Transcript .Net Table of contents • • • • • • • • • • • • • • • • • Introduction to VS 2005 Application and Page Frameworks GUI Controls Validation Server Controls Working with Master Pages Themes & Skins Collections & Lists Data Binding Data.

.Net
Table of contents
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Introduction to VS 2005
Application and Page Frameworks
GUI Controls
Validation Server Controls
Working with Master Pages
Themes & Skins
Collections & Lists
Data Binding
Data Management with ADO.Net
Working with XML
Site Navigation
Security
State Management
Caching
Debugging & Error Handling
File I/O & Streams
Configurations
Softsmith Infotech
Site Navigation
• We can access an aspx web application
by means of virtual path.
http://localhost/VirtualDirectoryName/Default.aspx
If Default.aspx file exists in the application, this
URL would open the file in browser.
We can also give any other valid aspx file name
in the browser to view that file
Softsmith Infotech
Security
• Threats faced by an application
– Spoofing
– Tampering
– Repudiation
– Information disclosure
– Denial of Service
– Elevation of privilege
Softsmith Infotech
Security in ASP .Net
• Security in the context of ASP.NET application
involves 3 fundamental terms
• Authentication
– is the process of identifying users who can use the
application (password checking)
• Authorization
– Defining what operations the users can do and to
what level (access rights check)
• Impersonation
– This is the technique used by a server application to
access resources on behalf of a client
Softsmith Infotech
Authentication
• Authentication Modes
– Windows Authentication – IIS authentication
– Forms Authentication - Application credential
verification
– Microsoft Passport Authentication
• Specifying Authentication Mode
– Can be specified in the Web.config file as follows
<authentication mode=“Windows" />
<authentication mode=“Forms" />
<authentication mode=“Passport" />
Softsmith Infotech
IIS Authentication
•
Basic
– IIS instructs the browser to send the user's credentials over HTTP
– Credentials are Base64 encoded which are not that much secure
•
Digest
– Digest authentication sends credentials across the network as a Message
Digest 5 (MD5) hash (encrypted)
•
Integrated Windows (Used in large organisation connected with Network)
– Uses either NTLM challenge/response or Kerberos to authenticate users with a
Windows NT Domain or Active Directory account
– A Hash of the credentials is sent, password is encrypted and sent
•
.NET Passport
– The credentials that are registered with Microsoft which can be used with any
microsoft application like – hotmail, msn messenger or skydrive or windows Live
etc
Softsmith Infotech
Authorization
• We can allow or deny Users using authorization tag in web.config
file
<authorization>
<deny users="?"></deny>
<allow users="*" /> <!-- Allow all users -->
<!-<allow users="[comma separated list of users]"
roles="[comma separated list of roles]"/>
<deny users="[comma separated list of users]"
roles="[comma separated list of roles]"/>
-->
</authorization>
Softsmith Infotech
Forms Authentication
• Can store credentials in web.config files
• For Login page, only if given the following
credentials it will allow.
<authentication mode="Forms">
<forms name="Login" loginUrl="Login.aspx">
<credentials passwordFormat="Clear">
<user name="smith" password="manager"></user>
<user name="Smith" password="manager"></user>
</credentials>
</forms>
</authentication>
Softsmith Infotech
State Management
•
Web forms are created and destroyed each time a client makes a request
•
Page state is not retained
– For postbacks
– Between pages
•
State management is implemented using
– Client side options
• Viewstate
• Cookies
• QueryString
– Server side options
• Application
• Session
• Database support
Softsmith Infotech
View State
•
•
Stores information as hidden fields
ViewState is enabled for every page by default
•
Saving Arraylist in a view state
protected void Page_PreRender(object sender, EventArgs e)
{
ViewState.Add("arrayListInViewState", PageArrayList);
}
We can access the same as follows
ViewState[“arrayListInViewState”]
Softsmith Infotech
Cookies
•
•
•
To store small amounts of information on a client
To store user-specific information
Store as key/value pair
//Create a cookie
HttpCookie uname = new HttpCookie("UserName");
uname.Value = txtUser.Text;
//Add the cookie
Response.Cookies.Add(uname);
//Set the Expiry date for the cookie
Response.Cookies["UserName"].Expires = d1.AddYears(2);
//Retrive the value of cookie
if(Request.Cookies["UserName"] != null)
{
//Display the value of cookie
