02 Development

2. Developing in .NET and C#

Objectives “Microsoft .NET development is based on an underlying framework of tools and classes. These tools and classes are known as the Framework SDK (Software Development Kit).”

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.NET development options Brief summary of C# Class-based development Component-based development

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Part 1 •

.NET development options…

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Recall assemblies •

1 assembly = 1 or more compiled classes – .EXE represents an assembly with classes + Main program – .DLL represents an assembly with classes code.vb code.vb code.cs

Development Tools

.EXE / .DLL

assembly Microsoft

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.NET development •

There are currently 3 ways to develop assemblies: 1) .NET Framework SDK • free (100 MB) • complete set of command-line tools and docs • available for Windows NT, 2000, XP Pro, 2003 • http://msdn.microsoft.com/net • other platforms? – FreeBSD / Mac OS X via Rotor (i.e. SSCLI) – Linux via Mono project

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Development options, cont'd 2) Visual Studio .NET • 5-6 CDs, 192 MB RAM (bare minimum) • powerful, integrated development environment (IDE) • one IDE for all: GUI, web-based, web service, DLLs, etc. • this is what 99% of the world uses • $$ – MSDNAA reduces cost to $800/year for unlimited access

3) free IDEs • #develop, a simplified clone of VS.NET • WebMatrix, for building web-based applications

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Hello World in C# •

Here's the source code: /* hello.cs */ public class Startup { public static void Main() { System.Console.WriteLine("Hello World!"); } }//class hello.cs

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Why System.Console prefix? • •

In .NET, all code & data must live within a module / class Often nested within namespaces to help organize things – a namespace is really just a named collection

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Example: System.Console.WriteLine("Hello World!"); System namespac e in FCL

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Consol e class WriteLine subroutin e

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Compiling and running • To compile C# with Framework SDK, use the C# compiler – open Visual Studio .NET command prompt window to set path – csc is the command-line C# compiler – use /t:exe option to specify console-based EXE as target c:\> csc /t:exe hello.cs Microsoft (R) Visual C# .NET Compiler version 7.00.9466 for Microsoft (R) .NET Framework version 1.0.3705 Copyright (C) Microsoft Corporation 2001. All rights reserved. c:\> hello.exe Hello World!

• To run, simply use name of assembly… Microsoft

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Viewing an assembly with ILDasm • •

IL = Microsoft's Intermediate Language (i.e. generic asm) ILDasm = IL Disassembler

c:\> ildasm hello.exe

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IL? •

Very similar to Java bytecodes: – generic assembly language – stack-based – strictly typed – no direct memory addressing – verifiable for safe execution

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Part 2 •

Development on FreeBSD…

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Development on FreeBSD •

Working on FreeBSD is exactly the same! – i.e. same command-line tools as Framework SDK – produces *binary-compatible* .DLL and .EXE files!

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Part 3 •

Brief summary of C#...

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C# • • • • • •

Case-sensitive Strict type-checking Operator and method overloading Single public inheritance; any number of interfaces All classes inherit from object; classes may be nested Garbage-collected

• Multiple classes may exist in one file • Multiple files may be compiled into one assembly • Each assembly typically written in one language

• When in doubt, think Java! Microsoft

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Part 4 •

Class-based development…

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A customer class •

Here's the source code for a simple Customer class: /* customer.cs */ public class Customer { public string Name; public int ID;

// fields

public Customer(string name, int id) { this.Name = name; this.ID = id; } public override string ToString() { return "Customer: " + this.Name; } }//class Microsoft

// constructor

// method

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Main class •

Here's the source code for Main, using our Customer class: /* main.cs */ public class App { public static void Main() { Customer c; c = new Customer("joe hummel", 94652); System.Console.WriteLine( c.ToString() ); } }//class

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Compiling and running application •

Compile and run as before… – /out: option specifies name of resulting EXE – in this case we are building monolithic app (single EXE, no DLLs)

c:\> csc /t:exe /out:app.exe main.cs customer.cs Microsoft (R) Visual C# .NET Compiler version 7.00.9466 for Microsoft (R) .NET Framework version 1.0.3705 Copyright (C) Microsoft Corporation 2001. All rights reserved. c:\> app.exe Customer: joe hummel

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Part 5 •

Component-based development…

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Example •

Let's rebuild previous app based on components – Customer class ==> DLL – Main class ==> EXE

customer.cs

main.cs

app.exe

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customer.dll

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Compiling a component •

Use the C# compiler… – with /t:library option to specify component library as target – csc produces a DLL in this case

c:\> csc /t:library customer.cs Microsoft (R) Visual C# .NET Compiler version 7.00.9466 for Microsoft (R) .NET Framework version 1.0.3705 Copyright (C) Microsoft Corporation 2001. All rights reserved. c:\> dir *.dll customer.dll

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Compiling and running application • Compile using C# compiler as before, except… – reference component so compiler can locate Customer class! – reference also stored inside assembly so CLR can locate c:\> csc /t:exe /out:app.exe main.cs /r:customer.dll Microsoft (R) Visual C# .NET Compiler version 7.00.9466 for Microsoft (R) .NET Framework version 1.0.3705 Copyright (C) Microsoft Corporation 2001. All rights reserved. c:\> app.exe Customer: joe hummel

• To run, use name of assembly containing Main… – CLR follows reference to locate DLL Microsoft

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Where are references stored? • •

Within assembly as part of assembly manifest Visible via ILDasm

c:\> ildasm app.exe

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mscorlib? • •

mscorlib = "ms-core-lib" Core FCL assembly – contains core system classes like string – contains System.Console class for console-based I/O

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Automatically referenced for us by C# compiler…

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Recall CLR-based execution •

All assemblies must be present: .DLL .DLL .DLL

.EXE

OS Process other FCL assemblies

JIT Compiler

obj code obj code obj code obj code

Core FCL assembly

CLR Underlying OS and HW Microsoft

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Summary •

.NET is multi-language – Framework SDK based on C# and VB.NET – lots of other languages available

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.NET development is component-based – helper classes implemented in one or more DLLs – EXE implemented using helper classes – if (assembly A uses a class from assembly B) then A must reference B!

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References • Books: – J. Richter, "Applied Microsoft .NET Framework Programming" • Web sites: – http://msdn.microsoft.com/net – MSDNAA: http://www.msdnaa.net/ – Rotor (SSCLI): http://msdn.microsoft.com/net/sscli – Mono: http://www.go-mono.com/ – Free IDEs: • http://www.icsharpcode.net/OpenSource/SD/default.asp • http://www.asp.net/webmatrix/ – Anakrino reverse-engineering tool: • http://www.saurik.com/net/exemplar/ Microsoft

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Lab? •

Work on lab #1, "Architecture"…

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