Introduction to ASP.Net ISYS 512

ASP.NET in the.NET Framework 1. The client requests a web page. 2. The web server locates the page. 3. If the page is an ASP.NET page, it is sent to the Common Language Runtime for compilation and execution. 4. The HTML produced by the CLR is returned to the browser.

Benefits of Server-Side Technology Browser compatibility: –Every browser reads HTML. Protection of source code. Controls are server-side objects with properties, methods and events.

Web Server Web Server: –VS Built-in Web Server Localhost Azure simulator ASP.Net project directory –Using the Built-In web server, a web project can be created in any folder of your choice.

ASP.NET Object Model Client Server Request Object Response Object Server Object Session Object Application Object

ASP.NET Request Object When a page is requested, much information is passed along with the request, such as the URL, queryString, and data from a form. The request object allows you to get the information passed along with the request. It is created from the System.Web.HttpRequest class.

Request Object Properties QueryString – –cid = Request.queryString(“CustID”) –cName=Request.queryString(“CustName”) Form –A form with two text boxes:CustID, CustName –cid = Request.Form(“CustID”); –cName=Request.Form(“CustName”); Cookies ClientCertificates Path, ApplicationPath, PhysicalApplicationPath, etc.

ASP.NET Response Object This object allows you to send information back to client. It is created from the System.Web.HttpResponse class. Properties: –Buffer –Cookies (a collection) Methods: –Response.Write (“…..”) *** MessageBox is not available for web project ***. –Response.Clear(), Response.Flush(): clear/flush buffer –Response.Redirect (“URL”)

Creating a New Web Project on Azure Visual C#/ Web/ASP.Net Web Application Select a template: Empty Check: Web Forms, and check Create remote resources Project/Add New Item to add a web form.

Web Form A web form contains: –A design file: Ex. webform.aspx Design view Source (HTML) view To set start up page: –Point to the web page in the Solution Explorer and right click to choose Set As Start Page. Web Form is capable of handling controls’ events just like Windows Form.

HTML Form vs Web Form HTML Form with HTML controls: EnterCID: ASP.Net Web Form with server-side controls: <asp:TextBox ID="TextBox2" runat="server" style="position: absolute; top: 39px; left: 164px; z- index: 1">

Web Form Demo: Create an ASP.Net Web Form to add two numbers Add controls: –Web form flow layout: Controls are positioned from left to right and from top to bottom. –To change a control’s position : Format/Set position –Absolute –Relative Add code: –Double-click the form to open the code view. –Events: Page_Load event and control’s events

Elements of an ASP.Net Page Design page: with file extension aspx –Contains: Directives ASP.Net controls HTML tags – Code-behind file: with file extension aspx.cs or aspx.vb

Directives A directive controls how an ASP.Net page is compiled. –Page directives: Specify default language, enable tracing and debugging for a page. –, –Imports name spaces –To process Access database, we need to import: –

Example of ASP.Net Control Tag Textbox: – Properties: –Control type –ID –BackColor, ForeColor, Height, Width –Runat=“server”

ASP.Net Controls: Textbox, listbox, radiobutton list, button, dropdownlist

Code Example double pv, rate, year, fv; pv = double.Parse(TextBox1.Text); rate =double.Parse( ListBox1.SelectedValue); year = double.Parse(RadioButtonList1.SelectedValue); fv = pv * Math.Pow(1 + rate, year); TextBox2.Text = fv.ToString("c");

ASP.Net Composite Controls Example: DropdownList: –Control tag + ListItem tag 5% 6% 7%

WebForm Wizard demo Creating a webform to show customer records with a dataGrid view. Project/Add New Item to add a web form. Open SQL Server Explorer and Add Server Add a connection using server Explorer Drag and Drop table from the Connection to the webform Test run Project/Publish

Bound GridView Creating bound DataGrid by dragging a table from the Server Explorer Smart tag: –Configure Data Source –Enable: Paging: records may be displayed in many pages Sorting Deleting Editing: –Update/Cancel

