The scariest search for which my blog is on Google rank #1
is power=work/time.
I knew that Google loves me, but this starts to become pretty ridiculous 
CNet
reports about Bill Gates’ announcement that Windows Anti-Spyware is going to
be free includes the following truly puzzling quote from the Check Point
Software CTO:
"I am glad to
see Gates is focusing on securing the desktop," said Gregor Freund, chief
technology officer of Check Point Software, which develops desktop security
software. "However, there are some serious downsides to Microsoft's approach.
Just by entering the security market, Microsoft could stall innovation by
freezing any kind of spending of venture capital on Windows security which in
the long run, will lead to less security, not
more."
Is it just me or do you also
consider the term “venture capital” as being a little out of place in this
context?
Jim Johnson, who works on transaction
technology at Microsoft’s Distributed Systems Group (aka „Indigo
team“), shares
an important insight on ACID’s “D” and that “Durable”
doesn’t always mean “to disk”, but is rather relative to the
resource lifetime. A transaction outcome can be “durably” stored in
memory, if that’s what the characteristic of the resource underlying the
resource manager (=transaction participant) is. That’s a very important perspective
to have. Once you get away from the “transactions are heavy duty”
thinking (because “D” seems to imply “disk” to many
people), transactions, especially with “lightweight transaction managers”
such as the one found in the .NET Framework 2.0’s System.Transactions.Ltm
namespace (or the
one I published a while back), suddenly become very attractive to coordinate
and resolve fault conditions between components within a process.
Aaron
Skonnard says I am clearly wrong with my
demand that one shouldn’t have to look at WSDL/XSD/Policy. Well, at
this point in time the tooling makes it indeed difficult to ignore angle
brackets. But that’s not a reason to give up. I also find the “it
all has to start at the angle bracket” stance overly idealistic.
I can type up an XML Schema in notepad, I can even type up a
WSDL in notepad. As much as one would like to have it different, both “skills”
are not so common amongst the developer population. I would think that for the
majority of ASP.NET Web Services in production today, their developers
completely ignored the XSD/WSDL details. But even if that were different: The
rubber hits the road when we talk about policy. Can you type up a complete and
consistent set of policy assertions for integrity and confidentiality and
authentication using Kerberos and vX509 tokens without looking at the spec or a
cheat sheet? How about combining that with assertions for WS-AT and WS-RM? As
long as we keep the story reduced to XSD and WSDL, dealing with angle brackets might
something that someone could reasonably expect from a mortal programmer who has
a life. One we take policy into the picture, we better start asking for tools
that hide all those details. The interoperability problems of getting secure,
reliable and transacted web service work together are far harder than just
getting services to talk. That’s part of the contract story, too. Yet, I
cannot imagine that anybody would seriously demand that we all sit down and explicitly
write these endless sequences of policy assertions and then feed our tools with
them. At least I don’t want to do that, but that may just be me getting
too old for this stuff.
Bruce
Williams illustrates how to turn my very simple “Hello
World” Indigo sample into a queued service by changing the transport binding
from HTTP to MSMQ (I think that’s radically cool). Now, the next step is
to illustrate a Duplex conversation to get the response back to the caller. If
Bruce or someone else isn’t going to beat me to it, I’ll show that
once I get home from Warsaw
tomorrow night. [Ah, by the way: Bruce! No need to “Mr.” me ]
Tim Ewald responds (along with a few
others) to my previous post
about WSDL and states: ”Remember that WSDL/XSD/Policy is the contract,
period. Any other view of your contract is just an illusion.”
WSDL and XSD and Policy are interoperable metadata exchange
formats. That’s just about it. The metadata that’s contained in
artifacts compliant with these standards can be expressed in a multitude of different
ways. I do care about “my tool” (whatever that is) to do the right
thing mapping from and to these metadata standards whenever required and I do
care about “my tool” guiding me to stay within the limits of what
these metadata formats can express.
But WSDL/XSD/Policy isn’t the contract. If you do
ASMX, you can create server and client without you or any of the tools ever
looking at or generating WSDL. And it works. If you use Indigo, you can do the
same and, in fact, for generating any XML-based metadata from within an Indigo
service, it’s even required to explicitly add the respective service
behavior at present. The required metadata to make services work comes in many
shapes or forms and is, for a given tool, typically richer than what you will
find in the related WSDL/XSD/Policy, because not all that metadata is related
to the wire format itself.
If I need to tell someone who is not using my tool of choice
how to talk to my service, I have my tool generate the respective metadata
exchange documents and I want to be able to trust my tool that they’re “right”.
What I am stating here is simply my demand and expectation
for the degree of “automatic interoperability” that I expect from
the tools. I can read WSDL/XSD/Policy; out there, most people absolutely don’t
seem to care about these details and I tend to agree with them that making this
stuff work is someone else’s problem.
