Jesus is back and His name is... svn?!?

Picture worth a thousand bibles.

Linq2sql running on Sql Compact Edition - calling on VistaDb to clean-up their act

There is a lot of misunderstanding on this subject. Even competitors of Microsoft seem to not understand fully what Linq2sql is made of or what it actually covers. One of these competitors is Vistadb that says on their product comparison:

SQL CE users will have to wait until the Entity Framework release before they can use LINQ against a SQL CE database.

I sent them an email to warn them that their comparison was erroneous, and an exchange has started in which they've assured me I was in the wrong and have neither acknowledged the confusion nor updated their comparison. As such I feel inclined to bring the conversation to the community, to get knowledge out there. I have not received their authorization to reproduce the exchange, so I'll have to represent as accurately as I can, in my own word, the different points they made. And I hereby invite them, and you dear reader, to the conversation.

Before you begin reading this, please note I do like the work the vistadb guys have been doing, I think it's a great internal database, and I probably would use their product still. But with greatness comes responsibility yada yada.

There is no provider model in linq2sql

This is an easy mistake to make if you don't spend your time in reflector. Linq2sql *has* a provider model that has been marked as internal late in the process, as described on the Wayward Weblog. If I was to guess the reasoning, I'd guess that there would've been a conflict of interest for partners to support both the Titanic Entity Framework model that leverages updates to the core ado.net classes and a provider model where they would've had to rewrite the sql code generation from the ground-up in linq2sql.

But I would concede that, as it's not public, for all intent and purposes, there is no provider model *you can build against*.

Linq2Sql gives you a Visual Studio GUI and a mapping tool

This is accurate, and very relevant to our conversation. There is several aspects to linq2sql.

• A provider model, with a provider implementing access to Sql Server 2000, 2005 and 2008, as well as Sql Compact Edition 3.5. This is the bit of code responsible for translating between the model and the sql code
• An abstract mapping model defining types such as MetaTable, MetaType and MappingSource, that let you implement different mappings. Linq2sql ships with two of those, one for xml mapping files, one for attributes.
• Visual studio ships with a designer that lets you generate an xml mapping file through a point-and-click UI. This only supports the full-fledge Sql Server, and this is where the confusion may be coming from.

So there is a bit more than a GUI and a mapping tool. It's a GUI, a mapping model and a provider model.

Sql Compact Edition queries don't support Linq, the compiler does

Well I've struggled quite a bit to understand that one. Linq queries are compiled by the compiler as extension methods or interfaces defined by the implementations of Linq (Xml, object, Sql, etc). However, I fail to see any connection with Sql Ce itself, as the one querying the database is the provider that, indeed, supports Linq2sql just fine. The provider is indeed distributed with Sql Ce 3.5.

Microsoft does not use Linq2sql as a term that covers Sql Compact Edition and it's unsupported

I don't see how it relates to the technical conversation. And the download page of Sql CE 3.5 specifies the following.

SQL Server Compact 3.5 introduces a host of new features including LINQ to SQL support

Again, it doesn't seem like unsupported to me.

Conclusion

Vistadb is a strong product in its own right. The product comparison however contains a mistake and the company hasn't responded to the two emails I've exchanged with a catchall email address.

All in all, this highlights two points. Microsoft has a communication problem around Linq2sql; Iif your competitors don't understand your product well, imagine your customers. Secondly, if you want to put product comparisons you should *really* double-check your facts. Responding in person to emails rather than through a customerservices@... address, and double-checking before responding the second time would probably have kept me a bit happier.

The Entity Framework paves the way to years of uneducating the masses

This is in substance the bitter taste that's left in my mouth as EF v1 gets ready to be released.. I've been debating on this topic in user groups, meetings and within my clients: adopting EF as it stands would be a mistake as it introduces fundamental issues in the way we write code and in the way we design our architectures. We will spend years undoing the massacre done by introducing that technology as it stands, just like we still have to suffer DataSets today.

That's why I signed the ADO .NET Entity Framework Vote of No Confidence.

