asp.net session 20

7/30/2019 ASP.net Session 20

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Developing Web Applications Using ASP.NET

In this session, you will learn to:

Monitor Web applications

Create mobile Web pages

Render content on mobile Web pages

Objectives





After deploying a Web application, a System Administrator

needs to constantly monitor the application for its proper

functioning.

By monitoring a Web application, you can detect the

problems occurring in the application and troubleshootthem.

Monitoring and troubleshooting are required to improve the

performance of a Web application.

To help you track monitor a Web application, ASP.NET

provides you with the following two features:Health monitoring

Performance monitoring

Monitoring Web Applications





ASP.NET health monitoring system:

Enables you to monitor the status of the deployed Web

applications.

Is used to track system events and errors, which can hamper

the performance of a Web application.

Enables you to get the detailed run-time information about

ASP.NET resources used by a Web application.

Is implemented by using the System.Web.Management

namespace.

Health Monitoring





You can configure applications to use built-in or customized

monitoring providers.

To use the health monitoring system you need to:

Configure and enable Web events to monitor.

Configure and enable event providers that listen for andprocess various Web events.

Web events contain information about the health of a Web

application.

Health Monitoring (Contd.)





There are several events that you can trap to monitor the

health of a Web application. Some of the important events

are:

WebBaseEvent

WebBaseErrorEvent

WebHeartbeatEvent

WebRequestEvent

WebErrorEvent

WebApplicationLifetimeEvent

WebRequestErrorEventWebAuditEvent

WebFailureAuditEvent






The event providers are used to listen for Web events that

are raised by a Web application. Some of the built-in

providers are:

EventLogWebEventProvider

SqlWebEventProvider

SimpleMailWebEventProvider and

TemplatedMailWebEventProvider

TraceWebEventProvider

WmiWebEventProvider



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Performance is an important factor in making a Web

application or project successful.

You need to monitor a Web application to troubleshoot any

performance-related issues.

You need to keep a track of such errors to improve theperformance of your Web application.

ASP.NET provides you with several performance counters,

such as Application Restarts, Requests Queued, and Errors

Total to help you keep track of the execution of your Web

application.

Performance Monitoring




ASP.NET supports the following two groups of performance

counters:

System performance counters

Application performance counters

Performance Monitoring (Contd.)




The following table lists some of the system performance

counters.


System Performance Counter Descript ion

Application Running Represents the number of applications running

simultaneously on a Web server.

Requests Disconnected Represents the number of requests that have been

disconnected due to a communication failure.

Request Wait Time Represents the number of milliseconds that the most

recent request waited in the queue for being processed

by the server.

State Server Sessions Active Represents the number of user sessions that have

become inactive because of some user action. This

counter is available only on the computer where the

state server service, aspnet_state is running.

Worker Process Running Represents the number of worker processes running ona Web server.




The following table lists some of the application

performance counters.


Appl icat ion Performance Counter Descr ipt ion

Anonymous Requests Represents the number of requests that are using

anonymous authentication.

Anonymous Requests/Sec Represents the number of requests per second that

are using anonymous authentication.

Cache Total Entries Represents the total number of entries in the cache.

Cache Total Hits Represents the total number of hits from the cache.

Debugging Requests Represents the number of requests that occur while

debugging is enabled.

Let us see how to configure performance counters by using

system monitor




Mobile devices have many limitations such as small display

area and low bandwidth.

Due to these limitations, a Web page created for desktop

browsers cannot be properly displayed on mobile devices.

You need to create specifically designed Web pages for mobile devices.

ASP.NET provides you with the System.Web.Mobile

namespace that is used specifically for mobile Web

development.

The System.Web.Mobile namespace contains the corecapabilities such as authentication and error handling,

required for building ASP.NET mobile Web applications.

Creating Mobile Web Pages




The ASP.NET mobile Web controls are contained in theSystem.Web.UI.MobileControls namespace that

provides the user interface elements for rendering mobile

Web applications.

Some controls that are specific to the mobile Web pages

are:

Form control

Command control

PhoneCall control

List and ObjectList controlDeviceSpecific control

SelectionList control

StyleSheet control

TextView control

Working With Mobile Web Controls




Form control:

A Form control is a container control that provides the

capability to group controls together.

Each Form control can hold a group of logically related

controls.

The Form controls can be displayed by setting theActiveForm property of the Web page.

Command control:

A Command control combines the functionality of the normal

Button, ImageButton, and LinkButton controls.

The Command control has properties similar to that of the

Button server control.

The Command control can be added to a mobile page by usingthe <Command> element.

Working With Mobile Web Controls (Contd.)




PhoneCall control:

A PhoneCall control is used to enable applications to initiate

telephone calls if the user's mobile device supports the

capability of placing phone calls:

If the mobile supports the capability, the phone number specified

by using PhoneNumber property of the PhoneCall control isdisplayed as hyperlink.

If the mobile device does not support the capability, the

PhoneCall control displays the phone number as text.

The PhoneCall control can be added to a mobile page by usingthe <PhoneCall> element. To use a PhoneCall control, you

need to: Add the control onto a Form or Panel control or inside a control's

template on an ASP.NET mobile Web page.

Specify the Text and the PhoneNumber properties.





List and ObjectList controls:

The List control includes the functionality that is provided by

the DataList and Repeater controls.

The List control can be added to a mobile page by using the<List> element.

The ObjectList control includes the functionality that is

provided by the DataGrid control.

The ObjectList control can be added to a mobile page by usingthe <ObjectList> element.





