PDC 2009 Session Links

I extracted the session titles and links into this PDF to make it easier for me (and for you) to find and navigate to the PDC 2009 session materials. Hope it works for you.

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Easing into Prism

I received a familiar email today:

Is it possible to start slowly with this Prism stuff and work my way into it gradually. Can I get something running quickly with DevForce as I know it now? My client has seen a prototype and I need to construct it soon. Then can I come back later and modularize the whole thing behind the scenes?

Here’s my reply:

You do not need Prism to get started!  You can introduce it into your application as you see opportunities that make sense to you. Prism is not a monolithic framework. It is a small collection of free-standing components that also work well together. You can adopt it a piece at a time; some of it you may comfortably ignore.

It’s definitely worth reading about. It’s worth looking at the Reference Implementation and the Quick Starts. Get the Composite Application Guidance book from Patterns and Practices, look at what folks are doing with it and saying about it.

Don’t get hung up on Prism itself. It is guidance first and implementation second. Poke around. See how other people tackle some of the same concerns. You might look at Caliburn, for example.

In other words, take your time and educate yourself.  You don’t have to dive into the deep end.

However, I feel strongly that you should start wrapping your head around Dependency Injection (DI) and Inversion of Control (IoC) containers as soon as you can.  They will completely transform the way you write your application. They will position you for future modularity and make your code ever so much easier to maintain.

Learning IoC is also a great career move.

When you see yourself writing “new XXX(…)” you will learn to stop and ask yourself, “Do I really want to lock myself into the XXX type or would I be better off if XXX were delivered to me instead?”  In recent years my answer has increasingly been to avoid “new” and let the IoC construct and inject the instance I need.

Don’t get carried away now. It’s a shiny new toy. Take it easy. But get used to it.

I know you asked about Prism and here I am waxing on about IoC. I only go on about this because your decision to use or not use DI/IoC is fundamental. Prism (and its ilk) will come along naturally if you use DI; they won’t seem so natural if your application is not DI-ready.

I promise the effort of learning DI (and it does takes some effort) will pay off quickly … and for the rest of your career. The principles are fundamental to emerging Microsoft technologies (see the Managed Extensibility Framework – MEF). Dependency Injection is the primary vehicle for implementation of most modern application development patterns.

You have plenty of IoC containers to consider. Microsoft Unity is one choice but by no means the only one: AutoFaq, Castle Windsor, Ninject, and StructureMap are popular (apologies to any I omitted).

Do not be overwhelmed! These alternatives are vying for your affections with tons of features and you may easily become convinced that DI is super-complicated.

You can ease into DI. Take a look at our “Prism Explorer” (which uses Unity); you’ll hardly notice IoC but it’s there. I limited myself to the simplest Unity techniques. If I remember correctly, I only use constructor injection, I register very few interface types, and I don’t use any of the attribute markup. You can go amazingly far without any advanced IoC features.

In sum, get going on your application and do not let these technologies distract you. They are important and valuable but you don’t want to destroy your business relationship by drowning in technologies that you know nothing about.

Get acquainted with Dependency Injection first and start using it experimentally. Learn about Prism in all that spare time.

Try partnering with someone who has been down this road before. If that is not possible, find a local users group and latch on to other like-minded developers. It’s much more fun when you play with others.

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Young @ Heart: The (2007) Movie

Stumbled into “Young @ Heart”, a documentary about a New England choral group performing punk, rock, and R&B covers; the hook is that the members are well over 70 (high of 92).

Sounds like an opportunity for terminal cuteness … “oh those feisty seniors … isn’t it amazing that they can sort of sing at all at their age? … it’s so inspiring!”.  That’s exactly the sense you get from the trailer which is delivered with the typical phone-it-in Fox Searchlight style. Exactly the kind of movie I avoid.

But this one caught me completely by surprise and I’m still roiling with emotions a day later. I’m trying to figure out why.

It should have been utter treacle like one of those sentimental movies about animals, or kids, or illness, or the mentally infirm. Instead it’s a rich character study in which each member of the cast takes you somewhere you’re likely to go … somewhere you want to go … if you’re lucky enough to live that well.