And today, it was announced that the Entity Framework team would adopt a transparent process in the same way as the ado.net data services team has. In this respect I'll have to remark that the ado.net data services team took the decisions they wanted to take, even when the community advised against them.

Furthermore, the objections that were made against the Entity Framework have been around for a while and apparently didn't make it into the V1.

I'll try and have an open and positive attitude towards this opening-up, but I'll notice that already there's a push within MS to adopt the entity framework everywhere. If you push for adoption of your v1 in the company and respond to criticism by promising to fix  fundamental scenarios in v2, you're doing more damage than good, and this is why I have a trust problem vis-a-vis the Entity Framework and its design team.

A real 3d-enabled web browser for WPF?

I know, some of you think that the browser control in the latest WPF 3.5 SP1 is the dog's bollocks. Sadly, it suffers from its origin as a wrapper around good old GDI and the lack of GDI redirection imposed by supporting WPF in Windows XP environments.

One thing I keep track of very closely is what the mono guys do. This is a fantastic pool of resources, skills and code, and if I had time to hack I'd probably join one of their many projects. And on their feed I came across Alp's post describing a WebKit-based 3d web browser. I can't wait to have a play with the code.

Technorati Tags: mono,c#,wpf,webkit

Alt.net London Beers #2 - 17th of June 2008

It's this time of the month again, and we continue with the tradition of organizing alt.net beers events monthly.

As usual, it's casual, it's about chit chat on alt.net things and its about beer.

The venue has kindly reserved a couple of tables in their upstairs bar where we'll be having some food and of course beer.

Don't hesitate to mail the details around, the more the merrier!

The Blue Posts
18, Kingly Street
London W1B 5PX

View Larger Map

Technorati Tags: alt.net,London,altnetbeers,altnetuk

NxtGenUG PreFEST08 Dinner & Fest08

NxtGenUG is the most thriving user group community around. They're organizing a dinner tonight, so come and join if you're around Reading (only 29 minutes on the train from London)

And of course, tomorrow is a day of pure geekiness with the Fest08 event in Reading. Come say hi!

Hello twitter?

Craig has been selling me twitter over the last few months and I always kept it on the back of my mind. From this morning twitteroo is installed and I'll be able to start moaning on my twitter feed about the poor QoS as soon as I get it. Right now it just looks like a web-based IRC to me.

Side note, when is too much information too much? Mailing lists, messenger (and often during the day visitors of this blog chatting away, usually introducing themselves with asdf or the time-proven testing), maybe I'm overcommitting?

Agile smell

Anthony talks about a potential agile smell and the concept of self-organizing teams. As with his brother's blog, I still can't figure out how to post a comment so it ends up on my blog. If I was to bother with putting categories on my entries, I'd probably have one specifically for commenting on other posts when I've been too dumb to find the reply or the register button.

Let's first separate Agile (as an enforced, recognized and lucrative book publishing business, as well as quite a bit of ego and a general lack of understanding or intelligence in applying the ideas), agile (as a bunch of methodologies you pick and choose from to try and get as many benefits as you can out from what others have spent years experimenting with, and that we alt.netters would consider the pragmatic choice), post-agile as a poorly worded (imho) variation of pragmatism, and scrum (as one particular self-organizing methodology, one of the most popular but also one of the most badly applied). They each represent different things and different steps you can and should follow in becoming more agile, and everybody should try to get more agile even when not wanting, refusing or considering being past the stage of, Agile.

Back to Anthony's post. He talks about a "conflict" with someone telling him that he should have chosen a story to pick on his own because teams are self-organizing, and Anthony argued that without prioritizations he should ask before committing to the work.

I'm not entirely sure which variance of agile that company is using, but here's what we do here. Stories are written on the wall and are negotiated with the client, and doesn't involve the dev team much at the early stage outside of simple feasibility study (when we're lucky). They get used for us to produce both the scenarios for the tester's acceptance criterias and the product backlog.

