Live Search is actually getting pretty good these days!

image Live Search got a refresh recently and it's actually pretty good, dare I say may be even better than Google.

  • Performance: The load times are very snappy now and it feels pretty much on par with google performance.
  • Image Search: Functionality on Image Search has been superior for some time with the ability to size the thumbnails and I quite like the "add to scratchpad" feature but wish it was available for video and web content as well. The ability to refine the search by size, aspect ratio, colour, Style (photo vs. illustration) and Face (i.e. head & shoulders, just face, etc.) is brilliant. It's not 100% accurate, but it is still quite useful. Google can do a subset of this, but frankly, never noticed it until I went looking for it. These features are more discoverable in Live. I have to say that I'm in love with the fact that I can preview the context of the pages split screen so I don't leave my list of results. As far as relevancy goes, I'm going to have to give it a try for a week. Google does a better job finding pictures of me, but Live does a better job of finding black & whites of Darryl Sittler.  Live found 12 good b&w's of the Sitler while google found absolutely nothing of relevance. Unfortunately, Live fails my vanity image search and google prevails with more pictures of me. 
  • Video Search: I honestly have never used video search on live or google until this blog entry. Live has a nice feature where it can play videos from the results page by just hovering over the thumbnails. It can't do it for every video type, some you have to click on but it is a lovely feature when it works which from what I can tell is about 60% of the time. Google only manages to get 10 thumbnails per page where live gets twice that. Live brought back a few extra total results. It seems like google favours primarily youtube.
  • Map Search: Mileage seems to vary greatly depending on where you are searching. Live has the great integrated 3D maps with buildings, contoured terrain and birds eye view vs. google with street view as it's killer feature. For Canadians, google hasn't made any of these features available yet. Live has thrown us Canadians a few bones with birds eye view available in Vancouver, Calgary, Toronto, and Montreal. Live also gives us some traffic in Vancouver, Toronto, Montreal, and Ottawa.

    Live maps has some great directional tools as well. I like the feature where I can just click on a point and ask for 1 click directions - which will give me generic instructions on coming to a location from all major available directions/arteries. This is great if you want to include directions on an invitation but you don't know where everybody is coming from. The Live Map collection editor and the ability to easily add pushpins and draw (with distances) on the map is great.

    One thing I do like about Google maps is the ability to take a set of directions and drag segments around to tell it how I really want to get somewhere. All in all though, I much prefer (as a Canadian) Live Maps as the most


  • Plain Old Web Relevancy: Plain old web results are perhaps the most important criteria. I think this will be impossible to provide any meaningful observations after spending < 1 hour using live search. I'm going to give live a shot as my default search engine for the next week and see how it does but a few immediate observations:
    • Live wins on relevancy for the "Barry Gervin" vanity search, easily. By the bottom of the first page (items 7th-9th), Google is showing results that are irrelevant - in fact, no mention of Barry or Gervin on any of those pages.
    • Searching for some things that I know are on MSDN Forums - posted yesterday, google seems to be crawling that site faster than Live. Google still has a dedicated newsgroups search engine. I used to use this a lot more than I currently do so I have mixed emotions about live search. In fact, in some of my tests for searching things that I knew were known to exist in newsgroups, live search actually referred me to google groups - so it does appear that live is indexing the google groups search engine. I think the thing I find most appealing about google groups is not the content that it finds, but the way it presents it, showing me what group a result was found in, and then making the detailed results essentially a web based NNTP client. Live could do much more than they are doing now that's for sure, I'm just not sure that it really matters.
    • I'm making more and more use of google alerts to have things I am constantly tracking or researching searched and emailed to me. Live has no equivalent to this.

I'm going to give Live Search a trial as my default search engine for the next week or so and see how it goes. I'm optimistic.

Visual Studio 2008 SP1 Beta &amp; SQL Server 2008

A quick heads up to let you know that VS 2008 Service Pack 1 is now available (links below). It typically takes a couple of months from this point before we'll see a final release.

This Service Pack includes new cool feature:

One interesting point is that MS is going to simultaneously ship SQL Server 2008 which actually has a hard dependency on SP1.

