Additional security when calling JSON serialized services
A security feature of ASP.NET web services that are JSON serialized through the ASP.NET AJAX extensions is that they must be requested in a specific way. This is an important deterrent against your services being used in XSS attacks. Scott Guthrie has a great post providing detailed information on the particulars. It boils down to is two things:
- The request must be an HTTP POST request
- The request’s content-type must be: “application/json; charset=utf-8?
When you register and call a web service through ASP.NET AJAX’s ScriptManager, you may safely enjoy blissful ignorance of these requirements. The framework transparently handles everything for you.
However, if you want to use a third party AJAX framework to request the JSON serialized output, you may run into trouble due to these security features.
Code Issues specific to partial methods
There are several conditions that are applied to partial methods, such as:
Partial methods must be void
Signatures of both parts of partial methods must match
Access modifiers are not allowed for partial methods
Partial methods must be declared in partial classes
etc
You don’t have to remember all these conditions if you have the CodeRush code issues feature turned on. When the rule of the partial method declaration is violated, code issues will show you an error or a hint, and you can fix it before you compile the code. These code issues are:
Partial method cannot have access modifiers or the virtual, abstract, override, new, sealed, or extern modifiers
If a partial method has an invalid modifier (e.g., virtual, abstract, override, new, sealed, extern, or an access modifier) you will see an error in the code editor, because partial methods cannot have these type of modifiers:
CodeRush Partial method cannot have modifiers
CodeRush Partial method cannot have access modifiers
Partial method cannot have out parameters
Out parameters are not allowed for partial methods. If a partial method is declared with ‘out’ parameters, you will see an error:
CodeRush Partial method cannot have out parameters
Partial method must be declared within a partial class or partial struct
Partial methods can only reside inside a partial class or a partial structure, otherwise, an error is shown:
CodeRush Partial method must be declared within a partial class
Partial method has only single part
When the partial method has only a single part without a declaration, it does not need to be declared as partial. This code issue has a hint type:
CodeRush Partial method has only single part
Volatile Fields
Software built on the .NET framework is subject to many optimisations. Some optimisation is performed when compiling your program or library in Visual Studio or using the command-line compiler. Other optimisations are applied when executing the compiled intermediate language (IL) code. These vary according to the type of processor used to run the program. In many situations these optimisations lead to faster code or smaller programs without any noticeable side effects.
One optimisation that can have side effects relates to publicly visible fields in classes or structures. When you request the value of such a field the program normally performs a non-volatile read. This type of read can be optimised to improve the performance of the program. For example, the processor may choose to read the value from memory earlier than expected, and potentially in a different order than specified, in preparation for its later use. This may move the value to the processor's cache memory, where it can be accessed more quickly than from the main memory, or to its registers for yet faster performance. In single-threaded code these changes are unnoticeable.
When you are creating a multithreaded application or one that uses parallel programming code, non-volatile reads can present a problem. To illustrate this, consider the following program:
how to upload an excel in c# ASP.Net?
protected void btnUpload_Click(object sender, EventArgs e)
{
if (fuUpload.HasFile)
{
string filename = fuUpload.PostedFile.FileName;
string strConn;
strConn = "Provider=Microsoft.Jet.OLEDB.4.0;"
+"Data Source="+ filename +";" +"Extended Properties=Excel
8.0;";
OleDbConnection con = new OleDbConnection(strConn);
con.Open();
OleDbCommand cmd = new OleDbCommand("select *
from [Sheet1$]",con);
OleDbDataAdapter dad = new OleDbDataAdapter();
dad.SelectCommand = cmd;
DataSet ds= new DataSet();
dad.Fill(ds);
DataGrid1.DataSource = ds.Tables[0].DefaultView;
DataGrid1.DataBind();
con.Close();
}
}
What is viewstate in ASP.NET?
The postback question is the heart of any interview on ASP NET. When a postback happens (i.e. when a form is submitted to a server), the variable values that are set in the code-behind page are erased from the memory of the client system. This concept would be different from what happens in Windows-based applications, where the variable variables persist in memory until they are freed from the memory either by the garbage collector, or by specific codes like dispose or finalize.
In web applications, variable values simply get erased. But it is very simple to persist these values. They may be persisted using the Viewstate object. Before the postback is invoked, the variable's value is saved in a viewstate object. In the recieving page, the viewstate's value may be retrieved back. See example code below...
//Save the value in ViewState object before the PostBack
ViewState("SomeVar") = txtFirstName.text;
//Retrieve the value from ViewState object after the PostBack
String strFirstName = ViewState("SomeVar").ToString();
difference between a document library and a form library in SharePoint?
What is the difference between a document library and a form library in SharePoint?
Document libraries in SharePoint consist of your main/core documents. For example a word document, excel, PowerPoint, Visio, pdf, csv, notepad etc. Form libraries consist of XML forms.
