Survey Applications of Web Services

Survey Applications of Web Services

YANG Weiwei 
School of Software and Electronics,Peking University
E-mail: eyesinshadow@gmail.com


 
Abstract

Web services , one of the most significant changes in the software industry ,is a truly distributed computing model in which applications "talk" to one another. Experts consider it as the next evolution of the Web, it takes web application to the next level. With web services, data can be exchaged between different applications and different paltforms, it provides solutions against interoperability problem. On the other hand, web services devote to reusing application components. In this article, a preparatory questing will be launched, some basic technology will be introduced, we will survey some web service applications which are currently used in the web At last, we’ll discuss the future direction of web service technology..

1. Introduction

Over the last couple of years, web services have expanded to become more and more popular. Web services technology represents an important way for businesses to communicate with each other and with clients as well. It shares business logic, data and processes through a programmatic interface across a network. It’s distributed computing model allows application-to-application communication. [1]

So, what are web services? It's hard to explain this in only several sentences, web services is complicated, it represent a new paradigm in application achitecture and development. However, let’s get a formalized definition from wiki: the term web services describes a standardized way of integrating web-based applications using the XML, SOAP, WSDL and UDDI open standards over an Internet protocol backbone. Generally speaking, web services refer to a set of programming standards used to make different types of software talk to each other over the Internet, without human intervention. 

In this article, we will delve into the concepts and technologies of Web services, and survey the applications using Web Services which are used in real wolrd enterprise entironment

2.Web Services Technology
 
2.1 Characteristics and Benifits

  Web services bring a unique characteristic to the table, namely interoperability. Why is this property flaunted so much in marketing literature and why is there such a rush for vendors to support web services? The world is a heterogeneous place and different organizations (and sometimes different departments within large organizations) will choose a wide variety of technologies and platforms to use in building their applications. As long as these applications operate as standalones it doesn't matter. However, when you need to collaborate with different applications within the same organization or a different organization, integration becomes a nightmare. One application might be using J2EE (EJB, etc.) while the other is a legacy application that's written using C/C++ or a .NET application. These may run on different operating systems, making things even more complicated. 

This is where Web services create its value. The interoperability will ensure that these heterogeneous systems can interact with each other in a standard way, thus reducing some of the ugly issues faced when integrating heterogeneous systems. It is often a mistake to think that web services are the silver bullet to all problems faced in integrating heterogeneous systems, but web services offer by far the most promise in this area, provided the technology survives vendor politics.

The main benefits of web services are : 
 Application and data integration 
 Versatility
 Code re-use
 Cost savings

  The inherent interoperability that comes with using vendor, platform, and language independent XML technologies and the ubiquitous HTTP as a transport mean that any application can communicate with any other application using Web services. This allows organizations to integrate disparate applications and data formats with relative ease. 

Web services are also versatile by design. They can be accessed by human via a Web-based client interface, or they can be accessed by other application and other Web services. A client can even combine data from multiple Web services to, for instance, present a user with an application to update sales, shipping, and ERP systems from one unified interface – even if the systems themselves are incompatible. 

Code re-use is another positive side-effect of Web services' interoperability and flexibility. One service might be utilized by several clients, all of which employ the operations provided to fulfill different business objectives. Instead of having to create a custom service for each unique requirement, portions of a service are simply re-used as necessary.

Web services are not “pull down and do over”, existing investments in the systems development and infrastructure can be utilized easily and combined to add additional value. Since Web services are based on open standards their cost is low and the associated learning curve is smaller than that of many proprietary solutions.

2.2 Web Services Technologies
   
Web services are built on several technologies that work in conjunction with emerging standards to ensure security and manageability, and to make certain that web services can be combined to work independent of a vendor. The term Web service describes a standardized way of integrating Web-based applications using the XML, SOAP, WSDL and UDDI open standards over an Internet protocol backbone.