The product backlog is the one being prioritised: high-level functionality cards of a couple of days, and the prioritization is done by us from the knowledge we extract painfully from the project managers. Sometimes they even come and do it themselves, but sadly that's as common as a solar eclipse.

From this, we commit at the beginning of the sprint to the amount of work we think we can deliver. After a couple of sprints we know roughly from our estimates how many virtual hours we deliver per sprint, aka how many of the hours we have estimated we manage to deliver. This is usually quite accurate even though the number itself doesn't mean much at all.

The team is self-organizing from that point because the *team* has committed to the *whole* of the sprint backlog. If we had over-committed we would've de-scoped. In that sense, at the stage of a daily stand-up, I'd agree that a team member asking what to do next is usually a practice smell:

• Priorities of tasks mostly don't exist as we're committed to all of them
• The ones that need to be worked on first are based on dependencies rather than priorities. If you ask you probably forgot what depended on what. With short sprints, that's the last thing you would forget when you've spent 3 or 4 hours deciding all of those on the Monday.

We use the wall for roughly clustering tasks that are inter-dependent, and the bottom of the wall for the nice-to-have. When you commit to a task, you commit to the team that you're wishing to do a task, so you probably don't have a reason to ask for permission.

The final thing that I've experimented on my latest project is to decouple the sprint backlog maintenance and the daily stand-up. It's now a real-time wall: you add, remove, complete and reshuffle tasks when you feel like it, the wall is visible and people will see the changes as they happen. The daily is a summary of all those movements: this relieves the pain of updating the wall, makes it more entertaining, and no one asks what to do next because they've either not finished their current task yet or they've already chosen their new one.

Being agile share many of the tenets of alt.net: flexibility, lookout for the best solution, pragmatism. In that respect I'll agree with Anthony that an Agile Anal can be annoying. But on the other hand (and I'll leave that to another post), only the teams that tried and mastered Agile can allow themselves to deviate to agile. If you've not tried hard enough a change in mentality in the way you work, you will fail, and what some would call "adapted agile" I call "bad habits are back".

[Updated: s/Jason/Anthony]

Pdc2008 here I come

One of the first thing I did this morning was to make sure I had registered for the 2008 edition of the Pdc.

Any brits travelling to LA or any alt.net guys want to organize an unconf, let me know.

Now they need to open the registration for TechEd Europe and I'll be booked for the year.

Technorati Tags: pdc2008

Retrospective on my asp.net MVC talk

I'm publishing this a bit late, but I took a few days (a whole two of them) without working. How refreshing!

In an effort for a more transparent process, here are a few things I think went well and didn't go too well. If you've been at the talk I would absolutely love your criticism. Practice makes perfection, but before that it makes for nicer presentations and a less worried Sebastien!

Preparation god damn it!

The font-sizes were all wrong in everything but the code-editor, this is quite unacceptable and certainly not like me at all. So be prepared if you install vs 2008 SP1 beta, it will reset all your settings. That explains the lack of proper configuration in visual studio. And of course, a problem never comes alone, vs refuses to start under my Presentation account that is set with ridiculously large DPI setting. But it all comes down to me installing this stuff too late, which left me no time to make sure everything was configured properly. Apologies to the audience, I should have had a VM up-and-ready with all my content. And apologies to myself for installing a beta service pack on my main development machines.

Tools

All the usual presentation tools were not installed on that laptop either, so no ZoomIt and no Keyboard Jedi. Again, with a reinstall of vista a couple of days before, I just didn't have the time to get it right.

One thing I find difficult is choosing a screen mode. When showing code, I want to show you my Visual studio and whatever other programs get spawned by it (ie, firefox, the command prompt) while still seeing them on my screen. For powerpoint, I want to keep presenter-specific stuff from your eyes (a timer, some notes, and in general the whole content of the slide you'll see appearing as I talk).

I need a hybrid between Clone and Span modes. I may have something working, so my next talk will guinea-pig the idea. I'll blog about it after trying it out. :)

Not having slides...

