registered in a registry for access to users A service can be called from another program using interface Service... Internet with Web Services.[r]
(1)Session 17
(2)Review
Controls help in reusability of visual as well as functional capabilities
Custom web controls can be created in two ways:
Pagelets
Web Controls using C#
Pagelets are custom controls that look like an asp page, and have the
extension ascx
Web Controls render HTML automatically
Custom Controls, which compose of other controls as well, are known
as composite controls
The System.Web.UI.INamingContainer interface has no methods;
(3)Objectives
Explain Web Services
Create Web Services using ASP.net
Consume Web Services using various protocols Create proxies for Web Services
(4)(5)Service Service has
to be
(6)Internet with Web Services
Web Server
Web Server
Web Server Constellation
Sites, services, and devices
collaborate
(7)Create a Web service
Define service interface and invocation methods for Web services
Publish Web services on Intranet or Internet Find Web service in order to use it
Invoke the web service in order to use it
(8)Accessed over the web Called using its Interface
Registered in a service registry
Standard Web protocols to communicate Loose coupling
An important aspect of loose coupling is that Web
services are integrated just-in-time when they
are necessary
(9)Cross business integration Improved efficiency
Closer customer relationships
Facilitation of just-in-time integration Complexity reduction
Legacy applications
(10)Potential risk of security in exposing the application assets of an organization
XML support is inevitable
Cost of deploying the Web service technology is slightly high
(11)<%@ WebService Language="C#" class="TestWS" %>
using System.Web.Services; class TestWS
{
[WebMethod]
public string SayHello(string name) {
return "Hello " + name; }
}
Save the file with asmx extension
Specifies that this asp page is a web service
Language in which the Web service is written Class containing Web methods
Import namespace
(12)Methods using which a web service can be consumed are listed below:
HTTP-GET HTTP-POST SOAP
Using Web Service Proxies
(13)(14)<html><body>
<p>Calling a web service using the POST method </p> <form name="form1" method="POST"
action="http://localhost/test1.asmx/SayHello"> <p> Enter your name :
<input type="text" name="name"> </p> <p> <input type="submit"> </p> </form> </body> </html>
(15)Lightweight protocol used to exchange information in a decentralized, distributed computing environment
Helps to access objects, services, and servers in a platform independent way
Provides the extensibility required by HTTP with the help of XML
HTTP/XML based protocol that is capable of invoking a method with specific values
SOAP – Simple Object Access Protocol
(16)
Information about the web service, such as the methods it contains, and the parameters that need to be passed to these methods, are described through WSDL language
Based on XML
Uses tags to define attributes of the service
(17)WSDL http://localhost/aspex/CH17/WebServiceDemo.asmx /n:FirstWS Web Service Proxies
The file TestWS.cs created is converted into a dll file using command:
(18)<script language="C#" runat=server>
public void Page_Load(Object Sender, EventArgs e) {
FirstWS.TestWS WSObj = new FirstWS.TestWS(); Text1.Text = WSObj.SayHello("Scooby");
}
</script> <form>
<asp:TextBox id=Text1 runat=server/> </form>
(19)UDDI is used to locate:
Information on Web services offered by a business partner List of providers for a particular Web service
Technical details about exposing a particular Web service Companies offering a particular Web service
Helps to register services provided by the service providers, so that they can be shared
Helps the service consumers or Web users to locate the Web services
(20)UDDI API Schema
UDDI Services UDDI
Specifications (Business Registrations)
(21)Summary 1-2
A service has two characteristics: Interface and Registration
Web services reduce the “communication-gap” among the Web applications,
enhancing interactivity Web sites thereby group together to form a constellation, providing users with a rich user experience
Advantages of Web Services
Cross business integration Improved efficiency
Closer customer relationships
Facilitation of just-in-time integration
The extension of a Web service file in NET is .asmx
The [WebMethod] tag notifies the ASP.NET compiler that the method to follow
should be a Web method, which is to be exported onto the Web
A Web service could be called from a browser, an ASP page or even another
(22)Summary 2-2
WSDL is the short form for Web Services Description Language
WSDL is the grammar for a Web service, or moreover, could be thought of as a language that describes or portrays a Web service
The proxy class does not contain any application logic Instead, it
contains the transporting logic as to how the parameters would be passed and the result retrieved
The proxy class will also contain a list of all the methods that are
present in the Web service and their prototypes
A proxy class can be created from any WSDL file
UDDI is the abbreviation for Universal Description, Discovery and
Integration
UDDI helps in registering the services provided by the service providers