PDC Day 2 – some details and reactions to LINQ


The high point of my day was seeing Anders Hejlsberg go through his
presentation (actually it’s more or a real-time code writing demo, with
few slides) on LINQ.  I had never seen him in person before this
week, and the experience can only be called Shock and Awe.  I had
read this stuff, talked about it for hours, seen other presentations,
but getting it from the source was really eye opening.  If you are
at PDC, I believe the talk is being repeated Thursday.  Find out
when and go!



A few tidbits I got from seeing it all in person:  First, he was
demoing the new type inference features of C# 3.0 and said something
like “Notice that this looks like script, but is really strongly
typed.”  It really does seem like the best of both worlds – the
programmer productivity of not having to fool with all that tedious
type declaration if the compiler logically could figure out the type,
but the safety, performance, intellisense, etc. advantages of having
the system be able to automate some of the tedium of typing and
checking code.  Also, Anders emphasized how this really is a much
more declarative style of programming,  even if it is hosted in an
imperative language.  This really could change the world — taking
concepts that are well-understood by SQL, XSLT, etc. programmers and
making them accessible to people working in a conventional programming
environment rather than a DBMS or XML.



The low point of the day for me :-)  was when Anders was
describing how XLinq addressed the numerous things he doesn’t like
about DOM, and Dave Campbell (the SQL Engine General Manager, hence my
boss’s boss’s boss) pointed to me and said “it’s all HIS
fault”.  All kidding aside, I must say that it is humbling to see how much more
elegant  something can be when designed by one person with the
knowledge and authority to make decisions can be, compared to DOM and
XQuery which were  basically designed by committee (remember Fred
Brooks’ chapter in the Mythical Man-Month about Conceptual
Integrity).  To be fair to my poor fragile ego, XLinq does reflect
a number of hard-learned lessons from DOM, and builds on 10 years of
advances in basic language technology. Newton is widely quoted as
saying “If I see farther it is because I stand on the shoulders of
giants.” In this case it seems to be a giant standing on a big pile of
us dwarves.



While almost all the reaction I’ve heard to LINQ etc. has been
positive, there are a few interesting notes of skepticism … partly
that anyone can make the DLinq and XLinq pieces work in a fully
scalable manner) (Michael Rys
has a nice discussion of this),  but also raising questions about
whether it is really a Good Thing to give programmers who don’t really
understand the workings of DBMS systems the ability to go wild.  I
talked with Esther Schindler
about this basic topic today, and came away with the impression that
she thinks(something like, putting words in her mouth) we might be
handing a 16 year old the keys to the family Ferrari and expecting him
not to go too fast. Maybe having people who understand the strengths
and limitations of a technology be the only ones capable of using a
technology is not such a bad thing? That basic point has come up in a
number of conversations, which might be summarized “our DBAs will NEVER
let us use this, it’s too powerful”.  I think those concerns are
valid and interesting, but premature — there is an IMMENSE amount of
work to do before that will be a real problem. 



Also, there’s the inevitable question of how LINQ / XLinq / DLinq
relate to XQuery. Just as SQL isn’t going away on the data tier (DLinq
generates SQL), XQuery won’t go away as a database query language even
when a mature LINQ -> XQuery mapping and code generation /
optimization component is built, maybe someday. There will always have to be escape
hatches for power users who need the ability to fine tune queries to be
fast, reliable, etc. As for the client side, someone asked in a comment
on yeserday’s post whether this affects the likelihood that we’ll ever
support XQuery in .NET itself. I replied:

First, XLinq is a statement of a vision, not a concrete product plan. The idea
is to get feedback from outside the rather small group that has worked on it so
far. For example, it would be interesting to hear from XQuery fans on what
XQuery does that LINQ doesn’t, other than run on multiple platforms of course.
Ultimately, decisions such as this are BUSINESS decisions; no matter how
geeked up we might be about LINQ/XLinq, if the market wants XQuery they’re gonna
get XQuery.

So, let us know what you think the market is going to say ….





http://msdn.microsoft.com/netframework/future/linq/

Comments (4)

  1. mrys says:

    Mike, please note that XQuery has the exact same type inferencing and strong typing behaviour that Anders is adding to C#. And XQuery got this from functional languages. Yes it is cool. But it is nothing completely new. And I think (as I outline in the blog posting you link to above), that (X)LINQ may not have happened (or look different) without XQuery having been done. However, I agree, that a few people doing the work (I would like to mention Erik Meijer besides Anders) will lead quicker to good results than design in a committee. But I personally think that XQuery is not bad for having been designed in a committee overall (compared to the DOM :-)).

  2. mikechampion says:

    Michael Rys is right, I should have mentioned Erik Meijer’s contributions to LINQ. Never fear, I’m going to rave about Erik when I talk about the XML features of VB9 IN ADDITION to LINQ, hopefully later today. I should have also mentioned Kent Tegels’ comparison of XQuery and XLinq at http://sqljunkies.com/WebLog/ktegels/archive/2005/09/14/16745.aspx

    I started to babble on about the design by committee issue, but realized that this is MY blog, so I’ll write a new entry.