Entry
Delphi: Internet: Web service: Overview: Can you tell me more about web services? [SOAP]
Oct 15th, 2003 23:53
Knud van Eeden,
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--- Knud van Eeden --- 16 October 2003 - 08:16 am --------------------
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Delphi: Internet: Web service: Overview: Can you tell me more about
web services? [SOAP]
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Web services:
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Web services are like entries in a yellow page on the Internet.
When you need some service (e.g. a language translation, or a stock
value, or driving directions), you search for that service on the
Internet (like browsing with your finger through the alphabetic entries
in a yellow pages booklet), and read them (like reading the printed
information about the specific vendor or company in your yellow pages
booklet).
You might here also write yourself entries (e.g. you add your own
information yourself, e.g. about some company, in that 'yellow pages
books' on the Internet.
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With the current software it is relatively simple (at least using
Delphi, Kylix, C++ Builder, C# Builder and JBuilder) to write
distributed object oriented applications who build on Microsoft's
COM/DCOM standards (Delphi, C++ Builder), or alternatively CORBA
(Delphi, Kylix, C++ Builder, JBuilder), if you want to be platform
independent.
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This standards (=COM/DCOM and CORBA) originated from the 90's and
are an acceptable answer for the demands you have on the local network
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On the other hand are they less adapted for the needs on the more
heterogeneous and asynchronous systems like the Internet offers.
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The alternative is named SOAP.
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We can build distributed applications with servers (=Web Services) and
clients
(=consumers) which communicate over the Internet.
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A Web Service defines an interface for its services through which one
or more clients can approach that services.
Here SOAP is the information carrier.
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For example, think about a stock market coupled to a web service with
its
database system, and which publishes an interface with amongst others
the method:
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in Delphi:
ShareValue( company : string ) : double;
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in C++:
double ShareValue( string company );
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For example:
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You then write a Delphi 7-, Kylix 3-, C++ Builder 6- or JBuilder 7 or
higher Java-client ,
"explain to" your application where to find this searched for web
service
(by supplying its URL)
and then call this service with
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in Delphi:
sharevalue := StockMarket.ShareValue( 'IBM' );
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in Delphi:
sharevalue = StockMarket->ShareValue( "IBM" );
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After which you get back your sharevalue (in reality with say 15
minutes delay, because of e.g. having to logon to the service)
and you can immediately integrate this sharevalues into your own
Delphi applications.
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Of course this can already be done today, without SOAP or web services.
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But the big difference is that there is now a *standard* which is
independent of the platform and programming language.
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You can write this stockmarket web service in the programming language
you like, but specially Delphi, Kylix, C++ Builder or JBuilder.
This because of BizSnap in Delphi 7, Kylix 3 and C++ Builder 6 or
'Web Services Kit' för JBuilder 7 or higher.
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With web services pay systems and e-commerce are going to develop in a
whole different
level.
Companies will for example be easily connected over all borders.
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[Internet: source:
http://www.databiten.se/products/delphi/delphi7/d7news3.htm]
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