I thought I’d take a moment to highlight some new features that Dev’s would care about in SQL Server 2008.

  • Change Data Capture: Async “triggers” capture the before/after snapshot of row level changes and writes them to Change Tables that you can query in your app. They aren’t real triggers as this asynchronously reads the transaction log.
  • Granular control of encryption, right through to the database level without any application changes required.
  • Resource Governor – very helpful when you allow users to write adhoc queries / reports against your OLTP database. Allows a DBA to assert resource limits & priorities.
  • Plan Freezing – allows you to lock down query plans to promote stable query plans across disparate hardware, server upgrades, etc.
  • New Date, and Time data types, no longer just DateTime types that you have to manually parse out the time or date to just get the real data you want.
  • DataTimeOffset – is a time zone aware datetime.
  • Table Value Parameters to procs – ever want to pass a result set as an arg to a proc?
  • Hierarchy ID is a new system type for storing nodes in a hierarchy….implemented as a CLR User Defined Type.
  • FileStream Data type allows blobish data to be surfaced in the database, but physically stored on the NTFS file system. ….but with complete transactional consistency with the relational data and backup integration.
  • New Geographic data support, store spatial data such as polygons, points and lines, and long/lat data types.
  • Merge SQL statement allows you to insert, or update if a row already exists.
  • New reporting services features such as access to reports from within Word & Excel, better SharePoint integration

Personally, haven't spent any time with SQL Server 2008 but that's a great set of new features that I can hardly wait to start using in real-world applications.

Downloads

· VS 2008 SP1 : http://download.microsoft.com/download/7/3/8/7382EA08-4DD6-4134-9B92-8585A5B07973/VS90sp1-KB945140-ENU.exe

· .NET 3.5 SP1 : http://download.microsoft.com/download/8/f/c/8fc1fe13-55de-4bf5-b43e-375daf01452e/dotNetFx35setup.exe

· Express 2008 with SP1:

o http://download.microsoft.com/download/F/E/7/FE754BA4-140B-413C-933F-8D35FB150F12/vbsetup.exe

o http://download.microsoft.com/download/F/E/7/FE754BA4-140B-413C-933F-8D35FB150F12/vcsetup.exe

o http://download.microsoft.com/download/F/E/7/FE754BA4-140B-413C-933F-8D35FB150F12/vcssetup.exe

o http://download.microsoft.com/download/F/E/7/FE754BA4-140B-413C-933F-8D35FB150F12/vnssetup.exe

· TFS 2008 SP1: http://download.microsoft.com/download/a/e/2/ae2eb0ff-e687-4221-9c3e-9165a942bc1c/TFS90sp1-KB949786.exe

Feedback Forum: http://go.microsoft.com/fwlink/?LinkId=119125

 

The Entity Framework vs. The Data Access Layer (Part 1: The EF as a DAL)

In Part 0: Introduction of this series after asking the question "Does the Entity Framework replace the need for a Data Access Layer?", I waxed lengthy about the qualities of a good data access layer. Since that time I've received a quite a few emails with people interested in this topic. So without further adieu, let's get down to the question at hand.

So let's say you go ahead and create an Entity Definition model (*.edmx) in Visual Studio and have the designer generate for you a derived ObjectContext class and an entity class for each of your tables, derived from EntityObject. This one to one table mapping to entity class is quite similar to LINQ to SQL but the mapping capabilities move well beyond this to support advanced data models. This is at the heart of why the EF exists: Complex Types, Inheritance (Table per Type, Table per Inheritance Hierarchy), Multiple Entity Sets per Type, Single Entity Mapped to Two Tables, Entity Sets mapped to Stored Procedures or mapping to a hand-crafted query, expressed as either SQL or Entity SQL. EF has a good story for a conceptual model over top of our physical databases using Xml Magic in the form of the edmx file - and that's why it exists.

So to use the Entity Framework as your data access layer, define your model and then let the EdmGen.exe tool do it's thing to the edmx file at compile time and we get the csdl, ssdl, and msl files - plus the all important code generated entity classes. So using this pattern of usage for the Entity Framework, our data access layer is complete. It may not be the best option for you, so let's explore the qualities of this solution.