 XML
 XML is short for Extensible Markup Language, a specification developed by the W3C. XML is a pared-down version of SGML, designed especially for web documents. It allows designers to create their own customized tags, enabling the definition, transmission, validation, and interpretation of data between applications and between organizations.

 SOAP
SOAP is short for Simple Object Access Protocol, a lightweight XML-based messaging protocol used to encode the information in Web service request and response messages before sending them over a network. SOAP messages are independent of any operating system or protocol which we called application language and platform independent, they may be transported using a variety of Internet protocols, including SMTP, MIME, and HTTP. So when messages are defined to abey SOAP, they can be transferred and exchanged between applications and can be used to impelement remote procedure calls. SOAP enable information can be collect from different mediums.

 WSDL
WDSL is short for Web Services Description Language, an XML-formatted language used to describe a Web service's capabilities as collections of communication endpoints capable of exchanging messages. WSDL is an integral part of UDDI, an XML-based worldwide business registry. WSDL is the language that UDDI uses. 

Though the WSDL, a web services client learns where a service can be accessed, what operations the service performs, the communication protocols the service supports, and the correct format for sending messages to the service.

 UDDI
UDDI is short for Universal Description, Discovery and Integration. It is a Web-based distributed directory that enables businesses to list themselves on the Internet and discover each other, similar to a traditional phone book's yellow and white pages.
 
Fig 2.1 Relationships between techologies[3]

In a word, as the figure 2.1 show above, XML is used to tag the data, SOAP is used to transfer the data, WSDL is used for describing the services available and UDDI is used for listing what services are available. Used primarily as a means for businesses to communicate with each other and with clients, Web services allow organizations to communicate data without intimate knowledge of each other's IT systems behind the firewall.

2.3 Web services applications

Web services are using in quite many fields, examples of web services are:

 Shopbots such as BiddersEdge or mySimon provide a convenient shopping service for the bargain hunters on the Web by scouring the Web for all auctions and present the user with the best deal for the item he/she seeks. These bots can be extended to automate functions such as evaluation and selection of suppliers for materials purchasing or identifying qualified and available product support specialist (or other available resources) for a customer email inquiry.

 Credit card verification and processing during an online purchase. Today, e-merchants would have to develop Web applications that collect user data and integrate with backend systems and proprietary databases/networks of credit card agencies such as Visa and MasterCard to provide their shoppers with this convenience. A Web service can fulfill this specific need by providing an encapsulated application(s) that can be added/removed/modified based on business needs without any (or zero) significant disruptions to the business or the other business applications.

 Package tracking applications available on the Web. These applications (provided by UPS and FedEx) integrate several applications and databases (internal and external) in the backend to determine the precise location of packages based on shipping number. These applications allow the Net merchants to provide superior customer service. Such applications can also enable build-to-order manufacturing of complex products based on materials availability and precise production scheduling and forecasting.

 Portfolio tracking applications available on many investment sites. When an investor wants to know the net worth of his/her stock portfolio on a day when NASDAQ goes up by 200 points, these applications update the portfolio value by updating individual asset (stock) prices and performing the associated math and computation in the background, thus providing the user with a personalized and tailored service. Such applications have potential uses in business decision-making systems such as forecasting, capital allocation, etc.

3.Web Services applications in enterprises

  Web services will be ubiquitous. Applications running anywhere, on any technology or device will have a Web Services capability available to them. As such, the applications of customers and business partners will be able to participate in an organizations business process, in real time. Web services potentially improves business process efficiency by reducing cost and particularly time to connect applications. Enterprise applications have really made significant strides over the past 10 years (especially in the past 4) to improve their ability to integrate into a larger corporate scheme. With the advent of Web services - a model for developing application components designed for sharing with other applications in a loosely coupled manner-the question to be answered is, "What problem does this solve for enterprises today?" As we've seen thus far, each of the advances in technology was incorporated into the enterprise application platform based on consumer needs. Initially, the need was customization, then communication of data with other internal systems, and finally, the need for real-time access for synchronization.

