CJ’s Tech Notes

IIS Application Pool FAQs

What is an IIS Application Pool

An Internet Information Services (IIS) application pool is a grouping of URLs that is routed to one or more worker processes. Because application pools define a set of Web applications that share one or more worker processes, they provide a convenient way to administer a set of Web sites and applications and their corresponding worker processes. Process boundaries separate each worker process; therefore, a Web site or application in one application pool will not be affected by application problems in other application pools. Application pools significantly increase both the reliability and manageability of a Web infrastructure.

IIS Worker Process

An Internet Information Services (IIS) worker process is a windows process (w3wp.exe) which runs Web applications, and is responsible for handling requests sent to a Web Server for a specific application pool.

IIS Application Pool Availability

Web sites and Web applications depend on the availability of Internet Information Services (IIS) application pools. IIS application pools in turn depend on the Windows Process Activation Service (WAS). If WAS is not running or errors occur during the startup or shutdown of an application pool, Web sites and Web applications may not be available.

IIS Application Pool Configuration

To ensure Web site and Web application isolation, Internet Information Services (IIS) application pools must be configured to have unique names and correctly configured identities. If errors occur during the configuration of an application pool, the application pool may not be available to serve the Web sites and Web applications that are assigned to it.

IIS Application Pool Recycling

Internet Information Services (IIS) application pools can be periodically recycled to avoid unstable states that can lead to application crashes, hangs, or memory leaks. By default, application pool recycling is overlapped, which means that the worker process that is to be shut down is kept running until after a new worker process is started. After a new worker process starts, new requests are passed to it. The old worker process shuts down after it finishes processing its existing requests, or after a configured time-out, whichever comes first. This way of recycling ensures uninterrupted service to clients. However, if an application in the application pool cannot run more than one instance of itself at a time, overlapping rotation can be disabled.

Add comment July 1st, 2009

What is the difference between debug and trace in dot net?

Debug is used while you are developing the product. It depends heavily upon
debug/symbol information that is additionally added to your Debug-mode builds.
When you switch the build options to Release mode, this information, and
any Debug code will not be compiled. The assumption is that you’ll no longer
need it because you’re done debugging the app and are compiling a release
version. Debug information and code can substantially decrease performance
and efficiency of an executable.

On the other hand, Trace is meant to instrument release builds. This helps
you monitor running code. Think of this like turning on Tracing for database
as an example. Trace is enabled by default, so it’s available in Debug and
Release modes, but you can optionally turn Trace compiling off.

Add comment July 1st, 2009

asp.net interview questions

ASP.NET Interview Questions

There are some questions in this list that I do not consider to be good questions for an interview. However, they do exist on other lists available on the Internet so I felt compelled to keep them here for easy access.

Describe the role of inetinfo.exe, aspnet_isapi.dll andaspnet_wp.exe in the page loading process.
inetinfo.exe is theMicrosoft IIS server running, handling ASP.NET requests among other things.When an ASP.NET request is received (usually a file with .aspx extension), the ISAPI filter aspnet_isapi.dll takes care of it by passing the request tothe actual worker process aspnet_wp.exe.

What’s the difference between Response.Write() andResponse.Output.Write()?
Response.Output.Write() allows you to write formatted output.

What methods are fired during the page load?
Init() - when the page is instantiated
Load() - when the page is loaded into server memory
PreRender() - the brief moment before the page is displayed to the user as HTML
Unload() - when page finishes loading.

When during the page processing cycle is ViewState available?
After the Init() and before the Page_Load(), or OnLoad() for a control.

What namespace does the Web page belong in the .NET Framework class hierarchy?
System.Web.UI.Page

Where do you store the information about the user’s locale?
System.Web.UI.Page.Culture

What’s the difference between Codebehind=”MyCode.aspx.cs” andSrc=”MyCode.aspx.cs”?
CodeBehind is relevant to Visual Studio.NET only.

What’s a bubbled event?
When you have a complex control, like DataGrid, writing an event processing routine for each object (cell, button, row, etc.) is quite tedious. The controls can bubble up their eventhandlers, allowing the main DataGrid event handler to take care of its constituents.

Suppose you want a certain ASP.NET function executed on MouseOver for a certain button. Where do you add an event handler?
Add an OnMouseOver attribute to the button. Example: btnSubmit.Attributes.Add(”onmouseover”,”someClientCodeHere();”);

What data types do the RangeValidator control support?
Integer, String, and Date.

