Apache POI, a project run by the Apache Software Foundation, and previously a sub-project of the Jakarta Project, provides pure Java libraries for reading and writing files in Microsoft Office formats, such as Word, PowerPoint and Excel.

History and roadmap

The name was originally an acronym for "Poor Obfuscation Implementation",^[1] referring humorously to the fact that the file formats seemed to be deliberately obfuscated, but poorly, since they were successfully reverse-engineered. This expansion ? and those of the similar names for the various sub-projects ? were removed from the official web-pages in order to better market the tools to businesses who would not consider such humour appropriate. The authors also noted the existence of the Hawaiian poi dish, made of mashed taro root, which had similarly derogatory connotations.^[2]

Office Open XML support

Work is underway to support the Office Open XML file formats. The work is currently in an SVN branch, and is expected to become POI 3.5. The targeted final release date was the summer 2008^[3], but although development has progressed steadily, the release has not shipped yet.

This work remains controversial and tentative due to questions regarding Microsoft's Open Specification Promise patent license.^[4]

Architecture

The Apache POI project contains the following subcomponents:

• POIFS (Poor Obfuscation Implementation File System) ? This component reads and writes Microsoft's OLE 2 Compound document format. Since all Microsoft Office files are OLE 2 files, this component is the basic building block of all the other POI elements. POIFS can therefore be used to read a wider variety of files, beyond those whose explicit decoders are already written in POI.
• HSSF (Horrible SpreadSheet Format) ? reads and writes Microsoft Excel (XLS) format files. It can read files written by Excel 97 onwards; this file format is known as the BIFF 8 format. As the Excel file format is complex and contains a number of tricky characteristics, some of the more advanced features cannot be read. For example, POI is unable to open spreadsheets that have filters or views .
• XSSF (XML SpreadSheet Format) ? reads and writes Microsoft Excel OOXML (XLSX) format files ? 3.5 branch only. Similar feature set to HSSF, but for Office Open XML files.
• HPSF (Horrible Property Set Format) ? reads "Document Summary" information from Microsoft Office files. This is essentially the information that one can see by using the File|Properties menu item within an Office application.
• HWPF (Horrible Word Processor Format) ? aims to read and write Microsoft Word 97 (DOC) format files. This component is in initial stages of development.
• HSLF (Horrible Slide Layout Format) ? is a pure Java implementation for Microsoft PowerPoint files. This provides the ability to read, create and edit presentations (though some things are easier to do than others)
• HDGF (Horrible DiaGram Format) ? is an initial pure Java implementation for Microsoft Visio binary files. It provides an ability to read the low level contents of the files.
• HPBF - is a pure Java implementation for Microsoft Publisher files
• HSMF - is a pure Java implementation for Microsoft Outlook MSG files

Currently (as of April, 2008), and apart from the base POIFS component, the HSSF component is the more advanced feature of the library.^[5] The other components (HPSF, HWPF, and HSLF) are in a working stage but still in early level of development.^[6][7]

The POI library is also provided as a Ruby extension.

References

1. ↑ Excelling in Excel with Java By Elango Sundaram, JavaWorld.com, 03/22/2004
2. ↑ POI homepage from October 2004, showing original explanations for naming
3. ↑ http://people.apache.org/~nick/POI-Talks/POI-FastFeatherTrack-ACEU08.odp POI OOXML/XSSF presentation at ApacheCon EU 2008
4. ↑ Mailing list archives
5. ↑ HSSF home page at Apache.org
6. ↑ HWPF home page at Apache.org
7. ↑ HSLF home page at Apache.org

External links

• Apache POI ? the official Apache POI project page
• POI presentation at OSCON2006

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