The goal of Web services is to componentize our legacy systems so they can participate in newly designed processes, which means that they will take some input and provide some output that will be used in downstream steps.

New business-to-business(B2B), enterprise application integration (EAI) and other applications which based on Web services to communicate with systems are designed to meet the requirement the data be formatted for the time being in something other than XML. Web services enables them to take advantage of these systems as components of a much larger process without having to first rewrite them - a very powerful and often overlooked capability of Web services.

3.1 eBay  

EBay’s goal is to set up a powerful and world-wide auction platform, on which, vendors release products’ information and customers hunting for their needs. Using eBay Web services, affiliates will be able to access the most current information on eBay's site, including real-time pricing, specific product details and bidding times for all listings. By now, thousands of developers have already created customized applications using the tools and have built direct links to the company's databases of products for sale on its sites. When an item is sold via an affiliate's link to eBay, the auction company pays the partner a commission based on the size of the sale. By doing this, eBay becomes to be the largest virtual retail trade center in the world.
3.1.1 Evolution of eBay web services
The online auction king has been aggressively developing its Web services platform by extending application programming interfaces that essentially turn its web site into a platform.  

In 1995, eBay founder Pierre Omidyar designed the web site with the idea of an on line marketplace where people would be able to sell and buy goods. After years of development, hunting for opportunities, eBay began to build a bran-new online-platform who's goal is helping consumers, suppliers and other group issue and share their information in order to brokerage of their deals through the platform. [4]
 
For doing this, the auction site's developer section gives soup-to-nuts information about deploying its eBay API. With the eBay application program interface (API), others can communicate directly with the eBay database in XML format, their application could provide a custom interface, functionality and specialized operations not otherwise afforded by the eBay interface. This made eBay became to be a loose, connecting oriented, services provider, which can also be seen as a web services platform. Actually , over 40% of eBay's listings now come through API calls. 

Now eBay offers more than 100 Web services calls available to developers to build applications that can connect to those services. They include pricing information, buy-it-now features, and payment options through its PayPal subsidiary. By doing this, eBay has established a new business-to-business(B2B) web application based on web services technology. 

3.1.2 Build applications with the eBay SDK and Web services
To make it even easier to build custom applications using eBay's Web services, eBay provides 2 SDKs[5] to wrap their APIs, giving developers the choice of whether to develop in Windows using .NET or in native Java language. The eBay SDK is a powerful, flexible, and ridiculously easy-to-use toolkit for interfacing directly with eBay. Before the SDK, developers had to format their own XML to make eBay API calls, but it was still a powerful way to access eBay's database.For several years there was only an eBay SDK for Windows, but now there is also an eBay SDK for Java technology. The SDK for Windows encapsulates the XML API, and the SDK for Java technology encapsulates the SOAP API. They both provide you with easy-to-use objects to wrap the XML/SOAP API calls to eBay. All other languages can still make API calls directly and have the same access to the eBay Web services.


 

Fig.3.1 eBay Web services Architecture

  There 3 basic steps to build up an application based on eBay SDK and Web services technology.
 Join the eBay Developers Program, after the account is setup, download the SDK and also get some support.
 Set up the execution environment, create an API call context object, authenticate the requesting user, and specify the URL for the eBay Web services.
 Make a specific API call to the Web service

  When a application is developed out, the APIs work with eBay is like:
 
Fig.3.1 Shopping Trading sequence of eBay

1. A user searches a wanted product in application;
2. The application makes a search request for the product using one of the eBay Web Services;
3. The eBay database looks for the information abot this product;
4. The eBay database sends the response back to the application using the API;
5. The application displays the search results to the user.

