries and pSeries, Java 2 Technology Edition, Version 1.4.2
IBM 31-bit SDK for Linux on zSeries, Java 2 Technology Edition, Version 1.4
IBM 64-bit SDK for Linux on zSeries, Java 2 Technology Edition, Version 1.4
IBM Developer Kit for Linux, Java 2 Technology Edition, Version 1.3.1, 32-bit version
IBM Developer Kit for Linux, Java 2 Technology Edition, Version 1.3.1, 32-bit version for POWER.
IBM Developer Kit for Linux, Java 2 Technology Edition, Version 1.3.1, 64-bit version
IBM zSeries Developer Kit for Linux, Java 2 Technology Edition, Version 1.3.1
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