Explain the differences between Server-side and Client-side code?
Server-side code executes on the server. Client-side code executes in the client’s browser.

What type of code (server or client) is found in a Code-Behind class?
The answer is server-side code since code-behind is executed on the server. However, during the code-behind’s execution on the server, it can render client-side code such as JavaScript to be processed in the clients browser. But just to be clear, code-behind executes on the server, thus making it server-side code.

Should user input data validation occur server-side or client-side? Why?
All user input data validation should occur on the server at a minimum. Additionally, client-side validation can be performed where deemed appropriate and feasable to provide a richer, more responsive experience for the user.

What is the difference between Server.Transfer and Response.Redirect? Why would I choose one over the other?
Server.Transfer transfers page processing from one page directly to the next page without making a round-trip back to the client’s browser. This provides a faster response with a little less overhead on the server. Server.Transfer does not update the clients url history list or current url. Response.Redirect is used to redirect the user’s browser to another page or site. This performas a trip back to the client where the client’s browser is redirected to the new page. The user’s browser history list is updated to reflect the new address.

Can you explain the difference between an ADO.NET Dataset and an ADO Recordset?
Valid answers are:
· A DataSet can represent an entire relational database in memory, complete with tables, relations, and views.
· A DataSet is designed to work without any continuing connection to the original data source.
· Data in a DataSet is bulk-loaded, rather than being loaded on demand.
· There’s no concept of cursor types in a DataSet.
· DataSets have no current record pointer You can use For Each loops to move through the data.
· You can store many edits in a DataSet, and write them to the original data source in a single operation.
· Though the DataSet is universal, other objects in ADO.NET come in different versions for different data sources.

What is the Global.asax used for?
The Global.asax (including the Global.asax.cs file) is used to implement application and session level events.

What are the Application_Start and Session_Start subroutines used for?
This is where you can set the specific variables for the Application and Session objects.

Can you explain what inheritance is and an example of when you might use it?
When you want to inherit (use the functionality of) another class. Example: With a base class named Employee, a Manager class could be derived from the Employee base class.

Whats an assembly?
Assemblies are the building blocks of the .NET framework. Overview of assemblies from MSDN

Describe the difference between inline and code behind.
Inline code written along side the html in a page. Code-behind is code written in a separate file and referenced by the .aspx page.

Explain what a diffgram is, and a good use for one?
The DiffGram is one of the two XML formats that you can use to render DataSet object contents to XML. A good use is reading database data to an XML file to be sent to a Web Service.

Whats MSIL, and why should my developers need an appreciation of it if at all?
MSIL is the Microsoft Intermediate Language. All .NET compatible languages will get converted to MSIL. MSIL also allows the .NET Framework to JIT compile the assembly on the installed computer.

Which method do you invoke on the DataAdapter control to load your generated dataset with data?
The Fill() method.

Can you edit data in the Repeater control?
No, it just reads the information from its data source.

Which template must you provide, in order to display data in a Repeater control?
ItemTemplate.

How can you provide an alternating color scheme in a Repeater control?
Use the AlternatingItemTemplate.

What property must you set, and what method must you call in your code, in order to bind the data from a data source to the Repeater control?
You must set the DataSource property and call the DataBind method.

What base class do all Web Forms inherit from?
The Page class.

Name two properties common in every validation control?
ControlToValidate property and Text property.

Which property on a Combo Box do you set with a column name, prior to setting the DataSource, to display data in the combo box?
DataTextField property.

Which control would you use if you needed to make sure the values in two different controls matched?
CompareValidator control.

How many classes can a single .NET DLL contain?
It can contain many classes.

Web Service Questions

What is the transport protocol you use to call a Web service?
SOAP (Simple Object Access Protocol) is the preferred protocol.

True or False: A Web service can only be written in .NET?
False

What does WSDL stand for?
Web Services Description Language.

Where on the Internet would you look for Web services?
http://www.uddi.org

True or False: To test a Web service you must create a Windows application or Web application to consume this service?
False, the web service comes with a test page and it provides HTTP-GET method to test.

State Management Questions

What is ViewState?
ViewState allows the state of objects (serializable) to be stored in a hidden field on the page. ViewState is transported to the client and back to the server, and is not stored on the server or any other external source. ViewState is used the retain the state of server-side objects between postabacks.