EBay provides two kinds of Web Services, they are Shopping Web Service which optimized for buyer shopping and browsing ; Trading Web Service which designed to provide robust support for transactional activities.:

1. eBay Sopping Web Service

 It opens our platform to enable users to integrate data from the eBay marketplace into their own sites.
 It's easy to use: 
1) As you're just browsing and searching, it doesn't require end-user authentication (no token required);
2) You can make 5,000 requests per IP per day. This is better for developers in terms of capacity. If your application requires more calls, you need to go through our application compatibility check process.
 It enables these kinds of features/functions:
1) Creation of buyer applications;
2) Searching for items, users, and social commerce .
 The Shopping calls are optimized to give very fast response times.

2. eBay Trading Web Services

 It enables users to contribute content (items, feedback, etc.) to the eBay marketplace, and to handle transactions that occur on eBay.
 As transactional data is specific to each eBay user, the Trading service requires end-user authentication (token required).
 You can make 5,000 requests per Application per day. If your application requires higher volume, you need to go through our application compatibility check process.
 The Trading calls are designed to enable these kinds of features/functions:
1) Selling on eBay
2) eBay transaction processing (retrieving transactions, leaving feedback, etc.)
3) My eBay
   
3.1.3 Using the eBay Web Service 
  Since eBay provided such a powerful platform for both vendors and customers, many applications emerged in large numbers. Vendors can sell their product in a more attractive way. A seller’s web site which is using eBay Web Service lays on below.
 
Fig. 3.2 Seller’s web site using eBay web service

  In this figure, a new feature was added to a traditional web site, you may already notice the segment which is circled by a red line. How it works? There two aspects: One is EBay sellers can make commissions on their own items. So they can highlight their own auctions on their site, get money from the sale of that item. Besides, when users buy something or become eBay members after going through their applications, sellers can also make money. This is a two-side-win form, sellors have more channels to sell their products, their products’ information is more easy to gain customers’ attention, and they can also get money from eBay as a spreader; In this form, eBay can have more commission users, who will do more deals through eBay.com.  

3.2 Google

Everyone knows Google, it is so famous in IT companies. Today, Google is a publicly traded company that handles one of the most used search engines in the world, with a stock price that was originally the highest in its class. Google search engine is so powerful [6], and it’s also the most popular search engine in the world, it remains netizens’ first and usually best choice for Internet-based research. Now, Google provides a Web service for searching through Google's database, retrieving cached versions of Web pages, and performing spelling checks. Using Google's Web service one can provide Google's search functionality on their own Web site or other applications.
3.2.1 A Quick Primer on Google Web Services
A Web service is an external interface provided by a Web site that can be called from other Web sites. Think of Web services as a self-contained component with one or more methods. This component can reside anywhere on the Internet, and can have its methods invoked by remote clients. For example, the Google Web service provides three methods: doGoogleSearch(), doGetCachedPage(), and doSpellingSuggestion(). The doGoogleSearch(), which we'll be examining in this article, has a number of input parameters that specify the search query. The method then returns an instance of the GoogleSearchResult object, which has the results of the search.

Here are the steps to start using Google SOAP Search API: First download the Google Web API Developer's Kit and then creating an account to obtain a license key. Following that, created a proxy class based on the Google Web service's WSDL file (GoogleSearch.wsdl, which is included in the Developer's Kit download). Armed with this proxy class, developers could then access the Web service in their applications.

3.2.2 Google SOAP Search API
  Google created the SOAP Search API for developers and researchers interested in using Google Search as a resource in their applications. In this way, developers write software programs that connect remotely to the Google SOAP Search API service. Communication is performed via SOAP, an XML-based mechanism for exchanging typed information. 

Developers can use Google Web Service to build plenty of applications. We can issue search requests to Google's index of billions of web pages and receive results as structured data, access information in the Google cache, and check the spelling of words. However, Google itself offers these suggestions for ways you can use their Web service:
 Auto-monitor the Web for new information on a subject
 Glean market research insights and trends over time
 Invent a catchy online game
 Create a novel UI for searching
 Add Google's spell-checking to an application
   
3.2.3 Using Google Web Services
Google’s web service API is so powerful, it allows developers to build plenty kinds of applications upon them. Typically, there are “Spell checker”, “Google search”, “Stock quotes”.