lblUser.Text = Request.Cookies["UserName"].Value;
}
Softsmith Infotech
Query string
•
•
•
Easy way to pass information
– Between pages
Way to pack information with URL
The URL with a query string look like below
http://localhost/Demo/Default.aspx?Uname=“guest”
To send page data as query string
Response.Redirect("welcome.aspx?category="+txtCategory.T
ext)
To retrieve data in next page
lblCategory.Text=“We welcome” +
Request.QueryString[“category”];
Softsmith Infotech
Session
– Can store information that we want to keep local to the current session
(single user)
– We can store values that need to be persisted for the duration of a user
– Every user session will be assigned a unique SessionId
protected void Session_Start(Object sender, EventArgs e)
{
Session["userName"] =“guest";
}
protected void Session_End(Object sender, EventArgs e)
{
Session.Remove("userName");
}
Softsmith Infotech
Session State
• Session state can be stored in three ways
– InProc
•
•
•
•
Stores session data in the memory of the ASP.NET worker process
Provides faster access to these values
Session data is lost when the ASP.NET worker process is recycled
Need to give in the Web.config file as follows
<sessionState mode="InProc“/>
– StateServer
• Uses a stand alone window service (State Server) to store session variables
– Independent of IIS as it can run as separate service
• Better load balancing management as clustered servers can share their session
information
• Need to give in the Web.config file as follows
<sessionState mode=" StateServer“/>
Softsmith Infotech
Session State
– SQLServer
• Similar to State Server, except that the information persists in MS-SQL
Server database tables
• Need to give the following in Web.config file
<sessionState mode=“SQLServer“/>
• Note: To use SQL Server as session state store, create the necessary
tables and stored procedures
• .NET SDK provides us with a SQL script InstallPersistSqlState.sql
Softsmith Infotech
Application
•
•
Provides a mechanism for storing data that is accessible to all users using
the Web Application
Are declared in a special file called as Global.asax
void Application_Start() {
Application["startTime"] = DateTime.Now.ToString();
}
void Application_End() {
Application["startTime"] = null;
}
Softsmith Infotech
Database Support
• Database support may be used to maintain state of your Web site
• Advantages of Using a Database to Maintain State
– Security
– Storage capacity
– Data persistence
– Robustness and data integrity
– Accessibility
– Widespread support
• Disadvantages of Using a Database to Maintain State
– Complexity
– Performance considerations
Softsmith Infotech
Caching
– In ASP.NET, page gets processed and is
destroyed for every request
– Some times, dynamic contents of page may
not change frequently
– ASP.NET holds such content in memory so
that it can be delivered again efficiently
without processing
Softsmith Infotech
Caching – Single Response
• Use the @OutputCache page directive to cache a Web form in the
server’s memory
– The Duration attribute of @OutputCache directive’s controls
how long the page is cached.
• Setting VaryByParam="None” caches only one version of the web
form
// Web form is Cached for 60 seconds
<%@ OutputCache Duration="60" VaryByParam="None" %>
Softsmith Infotech
Caching – Multiple Response
//This page sends item (Infopage.aspx)
private void btnSubmit_Click(object sender,
System.EventArgs e)
{
Response.Redirect("NextPageVaryParam.aspx?id="+drpTimeZone
.SelectedItem);
}
// Web form is Cached for dropdownlistbox selected item
//This page is cached depend on item selected from
//infopage.aspx
<%@ OutputCache Duration="60" VaryByParam=“id" %>
Softsmith Infotech
Fragment Cache
•
•
Cache regions of a page content
Attribute used
– @ OutputCache
– VaryByParam -varies cached results based on name/value pairs sent
using POST or GET
– VaryByControl -varies the cached fragment by controls within the user
control
<%@ OutputCache Duration="120" VaryByParam="none"
VaryByControl="Category" %>
Softsmith Infotech
Data Caching
• Data caching is storing of data internal to a web application
• This enables to use the cached object across all the pages of the
application
• Cache is global to entire web application and is accessible to all the
clients of that application
• The lifetime of such cached objects is that of the application itself
• If the application is restarted then all the cached objects are
destroyed
• Expiry time can be set for cache objects
– Absolute Expiry (Absolute value)
– Sliding Expiry (relative value – from now onwards 5 seconds)
Softsmith Infotech
Debugging
• Visual studio 2005 provides a built in
debugger.