DeviceSpecific control:

The DeviceSpecific control is used to specify a choice among

multiple content alternatives.

The DeviceSpecific control is used to specify template sets

and override properties.

SelectionList control:

The SelectionList control provides different visual

representations for a list of selectable items.

The SelectionList control combines the functionality of the

CheckBox, CheckBoxList, DropDownList, ListBox,

RadioButton, and the RadioButton Web server controls.You can use the SelectType property of the SelectionList

control to define the type of selection list button to render.





TextView control:

The TextView control is to display large quantities of text.

The TextView control supports device filters for overriding

property values.

The TextView control can be added to a mobile page by usingthe <TextView> element.


Let us see how to create a Web form for mobile devices




Device emulators:

Are software programs that simulate the environment of a cell

phone or PDA on the desktop of your PC.

Are treated as virtual mobile devices.

Are available, for most mobile devices, to simulate the

behavior of the hardware and browsers of the mobiles.

Allow you to view mobile Web forms as they would appear on

the actual mobile devices.

Enable you to test your mobile Web applications before

deploying.

Working with Device Emulators




There are various mobile devices available in the market

that have different capabilities and differ from each other in

terms of:

Screen size

Color combination

Browser type

Many other features

Due to these differences, a Web control is rendered

differently on different mobile devices.

Therefore, if you want to create a Web application that canrun on multiple mobile devices, you need to create a

separate user interface for each device, which is a tedious

and complex task.

This task can be simplified by using control adapters and

device filters provided by ASP.NET.

Rendering Content on Mobile Web Pages




Mobile devices have different screen sizes and capabilities.

The controls are rendered on the Web page on the basis of

the capabilities of a browser that requested for the page.

This type of browser-based rendering of controls is known

as adaptive rendering and can be implemented by usingcontrol adapters.

A control adapter is used for device-specific rendering of

mobile Web controls instead of using the control's default

rendering logic.

Implementing Control Adapters




To customize the behavior of Web controls, you need tospecify an object of the ControlAdapter class.

The ControlAdapter class:

Is an abstract class that defines the basic functionality for all

adapters.

Overrides certain methods and events of the Control class

to allow browser or markup-specific handling.

Implementing Control Adapters (Contd.)




Different mobile devices have different capabilities.

Therefore, you should design a Web page that caters to all

the possible types of mobile devices.

The ability to render a control based on the type of the

device is known as device-specific rendering.This requires you to set the properties of the controls based

on the capabilities of the mobile devices by using device

filters.

ASP.NET allows you to specify device filters for each type of

device by using the <DeviceSpecific><Choice> tags.You can insert the <DeviceSpecific> tag as a child

element of any mobile control on the Web page.

Implementing Device-Specific Rendering





The <Choice> tag represents device characteristic/value

pairs, where the device characteristic is drawn from a

number of sources.

A control can contain only one <DeviceSpecific> tag,

but many <Choice> tags.

Choices are evaluated in the order in which they appear in

the DeviceSpecific/Choice construct.

Each <Choice> tag contains:

A Filter attribute that specifies the devices that this choice

applies to. Additional property values that override the properties of the

original control when the device specified by the Filter attribute

is used.

Implementing Device-Specific Rendering (Contd.)





When the name of a method is used as a filter, the choice is

applied on the basis of the Boolean value returned by the

method.

The filter method must conform to the following signature:

public bool methodName(System.Web.Mobile.MobileCapabilities capabilities,

string optionalArgument);






The Filter attribute can also specify the name of a filter

defined in the web.config file. These filters can be of two

types:

Comparison filter

Evaluator delegate filter






Problem Statement:

The management of MusicMania has decided to make its Web

application available on mobile devices. In the initial phase, you

are only required to create the MobileMusic.aspx page that

should be displayed as the home page when a user requests

for the MusicMania website. This page should contain twoforms, frmHome and frmAlbum.

When a mobile device requests for the home page, the

frmHome form should be displayed on the MobileMusic page.

This form should display the colored logo of the company.

There should also be a button, DisplayAlbumDetails, on the

frmHome form. When the user clicks this button, the frmAlbum

form should be displayed. The frmAlbum form should display

the details of the latest album.

Activity 15.1: Creating a Web Form for Mobile Devices





Solution:

To design the MobileMusic page, you need to perform the

following tasks:

1. Add a new Web Page.

2. Design the new Web page.

3. Execute the application by using device emulator.

Activity 15.1: Creating a Web Form for Mobile Devices (Contd.)





In this session, you learned that:

ASP.NET provides you with the following two features for

monitoring a Web application:

Health monitoring

Performance monitoring

ASP.NET supports the following two groups of performancecounters:

System performance counters

Application performance counters

A Web page created for desktop browsers cannot be properly

displayed on mobile devices because mobile devices havesmall display area and low bandwidth.

ASP.NET provides you with the System.Web.Mobile

namespace that is used specifically for mobile Web

development.

Summary





Mobile Web pages have some specific controls. These are:

Form

Command

PhoneCall

List and ObjectList

DeviceSpecificSelectionList

StyleSheet

TextView

Device emulators are software programs that simulate the

environment of a cell phone or PDA on the desktop of your PC.

A control adapter is used for device-specific rendering of

mobile Web controls instead of using the control's default

rendering logic.

Summary (Contd.)




To customize the behavior of Web controls, you need tospecify an object of the ControlAdapter class.

The ControlAdapter class is an abstract class that defines

the basic functionality for all adapters.

The ability to render a control based on the type of the device

is known as device-specific rendering.

Summary (Contd.)

asp.net session 20

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