Galhano //127.0.0.1

Os arquivos criados em ASP.NET possuem a extensão .aspx . Você pode usar qualquer editor de texto para digitar o código de uma página ASP.NET.

No ASP tinhamos o código que era executado dentro das tags <% ... %> que atualmente não é mais compilado e seu uso não aconselhado, pois evita a mescla de código de servidor juntamente com o código HTML.

Uma das grandes inovações é o CodeBehind . Com ele é possível separarmos o código da programação do código HTML. O CodeBehind (neste artigo escrito em VB.Net) ao compilar o aplicativo esse código é “encapsulado” dentro da DLL, sendo necessário apenas o envio do arquivo ASPX para o servidor de produção. Ao criar um novo WebForm no Visual Studio .NET, são criados dois arquivos: o arquivo Arquivo.aspx (arquivo que contém o código HTML) e o Arquivo.aspx.vb (arquivo de código propriamente dito).
Nota: A extensão do arquivo de CodeBehind vai depender da linguagem escolhida pelo desenvolvedor. Para VB.Net temos .aspx.vb, C# temos .aspx.cs.

Uma mudança fundamental no processo de desenvolvimento é a possibilidade de se criar aplicações web SEM A NECESSIDADE DE SE TER O IIS INSTALADO. Isto se deve ao fato de o Whidbey possuir seu próprio servidor web embutido de forma que não é necessário o acesso administrativo para o debug das aplicações. Este servidor visa, entre outros objectivos, aumentar a segurança no desenvolvimento uma vez que estas aplicações não poderão ser acedidas remotamente, só estando disponíveis ao navegador local. Ao se fechar o Whidbey, o servidor embutido é removido da memória.

Este recurso não proíbe àqueles que desejam continuar a criar suas aplicações directo no IIS de fazê-lo: apenas abre uma nova possibilidade. Na figura abaixo vemos os repositórios das aplicações web, entre os quais percebemos projectos criados directamente no File System e executados pelo servidor http embutido além do Local IIS, FTP Sites e Remote Sites.

mais info aqui

The above code stores the user’s userid into a session variable called “UserId”. All other pages will check if the user id is set in the session and if not, it will give an error message saying “you have not logged in”.

The above validation will be required only in the pages which needs user login. For example, in AspSpider.com, you can access most of the pages without logging in. Only when you submit an article or feedback, we will use the above code and validate your login. If you are not logged in, we will redirect you to login page automatically.

If you look at the top left corner of this site, you can either see ‘Login” or “Welcome “. We have used a logic similar to what is shown below, to display appropriate message.

As you can see from the above examples, session variables are used to store small key-value pairs in the memory. You can use session variables to store values from one page and access the values from other pages for the same user. If you set a value in session variable from one page, you can retrieve the value from any other page in the same session.

The most important point to remember is, whatever value you store in session will be valid only until the session expires. Also, this value will not be accessible for another user/session.

ASP.NET provides a class called HttpSessionState, which is part of the namespace System.Web.SessionState.

Just like Request and Response objects, an HttpSessionState object is also created automatically for you in ASP.NET pages. This object is called “Session”. You can access various methods and properties of this object.
What is in a session ?

A session has several information including a session ID. Some information is created and used by the server itself. But the most important use of session is, it allows to store custom information.
You can store any key-value pairs in session.

How to store and retrieve values in ASP.NET session ?

Just like you can store values in variables, you can store values in session. Basically, you can assign values to session variables. See the following example:
The following code sample shows how to store a string value in session:
Session(“UserId”) = “john”

In the above sample, the value “john” is assigned to a session variable called “UserId”. One important different here is, you do not declare the session variable as any datatype. Just assign any value to any session variable. The session variables will be automatically created when you simply assign values to them.
How long a session variable is valid ?

A session variable retains it’s value as long as the session is valid. Session variables are valid across all pages, as long as you access all those pages from the same browser and within the timeout period.

What can be stored in a session? The above examples show storing and retrieving simple strings in session. But you can store complex datatypes like Dataset also into session. Many websites retrieve lot of user data from database and store into session so that it can be accessed faster from memory (session) rather than retrieving from database.

However, it is not reccommded to store lot of data into session for large websites. Session data is stored in memory and if there are thousands of online users at the same time, server may run out of memory.

ASP.NET provides a class called HttpSessionState, which is part of the namespace System.Web.SessionState.

Just like Request and Response objects, an HttpSessionState object is also created automatically for you in ASP.NET pages. This object is called “Session”. You can access various methods and properties of this object.
What is in a session ?

A session has several information including a session ID. Some information is created and used by the server itself. But the most important use of session is, it allows to store custom information.
You can store any key-value pairs in session.

How to store and retrieve values in ASP.NET session ?

Just like you can store values in variables, you can store values in session. Basically, you can assign values to session variables. See the following example:
The following code sample shows how to store a string value in session:
    Session(“UserId”) = “john”

In the above sample, the value “john” is assigned to a session variable called “UserId”. One important different here is, you do not declare the session variable as any datatype. Just assign any value to any session variable. The session variables will be automatically created when you simply assign values to them.
How long a session variable is valid ?

A session variable retains it’s value as long as the session is valid. Session variables are valid across all pages, as long as you access all those pages from the same browser and within the timeout period.

What can be stored in  a session? The above examples show storing and retrieving simple strings in session. But you can store complex datatypes like Dataset also into session. Many websites retrieve lot of user data from database and store into session so that it can be accessed faster from memory (session) rather than retrieving from database.

However, it is not reccommded to store lot of data into session for large websites. Session data is stored in memory and if there are thousands of online users at the same time, server may run out of memory.