Lecture 1

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COMPSCI 280 S2 2014
Enterprise Software Development
Getting Started with Microsoft Visual Studio, .NET and C#
Jim Warren, [email protected]
Welcome (to this part of 280)!
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Your lecturer: Jim Warren
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These 3 weeks will provide you skills to create .NET MVC
(model-view-controller) applications (a way of making
websites) and to connect them to an underlying database
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2
[email protected]
x86422
Office: Tamaki 723-318
Office hours: by arrangement (try email first, and we’ll start an FAQ
for assignment 2)
There’s a lab sheet for each week to walk through programming
methods
The tutor will also reinforce the topics from lecture
COMPSCI 280
Handout 01
Assignment 2
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Create an MVC application
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Assignment spec on course website
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3
Handles viewing and updating of a database
Does database connection, query and update from C#
Creates HTML form interaction in the MVC framework
Includes validation of user input
Due noon Friday (before class!) on week 8 (26th September)
Worth 5% of course mark
Do lab sheet 1 and then get into the assignment before the
break!
COMPSCI 280
Handout 01
Today’s learning objectives
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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 the MVC
paradigm and its rationale
COMPSCI 280
Handout 01
Visual Studio (VS)
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For Assignment 2, we will use Visual Studio to do our application
programming
What is Visual Studio?
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Why an IDE?
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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
Remember how our Java projects already consisted 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
COMPSCI 280
Handout 01
Visual Studio and C#
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Helpful background reading
 Visual Studio from the Microsoft Developer Network (MSDN)
 http://msdn.microsoft.com/en-us/library/dd831853.aspx (and
particularly the Application Development in Visual Studio link).
 C# introduction
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VS supports multiple languages (C#, C++,Visual Basic, J#) in the
one IDE
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All with nearly identical functionality and performance because the use a
common core
VS produces many types of applications
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http://msdn.microsoft.com/en-us/library/aa645597(v=vs.71).aspx
‘Console’ (processing with text interaction), Windows, Web, mobile
It can also integrate with Microsoft Office applications (Word,
Excel, etc.)
COMPSCI 280
Handout 01
.NET Languages
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All Visual Studio .NET languages are object-oriented
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No matter the language, all programs have a similar structure
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Files are grouped into projects
All programs compiled into Common Intermediate Language (CIL)
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with syntax similar to Java
File structure is similar for all languages
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With syntax similar to C++, but also borrowing a lot of ideas from Java
Visual J# is also a new language
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Note that if you've done VB 6 in the past - the language has changed
considerably!
C# (C-sharp) is relatively a new language
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True inheritance and polymorphism are supported
Also known as Microsoft Intermediate Language (MSIL)
COMPSCI 280
Handout 01
The .NET Framework
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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
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Manages memory, thread execution, code execution, code safety
verification, compilation, and other system services
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The .NET Framework class library
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Memory allocation, starting up and stopping processes
Provides developers with a unified, object-oriented, hierarchical and
extensible set of class libraries (‘application programmer interfaces’, APIs)
COMPSCI 280
Handout 01
Execution Management
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The managed execution process includes the following steps:
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Choosing a compiler
Compiling, code -> CIL/MSIL
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Compiling translates the source code into CIL and generates the required metadata (this
package is an ‘assembly’ (e.g. a DLL is an assembly)
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Compiling, CIL -> native code
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The format is similar to assembly language but is hardware independent
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
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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.
Compiling
Source
code
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Running Engine
Language Specific
Compiler
EXE/DLL
(CIL and
metadata)
COMPSCI 280
JIT
Compiler
Native
Code
Execution
Handout 01
Garbage Collection
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The CLR performs memory management
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It manages the allocation and release of memory for an application
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Automatic memory management can eliminate common problems,
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A contiguous area of memory allocated to a process is called the managed
heap
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Reference types are allocated from the managed heap
The CLR reclaims memory using the Garbage Collector (GC)
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The GC examines variables to reclaim unused memory
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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.