Some people didn't completely see how the asp.net MVC and the REST part of the talk connected together, and maybe I should've introduced that at the beginning on the slides. But if you know me, I don't like slides and will avoid them at all costs.

This is the first talk I give where I put some content on slides, to refresh everyone on MVP and MVC and how the models differ. I like how visual it makes the explanation, but I'd rather manage to do it graphics only, with no text whatsoever. That requires more work, a tiny bit of animation and very good graphics. Nothing that can't be done with enough time for pimping it up.

Body language

I used the MacBook remote to change slides, and the freedom to move around to move slides is next to none. I also find that having the remote to hold from the tips of my fingers helps me avoid leaving my hands hanging. Hold something to keep your hands at chest level, it puts your body language into explanation mode. Relax and put one hand in your pocket and you switch to opinion mode.

Eye contact is the best tool to calm anxiety. You'll always find a couple of people in the audience being very expressive, that lets you judge the rhythm of the presentation. There's nothing worse than an expression-less audience.

Messy content

I'm a bit in-between two waters on this one. The whole point of the talk was to see what toolkits you can use today to do REST applications, but, for various reasons, I fit in there an introduction to asp.net MVC as a first part. That just doesn't flow well, and I think I'll split those two in two different presentations: asp.net MVC introduction (I have some AJAX stuff to make that presentation complete), and REST today, rest tomorrow. They can both stand on their own feet, and it would leave me more time for doing what I prefer doing: talking rather than coding and rushing.

I'm not funny

I tend to make jokes during the talk, they're usually completely spontaneous, but they fall flat every time, except for a few friendly grins from people I've met or talked to before. I shall prepare my jokes in advance and only use them after having tested them. But not on animals.

Speak more slowly

My voice level seems to be alright, but I speak too fast. And I have those pet words that creep in, amongst them "I think" (very annoying one I have a lot of problems getting rid of, even in day-to-day conversation), and Ok (very patronising, hate it, think I managed to mostly kick it off my presentations).

It's quite funny how the brain gives you those little fetish words. I think they creep-in because they trick your brain think there's a rhythm to what you're saying, when simple punctuation and sentences should be enough. It may also be the case that they give your brain enough time to reformulate when you're mid-sentence and unsure about what to say next. Again, preparation is the key.

Have different solutions, not different projects

This one bit me during the presentation. As I prepare the code for all the major steps, I end up with the same project at different stages, and I made the mistake of keeping all the projects in the same solution, often resulting in the wrong code being ran when pressing F5 and the wrong files being shown when I expected to show some code.

From now on, I'll keep all the projects in separate solutions.

Conclusion

I really like giving talks. It is a bit frustrating to come up with new material every time and only use it once, as you don't get the opportunity to retrofit what you learnt from presenting it once. Hopefully that will change as I get new speaking opportunities.

Presenting at the London .net User Group: Put your webforms to REST - how to build rest-y architectures with .net

What:
With the raise of the web 2.0 meme, more and more web applications claim to support REST architectures. We'll explore together what is REST and what is not, and how we can write a testable web application that supports the REST concepts on the asp.net platform, with a code-intensive overview of current toolkits (asp.net MVC and others).

Where:
MRM Worldwide London
76 - 80 Southwark Street , Bankside Studios, London SE1 0PN

When:
Tomorrow Wednesday the 21st of May, 18:30

Why:
This, I have no idea of :)

That is, if I get Visual Studio 2008 SP1 installing properly on my demo laptop, which is no small feat in itself, or face a frantic rewrite of some of the presentation tomorrow.

Reflecting on my last project

Today is a day off, as I've accumulated 36 hours of work between Monday and Tuesday and needed some rest. The last project I've been working on has been one of the most interesting I've had in a long time, not only because I took more responsibilities than usual, being both a lead dev and as a scrum master, but because of the amount of technology we've fetched in one app. To give a quick run-down:

• Fluid database design with an object-based linq2sql database (no dbml file and no sql files in the whole project)
• Sql Compact Edition
• ado.net synchronization services to sync to a central database, and hopefully the sync framework for multi-party syncrhonization
• WPF all the way, with a ViewModel way of developing
• Castle stack, for Windsor and a bit of DynamicProxy2 love
• 3G support for an always on experience

I've learnt quite a few things in the process, so here's a few reflections for my own benefits.

