Web Services on Mobile Platform Documentation

7/27/2019 Web Services on Mobile Platform Documentation

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ABSTRACT

Web services are distributed application components that are externally available.You can use them to integrate computer applications that are written in different languages

and run on different platforms. Web services are language and platform independent because

vendors have agreed on common web service standards. A web service is typically an

application programming interface (API) or Web API that is accessed via Hypertext Transfer

Protocol (HTTP) and executed on a remote system, hosting the requested service.The W3C

defines a "web service" as "a software system designed to support interoperable machine-to-

machine interaction over a network. It has an interface described in a machine-process able

format (specifically Web Services Description Language WSDL). Other systems interact

with the web service in a manner prescribed by its description using SOAP messages,

typically conveyed using HTTP with an XML serialization in conjunction with other Web-

related standards."Web services are an emerging technology that provides interoperability

between applications running in different platforms. The Web services technology provide

the best approach to Service Oriented Architecture envision of component collaboration for

better business requirements fulfillment in large enterprise systems. The challenges in

implementing Web services consuming clients for low-resources mobile devices connected

through unreliable wireless connections are delimited. The paper also presents a

communication architecture that moves the heavy load of XML-based messaging.


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TABLE OF CONTENTS

LIST OF FIGURES PAGE NO

1. INTRODUCTION

1.1THE ROLE OF WEB SERVICES ON MOBILE PLATFORM

1.2THE SOAP

1.3DESCRIPTION OF WEB SERVICES

1.4LIMITATIONS OF MOBILE DEVICES

2. TYPES OF WEB SERVICES

2.1BIG OR SOAP WEB SERVICES

2.1THE SOAP MESSAGE EXCHANGE MODEL

2.3RELATION TO XML

2.4RESTFUL WEB SERVICES

2.5FUNDAMENTAL ENTITIES OF REST

3. INTRODUCTION OF A MIDDLEWARE COMPONENT

3.1FUNCTIONS OF MIDDLEWARE

ii


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FIG.NO FIGURE NAME PAGE NO.

1 WEBSERVER

2 MOBILEDEVICE

3 CLIENT AND SERVER

4 SOAP ARCHITECTURE

5 MIDDLEWARE

iii


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1. INTRODUCTION:

Web services are distributed application components that are externally available.You can use them to integrate computer applications that are written in different languages

and run on different platforms. Web services are language and platform independent because

vendors have agreed on common web service standards. A web service is typically an

application programming interface (API) or Web API that is accessed via Hypertext Transfer

Protocol (HTTP) and executed on a remote system, hosting the requested service. The W3C

defines a "web service" as "a software system designed to support interoperable machine-to-

machine interaction over a network. It has an interface described in a machine-process able

format (specifically Web Services Description Language WSDL). Other systems interact

with the web service in a manner prescribed by its description using SOAP messages,

typically conveyed using HTTP with an XML serialization in conjunction with other Web-

related standards."Unlike traditional client/server models, such as a Web server/Web page

system, Web services do not provide the user with a GUI. Web services instead share

business logic, data and processes through a programmatic interface across a network. The

applications interface, not the users. Developers can then add the Web service to a GUI (such

as a Web page or an executable program) to offer specific functionality to users.


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Web services allow different applications from different sources to communicate with

each other without time-consuming custom coding, and because all communication is in

XML, Web services are not tied to any one operating system or programming language.

1. Web server

Web services instead share business logic, data and processes through a programmatic

interface across a network. The applications interface, not the users. Developers can then add

the Web service to a GUI (such as a Web page or an executable program) to offer specific

functionality to users.


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1.1THE ROLE OF WEB SERVICES ON MOBILE PLATFORM:

Web services are an emerging technology that provides interoperability between

applications running in different platforms. The Web services technology provide thebest approach to Service Oriented Architecture envision of component collaboration for

better business requirements fulfillment in large enterprise systems. The challenges in

implementing Web services consuming clients for low-resources mobile devices

connected through unreliable wireless connections are delimited. The paper also presents

a communication architecture that moves the heavy load of XML-based messaging

system from the mobile clients to an external middleware component. The middleware

component will act like a gateway that lightly communicates with the device in a client-

server manner over a fast binary protocol and at the same time takes the responsibility of

solving the request to the Web service. Keywords: Web Services, SOA, Mobile

Computing, Mobile Devices.