To be clear, the assumption here is that our data access layer in this situation is the full EF Stack: ADO.NET Entity Client, ADO.NET Object Services, LINQ to Entities, including our model (edmx, csdl, ssdl, msl) and the code generated entities and object context. Somewhere under the covers there is also the ADO.NET Provider (SqlClient, OracleClient, etc.)

image

To use the EF as our DAL, we would simply execute code similar to this in our business layer.

var db = new AdventureWorksEntities();
var activeCategories = from category in db.ProductCategory
                 where category.Inactive != true
                 orderby
category.Name
                 select category;

How Do "EF" Entities Fit In?

If you're following along, you're probably asking exactly where is this query code above being placed. For the purposes of our discussion, "business layer" could mean a business object or some sort of controller. The point to be made here is that we need to think of Entities as something entirely different from our Business Objects.

Entity != Business Object

In this model, it is up to the business object to ask the Data Access Layer to project entities, not business objects, but entities.

This is one design pattern for data access, but it is not the only one. A conventional business object that contains its own data, and does not separate that out into an entity can suffer from tight bi-directional coupling between the business and data access layer. Consider a Customer business object with a Load method. Customer.Load() would in turn instantiate a data access component, CustomerDac and call the CustomerDac's Load or Fill method. To encapsulate all the data access code to populate a customer business object, the CustomerDac.Load method would require knowledge of the structure the Customer business object and hence a circular dependency would ensue.

The workaround, if you can call it that, is to put the business layer and the data access layer in the same assembly - but there goes decoupling, unit testing and separation of concerns out the window.

Another approach is to invert the dependency. The business layer would contain data access interfaces only, and the data access layer would implement those interfaces, and hence have a reverse dependency on the business layer. Concrete data access objects are instantiated via a factory, often combined with configuration information used by an Inversion of Control container. Unfortunately, this is not all that easy to do with the EF generated ObjectContext & Entities.

Or, you do as the Entity Framework implies and separate entities from your business objects. If you've used typed DataSets in the past, this will seem familiar you to you. Substitute ObjectContext for SqlConnection and SqlDataAdapter, and the pattern is pretty much the same.

Your UI presentation layer is likely going to bind to your Entity classes as well. This is an important consideration. The generated Entity classes are partial classes and can be extended with your own code. The generated properties (columns) on an entity also have event handlers created for changing and changed events so you can also wire those up to perform some column level validation. Notwithstanding, you may want to limit your entity customizations to simple validation and keep the serious business logic in your business objects. One of these days, I'll do another blog series on handing data validation within the Entity Framework.

How does this solution stack up?

How are database connections managed?

thumbs up Using the Entity Framework natively itself, the ObjectContext takes care of opening & closing connections for you - as needed when queries are executed, and during a call to SaveChanges. You can get access to the native ADO.NET connection if need be to share a connection with other non-EF data access logic. The nice thing however is that, for the most part, connection strings and connection management are abstracted away from the developer.

thumbs down A word of caution however. Because the ObjectContext will create a native connection, you should not wait to let the garbage collector free that connection up, but rather ensure that you dispose of the ObjectContext either explicitly or with a using statement.

Are all SQL Queries centralized in the Data Access Layer?

thumbs down By default the Entity Framework dynamically generates store specific SQL on the fly and therefore, the queries are not statically located in any one central location. Even to understand the possible queries, you'd have to walk through all of your business code that hits the entity framework to understand all of the potential queries.

But why would you care? If you have to ask that question, then you don't care. But if you're a DBA, charged with the job of optimizing queries, making sure that your tables have the appropriate indices, then you want to go to one central place to see all these queries and tune them if necessary. If you care strongly enough about this, and you have the potential of other applications (perhaps written in other platforms), then you likely have already locked down the database so the only access is via Stored Procedures and hence the problem is already solved.

