.NET Overview

Editor's Notes

• #6: History Application Styles Single User Multi-user sharing files Client/Server Internet – The network is the computer APIs DOS – API int 0x21 calls – single tasking Windows – Event driven programming, Windows API, long API names RAD development systems – VB, Delphi, PB, etc. Win32 – Event driven programming, introduced threading model, OOP Early 90’s VB encapsulation of windows events MFC Components – Mid 90’s MS introduces COM bastardized API sets Writing components was tedious VB and ATL made consuming components easier Versioning issues Many APIs added to Windows over the years – very inconsistent programming model Differences within single API sets – File I/O character string types Windows, Menus and Controls vs. Device Contexts, Pens, Fonts and Brushes Hodgepodge of disconnected API development Java
• #7: Enter .NET Software Development System .NET is a fresh start. Object oriented API replaces the previous flat Win32 API Component-based to the core Replaces COM and DCOM Language Neutral Class / runtime library - .NET Framework Runtime System Powerful runtime sandbox, very similar to the Java runtime Addresses Software Issues DLL Hell, versioning Installation – Touches too many places Start Menu Registry Shortcuts Files loaded in Directories Security Web Apps downloading code No way to limit what an application can access or do
• #12: J2EE and .NET Application Server and Web Services Benchmark Middleware Company, October 2002 - The Middleware Company specializes in advanced enterprise Java technology training and consulting.
• #15: They accomplished Language Neutrality through several techniques Common Type System Defines how types are managed What is a type All languages have types, such as integers, floats and pointers OOP Basis Common set of Types http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpconthenetframeworkclasslibrary.asp
• #16: Types have Members Fields Methods Properties Events Visibility
• #17: Value types Value types directly contain their data, and instances of value types are either allocated on the stack or allocated inline in a structure. Value types can be built-in (implemented by the runtime), user-defined, or enumerations. For a list of built-in value types, see the .NET Framework Class Library. Variables that are value types each have their own copy of the data, and therefore operations on one variable do not affect other variables. Reference types Reference types store a reference to the value's memory address, and are allocated on the heap. Reference types can be self-describing types, pointer types, or interface types. The type of a reference type can be determined from values of self-describing types. Self-describing types are further split into arrays and class types. The class types are user-defined classes, boxed value types, and delegates. Variables that are reference types can refer to the same object; therefore, operations on one variable can affect the same object referred to by another variable.
• #18: CLS rules define a subset of the Common Type System Establishes requirements for CLS compliance If your component uses only CLS features in the API that it exposes to other code (including derived classes), the component is guaranteed to be accessible from any programming language that supports the CLS. Components that adhere to the CLS rules and use only the features included in the CLS are said to be CLS-compliant components. CLS prohibits unsigned integral types CLS prohibits pointer types and jagged arrays CLS prohibits overloading based on case or member kind Language-specific keywords must be "escapable" http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpconthenetframeworkclasslibrary.asp
• #19: All Types that are created by .NET programs get placed in an Assembly. Assemblies are somewhat analogous to Win32 EXEs and DLLs, but they are much more than that. http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpconthenetframeworkclasslibrary.asp?frame=true
• #20: Assemblies are a fundamental part of programming with the .NET Framework. An assembly performs the following functions: It contains code that the common language runtime executes. Microsoft intermediate language (MSIL) code in a portable executable (PE) file will not be executed if it does not have an associated assembly manifest. Note that each assembly can have only one entry point (that is, DllMain, WinMain, or Main). It forms a deployment unit. When an application starts, only the assemblies that the application initially calls must be present. Other assemblies, such as localization resources or assemblies containing utility classes, can be retrieved on demand. This allows applications to be kept simple and thin when first downloaded. For more information about deploying assemblies, see Deploying Applications. It forms a type boundary. Every type's identity includes the name of the assembly in which it resides. A type called MyType loaded in the scope of one assembly is not the same as a type called MyType loaded in the scope of another assembly. It forms a reference scope boundary. The assembly stores information about what Types can be seen inside and outside the assembly. It forms a security boundary. An assembly is the unit at which permissions are requested and granted. It forms a version boundary. The assembly is the smallest versionable unit in the common language runtime; all types and resources in the same assembly are versioned as a unit. It is the unit at which side-by-side execution is supported. For more information about running multiple versions of the same assembly, see Side-by-Side Execution.