Singing is the glue and reason enough to watch. The songs - well-known pop tunes of youthful love, rage, despair, and hope – confess new moods and meanings as sung by performers far from adolescence.  The juxtapositions can be simple fun as in the raucous “I Want to be Sedated”, given literal treatment by a cast for whom the wheelchair is a serious threat. Or it can rip you open as when Bob Knittle’s rich baritone pleads “I will try to fix you” to the barely perceptible beat of his oxygen machine, counting down toward the inevitable. It would be contrived if it didn’t actually happen, inadvertently, before a packed house of loving fans.

The heart of the movie is the interviews and the lives of the cast as they orbit the rehearsal hall. The authenticity is striking. At a jail house concert the camera lingers on the prisoners’ faces each surrendering a thought of present loss or worrisome future. They are not being entertained (although they think they are); they are transported to the company of someone they miss, of someone they may become.

Death is a looming presence. Close as he is, the cast are no more ready for him than we are.

It’s not great filmmaking. It’s great human material triumphing over the pedestrian. It’s people being themselves, striving for meaning and community, just a few feet ahead of us down the road we travel together.

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Patterns and Frameworks

I just returned from the Microsoft Patterns and Practices Summit 2009 which may be my favorite Microsoft conference. Great for exposure to customers with real applications and to the wonderful, dedicated Microsoft developers who aspire to serve them. More on this in another post. I have another point to make here, which is …

Patterns are not Frameworks. We should draw a bright line between Patterns and their Implementations. A pattern only becomes a pattern if and when there are multiple implementations. You don't know a pattern well until you've seen more than one implementation. If there is a single, canonical implementation, the thing is not a pattern, it’s a framework.

“Duh” you say. We know this. And yet it eludes us in practice.

I had numerous conversations about this with folks who work in PnP. The conversation goes something like this:

The Conversation

“We are not a product group. We don’t want to be a product group.

“We’re trying to provide guidance to consumers of Microsoft development products. We are reluctant even to say ‘best practices’ anymore. It’s just the best guidance we can give today, built with time, and commitment, and our access to experts inside and outside Microsoft.

“We’re answering the customer call for Microsoft to demonstrate how to use its own products in real applications.

“This bleeds inevitably into more general questions about how to build applications and soon (and properly) we investigate and describe general design and implementation patterns that go beyond the particulars of Microsoft products.

“It’s not enough to talk about the patterns. We need to demonstrate those patterns … express them in real code that works with Microsoft technology.

“That is when it starts to get away from us. Our guidance, as it becomes code, starts to cover more and more customer cases. It begins to harden and the pattern becomes harder to see behind the bells and whistles. Customers say ‘wow, can I use that in my application?’ and we say ‘sure’. They say ‘it would really help our particular situation if it also did this’ and we say ‘sure’ again.

“Then they want us to give it a name, package it up, support it, develop a roadmap. They want us to productize it … and we start to do that because serving customers is also our mission. And, in our (not so) secret hearts, we all want to ship products … we’re wired that way.

“Then we start worrying about backward compatibility … because customers get angry at us if we change anything

“Then others in the community, especially the Open Source community, get on our case for having sucked the oxygen away from alternative implementations that may be better in many scenarios. They say we have imposed, de facto, a particular implementation of the pattern; people can’t tell the difference between the pattern and what Microsoft did to it. And I see their point.

“And now we have old code (e.g., CAB) that no longer represents our current thinking … that, in fact, embodies practices we would counsel against today … and we cannot walk away from it.

--

I don’t know that there is an easy answer to this one. I’m not willing to place all the blame on PnP either. The customer should know better.

“Best Practices” do not sit still. They evolve, leaving behind a trail of “formerly best practices” to which millions of dollars and entire careers are firmly attached. PnP is pulled in one direction by its responsibility to offer the best current guidance … and by its responsibility to customers who have placed big bets on its past guidance.

Perhaps we need some different rules of engagement.

Explicit Shelf Life

What if PnP put a “Sell By” date on their code? What if it had a shelf life and warning label: “Use with caution. Do not expect support beyond 3 years”. Stamp this at the top of every piece of code and every web page.

Then mean it. If you need to break, you break. Customers need to know that you are serious about your commitment to giving them the best advice you can and you do them no favors by clinging to outdated code.

This happens in OSS all of the time. Dead bodies are strewn everywhere.

You can do this. Microsoft can’t but you can. I think you can wean your customers away from thinking of you as a product group. If that means fewer customers served … that may be for the best … for everyone: your customers, you, and Microsoft itself.

Play Well With Others

My thesis again: a pattern is independent of any one implementation. You don't know a pattern well until you've seen at least two implementations.

