Editing Apache POI (section)

==Architecture==
The Apache POI project contains the following subcomponents (meaning of acronyms is taken from old documentation):

* POIFS (Poor Obfuscation Implementation File System<ref name="javaworld2004"/>) – This component reads and writes [[Microsoft]]'s [[OLE 2]] [[COM Structured storage|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<ref name="javaworld2004"/>) – reads and writes [[Microsoft Excel]] (XLS) format files. It can read files written by [[Microsoft Excel|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.
* 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<ref name="javaworld2004"/>) – 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 [[Microsoft Office|Office]] application.
* HWPF (Horrible Word Processor Format<ref name="apache1">{{cite web|url=https://poi.apache.org/apidocs/dev/ |title=POI API Documentation |publisher=Poi.apache.org |access-date=2019-03-07}}</ref>) – aims to read and write [[Microsoft Word|Microsoft Word 97]] (DOC) format files. This component is in initial stages of development.
* XWPF (XML Word Processor Format<ref name="apache1"/>) – similar feature set to HWPF, but for Office Open XML files.
* HSLF (Horrible Slide Layout Format<ref name="apache1"/>) – 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)
* XSLF (Open Office XML Slideshow Format)
* HDGF (Horrible DiaGram Format<ref name="apache1"/>) – 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{{citation needed|date=March 2019}}) – a pure Java implementation for [[Microsoft Publisher]] files.<ref>{{cite web|url=https://poi.apache.org/components/hpbf/index.html |title=POI-HPBF - Java API To Access Microsoft Publisher Format Files |publisher=Poi.apache.org |access-date=2019-03-07}}</ref>
* HSMF (Horrible Stupid Mail Format<ref>{{citation | url = http://npoi.codeplex.com/discussions/233518 | publisher = Microsoft | title = Codeplex NPOI|archive-url=https://web.archive.org/web/20120328092553/http://npoi.codeplex.com/discussions/233518|archive-date=2012-03-28}}</ref>{{Better source needed|date=January 2012|reason=[[WP:CIRCULAR]], as ref in source is this article}}) – a pure Java implementation for [[Microsoft Outlook]] MSG files.<ref>
{{citation | title = POI-HSMF | publisher = Apache | url = http://poi.apache.org/hsmf/ | access-date = 2011-07-31 | archive-url = https://web.archive.org/web/20110807211225/http://poi.apache.org/hsmf/ | archive-date = 2011-08-07 | url-status = dead }}
</ref>
* DDF (Dreadful Drawing Format<ref name="apache1"/>) – 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.<ref>{{citation | url = http://poi.apache.org/hssf/ | title = POI-HSSF | publisher = Apache}}</ref>  Other components (HPSF, HWPF, and HSLF) are usable, but less full-featured.<ref>{{citation | url = http://poi.apache.org/hwpf/ | title = POI-HWPF | publisher = Apache}}</ref><ref>{{citation | url = http://poi.apache.org/hslf/ | title = POI-HSLF | publisher = Apache}}</ref>

The POI library is also provided as a [[Ruby (programming language)|Ruby]]<ref>{{citation | title = POI-Ruby | publisher = Apache | url = http://poi.apache.org/poi-ruby.html}}</ref> 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.<ref>{{cite web|url=https://github.com/ZuInnoTe/hadoopoffice/wiki |title=HadoopOffice for Hive/Flink/Spark |publisher=Github.com |date=2018-07-19 |access-date=2019-03-07}}</ref><ref>{{cite web|url=https://github.com/crealytics/spark-excel |title=Spark Excel |publisher=Github.com |access-date=2019-03-07}}</ref>