What is the lifespan for items stored in ViewState?
Item stored in ViewState exist for the life of the current page. This includes postbacks (to the same page).

What does the “EnableViewState” property do? Why would I want it on or off?
It allows the page to save the users input on a form across postbacks. It saves the server-side values for a given control into ViewState, which is stored as a hidden value on the page before sending the page to the clients browser. When the page is posted back to the server the server control is recreated with the state stored in viewstate.

What are the different types of Session state management options available with ASP.NET?
ASP.NET provides In-Process and Out-of-Process state management. In-Process stores the session in memory on the web server. This requires the a “sticky-server” (or no load-balancing) so that the user is always reconnected to the same web server. Out-of-Process Session state management stores data in an external data source. The external data source may be either a SQL Server or a State Server service. Out-of-Process state management requires that all objects stored in session are serializable.

May 22nd, 2009

update mysql table using left join (same can be done inner join, right join)

mysql> update Company c left outer join CompanyDetail d on c.id = d.id set c.status=0 where c.status=1 and d.id is null;
Query OK, 17524 rows affected (8.43 sec)
Rows matched: 17524 Changed: 17524 Warnings: 0

May 5th, 2009

SQL Server how to check the rows in each table in a db quick?

Run the following command to check table size (in rows ) in sql server quick

SELECT [TableName] = so.name,[RowCount] = MAX(si.rows)

FROM sysobjects so,sysindexes si

WHERE so.xtype = ‘U’

AND si.id = OBJECT_ID(so.name)

GROUP BY so.name

ORDER BY 2 DESC

April 29th, 2009

How to run TSQL query for sql server from Dos command line?

You can connect to SQL server from DOS command line and run the select query as follows

command line by line on dos prompt

sqlcmd -E -S dbserver — E for trusted connection, S for server and instance name

use dbname
go

select top 20 * from dept
GO

3> go
id name deptid
———– ———- ———–
1 xxxzzcj 1
2 test 2
3 john 3
4 megan 2
5 bob 4
6 bob 2

(6 rows affected)
id name deptid
———– ———- ———–
1 xxxzzcj 1
2 test 2
3 john 3
4 megan 2
5 bob 4
6 bob 2

(6 rows affected)

Add comment April 29th, 2009

SQL Server Programming Error 7303: The OLE DB provider “Microsoft.Jet.OLEDB.4.0″ for linked server “(null)” reported an error. The provider did not give any information about the error.

Question When I attempt to execute the following:

select * into dbo.emp
from openrowset(’Microsoft.Jet.OLEDB.4.0′,’Excel
8.0;Database=C:\results.xlsx’,[Sheet1])

I receive the following:

Msg 7399, Level 16, State 1, Line 1
The OLE DB provider “Microsoft.Jet.OLEDB.4.0″ for linked server “(null)”
reported an error. The provider did not give any information about the error.
Msg 7303, Level 16, State 1, Line 1
Cannot initialize the data source object of OLE DB provider
“Microsoft.Jet.OLEDB.4.0″ for linked server “(null)”.

I am running SQL Server 2005 standard version on a w2k3. The spreadsheet is in the C drive of the machine.

FIX: for Excel 2007, the ole provider should be ‘Microsoft.ACE.OLEDB.12.0′

April 24th, 2009

SQL Server How to ‘Spool’ the query result to a file?

In oracle you can log all your query by runing the spool command, here is how you can save your sql server query result to a file.

put all your tSQL commands in a input file (which will be run)

on command prompt
run

SQLCMD -S QLINX -E -i test.sql -o C:\alin\Results.txt -e

-S Servername
-E trusted connection
-i input command file
-o output result file

Add comment April 24th, 2009

execute ftp command file from shell

here is the file

open ftp.comapnay.com
user xxxx
passxxxx
cd /www
prompt
get myfile.txt
put myfile.txt
bye

and the command

ftp -n s:filename.txt

April 21st, 2009

SQL Sever 2005 how to check number of db connections?

SELECT DB_NAME(dbid) as DatabaseName, count(dbid) as NoOfConnections,
loginame as LoginName
FROM sys.sysprocesses
WHERE dbid > 0
GROUP BY dbid, loginame

Add comment April 21st, 2009

CJ's Technotes