.NET Library ObjectsSo far we have looked at the following objects in

learning about ASP.NET:Controls

Used to control the screen / interface and gather input and display output. 

VariablesUsed to control the computers RAM and allow it to

store data / perform calculations.Custom Objects

Used by programmers to perform specialised tasks.

The .NET LibraryThe .NET part of ASP.NET refers to a library of

objects that allow you the programmer to perform a huge range of tasks

System

Input-Output Provides tools for file input and output

DrawingProvides graphical drawing tools

WebProvides tools for Internet interconnectivity

DataProvides tools for accessing databases

We will look at two examples

The mail message objectUsed to create and send emails.

The SMTP client objectUsed to control a mail server.

The Mail Message ObjectIt may be found in the following part of

the .NET framework…

System.Net.Mail

To create a mail message object we would use the following line of code…

Dim myMessage As New System.Net.Mail.MailMessage(From, to, subject,body)

So let’s say we wanted to create the following email…

We would use the following line of code…Dim myMessage As New

System.Net.Mail.MailMessage(“you@whatever.com”,

“johnsmith@nowhere.com”, “Hello John”,”Hi this is a test!”)

The SMTP Client ObjectA mail server is a specialised computer that

deals with the sending and receiving of email messages

DMU mail.cse.dmu.ac.ukVirgin smtp.ntlworld.co.ukOrange smtp.wannadoo.co.ukTiscali smtp.tiscali.co.uk

SMTP SMTP (Simple Mail Transfer Protocol) is the name of the software

that send emails.

It runs on a named machine so we need to know the name of the machine in order to send emails.

The SMTP client is stored in : System.Net.Mail

So to create a new SMTP client object we would use the following code...

Dim Server As New System.Net.Mail.SmtpClient("name of server")

E.g.

Dim Server As New System.Net.Mail.SmtpClient("mail.cse.dmu.ac.uk")

Sending the Mail MessageDim myMessage As New System.Net.Mail.MailMessage

(“you@whatever.com”, “johnsmith@nowhere.com”, “Hello John”,”Hi this is a test!”)

Dim Server As New System.Net.Mail.SmtpClient("mail.cse.dmu.ac.uk")

Server.Send(myMessage)

Working ExampleTo see all of this working we shall look at the

code for the resend password page “resend.aspx”

What is an Object Again?“An object is a way of representing

computer technology in such a way so that we may send it instructions and

data.”

Creating an email and controlling a mail server are quite complex tasks, however “wrapping up” the complexity in objects means that we can perform this whole process in three lines of code.

Questions1. Correct the following code...

Questions2. Write down as many uses you can think of on the web

for an email object 3. The following is the declaration for another .NET

library object: Dim MyFile As New

System.IO.StreamReader("myfile.txt") This object is used to read data from a file stored on the

hard disk, in this case “myfile.txt” 

QuestionsThink about what methods and properties this

object might use to manipulate the file so that we can read the data.

 Write a list of possible methods and properties. Where might we find information on the

methods and properties for this type of object?