Let's remind ourselves that sprocs are not innately faster than dynamic SQL, however they are easier to tune and you also have the freedom of using T-SQL and temp tables to do some pre-processing of data prior to projecting results - which sometimes can be the fastest way to generate some complex results. More importantly, you can revoke all permissions to the underlying tables and only grant access to the data via Stored Procedures. Locking down a database with stored procedures is almost a necessity if your database is oriented as a service, acting as an integration layer between multiple client applications. If you have multiple applications hitting the same database, and you don't use stored procedures - you likely have bigger problems. 

In the end, this is not an insurmountable problem. If you are already using Stored Procedures, then by all means you can map those in your EDM. This seems like the best approach, but you could also embed SQL Server (or other provider) queries in your SSDL using a DefiningQuery.

Do changes in one part of the system affect others?

It's difficult to answer this question without talking about the possible changes.

thumbs up Schema Changes: The conceptual model and the mapping flexibility, even under complex scenarios is a strength of the entity framework. Compared to other technologies on the market, with the EF, your chances are as good as they're going to get that a change in the database schema will have minimal impact on your entity model, and vice versa.

thumbs up Database Provider Changes: The Entity Framework is database agnostic. It's provider model allows for easily changing from SQL Server, to Oracle, to My Sql, etc. via connection strings. This is very helpful for ISVs whose product must support running on multiple back-end databases.

thumbs down Persistence Ignorance: What if the change you want in one part of the system is to change your ORM technology? Maybe you don't want to persist to a database, but instead call a CRUD web service. In this pure model, you won't be happy. Both your Entities and your DataContext object inherit from base classes in the Entity Framework's System.Data.Objects namespace. By making references to these, littered throughout your business layer, decoupling yourself from the Entity Framework will not be an easy task.

thumbs down Unit Testing: This is only loosely related to the question, but you can't talk about PI without talking about Unit Testing. Because the generated entities do not support the use of Plain Old CLR Objects (POCO), this data access model is not easily mocked for unit testing.

Does the DAL simplify data access?

thumbs up Dramatically. Compared to classic ADO.NET, LINQ queries can be used for typed results & parameters, complete with intelli-sense against your conceptual model, with no worries about SQL injection attacks.

thumbs up As a bonus, what you do get is query composition across your domain model. Usually version 1.0 of a convention non-ORM data access layer provides components for each entity, each supporting crud behaviour. Consider a scenario where you need to show all of the Customers within a territory, and then you need to show the last 10 orders for each Customer. Now I'm not saying you'd do this, but what I've commonly seen is that while somebody might write a CustomerDac.GetCustomersByTerritory() method, and they might write an OrderDac.GetLastTenOrders(), they would almost never write a OrderDac.GetLastTenOrdersForCustomersInTerritory() method. Instead they would simply iterate over the collection of customers found by territory and call the GetLastTenOrders() over and over again. Obviously this is "good" resuse of the data access logic, however it does not perform very well.

Fortunately, through query composition and eager loading, we can cause the Entity Framework (or even LINQ to SQL) to use a nested subquery to bring back the last 10 orders for each customer in a given territory in a single round trip, single query. Wow! In a conventional data access layer you could, and should write a new method to do the same, but by writing yet another query on the order table, you'd be repeating the mapping between the table and your objects each time.

Layers, Schmayers: What about tiers?

thumbs down EDM generated entity classes are not very tier-friendly. The state of an entity, whether it is modified, new, or to be delete, and what columns have changed is managed by the ObjectContext. Once you take an entity and serialize it out of process to another tier, it is no longer tracked for updates. While you can re-attach an entity that was serialized back into the data access tier, because the entity itself does not serialize it's changed state (aka diff gram), you can not easily achieve full round trip updating in a distributed system. There are techniques for dealing with this, but it is going to add some plumbing code between the business logic and the EF...and make you wish you had a real data access layer, or something like Danny Simmons' EntityBag (or a DataSet).

Does the Data Access Layer support optimistic concurrency?

thumbs up Out of the box, yes, handily. Thanks to the ObjectContext tracking state, and the change tracking events injected into our code generated entity properties. However, keep in mind the caveat with distributed systems that you'll have more work to do if your UI is separated from your data access layer by one or more tiers.

