asp.net session 14

7/27/2019 ASP.net Session 14

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Developing Web Applications Using ASP.NET

In this session, you will learn to:

Consume Web services in a Web application

Explain Asynchronous JavaScript and XML (AJAX) framework

Objectives


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Web services are the application components that can be

used by other Web applications.

You can create a Web service and publish it on a Web

server, thereby, making it available for other Web

applications to use.

Consuming Web Services in a Web Application


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A Web service:

Is a self-describing Web component that exposes its

functionality to the consumers through open standards such as

XML and Simple Object Access Protocol (SOAP).

Is a widely used method for implementing Service-Oriented

Architecture (SOA).

Allows integration of applications developed in different

languages and running on different platforms.

Communicates by using a standard protocol called SOAP.

SOAP defines a standard way of passing the XML-encoded

data.Developing ASP.NET Web services starts by creating an

.asmx file and hosting it on a Web server, such as IIS.

A Web service once hosted or published on the server can

be consumed by any client.

Invoking Web Services


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The client locates the service by adding a Web reference.

This adds a proxy class on the client side, which exposes

the methods, parameters, and return types of the methods

contained in the Web service.

After adding the proxy class, the client application createsan instance of the proxy class and accesses the methods

provided by the Web service through the instance.

The client requests are then handled by the proxy class.

After processing the request, the response is also sent as a

SOAP message to the proxy.The proxy then converts this SOAP message into method

return value, which is returned to the client.

Invoking Web Services (Contd.)


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In distributed computing, Web services along with various

other technologies, such as COM+, .NET Remoting,

Message Queues, and Web Service Enhancement (WSE)

were used to provide a wide range of functionality.

WCF:Unifies features of such discreet technologies under one single

framework.

Provides a unified programming model used to build a secure,

reliable, and robust Web service.

Aims at providing encoding, hosting, messaging patterns,

networking, security, and interoperability in a single

infrastructure.

Invoking Windows Communication Foundation Services


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The following figure shows the WCF architecture.

Invoking Windows Communication Foundation Services (Contd.)


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The following set of APIs is unified in the WCF architecture:

ASP.NET Web Services (ASMX)

WSE

System.Messaging

Enterprise ServicesRemoting

The design goals for building WCF services are:

Unification

Interoperability

Service orientation

Invoking Windows Communication Foundation Services (Contd.)




Problem Statement:

You need to include a Web part that allows a user to convert

currency values from Dollar to Euro in the Portal.aspx page of

the MusicMania website. To implement this requirement, you

are provided with a Web service called CurrencyConverter.

Activity 9.2: Creating a Web Part that Uses a Web Service




Solution:

To solve the preceding problem, you need to perform the

following tasks:

1. Add the CurrencyConverter project to the solution.

2. Add a reference to the Web service.

3. Create a user control to consume the Web service.

4. Add the user control to the Portal page.

5. Test the application.

Activity 9.2: Creating a Web Part that Uses a Web Service (Contd.)


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Problem Statement:

In the Portal.aspx page of the MusicMania website, you need to

include a Web part that allows a user to convert currency values

from Dollar to Euro. To implement this requirement, you are

provided with a WCF service called CurrencyConverter.

Activity 9.3: Creating a Web Part that Uses a WCF Service


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Solution:

To solve the preceding problem, you need to perform the

following tasks:

1. Add the CurrencyConverter project to the solution.

2. Add a reference to the WCF service.

3. Create a user control to consume the WCF service.

4. Add the user control to the Portal page.

5. Test the application.

Activity 9.3: Creating a Web Part that Uses a WCF Service (Contd.)


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AJAX is a technology, which when implemented in Web

applications makes the interaction between the client and

the server asynchronous.

AJAX implementation:

Allows users to interact with the Web application while waitingfor a response from the server.

Enables partial updates in Web applications.

Explaining the AJAX Framework


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AJAX is a Web development technique that:

Is used for creating dynamically interactive applications.

Enables Web applications to retrieve data from the server,

asynchronously in the background, without interfering with the

display and behavior of the existing page.

To understand the concept of AJAX, you need to understand

the relevance of the following terms:

Asynchronous communication

JavaScript

XML

Understanding AJAX


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The following figure illustrates the complete life cycle of an

AJAX-enabled Web page.

Working of an AJAX-Enabled Web Application


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AJAX-enabled Web applications offer:

Quick response to a users request

Asynchronous communication that allows a user to interact

with the rest of the Web page while the application is

processing the changed or updated parts of the Web page

Auto-generated proxy classes that are used to call Web

service methods from client script such as JavaScript

Support for the widely used Web browsers such as Microsoft

Internet Explorer, Mozilla Firefox, and Apple Safari

Advantages of AJAX-Enabled Web Applications


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Some of the limitations of AJAX-enabled Web applications

are:

Browser Integration

Dependency on JavaScript

Limitations of AJAX-Enabled Web Applications


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The preceding figure shows that the ASP.NET AJAX

architecture consists of the following components:

Client-based Microsoft AJAX library

Server-based AJAX features for ASP.NET

Architecture of ASP.NET AJAX (Contd.)


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In this session, you learned that:

A Web service is a self-describing Web component that

exposes its functionality to the consumers through open

standards such as XML SOAP.

WCF aims at providing encoding, hosting, messaging patterns,

networking, security, and interoperability in a singleinfrastructure.

AJAX is a Web development technique that is used for creating

dynamically interactive applications.

AJAX enables Web applications to retrieve data from the

server, asynchronously in the background, without interferingwith the display and behavior of the existing page.

AJAX includes the following terms:

Asynchronous communication

JavaScript

XML

Summary


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The advantages offered by an AJAX-enabled Web application

are:

Quick response to a users request less bandwidth usage.

Allows a user to interact with the rest of the Web page while the

application is processing the changed or updated parts of the

Web page.Auto-generated proxy classes that are used to call Web service

methods from client script such as JavaScript.

Support for the widely used Web browsers such as Microsoft

Internet Explorer, Mozilla Firefox, and Apple Safari.

The limitations of AJAX-enabled Web applications are:

Browser IntegrationDependency on JavaScript

The ASP.NET AJAX architecture consists of the following

components:

Client-based Microsoft AJAX library

Server-based AJAX features for ASP.NET

Summary (Contd.)

asp.net session 14

Documents