What if PnP routinely called out the other implementations of the patterns they describe? Front and center, not as an afterthought. Openly encourage customers to look at these alternatives … if only to gain a contrasting perspective on the PnP guidance.

One of the best ways to learn about the Composite Application Block (CAB), for example, was Jeremy Miller’s “Build your own CAB” series. I assure you I had no intention of following Jeremy’s advice and building my own CAB. It didn’t even occur to me. But that series was the best (unintentional) documentation of CAB I ever found, It introduced me to different ways of thinking about each issue (e.g., Event Aggregation and Dependency Injection). I learned indirectly what CAB was doing and the consequences of my choice. I’m not saying the consequences were all bad either; but there were consequences and I only recognized them in the oblique light cast by Jeremy’s series.

PnP might do more to highlight these alternatives and to encourage discussion about the contrasting choices. People who come to Prism should learn … right there on the home page … that a Caliburn exists. When they come to the Unity home page, they could learn that there are 5 to 10 other popular IoC containers to choose from and find links to learning more about IoC practices.

[I was just on the Unity page. It’s a fine product home page; it is not fine for guidance about Dependency Injection and IoC in general.]

I don’t think that PnP should endorse Caliburn or anything else for that matter. I’m not suggesting that PnP’s output is inferior or that PnP should express less than abundant enthusiasm for its own work.

I am saying that PnP is presenting itself as a product purveyor in a manner that conflicts with its role as a trusted source of guidance. This ensures that it will be trapped into long term support commitments, the kinds of commitments that some people there tell me they do not want.

PnP could say in some unambiguous fashion, “my dear customer, we offer a wonderful implementation of this pattern. HOWEVER … you ought to look at some alternatives, not only when first choosing your approach but also throughout your application development; there’s gold in seeing how others approach these same problems.”

True Open Source

What if PnP could accept contributions from the field? I don’t mean through “Contrib”; I mean directly into the guidance itself.

What if PnP developers actually read some of the Open Source code out there?

I’m pretty sure the legal guardians won’t permit it … in which case “Contrib” is the best they can do.

Conclusion

They call it "Microsoft Patterns and Practices", not "Microsoft Tool and Die".

It is time for customers to pull back from unrealistic expectations of Patterns and Practices. They are not your application infrastructure outsourcer. They are a trusted source of guidance. Rejoice if they provide more but do not expect or demand it.

Patterns and Practice doesn’t need to change what they build. I do think PnP can rethink its commitments to prior output. It can do a much better job of promoting the spirit of exploration and directing its community to external resources that offer contrasting implementations and points of view.

And now I descend from this soap box … in search of another.

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Man and Superman

I was reading Jeremy Miller’s musings on “Two Types of Developers”.

Developers fall into two different extremes … Some developers can jump right into any technology and find out how best to use it and new ways to twist it and apply it without really questioning the “goodness” of that technology.  Others look at a technology with preconceived notions of how it should work and are quick to drop a technology when it doesn’t fit their vision of “good.”

I am reminded that there are two kinds of people in this world: the people who divide the world into two kinds of people and the people who don’t. I am one of those two kinds of people.

What Jeremy really means it that there are two developer mindsets. Actually-existing developers indulge both modalities as he also observes in this second paragraph. Still, the thrust of his argument is that developers habituate to one or the other extreme.

Jeremy aligns himself mostly with the second. He describes an encounter with someone who, as Jeremy would have it, is inclined to the first.

I happen to have read the blog post on exhibit, know both parties (call the other “B”), and participated in some of the exchange that ensued. It got me wondering whether I buy Jeremy’s dichotomy.

Jeremy strives to be non-judgmental, averring potential advantages on both sides. I suggest that his phrase “without really questioning the ‘goodness’ of that technology” gives the game away.

I know “B” and he is a curious fellow (double entendre intended). His curiosity is evident in the post and manifold in conversation. “B” never takes a technology on face value, certainly not “Prism” which was the technology at issue in this example.

It may be relevant to note that “B” was deeply involved in Prism development. He is obviously comfortable with it. But “B” was as deeply involved in the debates, disappointments, and compromises that are inevitable when one works collaboratively on a framework. He may be blind to some of its faults but he can’t be accused of being uncritical by nature.

What happened here is that “B” chose to implement a solution to a problem using technology that Jeremy dislikes. One may say so. One may ponder the reasons. But to leap to the conclusion that “B” (or anyone who chooses similarly) is simply “unquestioning” …  that is unjust.