How does the Data Access Layer support transactions?

thumbs up Because the Entity Framework builds on top of ADO.NET providers, transaction management doesn't change very much. A single call to ObjectContext.SaveChanges() will open a connection, perform all inserts, updates, and deletes across all entities that have changed, across all relationships and all in the correct order....and as you can imagine in a single transaction. To make transactions more granular than that, call SaveChanges more frequently or have multiple ObjectContext instances for each unit of work in progress. To broaden the scope of a transaction, you can manually enlist using a native ADO.NET provider transaction or by using System.Transactions.

Live Search Maps - now with Bird's Eye View in Toronto

image

It's amazing what MS will give you, if you give them a Team Canada Hockey Jersey.

Entity Framework Links for April, 2008

  • During the past month, Danny Simmons let us all officially know that SP1 of VS 2008/.NET Framework 3.5 will be the delivery mechanism for the Entity Framework and the Designer, and that we should see a beta of the entire SP1 very soon as well. No release dates yet.
  • Speaking of the next beta, there have been some improvements in the designer to support iterative development. Noam Ben-Ami talks about that here.
  • There is also a new ASP.NET EntityDataSource control coming in the next beta. Danny demo'd that at DevConnections, and Julie blogged about it here.
  • In April, Microsoft released the .NET 3.5 Enhancements Training Kit. This includes some preliminary labs on ASP.NET MVC, ASP.NET Dynamic Data, ASP.NET AJAX History, ASP.NET Silverlight controls, ADO.NET Data Services and last but certainly not least, the ADO.NET Entity Framework. Stay tuned for updates
  • Julie Lerman has created a spiffy pseudo-debug visualizer for Entity State. It's implemented as an extension method and not a true debug visualizer, but useful just the same.
  • Check out Ruurd Boeke's excellent post on Disconnected N-Tier objects using the Entity Framework. His sample solution is checked in to the EFContrib Project and he demonstrates using POCO classes, in his words "as persistence ignorant as I can get", serializing entities with no EF references on the clients, yet not losing full change tracking on the client - and using the same domain classes on the client and the server (one could argue this last point as being not being a desirable goal - but it does have it's place).

The Entity Framework vs. The Data Access Layer (Part 0: Introduction)

So the million dollar question is: Does the Entity Framework replace the need for a Data Access Layer? If not, what should my Data Access Layer look like if I want to take advantage of the Entity Framework? In this multi-part series, I hope to explore my thoughts on this question. I don't think there is a single correct answer. Architecture is about trade offs and the choices you make will be based on your needs and context.

In this first post, I first provide some background on the notion of a Data Access Layer as a frame of reference, and specifically, identify the key goals and objectives of a Data Access Layer.

While Martin Fowler didn't invent the pattern of layering in enterprise applications, his Patterns of Enterprise Application Architecture is a must read on the topic. Our goals for a layered design (which may often need to be traded off against each other) should include:

  • Changes to one part or layer of the system should have minimal impact on other layers of the system. This reduces the maintenance involved in unit testing, debugging, and fixing bugs and in general makes the architecture more flexible.
  • Separation of concerns between user interface, business logic, and persistence (typically in a database) also increases flexibility, maintainability and reusability.
  • Individual components should be cohesive and unrelated components should be loosely coupled. This should allow layers to be developed and maintained independently of each other using well-defined interfaces.

Now to be clear, I'm talking about a layer, not a tier. A tier is a node in a distributed system, of which may include one or more layers. But when I refer to a layer, I'm referring only to the logical separation of code that serves a single concern such as data access. It may or may not be deployed into a separate tier from the other layers of a system. We could then begin to fly off on tangential discussions of distributed systems and service oriented architecture, but I will do my best to keep this discussion focused on the notion of a layer. There are several layered application architectures, but almost all of them in some way include the notion of a Data Access Layer (DAL). The design of the DAL will be influenced should the application architecture include the distribution of the DAL into a separate tier.

