Apache POI, a project run by the Apache Software Foundation, and previously a sub-project of the Jakarta Project, provides pure

Java Java is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea (a part of Pacific Ocean) to the north. With a population of 156.9 million people (including Madura) in mid 2024, proje ...

libraries for reading and writing files in Microsoft Office formats, such as

Word A word is a basic element of language that carries semantics, meaning, can be used on its own, and is uninterruptible. Despite the fact that language speakers often have an intuitive grasp of what a word is, there is no consensus among linguist ...

, PowerPoint and Excel.

History and roadmap

The name was originally an

acronym An acronym is a type of abbreviation consisting of a phrase whose only pronounced elements are the initial letters or initial sounds of words inside that phrase. Acronyms are often spelled with the initial Letter (alphabet), letter of each wor ...

for "Poor Obfuscation Implementation", referring humorously to the fact that the file formats seemed to be deliberately obfuscated, but poorly, since they were successfully reverse-engineered. This explanation – 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 humor appropriate. The original authors ( Andrew C. Oliver and Marc Johnson) also noted the existence of the Hawaiian poi dish, made of mashed taro root, which had similarly derogatory connotations.

Office Open XML support

POI supports the ISO/IEC 29500:2008 Office Open XML file formats since version 3.5. A significant contribution for OOXML support came from Sourcesense, an open source company which was commissioned by

Microsoft Microsoft Corporation is an American multinational corporation and technology company, technology conglomerate headquartered in Redmond, Washington. Founded in 1975, the company became influential in the History of personal computers#The ear ...

to develop this contribution. This link spurred controversy, some POI contributors questioning POI OOXML patent protection regarding Microsoft's Open Specification Promise patent license.

Architecture

The Apache POI project contains the following subcomponents (meaning of acronyms is taken from old documentation): * POIFS (Poor Obfuscation Implementation File System) – This component reads and writes

'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 Microsoft Excel is a spreadsheet editor developed by Microsoft for Microsoft Windows, Windows, macOS, Android (operating system), Android, iOS and iPadOS. It features calculation or computation capabilities, graphing tools, pivot tables, and a ...

(XLS) format files. It can read files written by Excel 97 onwards; this

file format A file format is a Computer standard, standard way that information is encoded for storage in a computer file. It specifies how bits are used to encode information in a digital storage medium. File formats may be either proprietary format, pr ...

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. * XSSF (XML SpreadSheet Format) – reads and writes Office Open XML (XLSX) format files. 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 An office is a space where the employees of an organization perform Business administration, administrative Work (human activity), work in order to support and realize the various goals of the organization. The word "office" may also denote a po ...

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. * XWPF (XML Word Processor Format) – similar feature set to HWPF, but for Office Open XML files. * HSLF (Horrible Slide Layout Format) – a pure Java implementation for

Microsoft PowerPoint Microsoft PowerPoint is a presentation program, developed by Microsoft. It was originally created by Robert Gaskins, Tom Rudkin, and Dennis Austin at a software company named Forethought, Inc. It was released on April 20, 1987, initially ...

files. This provides the ability to read, create and edit presentations (though some things are easier to do than others) * XSLF (Open Office XML Slideshow Format) * HDGF (Horrible DiaGram Format) – an initial pure Java implementation for Microsoft Visio binary files. It provides an ability to read the low level contents of the files. * HPBF (Horrible PuBlisher Format) – a pure Java implementation for Microsoft Publisher files. * HSMF (Horrible Stupid Mail Format) – a pure Java implementation for

Microsoft Outlook Microsoft Outlook is a personal information manager software system from Microsoft, available as a part of the Microsoft 365 software suites. Primarily popular as an email client for businesses, Outlook also includes functions such as Calendari ...

MSG files. * DDF (Dreadful Drawing Format) – a package for decoding the Microsoft Office Drawing format. * XDDF (XML Dreadful Drawing Format) The HSSF component is the most advanced feature of the library. Other components (HPSF, HWPF, and HSLF) are usable, but less full-featured. The POI library is also provided as a Ruby or ColdFusion extension. There are modules for Big Data platforms (e.g. Apache Hive/Apache Flink/Apache Spark), which provide certain functionality of Apache POI, such as the processing of Excel files.

Version history

References

External links