Work with Multiple Pages Add a new web form Choose the starting web form Redirect or transfer to another page: –Use Button click event: Server.Transfer("WebForm2.aspx"); Or, Response.Redirect("WebForm2.aspx"); –Use ImageButton: ImageURL PostBackURL: WebForm2.aspx –Use linkButton: PostbackURL Text

ASP.Net Inline Coding Example The time is now The time is now %> <% double iHour; iHour= DateTime.Now.Hour; if (iHour < 12) Response.Write(" good morning "); else Response.Write (" good afternoon "); %> Note: The page should have an.aspx extension, and with this directive:

Calling a ASPX Page from a HTML Page Adding a HTML page: –Project/Add New Item/HTML page

HTML Introduction Heading section –,,,, etc. Body section –,, to,, –Formatting:,,, –Comment: –List –Image –Table:, : a new row in table, : a new cell in a table row. –Form:,,, – : defines a division or a section in an HTML document. tag is often used to group block-elements to format them with styles.

TABLE Tag

HTML FORM Tag Form attribute: –Action: Specify the URL of a program on a server or an address to which a form’s data will be submitted. –Method: Get: the form’s data is appended to the URL specified by the Action attribute as a QueryString. Post: A prefered method for database processing. Form’s data is sent separately from the URL. –Name: Form’s name Demo: TestFormGet.Htm, TestFormPost.Htm

QueryString A QueryString is a set of name=value pairs appended to a target URL. It can be used to pass information from one webpage to another. Example:

Input Tag HTML textbox, radiobutton, checkbox, button, listbox, etc.

testFormPost.htm EnterCID: EnterName:

testFormPost.aspx <% Response.Write (" cid=" + Request.Form["cid"] + " "); Response.Write (" cname=" + Request.Form["cname"] + " ");%>

Compute Future Value Enter PV: Select Rate: 4% 4.5% 5% 5.5% 6% 6.5% 7% Select Year: 10 year 15 year 30 year

computeFV.aspx: with embedded code <% double PV, Rate, Year, FV; PV = double.Parse(Request.Form["PV"]); Rate = double.Parse(Request.Form["Rate"]); Year = double.Parse(Request.Form["year"]); FV = PV * Math.Pow(1 + Rate, Year); Response.Write( FV.ToString("c")); %>

computeFV.aspx: as a web form protected void Page_Load(object sender, EventArgs e) { double PV, Rate, Year, FV; PV = double.Parse(Request.Form["PV"]); Rate = double.Parse(Request.Form["Rate"]); Year = double.Parse(Request.Form["year"]); FV = PV * Math.Pow(1 + Rate, Year); TextBox1.Text = FV.ToString("c"); }

Buffer When ASP.Net is running the code, it gradually builds up the HTML that will be sent back to the browser. As the HTML is generated, it is placed in a buffer. Normally, the HTML is held in the buffer so that it isn’t sent to the browser until the page finishes executing. Response.Buffer: The default value for this property is true which means the page is buffered and sent in one block. –Response.Buffer=Falsesends html as it is generated.

The Application and Session Objects Application state: A central, site-wide store of variables that we can get from any page. –System.Web.HttpApplication A session is a single visit to a web site, and normally includes visits to a number of pages. Each time a visitor comes to your web site, a session object is created for the visitor. Session state is a store of variables that relates to a session. –System.Web.SessionState

Examples of Using the Application and Session Objects Examples of session variables are: user’s id, user’s name, Shopping cart, etc. Examples of application variables are: visitor counter.

Working with the Application and Session To place a value into the Application and Session simply assign it a key and then assign the value: –Application[“CustName”]=“Smith”; –Session [“Age”]=25; To read values from the Application and Session: –Cname=Application[“Name”].ToString(); –myAge = Session[“Age”].ToString(); To remove an item, or all items: Remove, RemoveAll() –Application.Remove[“Name”]; –Session.RemoveAll();