In addition to the goals of any layer mentioned above, there are some design elements specific to a Data Access Layer common to the many layered architectures:

  • A DAL in our software provides simplified access to data that is stored in some persisted fashion, typically a relational database. The DAL is utilized by other components of our software so those other areas of our software do not have to be overly concerned with the complexities of that data store.
  • In object or component oriented systems, the DAL typically will populate objects, converting rows and their columns/fields into objects and their properties/attributes. this allows the rest of the software to work with data in an abstraction that is most suitable to it.
  • A common purpose of the DAL is to provide a translation between the structure or schema of the store and the desired abstraction in our software. As is often the case, the schema of a relational database is optimized for performance and data integrity (i.e. 3rd normal form) but this structure does not always lend itself well to the conceptual view of the real world or the way a developer may want to work with the data in an application. A DAL should serve as a central place for mapping between these domains such as to increase the maintainability of the software and provide an isolation between changes  in the storage schema and/or the domain of the application software. This may include the marshalling or coercing of differing data types between the store and the application software.
  • Another frequent purpose of the DAL is to provide independence between the application logic and the storage system itself such that if required, the storage engine itself could be switched with an alternative with minimal impact to the application layer. This is a common scenario for commercial software products that must work with different vendors' database engines (i.e. MS SQL Server, IBM DB/2, Oracle, etc.). With this requirement, sometimes alternate DAL's are created for each store that can be swapped out easily.  This is commonly referred to as Persistence Ignorance.

Getting a little more concrete, there are a host of other issues that also need to be considered in the implementation of a DAL:

  • How will database connections be handled? How will there lifetime be managed? A DAL will have to consider the security model. Will individual users connect to the database using their own credentials? This maybe fine in a client-server architecture where the number of users is small. It may even be desirable in those situations where there is business logic and security enforced in the database itself through the use of stored procedures, triggers, etc. It may however run incongruent to the scalability requirements of a public facing web application with thousands of users. In these cases, a connection pool may be the desired approach.
  • How will database transactions be handled? Will there be explicit database transactions managed by the data access layer or will automatic or implied transaction management systems such as COM+ Automatic Transactions, the Distributed Transaction Coordinator be used?
  • How will concurrent access to data be managed? Most modern application architecture's will rely on an optimistic concurrency  to improve scalability. Will it be the DAL's job to manage the original state of a row in this case? Can we take advantage of SQL Server's row version timestamp column or do we need to track every single column?
  • Will we be using dynamic SQL or stored procedures to communicate with our database?

As you can see, there is much to consider just in generic terms, well before we start looking at specific business scenarios and the wacky database schemas that are in the wild. All of these things can and should influence the design of your data access layer and the technology you use to implement it. In terms of .NET, the Entity Framework is just one data access technology. MS has been so kind to bless us with many others such as Linq To SQL, DataReaders, DataAdapters & DataSets, and SQL XML. In addition, there are over 30 3rd party Object Relational Mapping tools available to choose from.

Ok, so if you're  not familiar with the design goals of the Entity Framework (EF) you can read all about it here or watch a video interview on channel 9, with Pablo Castro, Britt Johnson, and Michael Pizzo. A year after that interview, they did a follow up interview here.

In the next post, I'll explore the idea of the Entity Framework replacing my data access layer and evaluate how this choice rates against the various objectives above. I'll then continue to explore alternative implementations for a DAL using the Entity Framework.

MS MVP Summit 2008: Who did you give your Team Canada Jersey To?

The 2008 Microsoft MVP Summit concluded yesterday with a closing keynote from Steve Ballmer, which was great as usual. This was the second year that the Canadian MVP's wore their Team Canada Jersey's. I was a bit surprised that more countries didn't follow our lead on this one - although the Aussies did have touques, they were pretty subtle and they all didn't wear them or they didn't sit together at the keynotes. I saw some Russians with jackets, but again - sitting together is the key here.

One of the things I've always enjoyed watching at the Olympic games was the international bonding between athletes. During the opening ceremonies - countries file into the stadium very proudly in their matching uniforms and by the closing ceremonies - everybody is mingle and has swapped clothing. Maybe that has more to do with something else - but it's very heart warming nonetheless.

Likewise, the MVP Summit is a great place to make new friendships and renew old ones. So I decided on the final day to give my Jersey away....to Steve Ballmer.

