Getting Started with Microsoft Visual Studio,.NET and C# Jim Warren, COMPSCI 280 S Enterprise Software Development

Welcome (to this part of 280)!  Your lecturer: Jim Warren   x86422  Office: 303S-483  Office hours: by arrangement (try first, and we’ll start an FAQ for assignment 2)  These 4 weeks will provide you skills to create.NET applications in C# and to connect them to an underlying database  There’s a lab sheet for each week to walk through programming methods  The tutor will also reinforce the topics from lecture Handout 01COMPSCI 2802

Assignment 2  Create a.NET C# console application  Does database connection, query and update from C#  Includes interpretation and validation of user input  Assignment spec on course website  Due noon Friday on week 8 (25 th September)  Worth 5% of course mark  Do the first two.NET/C# labsheets and then get into the assignment before the break! Handout 01COMPSCI 2803

Today’s learning objectives  To be introduced to the.NET framework, including Visual Studio and C#  To be able to describe characteristics of the Common Language Runtime  To be able to describe the general characteristics of some important project templates  Console application  Windows Forms application  ASP MVC Web application (Well, we’ll just get a glance at these today, but we’ll learn them in more depth as we go) Handout 01COMPSCI 2804

Visual Studio (VS)  For Assignment 2, we will use Visual Studio to do our application programming  What is Visual Studio?  Visual Studio is an example of an "Integrated Development Environment" (IDE)  Think of an IDE as an application that combines code editor, compiler, debugging and other tools that make the design, maintenance, and documentation of large projects easier  Why an IDE?  Maybe you’ve had the experience of how Java projects consist of multiple files for different classes  This is characteristic for large projects  In MVC applications we’ll see that we have many types of files (for ‘M’, ‘V’, and ‘C’, and various aspects of the website template, system configuration and helper functions)  VS lets us manage these features and content in a convenient way Handout 015COMPSCI 280

Visual Studio and C#  Helpful background reading  Visual Studio from the Microsoft Developer Network (MSDN) us/library/dd831853(v=vs.120).aspx (particularly note the Visual Studio IDE User Guide and the Application Development in Visual Studio links). us/library/dd831853(v=vs.120).aspx  C# introduction   VS supports multiple languages (C#, C++, Visual Basic, J#) in the one IDE  All with nearly identical functionality and performance because the use a common core  VS produces many types of applications  It can also integrate with Microsoft Office applications (Word, Excel, etc.) Handout 016COMPSCI 280

.NET Languages  All Visual Studio.NET languages are object-oriented  True inheritance and polymorphism (ability to redefine methods for derived classes) are supported  No matter the language, all programs have a similar structure  Note that if you've done some kind of BASIC (e.g. VB 6) in the past - the language has changed considerably!  C# (C-sharp) is relatively a new language  With syntax similar to C++, but also borrowing a lot of ideas from Java  Visual J# is also a new language  with syntax similar to Java  File structure is similar for all languages  Files are grouped into projects  All programs compiled into Common Intermediate Language (CIL)  Also known as Microsoft Intermediate Language (MSIL) Handout 017COMPSCI 280

The.NET Framework  The.NET Framework define the rules for language interoperability and how an application is compiled into executable code.  It is also responsible for managing the execution of an application created in any VS.NET language.  The.NET Framework has two main components: the common language runtime (CLR) and the.NET Framework class library.  CLR  Manages memory, thread execution, code execution, code safety verification, compilation, and other system services  Memory allocation, starting up and stopping processes  The.NET Framework class library  Provides developers with a unified, object-oriented, hierarchical and extensible set of class libraries (‘application programmer interfaces’, APIs) Handout 018COMPSCI 280

Execution Management  The managed execution process includes the following steps:  Choosing a compiler  Compiling, code -> CIL/MSIL  Compiling translates the source code into CIL and generates the required metadata (this package is an ‘assembly’ (e.g. a DLL is an assembly)  The format is similar to assembly language but is hardware independent  Compiling, CIL -> native code  A just-in-time (JIT) compiler translates the assembly into native code (or runs it in a virtual machine)  Conceptually, the process is similar to the Java Virtual Machine  Running code  The CLR provides the infrastructure that enables managed execution to take place as well as a variety of services that can be used during execution. Handout 01COMPSCI 2809 Source code Language Specific Compiler Language Specific Compiler EXE/DLL (CIL and metadata) CompilingRunning Engine JIT Compiler Native Code Execution