Worse, it is lazy.

It forecloses a genuine attempt to investigate how developers actually make choices in the real world of customers and deadlines.

Are there drudge journeyman programmers who paint by numbers? Sure … but they aren’t relevant to this discussion and that is not what Jeremy thinks of “B”.

Do we often cheerily follow the easy, well-trod path? Of course. Do we challenge our every decision to be the best possible in the abstract. No. None of us do. Could “B” have made a better choice than Prism… even in his particular circumstances? Maybe … which makes it worth pursuing with “B” .

But Jeremy’s point isn’t that we are prone to be the willing captives of our familiar tools. No, he claims we are by nature either slaves or freeman, the “last man” or the “Übermensch”. That is the true import of his “interesting taxonomy of developers that I’ve observed for years”.

The earth has become small, and on it hops the last man, who makes everything small. … One still works, for work is a form of entertainment. But one is careful lest the entertainment be too harrowing. One no longer becomes poor or rich: both require too much exertion. … 'We have invented happiness,' say the last men, and they blink.

Behold, I teach you the overman. The overman is the meaning of the earth.Let your will say: the overman shall be the meaning of the earth! I beseech you, my brothers, remain faithful to the earth, and do not believe those who speak to you of otherworldly hopes!"

- Nietzsche's Thus spoke Zarathustra

It’s thrilling to hear … but I am not buying it.

I’m a huge Jeremy Miller fan; this was not his best day.

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Silverlight Spy 3 – First Look

Silverlight Spy 3 was just released. I think you’ll want this in your tool bag right away. Why? Because it is a great way of seeing what’s going on in your Silverlight application … and twiddling its appearance … at runtime.

It is especially helpful if you’re building a compositional application of many, independently-designed views; you want to see them playing together and understand what’s happening.

Quick Tour

I’m looking at my Prism Explorer demonstration app right now. This demo shows our DevForce Silverlight Data Services product working with Prism.

Fired it up in Visual Studio (to get the Cassini server side going), then pasted the URL (http: //localhost:9006/) into Spy’s address bar. Spy fires up the client in its browser just fine.

Spy drew the red highlight box, not me. I held down the ctrl + shift keys and moved my mouse around the browsed page; as I did, Spy highlighted each element in this manner; and then I clicked on the address to set the focus as you see it.

Now I swing over to the Explorer view and I see that the address is a TextBlock in the middle of a DataGridCell … deep in the visual (or logical) tree that begins with my Prism shell. I love being able to start from something I see on the page right to the element in the object tree.

I get the same effect in the other direction by navigating from the tree: select a node and watch Spy highlight the corresponding visual real estate in its browser.

I can see the XAML for this TextBlock in Spy’s View window:

Suppose I want to see what would happen if I gave the address a little more air. I open Spy’s Properties window, locate the Padding property and try “20” all around. I see the effect immediately:

Peeking and tweaking the look on the fly is value that can hardly be overstated especially in a composite app. Sometimes you just have to see the app run in a production context with real data behind it to understand what is going on. Adjusting some values to visualize how it might look after correction … that’s worth something to me.

Spy integrates seamlessly with Reflector so I can poke around in the client-side source code while in Spy. First, I tell Spy where to find Reflector through Tools / Options / Reflector. Then, in the Explorer window, “Object Browser” node, I navigate the assemblies in the XAP:

The View window exposes the disassembled code using Reflector:

I can also spy on other people’s applications. Now, when I see an effect I like, I’ll have a fighting chance to figure out how it’s done. Nothing evil in that.

Perhaps more productively, Spy can help me better support my customers. I don’t have their code. I don’t want their code! Now I can fire up their app in Spy from out here in Stinson Beach (yes, kicking back with the blog) and gain immediate insight. Having reflector baked in makes it easy to walk their code too.

Helpful Touches

Spy let’s me monitor mouse and key events which I can filter. In this snapshot, clicking on the event also takes me to the associated visual element.

I like to know when my app is visiting the server. Fiddler, Firebug (FireFox), and Web Development Helper (IE) are superior tools for the in-depth analysis. But if I just need to know that something went over the wire and peek at the headers, Spy does nicely. In this snap I just asked for a projection over all customers and their orders:

The top window is a grid of the traffic; double clicking a row reveals the headers panels in the lower half.

There’s a Performance Monitor with the visual familiarity of the one in Windows Task Manager.

