ZIM file format

From openZIM
Revision as of 20:22, 22 February 2009 by Manuel Schneider (talk | contribs)
Jump to navigation Jump to search

The ZIM file format is based on the zeno file format. It starts with a header, which is described here:

Header

length in byte, all types are littlendian

Field Name Type Offset Length Description
rMagicNumber integer 0 4 Magic number to recognise the file format, must be "1439867043"
rVersion integer 4 4 wp2006=2, wp2007=3, ZIM=4, version of the file format for backwards compatibility
rCount integer 8 4 total number of articles
integer 12 4 deprecated
rIndexPos integer 16 8 position of the article index
rIndexLen integer 24 4 length of the article index
headerLen integer 28 4 length of header (currently 60)
rIndexPtrPos integer 32 8 position to the directory pointerlist
rIndexPtrLen integer 40 4 length of directory pointerlist (always 4*rCount)
rMainPage integer 44 4 article index of main page or 0xffff if no main page
rLayoutPage integer 48 4 article index of layout page or 0xffff if no layout page
integer 52 8 deprecated

Each article in the zim file has a directory entry. Since the directory entry has a variable size, we have a index pointerlist, which is a list of 4-byte offsets, which points to the directory entries.

Directory Entries

Data

Namespaces

Namespaces seperate different types of data stored in the ZIM File Format.

They can be distinguished by prepending the article namespace before the article name in the URL path, eg. http://localhost/A/Articlename.

Namespace Description
- template data
A articles
I images, files - see Image Handling
J images, text - see Image Handling
U categories, text - see Category Handling
V categories, article list - see Category Handling
W deprecated - see Zeno File Format
X fulltext index
Y deprecated - see Zeno File Format
Z deprecated - see Zeno File Format