Thursday, 23 September 2010

Document embedding and OLE

There are a number of technical issues concerned with what I'm attempting to accomplish with the InScribe software. The biggest thorn in my side is the issue of embedding, visualising, and editing embedded data in compound documents. This is therefore something of a background note on the topic.

The notion of embedding or linking an ‘object’ in a document is commonplace. Web pages incorporate pictures, videos and specialized objects such as Flash or Silverlight interactive components. Word processing documents likewise contain objects, sometimes interactive objects, alongside the text. The idea of ‘compound document’ goes back to the 1980s.

The current situation with embedded objects is chaotic. Examples. Microsoft Office and Open Office, the two most popular office suites, have different schemes for add-ins. Even limiting attention to one vendor, Microsoft Office has added features in the 2003, 2007 then 2010 editions: all well and good but makes it difficult to support a diverse user base (Office 2003 is still widely used). Firefox, Chrome, Internet Explorer each has its own plugin approach and the story gets more complicated when considering non-Windows Internet browsers.

We are sorely missing standard, flexible, open approaches to embedding. On the web side of the coin, HTML5 is a move in the right direction though in itself no panacea despite what some less technically minded commentators may say on the subject (a topic for a future blog entry!).

A concrete example. There is no bottom line hardware-related reason nowadays that a simple photo editor plug-in software component could not operate on devices as diverse as eBook readers, smartphones, tablet computers, as well as notebook and desktop computers. Such a plug-in could enrich many applications, not only web browsing but word processors and camera management tools. In our Babel like world of 2010, to accomplish such a thing in software would involve writing versions for iOS, OS X, Android, Windows XP, Windows 7, Symbian, Kindle, Blackberry, Gnome, Wii... the list goes on. The developer then needs to tackle application-specific rules for plug-ins (if such exist). A relatively simple piece of software is almost impossible to deploy widely.

I am not advocating one ring to rule them all, simply highlighting the severe lack of standard ways for applications and components to interoperate and deploy.

In fact, for Microsoft Windows applications there has been one solution for almost 20 years. OLE (Object Linking and embedding) was introduced to Windows in 1990 and expanded substantially to version 2 in 1993. Parts of the OLE system were renamed ActiveX controls in 1996. I’ve exploited OLE with the InScribe software to enable in-place editing of Ancient Egyptian in Word Processing and other applications.

OLE has never been an ideal technology solution. Parts are overcomplicated and error prone during development. OLE design is too specific to classic Windows architecture. There was originally insufficient attention given to security issues although this is now largely addressed. Nevertheless, for Windows applications, OLE provided some solutions to the big problem of making applications and components work together by defining standard rules for interoperability of functions like embedding and compound documents.

Unfortunately, OLE development by Microsoft pretty much stopped well over a decade ago, more a victim of fashion rather than any logical reason I suspect. One side effect is that something as fundamental as how copy and paste works between Windows applications is still stuck in a 1990s time-warp.

As the internet grew and new technologies such as Java and .Net became available, inasmuch as there was any attempt to address application interoperability, solutions tended to be product specific. Microsoft themselves targetted ‘the enterprise’ with less focus on the general personal computer user. Rather than an OLE philosophy where third parties can expand the capabilities of Windows and its applications in a general way, Microsoft Office became focussed on enterprise oriented Office specific add-ons. Linux and other alternatives failed to rise to the challenge of developing a more open and flexible approach.

OLE continues to be supported in Windows and Office, but pretty much maintenance only. OpenOffice and other products continue likewise. I have not looked at the latest Adobe Creative Suite (CS5) but recall an earlier move around CS3 to remove some OLE functionality. Microsoft Office Word 2010 runs OLE embedding in a compatibility mode. I don’t expect OLE to disappear in the next few years but it is certainly becoming less usable.

If anyone reading this understands why the issue of application interoperability and OLE type functionality is missing from .Net and WPF I'd be delighted to find out.

This slow decline of OLE and the lack of practical modern alternatives proved a stumbling block in my development of a new version of the InScribe for Windows software. I expect other developers are in a similar situation of having to make some undesirable compromises in order to get a product released. On a positive note, the problem has stimulated a number of interesting ideas for future directions and I hope to touch on these here during the next few months.

Meanwhile a call for anyone working on document embedding to please learn from the past. Lets try to ensure whatever is latest and greatest at least accomplishes what OLE did 20 years ago (and still almost does).

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