Visual Studio Orcas, due for release at the end of 2007, promises numerous improvements for Visual Basic, a data query called the Language Integrated Query (LINQ), a new Entity Framework for ADO.NET and updated tools for ASP.NET AJAX and Office 2007 development.
Visual Studio Orcas is billed as the design surface for the .NET Framework 3.5, which itself is the merger of the .NET 3.0 toolset introduced earlier this year with updated versions of ASP.NET, ADO.NET, Visual Basic, C# and the CLR.
At the same time, though, Orcas allows developers to work backwards and develop specifically for .NET 2.0 or 3.0. In the words of Jeff King, program manager on the Visual Studio team, the tool and the framework are decoupled: "It really buys you freedom."
Once a framework version has been selected, Visual Studio Orcas will enable the reference features that are appropriate for that version of the framework. (In other words, don't try using LINQ in a .NET 2.0 application.)
N-tier application development
An n-tier application is spread among any number of different systems, typically a service layer, an access layer and a business logic layer. With such a model, it is easy to share validation logic between entities, said Young Joo, a Visual Basic program manager.
Unfortunately, developing such applications in Visual Studio 2005 is "pretty much impossible," Joo said, because a dataset and the code that connects it to a database are in the same file. The change in Visual Studio Orcas is subtle but important, as the table and the dataset now reside in different layers.
An improved designer
King described the Visual Studio 2005 designer as little more the Internet Explorer renderer turned into an editor. To improve upon this, the Visual Studio group turned to Expression, the Microsoft product suite for Web designers.
The new designer allows developers to apply styles in line, with an existing class, with a new class or with Internet Explorer. "We default manually nowadays," King said. In addition, changes such as margins and paddings around images can be applied to rules and not just individually. This also makes for cleaner CSS files.
Finally, the designer offers a split view, so developers can look at source code and design simultaneously. This is a response to the growing trend of development using two monitors, King said.
ASP.NET AJAX and VSTO for Office 2007
Right now, developers aiming to build cutting edge Web applications have to download the ASP.NET AJAX framework, and those who want to develop for Office 2007 have to download Visual Studio 2005 Tools for Office Second Edition.
The ADO.NET Entity Framework
The biggest changes to ADO.NET revolve around its Entity Framework, which, unfortunately, is now slated to be released quite a while after Visual Studio 2008. This framework consists of a conceptual layer, which fits between an application's logical database layer and its object layer, and the Entity Data Model, said Julia Lerman, consultant and owner of The Data Farm.
Run the Entity Data Model Wizard in Visual Studio Orcas and the output is three files -- a conceptual model that talks to object classes, a logical model that the relational database talks to, and map between the conceptual and logical models.
Within the conceptual layer, one finds entity types bundled into sets, associations that define the relationship between entities, and sets of associations. The information in this layer will handle the back and forth with SQL Server without touching data access code, Lerman said.
Once entities have been created, developers can use the either CreateQuery or new LINQ to Entities query to retrieve entity objects, data records or anonymous types, Lerman said.
LINQ: The Language Integrated Query
In Visual Studio 2005, querying a dataset typically involves a stored procedure, a newly created view and a bit of ADO.NET filtering. This is the case because data exists in rows, while .NET code deals with objects. "They are always two different worlds," said Jeff King, a program manager on the Visual Studio team. "LINQ puts queries inside the languages and merges the worlds together."
At its most basic level, the Language Integrated Query, a feature of both Visual Basic and C#, uses the concept of the SQL Select statement to make its queries. However, there are two important differences, said Markus Egger, president and chief software architect at EPS Software Corp. and publisher of CoDe Magazine.
First, LINQ statements begin with a From statement instead of the Select statement. By listing the data source first, IntelliSense is triggered, Egger said.
Second, since C# and Visual Basic are object-oriented languages, he said, "whatever you can express in C# or VB you can make part of LINQ queries." This encompasses anything that is IEnumerable -- entities, collections and even XML. Moreover, since the queries are being made in an object-oriented environment, Egger said, "you can do very, very complex things that result in a completely different result set," such as calling up an instance of objects that did not exist in the source at all.
LINQ also brings about the introduction of several new language concepts for Visual Basic and C#. The expression tree, for example, is a data representation of the LINQ expression that bridges the gap between the .NET code and the SQL Server. In addition, property initialization makes it possible to create an object and set its properties in a single line of code.
Other new language concepts, which will be discussed below, include implicit types and extension methods.
VB 9: Implicit types
In a nutshell, author and consultant Billy Hollis said, implicit types provide strong typing without forcing developers to figure out the type they need. The compiler does the work for them, since the type is inferred from the initializer expression.
Implicit types work well when looping through a collection, Hollis said, since in such a scenario a developer is likely to be looking only for a key and a value and will not know, or care, what the index type is.
In addition, inferring types makes it possible for extensions to bind to data types such as XML. This is fundamental to making LINQ work, Hollis said.
VB 9: Extension Methods
Extension methods, which Hollis described as "syntactic sugar," are another Visual Basic 9 feature coming straight from LINQ, since all LINQ query operators are extension methods. These methods are marked with custom attributes and are then added to other objects automatically (so long as they are not already there).
Hollis said extension methods can be used just about anywhere a developer would use a normal function. However, they cannot contain optional parameters, parameter arrays or generic arguments that have not been typed. Also, late binding cannot be done with extension methods, he said.
VB 9: IntelliSense
IntelliSense, already referred to as "Intellicrack" in some development circles, is set in Visual Basic 9 to encompass keywords, member variables and anything in scope. "Anything that would make sense there, IntelliSense will put it in," Hollis said.
Moreover, IntelliSense will work with implicit types, once the compiler has figured out what is they type, Egger said.
In addition, LINQ, as stated, is set up to take advantage of IntelliSense. In SQL syntax, the Select query comes first, but in LINQ, the From statement comes first. With the data source listed first, IntelliSense has a chance to kick in.
VB 9: Relaxed delegates, initializers and more For additional information on what's new in Visual Basic 9, including relaxed delegates and initializers, check out the MSDN article Overview of Visual Basic 9.0. The emphasis there is on productivity gains developers can expect to enjoy when building data-oriented applications with an increasingly dynamic language.