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WebSnap question

Posted on 2003-10-25
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Last Modified: 2010-04-05
with best wishes for EE experts,
I want to write a application that can recieve necessary information from client web pages and send appropriate response to it.
How can i get data from client web pages(i can generate web pages but i cant recieve requested information from client web pages)?
i need example about this issue.

i need a tutorial(or manual) about learning websnap
does anyone has a link for this issue?

best regards
shirin




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Question by:shirin
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by:nestorua
nestorua earned 25 total points
ID: 9619595
HI,
Go to "www.delphi.about.com", you find there a list of learning papers and examples you need and a few links as well.
Sincerely,
Nestorua.
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Assisted Solution

by:Wim ten Brink
Wim ten Brink earned 20 total points
ID: 9620164
Maybe have a look into SOAP. You can build a CGI/ISAPI application that can generate normal webpages but which can also be used as a webservice. A webservice application is quite powerful because the server just turns into a set of client-side objects with all kinds of methods that you can call. No need to retrieve the page, parse it to retrieve the useful information etc.
But it just depends on what kind of client-side tool you want to use. Will the client be just a webbrowser or will it be a Delphi application? In the latter case, use SOAP instead.
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Author Comment

by:shirin
ID: 9622956
nestoru,
do you sure you proposed link available on that site,
i dont see it !

workshopalex,
can you intorduce a manual for learnig SOAP components?
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Author Comment

by:shirin
ID: 9624094
workshop_alex
about:
"No need to retrieve the page, parse it to retrieve the useful information etc"
i think that when a button clicked in a web page,a link(server machine +application server+ data ) was made that go to server , and server
get this information,and send back appropriate answer.
but At first i dont know ,how can i generate this link
seconh how my application server can accept this link(configuring a application at server side for accepting client information)?

about:
Will the client be just a webbrowser or will it be a Delphi application?
The webbrowser is my purpose in this case.
0
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Expert Comment

by:nestorua
ID: 9628231
Yes I'm sure.
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Author Comment

by:shirin
ID: 9648799
nestorua,
can you bring me a link ?
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Expert Comment

by:nestorua
ID: 9652558
www.delphi.about.com
Ther you can find a lot of links to SOAP.
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Accepted Solution

by:
DeerBear earned 80 total points
ID: 9661651
Hi,

Since SOAP has been tipped, I'll tell you some things about it.
This small primer will be divided into several sections:

1) Overview of XML
2) Overview of object remoting
3) Overview of SOAP
4) Overview of WebServicing
5) My proposed solution

In this way each section will give you a better idea of what's going on.

Let's start:

1) Overview of XML

To start talking of XML, let's talk of HTML <g>.
No, it's not a joke, HTML and XML have a lot more in common
than anyone would like to admit.
They are, in fact, both subsets of a Standard Generalized Markup
Language( SGML ).
Since they're based on that, they're called SGML applications.
But this is the only thing they have in common, in fact XML is a "bit"
more than that.
XML was built from ground up to be an eXtensible Markup Language.
It doesn't only define tags to use, but also allows you to define
your own tags.
This is due to the fact that XML is more of a syntax rather
than a set of tags.
When you create an XML file, there're two things you have to take
into account: its well-form and its validity.

We say that an XML file is well formed when:
1) All open tags have a closing counterpart,
2) No tags overlap to each other,
3) It has a root node.

Let's see an example:

<animals>
  <dog name='Fuffy' age='9'>
     <doglocation>
        Philadelphia
     </doglocation>
   </dog>
</animals>

This is a well formed XML file.
The root node is the tag <animals> and it contains all the subnodes.
Each tag has a closing tag and they're not overlapped.
What do we mean by overlapped?
With HTML you can write something like this:

    <i> <b> Bolded text </i> </b>

In this case, you see, italics gets closed before bold is and that's an
overlap. In XML, you can't do this.

Now you may be saying "Yesh, ok, the one you showed was a
valid XML file". Nope, I never said that. I said it was "well formed" <g>.
An XML file is valid when it's structured according to its Document
Type Definition( DTD ), or  - to make it easier - DocType.

A Document Type Definition is a way to give rules for a
document to be considered valid.

We won't delve into these rules, it's enough to say that many
programs embed a validator instead of providing a DTD.

XML files have become so many, and they need rules so tuned
that the W3C eventually gave birth to XML Schemas.

That was a quite small overview of XML, but it was necessary to
back things up for a following section, SOAP :-)

Now let's see:

2) Overview of Object Remoting

Do you know Corba? or Java RMI?
These are two different ways to do Object Remoting.
The base of the stuff is that we want to be able to call an
object that resides on another computer, much like DCom in
Windows.

Where's the problem then? The problem is that all these methods are
mutually incompatible with each other.
And it's in fact a bit difficult to call from an AIX mainframe a
COM object, don't you agree? <g>

Let's see some of the methods:

1) DCom works only in Windows and it's a configuration hell.
2) Java RMI: works only in Java
3) Corba: it's a configuration hell, a resource waster and very
limited.

So you see the situation isn't very nice :-)

Delving into the details of each technology is very complicated, let's
just say that all these methods rely on some sort of "binary
walktrhough" but since it's binary you're destined to arrive basically
nowhere for things a bit more "complicated".

3) Overview of SOAP

Simple Object Access Protocol( SOAP ) was born on the lines of the last
sentence of the previous section.
It's a protocol based on XML messages. Each message is contained in
what is called an "envelope".

When you want to call the method of an object, you simply send to the
object provider an envelope containing the request.
The provider will analyze it and send an envelope back.
The response envelop can contain basically 2 things:

1) The response message
2) An error message

There's a lot more to say, for example how a WebService consumer
( the application that asks for the objects' methods ) determines the
format of the object call( through WSDL ) and other related technologies
like UDDI etc, but this is not the right place to discuss them.
If you want me to elaborate further on this, please let me know.

The main drawback of this protocol is that it's quite slow because it's
text , thus bigger buffers are required.

5) My solution:

http://www.remobjects.com

Gives you text/binary buffers, Smart Services and lots of cool things.
Just to try.

HTH,

Andrew
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Expert Comment

by:nestorua
ID: 9662404
HI, Andrew,
I wasn't the one who asks the question but your comment was very interesting to me, so thank you for it.
Sincerely,
Nestorua.
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