• When you don't know what you're building, you're going to have a hard time knowing when it's done
• Working under pressure can be fun, but it's exhausting and it does highlight a failure in the planning part. We're getting better but we're nowhere near there yet
• It's fun to see people with a background go around in WPF. It always starts quite code-centric and evolves into more XAML as time goes by
• I still don't see people using Blend for anything meaningful. There's a wide range of reasons why, from crashes to not liking esoteric Xaml to the recording model. It doesn't go down well with either populations right now, at least as far as WPF is concerned.
• The only reasonable way to monitor the correct use of patterns and abstractions is to do it continuously. Not paying attention to the code base and coming back with changes weeks later is not a good idea, and a complete failure on my part. I need to get better at agreeing, explaining and enforcing design decisions.
• No one can work on several projects within a company and stay focused. This doesn't work at all. From now on, I will flat out refuse to work on  something else in the same day. If you want my time for two projects, my minimum time unit will be a day. Interruption decreases my productivity so much it's unreasonable, and the project (and my nerves) suffer.
• Frameworks that hide all of their internal implementation suck big time. Understanding object tracking in linq2sql is not easy or enjoyable, and bite you. Badly.
• Frameworks that show all of their internal implementations suck big time. Castle Windsor (at least RC3) throws exceptions in all the wrong places, and make dealing with registration more painful than it needs to be (when it works at all).
• Designers and UE people *need* to be involved throughout the process, and work on the same stuff as the rest of the team. The way people think they can go off and work on the UE or the design on their own schedule, with only validation from tech (when they don't send the work done the day before a release) is driving me absolutely insane. This doesn't work for them (we can tell them how much more flexibility they can have in their own design), it doesn't work for us (they provide diagrams of stuff we've already delivered, or stuff that is completely limiting the capacities of the platform). It's the typical waterfall model, and fall and fail it usually does.
• Someone needs to wake up and realize that the technology is not there to support the design, and the design is not there to put a nice face on technology. They're two sides of the same silver coin, they need to work together to deliver. That's what Apple does and it works great.
• I'm always amazed at how little is still invested in most of my clients companies around supporting other development teams. With a core team of a couple of peoples working to support other teams and evangelize the company's infrastructure, any company would save *so much time* on all other projects, from enforcing good standards, deployment procedures, automation etc. Think a few weeks per project.

Overall, a very good project, a great team and a freedom that I don't have very often with clients. I think it'll be difficult to move to my next project, the comparison will suffer!

alt.net drinks moved, only slightly

Got a message from Catriona, and the original location for our alt.net beers event was fully booked, so it's now around the corner from the previous location. See the original post for the details.

Implementing INotifyPropertyChanged with DynamicProxy2

22:30 and still working on various bits and bobs, so I thought I'd take a well deserved break to tell you about one nice way to implement INotifyPropertyChanged, the one and only interface any class that will be bound in WPF should be implemented.

I used to (circa .net 2) not see a bit issue in this kind of code.

public class MyClass : INotifyPropertyChanged

{

    private string _myValue;

    public event PropertyChangedEventHandler PropertyChanged;

    public string MyValue

    {

        get

        {

            return _myValue;

        }

        set

        {

            _myValue = value;

            RaisePropertyChanged("MyValue");

        }

    }

    protected void RaisePropertyChanged(string propertyName)

    {

        if (PropertyChanged != null)

            PropertyChanged(this, new PropertyChangedEventArgs(propertyName));

    }

}

But I've been badly spoiled by automatic properties in C# 3.0, and this all sounds like a lot of noise. How great would it be if we could instead simply have the following.

public class MyDreamClass : INotifyPropertyChanged

{

    public event PropertyChangedEventHandler PropertyChanged;

    public string MyValue { get; set; }

}

Definitly much cleaner.  We're going to use DynamicProxy2, which is part of the Castle framework, and is used amongst other things in nhibernate.