I don’t need to be able to read and write PDF to use
PDF. I use PDF if I know that someone will open my document who is not using Microsoft
Word. Still, that PDF doc isn’t the
document. My Word source document is the document
I edit and revise. The PDF is just one of several possible representations of
its contents.
I wish I was at VSLive! in San Francisco to hang out with all of my
friends. Instead (and that isn’t too bad, either), I am sitting in my
hotel room at the Warsaw Marriott watching the sun rise over the Polish
capital. Today and the next two days, my partner Achim
Oellers and myself will be teaching a class on service
orientation principles, explaining fundamental ideas, patterns, techniques and
will go through a lot of concrete implementation guidance for today’s Microsoft
MSMQ/WSE/ASMX/ES stack so that our customers can start writing services today. The
fundamental principles about data contracts, message contracts and service
contracts that we teach will carry forward to Indigo – along with a lot
of the implementation techniques (and the resulting source code) that we will
suggest. Of course, that has been a bit of a hidden agenda in past workshops,
because I couldn’t openly speak about anything that happened to Indigo
past PDC03, but now that the Indigo day at VSLive! is over, I can. That makes
it even more fun.
XML is ugly and angle brackets are for plumbers. Unless you
have a good reason to do so, you shouldn’t have to look at WSDL. Sharing this
C# snippet here
[ServiceContract]
interface IHello
{
[OperationContract]
string
SayHello(string name);
}
is a perfectly reasonable way to share contract between server and client, if
you’ll be sticking to Indigo. A service can expose all the
WS-MetadataExchange and XSD and WSDL you like so that other Web Service clients
can bind to your service, but as long as you stay on the System.ServiceModel level and focus on
writing a distributed systems solution instead of writing something that “does
XML”, you won’t have to worry about all the goo that goes on in the
basement. Staring at WSDL is about as interesting as looking at the output of “midl
/Oicf”.
using
System;
using
System.ServiceModel;
namespace IndiHello
{
[ServiceContract]
public
class Hello
{
[OperationContract]
public string SayHello(string name)
{
return "Hello " +
name;
}
}
class
Program
{
static void Main(string[] args)
{
ServiceHost<Hello>
host = new
ServiceHost<Hello>(new
Uri("http://localhost/hello"));
host.AddEndpoint(typeof(Hello), new
BasicProfileHttpBinding(), "ep");
host.Open();
Console.WriteLine("Press
ENTER to quit");
Console.ReadLine();
host.Close();
}
}
}
I am told that I can talk, so I do Here’s a
simple Indigo server. If you looked at the PDC 2003 Indigo bits, you will
notice that the programming model changed quite a bit. I think that in fact,
every single element of the programming model changed since then. And all for
the better. The programming model is so intuitive by now that I am (almost) tempted
to say “Alright, understood, next technology, please”.
So up there you have a class with an implicit service
contract. An explicit service contract would be a standalone interface (that’s
the proper way to do it, but I wanted to keep the first sample simple) with a [ServiceContract] attribute. Here, [ServiceContract] sits right on the class.
Note that the class doesn’t derive from any special base class. Each method
that you want to expose as an endpoint operation is labeled with [OperationContract]. These and a set of
other attributes (along with a bunch of options you could set, but which I am
not doing for the moment) control how the class contract is exposed to the
outside world via Indigo.
In the Main
method, you have a ServiceHost, which hosts the service (the class is
parameterized with the implementation type) and which is initialized with the
base-adress at which the service shall be hosted. The base address here is “http://localhost/hello”
and with that maps into the namespace of http.sys at port 80. The endpoint can
exist alongside any IIS-hosted websites, even though this particular app is
hosted in its own little console-based app.
Into this host, I map the service contract with a
BasicProfileHttpBinding() to the endpoint address “ep”, which means
that messages to that particular service that flow through HTTP using the WS-I
Basic Profile 1.0 shall be directed to the “http://localhost/hello/ep”
endpoint. Once I have a binding in place (that could also be done in config), I
Open() the service and the
service listens. Once I am done listening, I Close()
the service.
Isn’t too hard.
I have been invited to speak at the Denver Visual Studio Usergroup on Monday, March 28th. Because I just happen to be in Denver I am delighted to volunteer and talk about the principles of Service Orientation and how to make it happen for real now (ES, ASMX) and tomorrow (Indigo). Mind that this is after VSLive! and I'll be able to tell things I've been told not to tell.
There you go:
Happy Stewardesses who like my Alienware notebook (seems to
work just as well as driving a Lamborghini)
 
And ... chatting with Hanselman and having (economy class
... so much for Lamborghini) food

I am aboard SK938 (SAS) right now. I am on the Internet. Connexion by Boeing. Chatting with Scott Hanselman using MSN Messenger. Blogging this. If there is something like "geek orgasm", this is it. Eight hrs to go to Copenhagen. This R-O-C-K-S.
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