Techie's Blog for Techies

Web Services .Net

2007-02-22T01:02:00.000-08:00

How a WebService is processed in .NET?

How a C# WebService is getting executed in .NET?

The Answer is :
First Client(end user) will request the Web Service in Form of (URI).

Then the DNS will resolve the URI and identifies the ip and route the HTTP request to the corresponding web server (which has the C# WebService ).

Then IIS which is responsible to hold the WebServices and web application identifies that the application is a .NET and map the ASP.NET ISAPI to receive the request.

(Note : IIS can find that a ISAPI is ASP.NET but it cant find it is a WebService or WebApplication in .NET)

Now, the ASP.NET ISAPI will identify that this is a WebService in .NET and forward the request again to .NET HTTPRuntime.
(This process will change unmanage code to manage code)

HTTPRunTime will also can identify a request as an application .

So, as HTTPRunTime identifies that the request is a WebService .NET request , this delegate the SOAP request(converted in previous step) to .Net WebServiceHandlerFactory.

The .Net WebServiceHandlerFactory deserialize the SOAP payload and executes.
(Payload is networking term which contains the actual body of the message) and also execute the request for the WebService.

Again, to display the Response to client as HTML, HTTPRunTime takes the result and serialize to SOAP message and add as SOAP payload of HTTPRunTime.

When HTTPRunTime delegate the response, .NET ISAPI will take and send back to the IIS which in turn returns the response and the Client gets SOAP Message.

Hence the receiving end(Consumer application which grabs the .NET WebService has to deform it and display the HTML response to user.

Object reference not set to an instance of an object

2007-02-14T21:19:00.000-08:00

Object reference not set to an instance of an object.

In Asp.Net this error is so common.

When you are trying to access a member of a class without instance object you will get Object reference not set to an instance of an object error.

So ensure that you are accessing the members with the instance of the class.

Example:

Cause of error:

public class ABC{
public void function xyz{....}
}

public class DEF{
ABC obj1;
obj1.xyz();
}

The highlighted line indicates that you have declared a variable of type ABC, but not the object reference or you just have created Object instance.

We can call methods or member variables only if we get reference to the instance of a object.

More technically,
ABC obj1; will not create any reference in memory.

Solution:
After the line ABC obj1 or in the same line itself ,

obj1=new ABC();

the keyword new will allot memory for the instance obj1 and assign the object reference to the instance of the object.

Other lines would be normal and kept unchanged.

Unusual:

Even after this if you are getting the same error Object reference not set to an instance of an object, it means that you have to initialize some member variables.

Example:

string example;
if(example=="answer")
.......

Obviously this error would come.
since we failed to initialize this variable no reference would have have got.
So before checking any variable comparison, kindly make ensure to add these lines

if(example!=null)
if(example=="answer")
.......

So that you can avoid comparing a null object(for which reference not been set) as well as the
above said error Object reference not set to an instance of an object.

Same discussion is available in Object reference not set to an instance of an object.

Error: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.Asp Net SqlConnection

2007-01-22T00:44:00.000-08:00

When you are trying to connect or access from a Database table which is having large volume of data (more than a lakh), query execution time will be more.

The error ( Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.) occurs when the execution time crosses Timeout Property.

There are two main Timeout property in ADO.NET.

1. Connection Timeout for Connection
2. Timeout for Data Access( Command Object or DataAdapter)

The Former, could be solved by setting ConnectionTimeout Property of Connection object either in on Connection String.

This string will make a connection object to wait 400 seconds to get connected to the database.

Even after this, you may still get the same.
Because this property will set timeout only to Connection object.
So it will wait for xxx seconds for the connection to the database.

2.If this error Timeout Expired still persists, then it is not with the Timeout property of Connection object instead it is with Data Provider objects say in DataAdapter or Command Object

To overcome this , set Command.Timeout='0'(Zero) which makes adapter or command to wait for indefinite time before terminating the attempt to execute a command and generating an error.

Complete Forum Discussion in ASP.NET Error: Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.Asp Net SqlConnection

Asp Net Unable to start debugging.

2007-01-08T01:14:00.000-08:00

Error Message:ASP NET Unable To Start Debugging

The Error Message Unable to start debugging, will be displayed in the browser, when you try to debug an asp.net application.
The Problem could have happened by one of these.
1. Check the existence of web.config file in your application.
If its not there, create one web.config file.

2. If its there already, check for its xml formation of tags.
Make sure that this is well formed and the debug section should be like this below.

For more information::
PRB:ASP NET Unable to Start Debugging: