Mobile WebServices

Respa PeterRoll no 12

ASIET Kalady

Understanding Service Types

Web services have made the development of mobile Web

applications much easier and more powerful.

Thus these types of applications are steadily replacing native

applications that are usually platform-specific and proprietary .

The tendency to include sensors of all types in mobile devices is

making the mobile Web a very rich service indeed.

The mobile web is fractured into many different competing operating systems

and proprietary hardware.

There are open-system alternatives to systems like the iOS or BlackBerry OS.

The two best examples are the Android OS and the Symbian OS.

Open-system hardware and software tends to evolve more quickly than

proprietary systems because there are more players and the work tends to get

wider review.

One effort to make mobile devices more interoperable is the W3C Mobile Web

Initiative.

It make browsing the Web with mobile devices more reliable by setting

standards that Web site designers can use to make their sites mobile-friendly .

Mobile interoperability

The problem with mobile site optimization is that many different devices exist. These factors need to be addressed,

Variable screen sizes and resolutions

Slow transmission over the connection and limited rendering speeds

on the device (something that is im-proving over time)

Different methods of navigation through the interface

Limited use of windows and lack of some standard graphical user

interface controls

Exclusion of certain file formats such as PDF , rendering engines

such as Adobe Flash, and cookies

Message size limitations

Nonstandard and often onerous transmission costs

Vendors approach the problem of interoperability in several ways.

A common way is to create individual sites within a Web site for

different devices.

With the rise of smartphone applications, many organizations are

creating application frontends to their sites.

The front page for the Web site of the New York Times on a standard

1024x768 resolution monitor versus the same content displayed on an

Apple iPhone 480x320 resolution screen.

•One approach to improving interoperability that was to create a database of

device characteristics, called a Device Description Repository .

• This repository would then be used in concert with the DDR Simple API to

modify content so screen size, markup language, and image format support is

delivered to a device correctly .

•A specific top-level domain has been created for the producers and consumers

of mobile services and products called .MOBI.

• which is maintained as a registry called the Mobile Top Level Domain

(mTLD). The purpose of this domain is to create sites that render correctly on

mobile devices.

•This domain was created by a group of companies in the mobile space that

include Ericsson, Google, GSM Association, Hutchison Whampoa, Microsoft,

Orascom Telecom, Samsung, Telefónica Móviles, Telecom Italia Mobile, Syni-

verse Technologies, T-Mobile, Visa, and Vodafone.

•It is suggested, that a better mechanism for content compatibility on the

mobile Web is to use content negotiation, cascading style sheets, or other

devices.

•Another effort aimed at promoting standards on mobile networks is the

Open Terminal Platform (OMTP).

•several mobile vendors, including Huawei, LG Electronics, Motorola,

Nokia, Samsung, and Sony Ericsson.

•OMTP became part of the Wholesale Applications Community (WAC).

Performing Service Discovery

•Web services are useful only if they can be discovered by mobile devices and

accessed by those devices by mutually supported protocols.

• If protocols are standard and open, the chances of being able to exchange

information is increased.

•Web services are a form of publishing:

In some cases, they involve messaging;

they use a publish/subscribe metaphor; and

They are broadcast.

•One standard for publishing a Web service that is used in cloud computing

and contributes to the Service Oriented Architecture (SOA) is the Web Service

Description Language (WSDL).

• As mobile computing has grown, each mobile device contains and is

capable of transmitting a large amount of information concerning

the condition or state of the device and the user who carries the

device.

• When parsed properly , this information can provide intelligent

systems with not only the user's identification, but the context in

which that user finds himself.

• Location is the prime example of context.

• When we search for something near us, the search engine returns

results that are location-based and thus have context.

Context-aware services

• When a mobile user is connected to her mobile service, she is exchanging

two different sets of information:

•Physical context: Information derived from measurements made from the

mobile device or its sensors

• Logical context: Information derived from the user or from the manner

in which the user has interacted with services over time

•In a Web service, the mobile client plays the role of a service consumer

and the Web service is the service provider.

• In Figure, a system for processing contextual information is shown, based

on the ideas of a Service Oriented Architecture.

•A system of this type provides a much richer environment in which to respond to

requests and allows both service providers and content providers to either

narrowcast or tailor information for a specific user based on his current context.

•Context Logic Processor : plays the role of the orchestrator providing

programmed logic that works with the data parsed by the Context Parser.

• Context Parser : takes all the input data and applies a logical schema to create

the needed structured objects for the Logic Processor's use.

•This infrastructure can be placed in the cloud.

•The concept of creating a structured representation of concepts and their

relationship in a domain is referred to as ontology .

•Ontology is a formal way of specifying a shared abstraction.

•Ontologies are used in all fields of computer science and are at the heart of efforts

to create the Semantic Web, in artificial intelligence, library classification scheme,

and so on.

• MEMS stands for microelectromechanical systems and is a class

of very small sensor or actuator devices where small mechanical

systems are driven by electricity to indicate a position.

• MEMS as a class can be between 1 and 1000 micrometers in size,

and they are packaged into components that often include a

microprocessor, memory and other components.

• Several MEMS are packaged in smartphones, and their numbers

and complexity are growing over time.

MEMS

The following are built into the latest cell phones:

• Accelerometers for measuring relative motion changes

• Gyroscopes

• Image sensors in the form of CCD chips.

• Proximity sensors

• Light sensors

• Sound sensors

• Compasses

• Pressure sensors (barometer)

• Thermisters (resistance thermometer devices or RTDs)

• Device is constantly being polled for or sending data from its sensors

that indicate the condition of the device.

• For a desktop that never moves anywhere, knowing the location is a one-

time thing. Suppose you type a search in google on your desktop like

this:

Pizza 02052

• Google returns a search that shows you the pizza joints in that ZIP code.

• This kind of search would be helpful for shopping, social networks,

services, and other location-based information.

Location awareness

• Push services are a technology where the transaction is initiated on a server and sent automatically to the client.

• The opposite of a push is a pull technology , in which the client polls for and requests a transaction.

• In some instances, push can be a form of publishing and is described as conforming to the publish/subscribe model.

• The following services are examples of push technologies:Automated software updates Comet, an Ajax application data transfer (Comet uses either

HTTP streaming or long polling) Instant Messaging e-mail HTTP streaming (also known as HTTP server push) Java pushlet RSS services

Push services

Developers use the BlackBerry Push Service to push application updates,

images, text, audio, and other content to BlackBerry users using Java

applications or BlackBerry Widgets .

The Push Service transfers up to 8KB messages directly .

If the content is larger than that, the content provider sets up its system so

the notification is a push service and the device downloads the data from the

content provider.

The BlackBerry Push Service

BlackBerry Push Service uses the following steps:

1. Content provider sends a push request to the server.

2. BlackBerry servers send a response back to the content provider.

3. BlackBerry servers push the data out to BlackBerry clients.

4. BlackBerry clients send a response to the BlackBerry server that the

message was received.

5. BlackBerry servers forward the acknowledgement to the content

provider.

6. The content provider sends a read notification to the BlackBerry

server.

Using SMS•The Short Message Service (SMS) is a text-notification service that has evolved

into a primary communications protocol for near-real-time message passing.

•SMS, or texting, for mobile users to communicate with one another, and it's

valuable because it occupies a middle ground between an Instant Message and a

Chat.

•This maximum size in characters is as follows:

For 7-bit characters (upper ASCII), which includes numbers, letters, and

symbols, the limit is 160 characters.

For 8-bit characters (full ASCII), the limit is 140 characters.

For 16-bit character representations, like those used by pictographic languages,

there's a lower limit of no more than 70 characters.

Many of the smartphone providers offer upgrade versions of SMS, including

the following:

• Enhanced Messaging Service (EMS): EMS allows you to attach sounds,

pictures, icons, and even formatted text with your message.

• Multimedia Messaging Service (MMS): MMS supports the sending of audio,

video, and even animation with the SMS text. (MMS uses a combination of

WAP and SMS for its transport.).

•Some SMS services go through an SMS gateway.

WAP and Other Protocols

•The Wireless Application Protocol (WAP) is an application-layer network

protocol .

• It allows a WAP browser on a mobile device to communicate with a WAP-

enabled Web site.

•Data is transferred between the two in the form of the Wireless Markup

Language and is specially formatted to fit on that mobile device.

• Web sites can be composed in WML, or the data can be automatically

converted to WML.

•Fig: WAP Push uses a set of gateways to push content onto wireless clients.

•WAP Push is a form that allows content to be pushed from content providers

to mobile clients using a gateway service.

•WAP Push works sending messages that contain the link to the WAP address

over a WDP carrier such as GPRS or SMS.

• GSM networks don't use GPRS and must use SMS.

•When a WAP Push Service Indication (SI) notification is received, the user has

the option to download the content using this service.

Performing Synchronization•Data synchronization is an important Web service for mobile devices.

• Contact, calendar, and information on devices often need to be

synchronized between multiple systems.

•The most commonly used standard for performing synchronization is

SyncML (Synchronization Markup Language).•All or some the following data types may be synchronized by SyncML:

Bookmarks Calendar Contacts E-mail Files Memos Music Photos

Thank You