The process is quite simple. You ask a ProxyGenerator to create a type for you, and pass it an interceptor object that will... Intercept any call!

First, let's clear up our class. Because the object generated by DP2 inherits from the original type, it needs to have a virtual modifier on the property. Furthermore, I wanted to add an attribute to specify which properties were to trigger the notification.

public class MyBetterClass : INotifyPropertyChanged

{

    public event PropertyChangedEventHandler PropertyChanged;

    [Notify]

    public virtual string MyValue { get; private set; }

}

Now, let's see how we create the object.

static void Main(string[] args)

{

    var proxy = new ProxyGenerator();

 

    MyBetterClass myClass = proxy.CreateClassProxy<MyBetterClass>(new NotifyPropertyChangedInterceptor());

 

    myClass.PropertyChanged += (src,prop) => Console.WriteLine(prop.PropertyName);

 

    myClass.MyValue = "testValue";

}

Fairly simple so far. Now let's see the meat of the code, the interceptor.

public class NotifyAttribute : Attribute { }

public class NotifyPropertyChangedInterceptor : IInterceptor

{

    public void Intercept(IInvocation invocation)

    {

        // let the original call go through first, so we can notify *after*

        invocation.Proceed();

 

        if (invocation.Method.Name.StartsWith("set_"))

        {

            string propertyName = invocation.Method.Name.Substring(4);

            var pi = invocation.TargetType.GetProperty(propertyName);

 

            // check that we have the attribute defined

            if (Attribute.GetCustomAttribute(pi, typeof(NotifyAttribute)) == null)

                return;

 

            // get the field storing the delegate list that are stored by the event.

            FieldInfo info = invocation.TargetType.GetFields(BindingFlags.Instance | BindingFlags.NonPublic)

                .Where(f => f.FieldType == typeof(PropertyChangedEventHandler))

                .FirstOrDefault();

 

            if (info != null)

            {

                // get the value of the field

                PropertyChangedEventHandler evHandler = info.GetValue(invocation.InvocationTarget) as PropertyChangedEventHandler;

                // invoke the delegate if it's not null (aka empty)

                if (evHandler != null)

                    evHandler.Invoke(invocation.TargetType, new PropertyChangedEventArgs(propertyName));

            }

        }

    }

}

And that's it. Get the field in which the event is stored and invoke it whenever a property has been modified.

Thought of the evening

MSBuild + SqlCompare + DataContext == FluidDatabaseDesign

The tale of the 6.4 Megapixel desktop

Just upgraded my development environment, here's the picture.

The laptop looks tiny next to the screen, but it is in fact a high res MacBook Pro, 1920x1200, driving as a secondary screen an Apple Cinema Display 30" for an added 2560 x 1600.

That's freakin' 6.4 megapixels of vista goodness! Surprisingly enough, Aero runs without a hitch.

Couple of other interesting points: new apple keyboard as I fell in love with the feel of the MBA keyboard, the mouse is not the one i usually have (but ran out of batteries). And Prada sunglasses for the one day of sun we've had in London so far.

As for drinks, the coffee mug is the property of the client at which I keep this equipment, and the can of Redbull kinda explains the name behind my company name: caffeine IT :)

IIS and asp.net URL validation weirdness and links

In my Migrating to IIS7 post, I highlighted that building REST frameworks that do meaningful things with Urls is hard on microsoft's platforms.

I encourage you to go and read the comments left by Mike Volodarsky on the issue. He's a Program Manager at Microsoft. Having people from the team building IIS7 responding to people like me highlighting issues shows how some teams really engage proactively with their customers. Kudos!

The other team at Microsoft that understand REST a bit (and IMO the most out of all the teams working on this), is the Astoria team. And of course, because they do funky stuff with their URLs, they hit the same issues as me. So here's a link on how to deactivate some of the checks asp.net does. Nasty registry editing...