1. Using Google's Spell Check Web Service
 
Fig. 3.3 Spell check using Google spell check web service

 2. Using Google’s Search Web Service

 

Fig. 3.4 Spell check using Google Search web service

3. Using Google’s Stock quotes Web Service
 

Fig. 3.5 Stock Quotes using Google’s Stock Quotes Web Service

It’s not too hard to develop all of these applications on the help of Google SOAP Search API, it provides developers a simple, but rich, set of APIs that you can use in your own application in the form of Web Services, which you can find in site :
http://code.google.com/apis/soapsearch/index.html

3.3 FedEx
 
3.3.1 Demand for Web Service in Express-delivery vocation
FedEx is one of the largest express-delivery company in the world, it owns a huge number of customers. By the shock of e-commerce, vendor wants shopping cart functionality on his e-commerce web site. The site visitor must be able to add items to the shopping cart, register, pay using credit card and checkout. The client wanted to incorporate FedEx functionalities like "Available Services", "Address Verification" and "Package Tracking". They wanted to be able to select multiple destinations for selected orders so that user can ship the gifts to multiple shipping addresses. 

Fortunately, all of these had to be implemented using web services integration.

With FedEx Web Services, you can integrate FedEx Express® and FedEx Ground® services into your business systems, retail website or order management system. FedEx Web Services is the next generation API for integrating software applications with FedEx Systems to create shipping labels, track shipments, obtain rate quotes and generate reports.[8] 

Web services differ from traditional client/server models in that they allow for application-to-application communication. In other words, applications interface with each other, not with the users. This means applications can be combined to create more powerful services. For example, a user could choose to combine FedEx Web Services with Web services from other organizations to create unique, customized solutions. FedEx is currently refocusing its web integration capabilities toward Web services. Developers are encouraged to use FedEx Web Services in order to take advantage of all of the new and improved features and benefits that will be available through FedEx Web Services.

3.3.2 Benefits of using FedEx Web Services
From a business and product planning standpoint, FedEx Web Services is an ideal choice for integration. FedEx Web Services are designed to achieve the following:

 Integrate common FedEx functionality into companys’ business workflow, including the ability to locate the best rates, estimate transit times, and track shipments.

 Save time by automating common processes like rate and service selection, generating labels, and exchanging data between information sources

 Conforms to industry standards and is compatible with a comprehensive array of developer's tools to provide faster time to market and increased flexibility to integrate FedEx transactions and information into applications.

 FedEx WSDLs are designed to be fully inter-operable with any product or developer's tool that also conforms to the WS-I Basic Profile.
 
3.3.3 Applications using FedEx Package Tracking Web Service
 FedEx

 
Fig.3.6 Package tracking application on FedEx.com

 Packagetrackr
  Packagetrackr.com is a web site designed for tracking FedEx and UPS packages, it used FedEx Package tracking web service to fulfill this.

 

Fig.3.7 Package tracking application on Packagetrackr.com

 Yahoo
Yahoo owns a lot of applications using web services, this is one is designed for the need of tracking FedEx pakages which used FedEx web service API.
 

Fig.3.8 Package tracking application on Yahoo

  Further more, FedEx web service, like all web service providers, encourages developers to build their own applications. For example, a sales company may be concerned about how their products are when they are on their way deliveried by FedEx, to reach this requirement, FedEx web service offers a solution to build their own application. This application can track the target by using the real-time information offered by FedEx. 
 