It looks for memory without a corresponding variable (root)
COMPSCI 280
Handout 01
Namespace
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Physical assemblies are organized into logical components called
namespaces
Namespaces are organized into a hierarchy
Microsoft has divided VS .NET into two primary namespaces:
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Common Namespaces:
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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
The ‘System’ namespace contains fundamental classes
System.Data namespace contains classes supplying data access capabilities
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As compared to e.g. Microsoft.Media.AdaptiveStreaming Namespace (we’ll
mostly use parts of the System namespace)
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You’ll create namespaces for your own content (e.g. the data ‘model’ in your
MVC application)
COMPSCI 280
Handout 01
Creating a Console Application with VS
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Open Visual Studio (note I’m using VS 2012 – a few features get added most years, but mostly
it stays the same)
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To create a new project called HelloWorldApp
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Note:
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Console.WriteLine("Hello World");
Console.ReadLine();
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
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Choose File->New Project
MessageBox.Show("Hello,
Select the project type: Visual C#
world!");
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:
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You could also create a Windows
Forms Applications and might use
Press F5 to run the application, or
Click the ‘Start’ button (with the green triangle [‘play’]
icon)
COMPSCI 280
Handout 03
The Model-View-Controller approach
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MVC is an architectural pattern
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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
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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.
See http://www.asp.net/mvc/tutorials/older-versions/overview/asp-net-mvc-overview
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COMPSCI 280
Handout 01
An MVC Project in VS
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Open VS
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File/New Project… select Visual C# and the ASP
.NET MVC 4 Web Application type*
Give it a name and location, press OK
Select the default ‘Internet Application’ template
with the Razor view engine
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)
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In this one I’ve added an additional C# class file (.cs)
for entities in an employer database
The default template includes account management
(login, new user) MVC elements
* I went with v4; 5 is out – there’s always something newer
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COMPSCI 280
Handout 01
MVC application from the template
Runs at ‘localhost’ served up by the
built-in IIS Express local Web server
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COMPSCI 280
Handout 01
The
Controller
The controller has a
method of type
ActionResult for
each webpage in the
solution
 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
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using
using
using
using
using
System;
System.Collections.Generic;
System.Linq;
System.Web;
System.Web.Mvc;
namespace DefaultMVC.Controllers
{
public class HomeController : Controller
{
public ActionResult Index()
{
ViewBag.Message = "Modify this
template to jump-start your ASP.NET MVC
application.";
}
return View();
public ActionResult About()
{
ViewBag.Message = "Your app
description page.";
}
return View();
COMPSCI 280
Handout 01
The Model
Defines a database context
(invoking the parent [base] class
constructor to establish the
database connection
...
using System.Data.Entity;
using System.Globalization;
using System.Web.Security;
namespace DefaultMVC.Models
{
public class UsersContext : DbContext
{
public UsersContext()
: base("DefaultConnection")
{
}
}
public DbSet<UserProfile> UserProfiles { get; set; }
Creates model definition for a table
in the database (autogenerated
primary key and a username). The
context’s DbSet is a collection of
user profile objects
[Table("UserProfile")]
public class UserProfile
{
[Key]
[DatabaseGeneratedAttribute(DatabaseGeneratedOption.Identity)]
public int UserId { get; set; }
public string UserName { get; set; }
}
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COMPSCI 280
Handout 01
The
View
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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
@{
ViewBag.Title = "Home Page";
}
@section featured {
<section class="featured">
<div class="content-wrapper">
<hgroup class="title">
<h1>@ViewBag.Title.</h1>
<h2>@ViewBag.Message</h2>
</hgroup>
<p>
To learn more about ASP.NET
MVC visit
<a href="http://asp.net/mvc"
title="ASP.NET MVC
Website">http://asp.net/mvc</a>.
...
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The @ indicates Razor Syntax markup that is converted at run-time into HTML
 Can be a code block (essential C# syntax inside curly braces)
 Or can be an expression (e.g. @ViewBag.Message)
Can be cryptic (e.g. @section featured is interpreted by the @RenderSection
expression in the autogenerated _Layout.cshtml file
COMPSCI 280
Handout 01
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