Thanks Steve for humouring us Canadians by wearing it. You'd make a totally wicked hockey player! There was a find the secret hockey puck thing going on all week at the Summit and 10 lucky non-Canadian MVPs ended up finding all the pucks and scoring themselves a Jersey. But after this keynote, I saw a lot of people coming up to us Canadians followed by spontaneous Jersey giving. I saw a French guy wearing one (he took this video but I forgot his name - sorry), and then also saw Ken Cox and Rob Windsor giving their jersey's away to somebody from China (I think) and Italy.

Steve Ballmer's call to action in this video is that each Country bring their national pride next Summit which has already been announced as March 1, 2009. Bring it on World! Bring it on!

Bring Your Data to Life with WPF Session

The premise behind this session is the idea of separation of UI designers and developers. The UI people don't know how to code business rules. But the UI people need to be able to 'try out' the user interface and easily make changes. This is the designer/developer separation that is in the Web space, only in this case, it's for Windows Forms applications.

For those of you who aren't aware, one of the drawbacks of WPF is the lack of data binding support. This is a significant step back in functionality, if you're used to creating ASP.NET or Windows Forms apps. And it stopped me from using WPF to any great extent.

The session starts out slow, talking about the rationale behind data binding. This is something that I would expect most developers to be aware of, although if he's including designers in his target audience, then I can understand the digression.

Databinding in a WPF form can be done through the latest version of Expression Blend. A new Data pane allows for the selection of a data source (a class, for example). Once the data source has been specified, the property sheet for a control allow the mapping between the control's property and the data source's property to be made. This is a familiar process, although very new to WPF and Expression Blend.

WPF includes the concept of a value converter. This is a function that operates on a bound value with the result from the conversion being displayed. As well, the data binding appears to be hooked up to the property change notification mechanism, in that if a property is programmatically changed, the updated value appears in the form.

There is also a mechanism (INotifyCollectionChanged) which raises an event when the collection is changed. The idea of 'change' in a collection is the addition or removal of an item from the collection. WPF data binding is able to detect and respond to these events.

WPF has replaced the ObjectDataSource class with an ObjectDataProvider. Without seeing the details, I'm guessing there is a lot of similarity in terms of functionality, if not the details.

In the WPF itself, the binding notation looks like the following

<TextBox Test="{Binding Path=Sun.Name, Source={StaticResource solarSystem}}" />

This notation takes the Name property of the Sun object found in the ObjectDataProvider named solarSystem. A little cumbersome, but since it's definable through Expression Blend, that's only an issue for those of you who code in Notepad 2008.

As part of the data binding mechanism, there is the concept of a data template. This greatly resembles a template within ASP.NET, where different fields and controls are displayed based on the mode of the control. One twist is that WPF data templating can be defined based on the type of object being displayed. Within the same list box, a collection of Products will appear with different fields then a collection of Customers, even though the underlying WPF is the same.

The final reveal for the demo is a list box that displayed the information about a solar system not as a list of planet names, but as a graphical representation of the solar system orbit with the images of the planets and the positioning away from the sun based on properties from the object. The cool part is that there is no change to the underlying object necessary to change from a drop down list of properties to the graphical view. Only the XAML needs to be modified. But again, that is the power of WPF.

One word of warning. Not all of the advances in WPF are necessarily available in Silverlight. A concept called a CollectionView was explicitly called out as not being part of Silverlight 2. So if you are developing for the Silverlight market, make sure that the data binding techniques you use are supported before you spend time on it.

WPF provides support for a hierarchical data template. This template because useful when you are trying to create a tree view visualization for your data. It's similar to the list box data template in concept, but the level within the hierarchy becomes part of the mechanism for distinguishing between the different data fields and styles that are used.

It looks to me like data binding for WPF has finally moved towards the standards that we have been used to. The presentation didn't cover error providers and error notification, but a slide at the end suggests that it is, using the IDataErrorInfo interface.

Steve Ballmer Keynote - 2

Continuing from the previous post

Guy commented on how Microsoft is different. Responsive, helpful and a change from what Microsoft's image has been historically.