Garbage Collection  The CLR performs memory management  It manages the allocation and release of memory for an application  Automatic memory management can eliminate common problems,  such as forgetting to free an object and causing a memory leak, (common problems in C and C++ that lack garbage collection!) or  attempting to access memory for an object that has already been freed.  A contiguous area of memory allocated to a process is called the managed heap  Reference types are allocated from the managed heap  The CLR reclaims memory using the Garbage Collector (GC)  The GC examines variables to reclaim unused memory  It looks for memory without a corresponding variable (root) Handout 0110COMPSCI 280

Namespace  Physical assemblies are organized into logical components called namespaces  Namespaces are organized into a hierarchy  Microsoft has divided VS.NET into two primary namespaces:  The System namespace contains components developed by the.NET team  The Microsoft namespace contains components developed by Microsoft but outside of the.NET development team  Common Namespaces:  The ‘System’ namespace contains fundamental classes  System.Data namespace contains classes supplying data access capabilities  As compared to e.g. Microsoft.Media.AdaptiveStreaming Namespace (we’ll mostly use parts of the System namespace)  You’ll create namespaces for your own content (e.g. the data ‘model’ in your MVC application) Handout 0111COMPSCI 280

Creating a Console Application with VS  Open Visual Studio  To create a new project called HelloWorldApp  Choose File->New Project  Select the project type: Visual C#  Select the project template: Console Application  Enter a name, Select a save Location and enter solution Name  Select Create directory for solution  Click OK – a program skeleton with a Main method that appears in the editor  Insert the following code:  Note:  The Main method is the entry point of your program, where the program control starts and ends  Insert Console.ReadLine() to the Main method which causes the program to pause until ENTER is pressed  To run your application  Press F5 to run the application, or  Click the ‘Start’ button (with the green triangle [‘play’] icon) Handout 03COMPSCI Console.WriteLine("Hello World"); Console.ReadLine();

Creating a Windows Forms application  This type of project starts with a blank form  You can drag and drop useful components onto the form from the ‘Toolbox’ (available under the View menu) Handout 01COMPSCI  Use the Properties window to edit attributes of the selected control  Double-click a control to add code into its event handler  E.g. MessageBox.Show(" Hello, world!");

The Model-View-Controller approach  MVC is an architectural pattern  Well, it’s ‘architectural’ when you make a project with directories for the 3 areas of concern; conceptually, it’s a design pattern  Separates responsibilities in the application  Model – the data (including the connection and mapping to the DBMS) and its integrity constraints (e.g. legal values of variables in terms of the domain logic)  View – the rendering. What it looks like to the user and the detail of how they interact with the application  Controller – Handles and responds to user interaction. Uses the model and selects the next view to offer the user. Handout 01COMPSCI See

An MVC Project in VS  Open VS  File/New Project… select Visual C# -> Web -> ASP.NET Web Application and the MVC template  Give it a name and location  Press OK and listen to the hard drive grind  Solution Explorer (righthand side of screen in IDE) produces folders for the Controllers, Models and Views (alphabetical order)  The default template includes account management (login, new user) MVC elements Handout 01COMPSCI 28015

MVC application from the template Handout 01COMPSCI Runs at ‘localhost’ served up by the built-in IIS Express local Web server

The Controller  The controller has a method of type ActionResult for each webpage in the solution  This is run when the application serves up that page  The ViewBag object is dynamic; shortcut for tossing data to the View  C# moment: note the “:” operator to indicate deriving a child class from a base class Handout 01COMPSCI using System; using System.Collections.Generic; using System.Linq; using System.Web; using System.Web.Mvc; namespace WebApplication1.Controllers { public class HomeController : Controller { public ActionResult Index() { return View(); } public ActionResult About() { ViewBag.Message = "Your application description page."; return View(); } public ActionResult Contact() { ViewBag.Message = "Your contact page."; return View(); }

The View  One.cshtml (C# HTML) file for each page of the solution  Here we have the HTML for what the user sees on the index / home page  But it’s not just HTML Handout 01COMPSCI ViewBag.Title = "Home Page"; } ASP.NET ASP.NET is a free web framework for building great Web sites and Web applications using HTML, CSS and JavaScript. Learn more »...  indicates Razor Syntax markup that is converted at run-time into HTML  Can be a code block (essentially C# syntax inside curly braces)  Or can be an expression )

Conclusion .NET is a framework for creating applications featuring  Common language run-time (CLR) .NET Framework class library  The CLR provides execution management  Just-in-time compiling  Memory management (via garbage collection)  Visual Studio (VS) is an integrated development environment (IDE) for.NET  Allows you develop in any of several languages, including VB and C#  VS provides a number of application templates  Can create terminal, Windows or Web applications  Next – we’ll get into C# as a language… Handout 01COMPSCI 28019