4.2 Size breakdown

Figure 4 shows the breakdown of document sizes for Word documents. For every size category it shows the contributions of text, formatting information, embedded objects, and images to the documents size. We measured similar breakdowns for PowerPoint and Excel document, but because of space concerns we do not include them in this paper. The PowerPoint documents showed a similar trend to that of figure 4, while in Excel documents the text component accounts for over 95% of the document size in all the size categories.

Figure 4 show that small Word documents are dominated by text and formatting information. For larger Word documents, however, image and embedded component data become the prevalent contributors to document size. This data strongly suggests that efforts to improve access to compound documents should focus on the image and the embedded component data.

One possible optimization would be to remove the embedded component native data from documents that are fetched exclusively for reading. As described in section 2.2, this data is only necessary when editing an embedded component. Users are still able to display the document using the cached image of the component. We measured the savings of this schema and found that it would lead to a reduction in bandwidth requirements for Word and PowerPoint documents as high as 35% and 21%, respectively. PowerPoint documents show less potential benefit because PowerPoint compresses its components data before storing it in the OLE archive, whereas Word does not use compression.

  

Figure 4: Size breakdown of Word documents. The plot shows that as documents get bigger, images and embedded component data account for most of the document's size.