2. Mobile Device


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1.1THE SOAP:

The current trend in the application space is moving towards Service-Oriented

Architecture (SOA) paradigm which describes a flexible set of design principles for building

interdependent and interoperable application components that act like services by

implementing a specific functionality and publishing a communication interface to access it.

The paradigm envisions component collaboration for better fulfillment of business

requirements in large enterprises systems. Systems built with these principles will be more

flexible to changes in business requirements as opposed to traditional monolithic systems that

are extremely sensitive to any change in one of its subsystems.

The Web services technology evolved from the most logical approach of applying the

SOA vision to the Web space. This technology provides interoperability over the Web

between applications running on different platforms, ensuring a standardized protocol for

business partners to exchange information. Being built over the extensible Mark-up Language

(XML) and Hypertext Transfer Protocol (HTTP) standard protocols, Web services can be

easily deployed and accessed from anywhere over the Web. Web services are software

components build upon Web-based technologies including HTTP and XML and allowstandard means of interoperability over the Internet or intranets between application running

on a large variety of hardware and platforms. Web services act like self-contained

components that are published, located and invoked over the Web. The key concept behind

Web services is to provide a standard platform and operating system independent mechanism

for application communication over the Web.


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1.3. DESCRIPTION OF WEB SERVICES:

Web services are software components build upon Web-based technologies including

HTTP and XML and allow standard means of interoperability over the Internet or intranets

between application running on a large variety of hardware and platforms. Web services act

like self-contained components that are published, located and invoked over the Web. The

key concept behind Web services is to provide a standard platform and operating system

independent mechanism for application communication over the Web.

3. Client and Server

There are two major limitations that SOAP-based Web services have: performance issues

due to XML processing overhead and lack of support for transaction in communication.

Communication with a Web service may suffer poor performance over busy or unstable.


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1.4 LIMITATIONS OF MOBILE DEVICES:

About fifteen years ago the mobile phones had huge sizes and carrying them was an

issue. They were about phone calls only. Today the mobile revolution brings mobile devices

that can easily fit in your back pocket and feature incredible entertainment and multimedia

capabilities. The capabilities of mobile devices are constantly increasing to satisfy an even

more increasingly need for flexibility in terms of mobility and connectivity. Cellular

networks are expected to sustain a 40 time increase of data traffic in the next 5 years. Data

traffic will come from Web browsing in general and video watching in particular.

Sites like give an up to date hardware features comparison of existing smart phones - the

most appealing mobile devices on the market in terms of mobility. Besides the obvious

advances in computational capabilities (e.g. faster processor, greater amount of ROM and

RAM), the trend is towards providing wireless network communication capabilities and high

connectivity features. The main hardware limitations of mobile devices that need to be

addressed in the near future are huge battery consumption - that translates into poor battery

ower and network.

Except for the Windows and Nokia platforms that provide a level of support that

allows the developer to concentrate on design and creativity rather than finding dirty

workarounds, developing SOAP Web services clients requires a lot of extra effort mostly due

to the lack of native support. Moreover, specific workarounds are required for specific

platforms making very resource consuming the task of implementing a Web application on

all mobile platforms.


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2. TYPES OF WEB SERVICES

Types of Web Services:

On the conceptual level, a service is a software component provided through a

network-accessible endpoint. The service consumer and provider use messages to exchange

invocation request and response information in the form of self-containing documents that

make very few assumptions about the technological capabilities of the receiver. On a

technical level, web services can be implemented in various ways. The two types of web

services can be distinguished as

big web services (SOAP) Restful web services

2.1 Big OR SOAP Web Services:

SOAP, originally defined as Simple Object Access Protocol, is a protocol

specification for exchanging structured information in the implementation of Web Services in

computer networks. It relies on Extensible Markup Language (XML) for its message format,

and usually relies on other Application Layer protocols, most notably Remote Procedure Call

(RPC) and Hypertext Transfer Protocol (HTTP), for message negotiation and transmission.