I really wish asp.net could recognize when an IHttpHandler does not want validation and let it handle the request, its validation and etc.

Alt.net London Beers #1

[Update: new location, see below]

Here's the latest development. The alt.net London Beers event is being moved!

Skills Matter is organizing a talk by Gojko Adzic on the Castle Framework on the day we originally planned for the drinks. As everybody has shown strong interest in attending both events, Skills Matter has been kind enough to help us organize the drinks in the Crown Pub in front of their office, so you can now attend both events.

Not only that, but they have also opened the possibility for another presentation on an alt.net subject, so if you feel like presenting, drop me a mail!

I have to thank Catriona at Skills Matter for sponsoring the alt.net London Beers event and inviting all the alt.netters to attend the Castle presentation, as well as Gojko for suggesting the merge of the two events.

So here's the recap:

• What: Alt.net London Beers #1
• Where: The priory bar in St Johns Square, right by Farringdon station
• When: 15th May 2008 from 20:30

We'll probably move back to the planned Tottenham Court Road location for our second meet, on the 16th of June. Keep your calendars open!

Using Rasta #2 - Rasta in it's simplest form

Lack of time and sleep pushes me to be very lazy and present only the most trivial example of what Rasta was built for. Hopefully the future editions will become more interesting.

Rasta does many things, but one of the things you can use it for is Url rewriting for webforms. Simply declare the following in your global.asax file:

using (RastaConfiguration.Manual)

{

    UriSpace.HasTheUri("/home").ForThePage("~/pages/default.aspx");

}

And if you want to provide a url that matches a specific language, just expand this a bit:

UriSpace.HasTheUri("/accueil").InLanguage("fr").ForThePage("~/pages/default.aspx");

This will automatically set the language for the current request in the correct language, while still going to the same aspx.

Another fancy thing in Rasta's manual declaration is the using block. All the configuration needs to happen within that block, and is only applied when you exit the block. The fluent api is built using a chain of language elements that form a sentence. Each element you add to a sentence either replace it's predecessor in the list of sentences, or initiate a new sentence, and each fully-formed sentence will get called whenever the Dispose method is called on the object returned by the call to RastaConfiguration.Manual.

How do sentences get added? When you enter the block, the new object returned by the Manual property sets a CallContext that stores that list. When it is disposed, it calls the chain of sentences to configure itself. And finally, it makes most of the routing structures read-only to optimise them (a typical example is building a read-only tree of the Urls you can use for a site in a structure that is more efficient than if it was write-only).

That also means that trying to apply a configuration at runtime to replace the existing configuration will only succeed when the whole of the operation succeeds. This happens by only writing to a new copy of the configuration data, and committing the write if no exception happened. If you got the configuration wrong, the previous configuration will happily stay on to continue serving request.

Migrating to IIS7

Over the last couple of weeks I've been upgrading my Rasta framework to support IIS7. Here's the highlights:

• I automatically detect the base Url address for a site based on the application path and the first requested Url, at which point I create all the routing tables. This used to be at the end of the configuration code that used to run in Application_Start.
  You cannot access HttpContext.Request from there anymore, so this has to change. Right now I delay the discovery at a later stage (on first request), but this solution only support a single domain per web app.
• DefaultHttpHandler is not supported anymore, so I have to implement the equivalent functionality for when Rasta doesn't recognize a Url and try to delegate to a registered handler. This probably won't land for a couple of weeks.
• More Url processing weirdness than IIS6, with no support for unencoded + in paths. This goes against the RFC for uris that specify quite clearly that segments in a path should be opaque until handled. IIS considers it has the right to handle them and crashes. This is seriously limiting our ability to provide a virtualized Url space on a web site (any character not supported by the file system will automatically crash the request before a handler is called, as asp.net tries and do a MapPath, even when you percent-encode the special chars. I consider this to be quite unacceptable and limits my choice of Uri.

I also ended up with some weird issues where upon building, the ccnet machine would see its access to web.config denied, and the only solution is to go and copy the files manually the first time around. I'm still trying to investigate what happened there.