Some questions from the audience

On Adobe

They are a big competitor in some areas. Specifically in the Silverlight and .NET vs Flex and Flash arena. There is no expectation that they are going to "go away". Will continue to work with Adobe where it makes sense.

On Internet Explorer not moving at the speed of .NET

Many innovations, including the browser, were tied to the "next O/S after XP". Microsoft .NET was not. It was because they took dependencies on the O/S. That will not happen in the future. Future IE will incubate the innovations outside of the O/S and move them into the O/S once they have been proved out

On the PHP applications that Yahoo has

There will be some refactoring of the search, ad and email technologies when Yahoo and Microsoft get together. Some technology will come from Microsoft. Some will come from Yahoo.

On the Synergies between Microsoft and Yahoo

Scale is an advantage in the search game. More search = more ads = higher bids on ads. The more ads you have, the larger the number of ads that can be inserted into the results of a search. Google has more ads that either Yahoo or Microsoft. The merger will help scale out in this market.

On the Virtualization Server Licensing Scheme

The question was regarding the licensing cost for virtualization to be able to compete with Amazon's computing in a cloud (ECC or EC2, I can't remember the acronym). The answer was that Microsoft has plans to provide a similar service.

On Silverlight on the iPhone

Microsoft would love to get Silverlight on every mobile platform they can. There is currently no free runtime license for apps on the iPhone. Apple apparently wants 30% of all of the revenue generated through the iPhone. So while it would be nice to have, the expectation is that developers are unlikely to bite. And it was suggested that perhaps Apple is not being embracing of external developers.

On Silverlight and Microsoft applications

The question is whether Silverlight will become part of Microsoft apps, such as Hotmail. As the product cycle for the relevant products is appropriate, Silverlight will become part of the deliverable. But only on those technologies where appropriate. MSN Messenger was called out specifically as not a likely choice.

On HD DVD vs Blu Ray

Microsoft doesn't make peripherals. They support the devices where the demand is and will continue to do so. In the long term, the format isn't that important, as content is more likely to be delivered over the network.

On Enterprise adoption of social networking

The ways in which people interact with each other within the corporation is changing. Sharepoint provides collaboration services, so there is already some knowledge about how people interact. The key is to leverage these areas to provide more 'social-like' capabilities. This area is early technology, so there will be advances in the future.

Steve Ballmer Keynote - 1

The keynote is actually an interview between Guy Kawasaki (as interviewer) and Steve (as interviewee). A number of interesting points.

Regarding competing with Google

Of the four areas in which Microsoft is focused, Google is really only present in one of them (on-line ads). But the on-line ad space is expected to be the next big thing.

On why he keeps working

This is the answer that everyone should give. He:

  • Loves what he does
  • Works with smart and energetic people
  • Enjoys the challenge

From personal experience, this should be what everyone strives for.

On the place of XBox in the Microsoft world

Steve put it into perspective. XBox has 25 million users world wide who are passionate about the products that Microsoft creates. But there are 1 billion Office users. It makes sense to focus efforts on driving passions appropriately

On Web and Windows forms technologies

Microsoft is trying to blur the boundaries between Web and Forms, in terms of capabilities. Apparently 1.5 million Silverlight downloads per day. WPF currently has a broader reach because of Windows Update

On Apple's MacBook Air

"My laptop is lighter", "It's missing half the features of my laptop", "Where's the DVD?", "We'll get rid of this (the Air that Guy has) and get you a real machine"

On Vista

The number one issue for Vista is application compatibility and driver compatibility. Made choices to create a secure O/S. The result is that compatibility is hurt. As drivers and applications are updated, the compatibility issues have decreased. With SP1, the uptake in the business market will increase.

On Microsoft's Skill Set

Microsoft is trying to focus on two skill sets: consumer devices and business platforms. Most companies only attempt to create one. Microsoft is lucky enough to be able to focus on two, with a third and fourth still a possibility

On Social Networking

People will continue to use the Internet to keep in touch, to find friends, to connect with people. It is unlikely that any one company/website/technology will be able to stay on top forever.