SOAP can form the foundation layer of a web services protocol stack, providing a basic

messaging framework upon which web services can be built. This XML based protocol

consists of three parts: an envelope, which defines what is in the message and how to process

it, a set of encoding rules for expressing instances of application-defined data types, and a

convention for representing procedure calls and responses.


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SOAP consists of three parts:

The SOAP envelope construct defines an overall framework for expressing what is ina message; who should deal with it, and whether it is optional or mandatory.

The SOAP encoding rules defines a serialization mechanism that can be used toexchange instances of application-defined data types.

The SOAP RPC representation defines a convention that can be used to representremote procedure calls and responses.

4. Soap Architecture


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2.2 THE SOAP MESSAGE EXCHANGE MODEL:

SOAP messages are fundamentally one-way transmissions from a sender to a

receiver, but as illustrated above, SOAP messages are often combined to implement patterns

such as request/response.SOAP implementations can be optimized to exploit the unique

characteristics of particular network systems. For example, the HTTP binding provides for

SOAP response messages to be delivered as HTTP responses, using the same connection as

the inbound request. Regardless of the protocol to which SOAP is bound, messages are

routed along a so-called "message path", which allows for processing at one or more

intermediate nodes in addition to the ultimate destination.

A SOAP application receiving a SOAP message MUST process that message by

performing the following actions in the order listed below:

1. Identify all parts of the SOAP message intended for that application2. Verify that all mandatory parts identified in step 1 are supported by the application for

this message and process them accordingly. If this is not the case then discard the

message. The processor MAY ignore optional parts identified in step 1 without

affecting the outcome of the processing.

3. If the SOAP application is not the ultimate destination of the message then remove allparts identified instep 1before forwarding the message.

2.3 RELATION TO XML:

All SOAP messages are encoded using XML A SOAP application SHOULD include

the proper SOAP namespace on all elements and attributes defined by SOAP in messages that

it generates. A SOAP application MUST be able to process SOAP namespaces in messages

that it receives. It MUST discard messages that have incorrect namespaces and it MAY

process SOAP messages without SOAP namespaces as though they had the correct SOAP

namespaces.
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SOAP defines two namespaces:

1. The SOAP envelope2. The SOAP serialization

2.4 RESTFUL WEB SERVICES:

REST is a collection of architecture principles and a software architecture style to

build network-enabled systems based on mechanisms that define and access resources, such

as the World Wide Web. The term REST is often used rather loosely to describe a framework

to transmit data over a protocol such as HTTP without adding additional semantic layers or

session management.

REST defines a strict separation of concerns between components that participate in a

client-server system that simplifies the implementation of actors involved. REST also strives

to simplify communication semantics in a networked system to increase scalability and

improve performance. REST relies on autonomous requests, between participants in a

message exchange which implies that requests must include all information that a client orserver requires understanding the context of the request. In a REST-based system, you use

minimal sets of possible requests to exchange standard media types.


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2.5 FUNDAMENTAL ENTITIES OF REST:

REST defines the following fundamental entities:

Data elements: Data, identifiers (URIs and URLs), and representations of data suchas HTML documents, XML documents, and images

Components: Origin servers such as Apache http and Microsoft InternetInformation Services (IIS), gateways such as Squid and CGI, proxies such as Gauntlet

and Netscape proxy, and user agents such as Web browsers or mobile devices

Connectors: Client connectors such as libwww, server connectors such as NSAPI,caches such as a browser cache, and others

Some of the fundamental REST entities and how they can interact within a typical

networked system. Notice that requests are transmitted and received by connectors that are

tied to a given entity, such as a server or database. Connectors handle transmission duties for

a given protocol, thereby allowing an entity to transmit or receive requests in the same

manner over any protocol, as long as a connector is present for the desired protocol.


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3. INTRODUCTION OF A MIDDLEWARE COMPONENT

Middleware is the software that connects software components or enterprise

applications. Middleware is the software layer that lies between the operating system

and the applications on each side of a distributed computer network. Typically, it

supports complex, distributed business software applications. Middleware is the

infrastructure which facilitates creation of business applications, and provides core

services like concurrency, transactions, threading and messaging for service-oriented

architecture (SOA) applications. It also provides security and enables high availability

functionality to your enterprise. Middleware includes Web servers, application

servers, content management systems, and similar tools that support application

development and delivery. It is especially integral to information technology based on

Extensible Markup Language (XML), Simple Object Access Protocol (SOAP), Web

services, SOA, Web 2.0 infrastructure, and Lightweight Directory Access Protocol

(LDAP)m etc.