The processor metric seems parallel to the Task Manager’s. The memory metric probably tracks just your app’s usage although how and how precisely I can’t tell. I noticed unpredictable figures simply by refreshing the application address to restart the app. I think of it as a rough gauge of relative behavior. You’ll get a general feel and you might be able to detect some memory leaks this way.

There are other goodies. These are just the features that attracted my immediate attention and made me want to buy.

Price

Spy was free in earlier incarnations. It now sells for roughly US$100 for a personal copy. You can download an evaluation copy that’s good for 27 days.

Frankly, I’m glad to see a price. I love “free” as much as the next guy but nothing is truly free. I want Spy’s author to keep improving this tool and he has to make a living at it to do it well. I’m bummed when a great free tool comes along and then it just sits there, waiting upon the author’s free time to answer questions, fix bugs, and take the next giant leap.

The biggest shortfall (as I will repeat) is the utter absence of documentation. With a little dough, Koen Zwikstra - the man behind spy - can afford to hire a tech writer and cut some videos.

Full disclosure: I got a free copy as an MVP. This review, however, is entirely my idea with no promise of reward.

Wrap Up

Silverlight Spy 3 is a super tool and a fine piece of work. Runs like a top. No install issues, no runtime glitches so far.

No documentation! None that I could find. This is a huge weakness. Thank goodness for Koen’s Channel 9 video with Adam Kinney recorded at MIX in March 2009; it opened my eyes to the potential and gave me valuable operating clues. How else would I discover “Ctrl+Shift+Mouse+Click”? Web search revealed nothing else (there is material on Spy 2).

Fortunately, it is pretty intuitive. Just bang around on it awhile and it starts to make sense. But some kind of guide needs to come out soon.

I’m hopeful this introduction piques your interest and gets you started.

A few minutes with Spy and you remember in a hurry never to put anything secret in your Silverlight client; that’s the wrong place for the Coca Cola recipe. Sure other tools can do it …. but Spy makes it so easy.

Go Spy!

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AdventureWorks 2000 tinyint nightmare

You’re going to love this one!

Some of our integrations tests use AdventureWorks 2000. One developer’s test updated a Sales.SalesOrderDetail. The test suddenly blew up with a SQL Server 2005 error that complained about exceeding the size limit of a TinyInt.

The error didn’t say where this TinyInt lived or what the column was called. The best we could tell was that the exception occurred while updating Sales.SalesOrderDetail.

SalesOrderDetail has a TinyInt column, “LineNumber”, which was not jeopardized by the update.

Aside: I have a different AdventureWorks db on my machine that doesn’t have “LineNumber” or a TinyInt but it does have, “OrderQty”, which is a SmallInt. I would have suspected that (“SmallInt, TinyInt, what’s the difference?”); there would be no problem there either.

No other developer could reproduce the SQL exception.

After hours of hair-pulling, the developer found that there is an update trigger on SalesOrderDetail that updates the parent Sales.SalesOrderHeader. SalesOrderHeader has an update trigger that increments SalesOrderHeader.RevisionNumber … which is a TinyInt.

Over the course of many tests, that RevisionNumber kept creeping up … until it hit 255. Each developer has his own AdventureWorks copy so no surprise no one else could reproduce it.

You can blame the victim if you wish; should have had adequate rollback logic all along.

But I have to admire the genius who decided that you’d never exceed 255 updates of a SalesOrderHeader in a test database.

Let’s thank SQL Server for throwing an exception on exceeding the max for a TinyInt without telling us the name of the column or table involved.

Kudos also to the other evil genius in this mess who wrote a trigger on one table that fires a trigger on another table to update the RevisionNumber … and didn’t bother to check the type or implement exception logic that would help clarify the problem.

There must be an award for this kind of thing.

Lesson #1: If you are using AdventureWorks 2000, be sure to reset all SalesOrderHeader.RevisionNumber values to 0. It’s too late to mess with the schema.

Lesson #2: Hey, SQL Server folks, how about a little more help in exception messages?

Lesson #3: Please write good exception messages yourself … messages that would give the poor sod who received it a fighting chance of understanding the problem. Extra credit if you suggest how to fix it.

Lesson #4: Business logic in the database is killing us out here. You DBAs have got to be more helpful.

Lesson #5: Stop trying to squeeze every last byte out of the schema. TinyInt should be used only in the most extreme circumstances and never where it could be incremented.

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