AutoCAD 2008: DWF versus DWFx differences

XPS is Microsoft's XML Paper Specification. It is built-in to the Microsoft Vista operating system. An XPS Viewer will also be available on a variety of other Microsoft operating systems such as Windows XP. It is possible to download and install XPS viewing components so that XPS files are viewable in Internet Explorer 7.

DWF has been around since 1995. The format has evolved over time. Originally it was a single image that could be zoomed - much like a JPEG on steroids. Then an underlying page was added with a designated page size. This facilitated printing to scale. Although originally single page, the format was also enhanced to allow multiple pages.

This evolution is continuing. DWF is now being enhanced to be compliant with Microsoft XPS. This allows Microsoft to support the viewing of DWF files on Microsoft Vista without requiring users to install additional software. It also allows users who have installed XPS viewing components to view the files. Of course, anyone with Autodesk Design Review 2008 can also view, print, markup, and measure these files. So users can tell which DWF files are in this newest format, versus the millions of files that are in the old format, the extension for the new format DWF files is .dwfx. Hence this latest DWF format (version 7.0) is often called DWFx. (One technical publications writer once joking asked if we would also have DWFr, DWFpg-13, and DWFnc-17. No we will not. We will not have DWFxxx either.) Opening and saving DWFx files does take a little longer in Autodesk Design Review 2008 than corresponding DWF files.

As shipped, AutoCAD 2008 comes with the ability to publish DWF files. DWF publishing has been a part of AutoCAD since R13. As shipped, AutoCAD 2008 uses the DWF6 ePlot pc3 driver to create DWF files in the time honored (version 6.x) format. If you want to publish DWF files in the XPS compatible format, you will need to download and install a separate DWFx driver. Like Autodesk Design Review 2008, the project schedule for the DWFx Driver completed later than the ship date for AutoCAD 2008. That's why both of these applications are available separately.

When AutoCAD users decide to publish a DWF or a DWFx, AutoCAD Software Development Manager, Eileen Sinnott, and AutoCAD Senior Product Designer, Jon Page, note that there are some differences:

AutoCAD 2008	DWF	DWFx
install	DWF6 ePlot pc3 included	separate download and install of DWFx Driver
Sheet Set Manager Publish	available in 2008	available in 2008
Model or Paper Space (Layout) Publish	available in 2008	available in 2008 using page setup overrides (See Note)
Model or Paper Space (Layout) Plot	available in 2008	available in 2008
Markup Set Manager Load	available in 2008	planned for a future release
DWF Attach	available in 2008	planned for a future release
Auto Publish	available in 2008	planned for a future release
File Size	typically 1/20th the size of the DWG	typically 1/10th the size of the DWG (See Comments section)

Note: Publishing a DWFx with the Publish command is possible. Similar to the Sheet Set Manager Publish capability, it will require the same page setup override to be applied to all sheets. Page setups are different for the Model tab and Layout tabs. Since the page setup needs to be the same for all sheets for DWFx, you can not mix them in a multi-sheet DWFx. The Sheet Set Manager ensures this for AutoCAD by only containing Layouts as sheets and applies the same page setup override to all sheets.

General Note: Multi-sheet creation will require the new PUBLISHCOLLATE sysvar to be set to 1.

This is the first release of DWFx publishing. As the format evolves, so too will the associated capabilities from AutoCAD. For AutoCAD users who have a desire to share design data with users who only need to view and print - who also do not have the free Autodesk Design Review 2008, DWFx is a viable alternative to traditional DWF files. For users who wish to take advantage of the round trip electronic review process, for now, DWF is still the answer.

Comments

[Robin Capper]

Why the 2 x larger file size for DWFx?

[Scott Sheppard]

DWFx file sizes will vary based on the content. When DWF was first invented, it was a binary format to keep the file sizes down. This was 1995 so bandwidth was not what it is today. As such, the DWF team wanted to do everything to make the file as small as possible. For example, the opcode for a line is not "LINE" but "L" which allowed the opcode to save 3 bytes. I admit that 3 bytes does not seem like a lot, but if you have thousands of lines in your design data, it starts to add up. The DWF team knew small differences like this would add up based on the nature of CAD data - quite intense in its graphics. If you recall your history, early AutoCAD had its own Autodesk Device Interface (ADI) because the Windows system printer drivers could not handle the printing demands of CAD users. AutoCAD had to invent its own. Such was the case with DWF. Using industry standards like VRML, a proposed ASCII-based 3D standard, resulted in design data files that were too large for the times. So unlike any generic document format, DWF was crafted specifically to the needs of CAD data.

Today we are in a different world. Bandwidth is much greater than it was in 1995. Customers are more concerned with interoperability. XML is all the rage. So whereas the binary number 75 (for "L") is the one byte opcode for a line in DWF, in DWFx opcodes look something like this:

Path Name="N6621E1D4671645788327E45A88D0BE90_4" Stroke="#00FF00" StrokeEndLineCap="Round" StrokeStartLineCap="Round" StrokeLineJoin="Round" StrokeThickness="12"...

No longer do applications have to know that 75 represents a line. Applications can simply parse the XML associated with the Path opcode and gain information about the design data.

DWF files optionally embed fonts. For example, AutoCAD users can embed all, some, or none of the fonts. With DWFx, the only choice is "all." This will be welcome news to people who have shared DWF files with others who did not have the same set of fonts on their systems; however, it does make the DWFx files larger.

So the short answer to your question is that the original DWF was specifically honed to be as optimal as possible in terms of file size. The Microsoft XPS standard is designed is based on XML, which by its nature, results in larger file sizes. The forecast is not all gloom and doom though. DWFx files (with the .dwfx extension) tend to be 30% - 100% larger than their corresponding DWF files (.dwf extension). Comparing raw XPS files (with the .xps extension) to DWF is not a valid comparison, since the Microsoft XPS Writer produces XPS files using a different process. A similar condition exists for DWF today. The DWF Writer is implemented as a virtual printer. Hence DWF files published by the DWF Writer go through the Microsoft Graphics device Interface (GDI). Using GDI makes the DWF files larger than DWF files produced by the DWF6 ePlot pc3 driver used directly by AutoCAD. So in the same way that the DWF Writer is not recommended for people using AutoCAD, the AutoCAD DWFx Driver will be recommended instead of the Microsoft XPS Writer.

Please keep in mind that both the DWF and the DWFx are smaller than the DWG.

AutoCAD has come a long way. It is common for people to use Windows printer drivers to plot CAD data. It no longer has its own ADI printing system. Windows has made advancements in its printer drivers. Working together, Autodesk and Microsoft are going to apply similar advancements with design data. This is just the start.

Thanks for your question Robin.

[Ralph Grabowski]

I recall that that the first DWF format was in ASCII and binary; later, it became available in compressed formats.

The reason L was used for the Line opcode was because the first DWF format only drew lines. So, using L definately saved space!

[Grant Buote]

What's the difference between the "DWF6 ePlot" driver and the "DWF6 ePlot DETE" drivers that are standard installs in 2008? I can't seem to find a reference to it anywhere.

Thanks

[Volker Joseph]

I believe that the "DWF6 ePlot DETE" is a Map Guide specific *.pc3 file. There are other "DWF6 ePlot + XXX" *.pc3 drivers out there, mostly for vertical products deriving of the AutoCAD platform.