3.1 FUNCTIONS OF MIDDLEWARE:

Applications use intermediate software that resides on top of the operating systems

and communication protocols to perform the following functions: The function of

middleware is to mediate interaction between the parts of an application, or between

applications. Therefore, considerations for architectural structure play a central role in

middleware design. The architectural design encompasses the organization, overall structure,

and communication patterns, both for applications and for the middleware itself.

Besides architectural aspects, the main problems of middleware design pertain to

various aspects of distributed systems. Any middleware system relies on a communication

layer that allows its different pieces to interoperate. In addition, communication is a function

provided by middleware itself to applications, in which the communicating entities may take

on different roles such as client server or peer-to- peer. Middleware allows different

interaction modes (synchronous invocations, asynchronous message passing, coordination

through shared objects) embodied in different patterns.


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Hide the distributed nature of the application. An application represents a collection

of interconnected parts that are operational and running in distributed locations, out of

view Hide the heterogeneity of the enterprise. This includes the hardware components

used, computer operating systems, and communication protocols. Provide uniform,

standard, high-level interfaces to the application developers and integrators, so that

applications can be easily composed, reused, ported, and made to interoperate.

5. Middle ware

Middleware systems rely on interception and indirection mechanisms, which induce

performance penalties. Adaptable middleware introduces additional indirections, which make

the situation even worse. Widespread computing is a vision of the near future, in which an

increasing number of devices embedded in various physical objects participate in a global

information network. Mobility and dynamic reconfiguration will be dominant features,

requiring permanent adaptation of the applications. Managing large applications that are

heterogeneous, widely distributed, and in permanent evolution raises many questions, such as

consistent observation, security, trade-offs between autonomy and interdependence for the

different subsystems, and definition and implementation of resource management policies.


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CONCULSION:

The J2ME web services have to depend on third party apis for integration with maps,

mail, videos & etc..Though these services have better performance, still we need to

understand that these services were designed while keeping feature phones in mind.The

J2ME service market is quite large, but Android service market is rising fast (for smart

phones) a segment which has become more and more popular in the recent years. It depends

on the requirements that which kind of technology we select for creating & hosting our

services, who are the end consumers & what level of performance is required from these

services.Until wireless networks are as reliable, cost-efficient and fast as LAN networks,mobile applications still need to be a blend of online and offline models. The most obvious

difference is the performance of the emulators: The J2ME emulator is by far the fastest &

about thirty times faster than the Android emulator. This difference in performance could be

explained by the efficient low-level nature of J2ME.A similarity between the two emulators

is that they all use very little processing power of the host PC. So processing power is not the

bottleneck but opening/closing connections are probably the bottleneck. The scalability

differs enormously. The Android version has a zero error rate at a load of 25 clients probably

caused by the low performance. J2ME OS emulator has a very bad scalability.


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BIBLIOGRAPHY:

[1] Touching mobile apps the Artisan way delivers real-time UI/UX changes without

coding, 1998

[2] Partnerpedia evolves the intranet for a range of endpoints with a unified app

store,sept.2001

[3] Mobile apps blossom when powered by SAP HANA, and integrate faster with

RDS,Singapore,1997,2.2

[4] Getting control of mobile management disorder,july 2001,George Mason

University,Fairfax,Virginia,USA
https://451research.com/report-short?entityId=77882https://451research.com/report-short?entityId=77882https://451research.com/report-short?entityId=77740https://451research.com/report-short?entityId=77740https://451research.com/report-short?entityId=77193https://451research.com/report-short?entityId=77193https://451research.com/report-short?entityId=74478https://451research.com/report-short?entityId=74478https://451research.com/report-short?entityId=77193https://451research.com/report-short?entityId=77193https://451research.com/report-short?entityId=77740https://451research.com/report-short?entityId=77740https://451research.com/report-short?entityId=77882https://451research.com/report-short?entityId=77882

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Web Services on Mobile Platform Documentation