• #21: Assemblies are made up of Modules. A Module is the smallest compilable unit in .NET. Typically, an Assembly contains only one Module. This is all that is supported in VS.NET. To create a multi-module assembly, you must use the command line tools. See slide for info.
• #27: The most important component of the .NET Framework is the Common Language Runtime or CLR. A program that runs on the Windows operating system. The CLR was written from scratch and was not an add-on like MFC or ATL. It manages and executes code written in .NET languages. It activates objects, performs security checks on them, lays them out in memory, executes them and performs garbage collection on them. Conceptually the CLR is roughly the equivalent to the JVM - 2 major differences 1st difference Java compiler creates bytecode – and the JVM interprets the code .NET Compilers create IL which are JITted into platform specific machine code. 2nd difference JVM runs on many different platforms CLR runs on MS Windows
• #28: The two pieces that actually run in the environment are the CLR and your application – the assemblies you created as EXE’s or DLL’s The CLR is the runtime engine that loads the required classes performs just-in-time compilation on needed methods, enforces security checks, and performs other runtime functions like garbage collection.
• #29: Windows executable exe or dll must conform to the PE/COFF format An updated loader knows how to load these and then check for the CLR Header In the CLR Header there is an imported fuction _CorExeMain which is implemented by mscoree.dll , the core execution engine of the CLR. So the CLR gets started up and windows surrenders control to it . It will then execute your main() function
• #33: Bring up hello.exe in ildasm
• #35: Class loader finds and loads the class that exposes main() and instantiates and object of the class The first time a type is referenced Verifier – runtime type verifier – checks the metadata to assure it is well-formed (valid) Checks the IL code to make sure the type signatures are used correctly Done when invoked not at load time
• #44: Datastore – SQL SERVER or Oracle Managed provider components connections and commands are objects for managing connections and duh commands (sql statements) Data reader object fast forward only read only record set (snapshot) similar to a server side cursor in ADO Recordset DataSet Readwrite disconnected DataAdapter high level abstraction of the command and connection classes
• #46: Can set up tables and the relationships between the tables and use the class methods to Manipulate the data just as you would through an external dbms In memory database
• #48: To write your own managed provider you would implement these common classes
• #49: Both implement the system.data.xxx class
• #52: Web Services XML Web services allow applications to communicate and share data over the Internet, regardless of operating system or programming language.  .NET makes exposing and calling XML Web Services simple Makes it simple to publish any functionality as a Web Methods Integration into Visual Studio.NET Remoting Communication between Application Domains Same Process Diff Process Diff Machines Remote Objects Hosted By Any Managed .EXE IIS .NET Component Services (COM+) http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpsamples/html/remoting_advanced.asp Choosing Your Methodology Web Services for interop Remoting when doing all .NET Message Queues Message Queuing, Microsoft's messaging technology, provides messaging and message queue facilities for any application and among any combination of computers that have Microsoft Windows installed, regardless of whether they are on the same network or online at the same time. For example, suppose you have a retail point-of-sale application that must run 24 hours a day, seven days a week. If the database system behind the application goes down your sales staff might need to start taking orders manually. Using Message Queuing, you can set up the system so that the orders that cannot be processed during the downtime are automatically put into a queue and processed as soon as the database comes back up. http://www.microsoft.com/msmq/
• #53: http://www.asp.net
• #56: 1. Locates the DLL containing the function. 2. Loads the DLL into memory. 3. Locates the address of the function in memory and pushes its arguments onto the stack, marshaling data as required. Note    Locating and loading the DLL, and locating the address of the function in memory occur only on the first call to the function. 4. Transfers control to the unmanaged function. 5. Platform invoke throws exceptions generated by the unmanaged function to the managed caller.
• #58: To call managed (.NET) components from unmanaged code, a com wrapper class is needed to