• Breakpoint – Press F9 to insert break point
at a location or Select Insert Break Point
from Debug Menu
• We can Step Over using (F10 key) or Step
Into using (F11 key) a function
Softsmith Infotech
Error Handling
•
•
.NET CLR provides structured Exception handling
– Using try catch block
ASP.NET provides declarative error handling
– Automatically redirect users to error page when unhandled exceptions
occur
– Prevents ugly error messages from being sent to users
The Web.Config should have these lines
<configuration>
<customErrors mode=“On” defaultRedirect=“error.htm”>
<error statusCode=“404”
redirect=“adminmessage.htm”/>
<error statusCode=“403”
redirect=“noaccessallowed.htm”/>
</customErrors>
</configuration>
Softsmith Infotech
Error Handling
•
The mode attribute can be one of the following:
– On
•
•
– Off
•
•
•
Error details are not shown to anybody, even local users
If you specify a custom error page it will be always used
Everyone will see error details, both local and remote users
If you specify a custom error page it will NOT be displayed
– RemoteOnly
• Local users will see detailed error pages
• Remote users will be presented with a concise page notifying them
that an error occurred
Note : Local user means User browsing the site on the same machine
where web applications are deployed
Softsmith Infotech
File Handling
• System.IO name space will have Methods
and classes for File Handling
• FileInfo and DirectoryInfo class helps us in
managing files and directory
• Both these classes are inherited from
FileSystemInfo class
Softsmith Infotech
FileSystemInfo
• Used to discover general characteristics about a
given file or directory.
• Properties
- Attributes
- Creation Time
- Exists
- Extension
- Full Name
- Last Access Time
- Last Write time
- Name
Softsmith Infotech
FileInfo
• Methods
- AppendText()
- CopyTo()
- Create()
- CreateText()
- Delete()
- MoveTo()
- Open()
- OpenRead()
- OpenText()
- OpenWrite()
• Properties
- Directory
- DirectoryName
- Length
- Name
Softsmith Infotech
FileInfo Example
FileInfo FI = new FileInfo(@"form1.cs“)
MessageBox.Show(FI.DirectoryName.ToString());
MessageBox.Show(FI.Extension.ToString());
MessageBox.Show(FI.LastAccessTime.ToString());
MessageBox.Show(FI.LastWriteTime.ToString());
Softsmith Infotech
Streams
• Streams are channels of communication between programs and
source/destination of data
•
•
•
•
– A stream is either a source of bytes or a destination for bytes.
Provide a good abstraction between the source and destination
Abstract away the details of the communication path from I/O
operation
Streams hide the details of what happens to the data inside the
actual I/O devices.
Streams can read/write data from/to blocks of memory, files and
network connections
• Stream can be File or Console or Network or Hardware
Softsmith Infotech
Stream
• Byte Stream
– FileStream – Works with File
– MemoryStream – Works with array
– BufferedStream - Optimized read/write operations
• Character Stream
– TextReader
– TextWriter
Softsmith Infotech
Byte Stream
• FileStream class is used to read from, write to, open, and close
files on a file system
• The MemoryStream class creates streams that have memory as a
backing store instead of a disk or a network connection
– encapsulates data stored as an byte array
• BufferedStream
– A buffer is a block of bytes in memory used to cache data
– reduces the number of calls to the operating system
– Buffers improve read and write performance.
Softsmith Infotech
Character Stream
• Both are abstract classes used read and write data using characters
from different streams
• TextReader
– Represents a reader that can read a sequential series of
characters
• TextWriter
– Represents a writer that can write a sequential series of
characters
• To read and write we use derived classes like StreamReader and
StreamWriter
Softsmith Infotech
Binary Reader/Writer
It can be used in the way StreamReader/Writer are used.
The BinaryReader methods
– bool ReadBoolean()
– byte ReadByte()
– char ReadChar()
– float ReadSingle()
– double ReadDouble()
– int ReadInt32()
The BinaryWriter method
-void Write( any single primitive type argument )
Softsmith Infotech
Configurations
• These two files helps us in setting
configurations
• Machine.Config – Machine level
configuration
• Web.Config – Application level
configuration
Softsmith Infotech
Configurations
•
•
Configuration files can be stored in application folders
– Configuration system automatically detects changes
Hierarchical configuration architecture
– Applies to the actual directory and all subdirectories
Examples:
<compilation defaultLanguage="c#“ debug="true“/>
<sessionState>
<!--- sessionstate subelements go here -->
</sessionState>
Softsmith Infotech