Help on HTML server control vs HTML control

[Guest]

Dear all,

I am new in asp.net and prepare myself for exam
I still have dificulties to understand the difference between server control
and HTML control.
Okey things whcih are clear are the fact that for server control component ,
code is running on the server side.

But if I take as example a Label. I place on a webform an HTM label control
and a WebForm label control, I could see that properties are different for
sure server control offer more tuning possibilities in property side. But
then if I double click on an HTML label control it prompts me if I want to
change it to runat server side...

In that way could we say that that if we need to add code behind a control
we msut use server control instead of HTML control ?

thanks for your clarification
regards
serge

 

[Guest]

adding a "runat=server" to an HTML control makes it accessible to the server
code, but it doesn't make it a server control. Well, sort of... what it does
is usually turn it into a generic server control, not a nice functional one
like the others. You'll have SOME functionality but the big thing is that the
set of server controls were specifically designed for access and control from
code. Most of these, in the background at least, probably inherit from basic
html controls but they've (the MS people) added layers of control and
functionality.

Not sure if that helps a ton...but I tried :}

 

[Kevin Spencer]

I still have dificulties to understand the difference between server

control
and HTML control.

This can be confusing to new ASP.Net developers. In fact, it is important to
distinguish between several different types of ASP.Net Controls. Let me
elaborate, if I may:

To begin with, let's start with the parent NameSpace/Class for all ASP.Net
Controls: System.Web.UI.Control. All ASP.Net Controls inherit this class.

Under this, there are about a dozen different classes and NameSpaces. I will
only mention the most important ones here:

System.Web.UI.HtmlControls.HtmlControl

This is the base class from which all HtmlControls are derived. An
HtmlControl is, at the very least, a simple, client-side HTML element, such
as <span> (Label), <form> (HtmlForm), or <table> (HtmlTable). There is no
server-side aspect to any HtmlControl, unless you add a runat="server"
attribute to it. Adding this attribute gives you server-side control over
the client-side HTML. You can create an HtmlControl from any client-side
HTML element. There are several ready-made HtmlControls, and an
HtmlGenericControl which you can use for any other HTML element.

System.Web.UI.TemplateControl

This is the base Class for any ASP.Net Control that uses an HTML Template.
There are 2 ready-made classes in the CLR that inherit this class.
System.Web.UI.Page, and System.Web.UI.UserControl. Generally, when people
talk about "Web Controls," they are talking about HtmlControls, WebControls,
or the UserControl class, and not the Page class, although the Page class
is, in fact a "Web Control" (Note the space in the term, which distinguishes
"Web Control" from the class WebControl).

A UserControl is a Templated Control that is a container for pure HTML and
other Web Controls. Of all the "Web Controls" that are used frequently in
ASP.Net, the UserControl is the only one that has an HTML Template. It
allows a block of HTML and server-side Controls to be treated as a single
unit, or Control.

System.Web.UI.WebControls

This is a NameSpace, not a class. It has 6 different top-level classes:

System.Web.UI.WebControls.Literal

This class is used to encapsulate pure HTML in a container. It does nothing
else. As ASP.Net is fully object-oriented, any HTML in a template that is
not a server-side control is encapsulated in a Literal Control at run-time.
It can also be used to pop any block of HTML into a Page or Control at
run-time.

System.Web.UI.WebControls.PlaceHolder

This class is used, quite literally, as a "place holder." It renders no
HTML, but as a "Web Control," (System.Web.UI.Conrol) it has a Controls
Collection to which any other Control can be added. As it exists in a
certain location in a Page or other Control, any Control can be popped into
it at run-time. A UserControl could be used for this, by not having anything
in it. But what would the purpose of the Template be? This class is not
Templated, so it is easier to work with for this purpose.

System.Web.UI.WebControls.Repeater
System.Web.UI.WebControls.RepeaterItem

These 2 WebControls comprise a Repeater Control. The Repeater is a container
for RepeaterItems. In addition, it has properties that allow for the
addition of a number of System.Web.UI.ITemplate classes for fomatting the
data contained in it. A Repeater is a sort of hybrid. While it is not a
Templated Control, it is hosted in a Templated Control, and the Templates in
it are placed in the Template of the hosting Templated Control. It is used
for binding aggregate data (arrays, Collections, etc) to a block of
repeating HTML in any format desired.

System.Web.UI.WebControls.WebControl

This is the base class for most of the Controls that are often confused with
HtmlControls. A WebControl is a Control that ALWAYS has a server-side
component, and WebControls all share the same fields, properties and methods
of System.Web.UI.WebControl. In addition, each WebControl has fields,
properties, and methods that correspond uniquely to the type of HTML element
that the WebControl renders and interacts with at run-time.

HtmlControls are, therefore, by nature, leaner (consume less resources) than
WebControls, but have less functionality as well.

System.Web.UI.WebControls.Xml

This class displays XML without any formatting or using XSLT. It is
genreally used to display embedded XML in a web page.

In summary, the term "Web Control" is a fairly common, and confusing term
that is generally used to encompass HtmlControls, WebControls, and the
UserControl ASP.Net System.Web.UI.Control classes. It is important to
distinguish between what type of "Web Control" is being discussed. The main
differences between these 3 types of Controls are:

HtmlControls are lightweight Controls that can represent pure HTML, or add
server-side functionality to client-side HTML.

WebControls are Controls that always have a server-side class associated
with them, and provide a common server-side functionality for working with
various HTML elements, and specific functionality for specific HTML
elements.

A UserControl is a Templated Control which has a Template file, a container
for both pure HTML and server-side class references in it, and allows for
server-side manipulation of the server-side Controls in it. It allows a
block of HTML and server-side Controls to be treated as a single unit, or
Control.

--
HTH,

Kevin Spencer
Microsoft MVP
..Net Developer
Neither a follower nor a lender be.

 

[Guest]

Wooooow
Thats already too deep as a startup...now I am confuse in confusion...
Is there any simple general terms for beginners which could help answer the
question like :

"Should I use Label webcontrols or Lable HTML controls ?"

For example for me a Label is used to contains a simple text whatever it is
web or HTML control.

A check box will display a selection (checked or not checked) whatever it is
Web or HTML control

I think the confusion comes also from the fact that for a beginner HTML is a
simpple formated page with specific sytax and Web controls is more like real
VB code, but we tuse also the word HTML when talking about webcontrols, thats
make confusion

Do you have any other simple explanation ?

thnaks

 

[Bruce Barker]

you can think of the html on a web page as three categories

raw html output as a literal text (all html on the page with out a
runat=server tag). all the html between server controls is stuffed into a
generic web control


Web.UI.HtmlControls
these are server controls (runat=server) named after their html
counterparts. they have simular method to the html. use these if you want to
work at the html level, or do lots of client script.

Web.UI.WebControls
these are server controls with a common set of methods and may generate
multiple html elements. use these if you want to use abstracted controls.

note: server controls are seperate objects to the server code.

-- bruce (sqlwork.com)

 

[Guest]

thanks for your reply

what is the reson then to have both type of controls for building asp
application, why not using only server controls ? sounds safere as the
buisness logic is always at the server side and could be less hacked ?

In client side script anyone could chanage it and you application
not working anymore ?

thnaks
serge