Flat ODF as the Swiss Army Knife

Transcript

1. Flat ODF as the Swiss Army Knife Fridrich Štrba Software Engineer SUSE/Attachmate
2. What is Flat ODF
3. 3 “Normal” ODF File • Package OpenDocument File ‒ Chapter 3.1.3 of ODF 1.2 specifications ‒ Collection of xml files in a ZIP container ‒ <office:document-content> ‒ <office:document-styles> ‒ <office:document-meta> ‒ <office:document-settings> ‒ Images and OLE objects sub-streams in the ZIP container ‒ Referenced by xlink:href attribute
4. 4 “Flat” ODF file • Single OpenDocument XML Files ‒ Chapter 3.1.2 of the ODF 1.2 specifications ‒ Contains the whole document ‒ <office:document> root element ‒ office:mimetype and office:version attributes ‒ Images and OLE objects inlined ‒ <office:binary-data>[base64 data]</office:binary-data>
5. 5 ZIP Storage (1) • Main entry point is the Central Directory End located at the end of the ZIP file. ‒ Scanning for it towards the end of the file ‒ Whole file must be present • Pointing at the Central Directory containing entries ‒ For name access, iterate over them ‒ Need to seek back to read the entry • Which contains pointer to Local File Header ‒ Seek to local file-header offset ‒ Need to seek back again ‒ The content of the stream comes after the header
6. 6 ZIP Storage (2) FILE ENTRY 1 <data> FILE ENTRY 2 <data> FILE ENTRY 3 <data> FILE ENTRY 4 <data> Local header 1 Local header 2 Local header 3 Local header n Relative offset 2 Relative offset 1 Relative offset 3 Relative offset n File entry 1 File entry 2 File entry 3 n CENTRAL DIRECTORY
7. Advantages of Flat ODF
8. 8 No Need for Special tools • No need for compression and stream extraction tools ‒ ODF documents can be generated manually ‒ Developer modifying a document ‒ XSLT tools ‒ Programmatic generation of documents ‒ Further processing of documents ‒ Easier parsing of document and extraction of relevant information
9. 9 Sequential Access to File • Difference with ZIP file ‒ No need to know the end of the file to start to parse it • Exchange file-format par excellence ‒ Possibility to communicate document as SAX messages ‒ Communicate XML to an application sequentially ‒ Possibility to stream document over wire ‒ Collaboration protocol? ‒ Communication with CMS systems?
10. 10 Storing documents in SCM • Package ODF file ‒ Stored as binary file ‒ Impossibility to see reasonable diff to previous version • Simple XML ODF file ‒ A text file after all ‒ Difference are easily visible between revisions ‒ SCMs are designed to handle text files the best ‒ Example of LibreOffice templates ‒ Stored in git repository
11. Examples of Flat ODF use
12. 12 LibreOffice UNO Filter API • XSLT based filters ‒ com.sun.star.comp.Writer.XMLOasisImporter ‒ pushes to LibreOffice flat ODT ‒ com.sun.star.comp.Calc.XMLOasisExporter ‒ receives from LibreOffice flat ODS • XML based filters ‒ com::sun::star::xml::sax::XDocumentHandler ‒ com.sun.star.document.ImportFilter pushes SAX messages to com::sun::star::xml::sax::XDocumentHandler ‒ com.sun.star.document.ExportFilter is itself a com::sun::star::xml::sax::XDocumentHandler and receives SAX messages from LibreOffice
13. 13 File importers • Writerperfect ODT generator ‒ Libwpd – WordPerfect documents ‒ Generates ODT with embedded WPG files as <office:object> elements in flat ODG ‒ Libwps – Microsoft Works ‒ Generates ODT • Writerperfect ODG generator ‒ Libwpg – WordPerfect graphics ‒ Libvisio – Microsoft Visio diagrams ‒ Libcdr – CorelDraw drawings ‒ Libmspub – Microsoft Publisher publications ‒ Generate ODG documents
14. Thank you. 14 Single XML OpenDocument representation is an important part of the ODF ecosystem
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