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Interviews

15 April 2003
Interview with Marcus Meissner by Brian Vincent

Marcus Meissner's involvement with Wine stretches all the way back to 1995. He's been responsible for significant contributions including CUPS printing support, DirectDraw, and COM architecture.

Marcus was born in 1973 and currently lives in Erlangen, Germany. He graduated from the University of Erlangen in 1997 with a degree in computer science and went to work for Caldera. Now he works as a developer for SuSE. We caught up recently with him to ask about the various parts of Wine he's been involved with.

BV: Next to Alexandre, you've been active with Wine the longest. Are there any areas of Wine you haven't worked on?

Marcus: Well, a lot of areas ;) I did not work on GDI, USER and higher level GUI stuff, except for occasional small bugfixes. I bugfix whatever I encounter and am able to.

BV: How did you get involved with Wine?

Marcus: I was kinda addicted to Solitaire and Winmine on my Windows 3.1 System, which at some point where the only reason I booted to Windows. Then I heard of this strange Windows Emulator thing and downloaded and compiled it and could play them under Linux.

Pretty soon afterwards I was just trying out other .exes and trying to understand WINE and fix the problems.

BV: Do you remember the first patch you submitted?

Marcus: I do, it was a fix make winfile.exe display the full recursive tree view (which it could not do due to a limit on open filedescriptors).

BV: If there is one thing you'd like to see Wine do, what would it be? Or has it already been done?

Marcus: Hmm, I just have the pretty general goal of that everyone can go and type 'wine foo.exe' and it just works.

BV: It seems we're pretty close to that. CodeWeavers in particular has made installation pretty easy. Do you think regular old Wine will ever catch up to CodeWeavers? Or will the commercial version always be better?

Marcus: Well, a lot of work CodeWeavers does for the emulator itself is happening in the free WINE tree or getting merged back to it sooner or later.

As for installation and integration, they will stay better, since this is their major focus for the CrossOver product.

As for ease of installation and integration I think the free WINE is at capable of it even if not as good. The packaging work I did for Caldera in 1999 and now for SuSE makes the installed WINE require no configuration on the users side, he just can run "wine foo.exe" and it at least starts.

The CrossOver products have the advantage of doing some of the handholding you still need to do for a lot of programs with the normal WINE.

BV: To what extent does packaging play a role? Trying to make Wine work nicely with each distribution seems pretty hard.

Marcus: It is not hard. The additional scripts I need come to around 200 or 300 lines of code for making life easy for the user.

BV: You left Caldera last year and went to work for SuSE, do you work on Wine there? Or is it strictly a hobby?

Marcus: I did not actually leave, the Caldera engineering was closed down, the engineers at the site laid off and to some part 'migrated' to SuSE in the whole UnitedLinux startup phase.

I do some work on WINE here. I do the WINE package itself, and some help in the integration of the SuSE Linux Office Desktop, which we ship with CrossOver Office. Also some other side work with WINE.

But mainly I work on PowerPC architecture maintenance and distribution development.

BV: Does SuSE support Wine? I know you did some recent work trying to get it to work with glibc 2.3 that SuSE was going to ship.

Marcus: In so far that it is included on SuSE Linux (the box product). It is not officially supported in there.

Additionally if we have a customer who wants fixes for WINE, we are offering support.

We also have released a desktop product, the SuSE Linux Office Desktop, which is using CrossOver Office.

Another product which will use both CrossOver and normal WINE is in the making, this will include a better supported WINE.

BV: You've been to a lot of conferences and given quite a few talks on Wine, do you find it helpful to meet other developers?

Marcus: Most of the talks were for non WINE developers, basically to show people 'We WINE developers are still here, here is what we can do, we are working on it.' I am never sure how much that helped people ;)

As for conferences and fairs, basically still the same, showing presence of the project.

As for meeting other developers ... Well, it was nice to meet and to get to know them, but I think for most of the communication E-Mail is sufficient. There is not much need for direct personal coordination, since we are not enough people with conflicting interests/areas.

BV: What was the most interesting addition you've made to Wine?

Marcus: DirectX. :)

BV: Last year you did a bunch of COM work to get InstallShield to work. Since then, more work has been done. Could you give a brief overview of COM and the problems with implementing it Wine?

Marcus: Huh. Brief.

The whole OLE/COM corner is about integrating components, without them knowing of each other.

The first step to independence is the notion of objects and interfaces attached to it. Every interface is associated with a 128 bit identifier called GUID (Generic Unique IDentifier) or IID (Interface IDentifiier).

The core interfaces are:

IUnknown
basic functionality that care about reference counting and querying of other interfaces based on the IID.
IClassFactory
basic object creation.

There are predefined interfaces from Microsoft which have a well defined API, or you can have other interfaces of your own with their own IIDs.

As for interface access, this was always at compile time. As for object creation and interface, access was possible for runtime.

This was all in-process up to then.

Next step is do it across processes, like if you want to embed a table from Excel into a Word document. Somehow the interface accesses needed to happen between the processes. A set of RPC (remote procedure calls) proxies and stubs is used that pack the function arguments into a datastream and unpack it on the other side, call the remote function, and send the return value back. This can be done across processes on the same machine, but also between different machines.

These proxies and stubs can be written by hand, or they can be generated from interface descriptions files (.IDL or .ODL). Some of them cannot be automatically generated, for these special proxies/stubs needs to be programmed.

The next interesting thing is to be able to find out about new interfaces and their methods in runtime, like for scripting languages or for fully automated RPC generation. The descriptions and techniques that allow this are called 'OLE Automation' and are extensively used in Visual Basic and others.

The status of the implementation in WINE:

  • The object and interface handling is not WINEs task, so it works.
  • OLE Automation helper functions have been implemented to a large degree, but not fully.
  • DCOM. We currently support the marshalling based on OLE automation data, but no the custom generated. There is work done by Greg Turner and TransGaming currently.

As for implementing and problems with it, it is a rather large piece of Windows, which is, well, not really documented and rather complicated.

BV: How much of that work was a repetition of what TransGaming had already done?

Marcus: At the time I did it, it was 99% repetition.

BV: How is their implementation different? Is theirs more advanced than the LGPL'ed Wine?

Marcus: At the time both were done to run InstallShield v6 and basically could just do that.

I did most of it with not looking at TransGaming code, I just took one or two hints when I did arrive at problems.

I did enhance the typelib based marhsaller over the time to support more visual basic programs coming my way.

Ove of TransGaming did start the development of the generic RPC framework, and contributed this to Rewind and to WINE.

So ours is a bit better currently, but the enhanced framework will make

BV: OLE over RPC would be really cool. Is the remaining work 'just' to write a complete RPC implementation?

Marcus: Basically the RPC stuff and the marshalling wrappers generated from IDL. "just" is however still a lot of work.

There is most likely also work in the component interfaces for the user visible OLE.

BV: You mentioned the interfaces are well-defined but a lot of the implementation is undocumented. Are there any useful resources for figuring how something is supposed to work?

Marcus: The same as for the standard APIs, MSDN specifies those interfaces. Those it doesn't, the usual guessing and header checking is needed.

BV: Are you working on any major Wine projects right now?

Marcus: Unhappily, no. I just don't have the time.

BV: For about the past eight years Wine has continuously been 6-12 months from being completed. Do you think 2003 might be the year a beta release comes out?

Marcus: Hey, I have been telling this at conferences in 1999 and 2002. In 2002 more as a running gag ;)

I am still full of hope.

BV: Do you think .Net will render Wine obsolete?

Marcus: WINE might render itself obsolete, after all users have migrated. So most likely never.

As for .NET, I do not know.

BV: Thanks for the interview!