Notes

Outline

Visual Basic .NET Tim Marshall

Agenda What is .NET? Architectural Overview Common Language Runtime New Language Features of VB.NET Core Language Features VB and the Web

Architectural Overview

A New Generation Of Software From Microsoft

Third Generation Internet

Web Services

XML – A Key Ingredient A universal data exchange format Simple, open, broadly adopted Contract for interactions between services Enables powerful distributed apps Impacts the evolution of all software

.NET Framework Common Language Runtime Multi-language development and integration Secure, integrated class libraries Facilitates Web services development Integral SOAP support Encapsulates Windows and COM+ services ASP.NET Takes ASP to the next level Build Web sites or Web services

Framework, Languages, And Tools

Framework, Languages, And Tools

Common Language Runtime

CLR Outline Common Language Runtime Goals Design and Compile Time Deployment Time Execution Time Summary

Simpler Development Write less, reuse more Broad, consistent framework Classes as well as interfaces Plumbing disappears Metadata Transparent proxies Memory management Great WYSIWYG tool support Designers and wizards Debuggers Profilers

Simpler, Safer Deployment No registration, zero impact install XCOPY deployment, incremental download Side-by-side versions of shared components Capture version at compile time Administrative policy at run time Evidence-based security policy Based on code as well as user Code origin (location) Publisher (public key)

Scalability Smart device to Web farm Automatic memory management Thread pool Asynchronous messaging Object remoting Events Smart device version Multiple RTOSes Same tools used for desktop

Rich Web Clients, Safe Web Hosting Win Forms on the client ASP.NET Web Forms on the server Code is granted permissions Evidence is used by policy to grant permissions Application that starts runtime Like Internet Explorer, IIS, SQL Server™, Shell Provides some evidence Controls code loading Maps applications to processes

Multiple Languages Common type system Object-oriented in flavor Procedural languages well-supported Functional languages possible CLS guides frameworks design Rules for wide reach All .NET Framework functionality available Over 20 languages “under development”

Outline Common Language Runtime Goals Design and Compile Time Deployment Time Execution Time Summary

Metadata Key to simpler programming model Generated automatically Stored with code in executable file (.dll or .exe) Uses existing COFF format Via existing extension mechanism Stored in binary format Convertible to/from XML Schema Convertible to/from COM type libraries

What’s In The Metadata Description of deployment unit (assembly) Identity:  name, version, culture[, public key] What types are exported What other assemblies it depends on Security permissions needed to run Description of types Name, visibility, base class, interfaces implemented Members (methods, fields, properties, events, nested types) Custom attributes User-defined Compiler-defined Framework-defined

Metadata:  Creation And Use

Compilers Use Metadata For cross-language data type import Emit metadata with output code Describe types defined and used Record external assemblies referenced Record version information Custom attributes can be used Obsolete CLS compliance Compiled for debugging Language-specific markers

Outline .NET Framework Common Language Runtime Goals Design and Compile Time Deployment Time Execution Time Summary

Assemblies Unit of deployment One or more files, independent of packaging Self-describing via metadata (“manifest”) Versioning Captured by compiler Policy per-application as well as per-machine Security boundary Assemblies are granted permissions Methods can demand proof that a permission has been granted to entire call chain Mediate type import and export Types named relative to assembly

Applications Applications are configurable units One or more assemblies Application-specific files or data Assemblies are located based on… Their logical name and The application that loads them Applications can have private versions of assemblies Private version preferred over shared Version policy can be per-application

CLR Outline .NET Framework Common Language Runtime Goals Design and Compile Time Deployment Time Execution Time

Execution Model

Managed Code Managed code provides... Metadata describing data Location of references to objects Exception handling tables So runtime can provide… Exception handling Security Automatic lifetime management Debugging and profiling

Compiling IL To Native “Econo” JIT Generates unoptimized native code Code can be discarded and regenerated “Standard” JIT Generates optimized native code Includes verification of IL code Install time code generation Done at install time Reduces start-up time Native code has version checks and reverts to runtime JIT if they fail

Calling Unmanaged Code

COM Interop Uses P/Invoke mechanism for calls Object identity is maintained (IUnknown) Selected COM interfaces automatically created Types are automatically exported to COM and registered COM type libraries can be converted to metadata and imported Many data types are automatically marshaled

Framework, Languages, And Tools

Framework Design Goals Web standards and practices as the foundation Unify application models Make it simple to use Factored and extensible

Web Standards/Practices The .NET Framework supports HTML, XML, SOAP, XSLT, XPath… Internet Ready distributed apps The traditional tightly connected, stateful model just doesn't work on the Web The .NET Framework favors loosely connected, stateless Web Services This affects everything Base services, data access, UI, invocation/activation, programming model

Unify Programming Models

Make It Simple To Use Organization Code organized in hierarchical namespaces and classes Unified type system Everything is an object, no variants, one string type, all character data is Unicode Component Oriented Properties, methods, events, and attributes are first class constructs Design-time functionality

The .NET Framework

Framework, Languages, And Tools

Languages The .NET Platform is Language Neutral All .NET languages are first class players You can leverage your existing skills Common Language Specification Consumer: Can use the .NET Framework Extender: Can extend the .NET Framework Microsoft provides: VB, C++, C#, Jscript, J# J Third-parties are building APL, COBOL, Pascal, Eiffel, Haskell, ML, Oberon, Perl, Python, Scheme, Smalltalk

Visual Basic.NET First class player VBRUN replaced by .NET Framework Every feature of the .NET Framework is directly available Substantial Language Innovation Classes, inheritance, constructors, polymorphism, overloading, etc. Structured exceptions One form of assignment Optional stricter type checking

Summary Simpler… Development, deployment, administration Multi-language, secure, mobile code All code compiled before execution Not your traditional virtual machine! Full interoperation with unmanaged code COM, COM+ 1.0 Services, Win32®, your DLLs .