3.4 Summary

In this section, we discussed three kinds of application using web services, the providers are eBay, Google and FedEx. Ebay is the bigest auction company in the world, well Google becomes to be the bigest inforamtion provider by handling the powerful search engine and FedEx is the bigest express-delivery company. By providing web services, these companys expand their business, anyone can use their convenient services in their distributed or virtual applications. Actually, there are much more companys provide web services, like UPS, Amazon, PayPal, Yahoo and so on. Most of them are much alike with the upon three kinds, we are not going to list them on by on. Howerver, they all have a feature, which is also the feature of web service, that is interoperability. This feature makes a flourishing vision on our internet.

4 Future Web Service Directions

Recently, Web services have generated great interests in both vendors and researchers. Web services, based on existing Internet protocols and open standards, can provide a flexible solution to the problem of application integration. With the help of WSDL, SOAP, and UDDI, Web services are becoming popular in Web applications. However, the current Web services architectures are confronted with a few stubborn problems, for instance, security. In this section, I'll look at some of the larger issues facing web services, including the complexity of development, the need for a business model, security, and finally present a mental model for tracking the evolution of web services over the near future.

4.1 Break down the complexity

Web service has a attractive feature, that is code-saving, it saves a lot of money and time to build a application. However, the development isn’t easy because of technology complexity. Develop a web service application, for example, a application using eBay shopping web services, developers should at least be familiar with technology system, including SOAP, XML, WSDL, UDDI, what’s more, development will be depended on eBay SDK. This is a complex work.

As the component model for web application development matures, it's possible that the use of the more complex web service infrastructure such as SOAP and WSDL will be sufficiently encapsulated so as to make the development of web service applications accessible via visual builder tools. For example, several commercial tools now available allow a user to specify a WSDL and automatically generate web service components.

4.2 Understanding the Business Model

Almost all of the web services offered by various companies are provided for free in conjunction with an offline service of some kind. An open question is the viability of charging for web service access in and of itself. A new model to earn money on web service, which also is significant for the future of the Internet, should be called for. For example, an inexpensive pay-per-access web service model could pave the way for a micropayment system for access to content and software. Alternatively, it could also provide for richer integration between a client and a server for specific applications.

Howeve, to date, this has been limited by the tendency of a corporation to want to own the entire chain of experience between themselves and the end user.

4.3 Security

Security in web services is still a somewhat mixed system. Throughout this text, we've seen a variety of approaches, and this variety is likely to continue for some time. Some services support HTTPS- and SSL-based connection encryption. A minor gesture is made toward security with the use of an MD5 hash for passing along passwords. There are a variety of tokens required to access different systems. At minimum, the following are all required to access a service: a single developer token, an authentication token, an application token, a user account, and a password.

It's easy to criticize the efforts with regard to security that have been made, but one of the biggest advantages of web services is the very reliance on the underlying standards. For higher security environments, it's easy to envision using existing technologies such as SSH or a VPN. Proxy servers and services can provide for robust logging and debugging capability. The same XML that SOAP relies on makes it easy for a proxy system to inspect the messages being sent.

4.4 Semantic Web Services

The current Web services technology basically provides a syntactical solution and still lacks the semantic part. A Web service is described in WSDL, outlining what input the service expects and what output it returns. To exploit their potentials (beyond the enterprise application integration), Web services must be able to orchestrate themselves into more complex services. Thus, we need methods to combine individual Web services into a distributed, higher-level service. The Web Service Flow Language (WSFL), which can express the sequencing of individual services, is taking the first steps. WSFL lets the user decide which Web services to combine and in what order. However, we still need a framework that semantically describes services so that software agents can locate, identify, and combine these services.

Current Web services standards, such as SOAP, WSDL, XLANG, WSFL, BPEL4WS, WSCI, and BPML; all describe Web service content in terms of XML syntax. Unfortunately, XML alone lacks both a well defined semantics and sufficient expressive power to realize the vision of diverse Web services having wide-scale interoperability. Seamless interoperability between services that have not been pre-designed to work together requires programs to describe their own capabilities and understand other services’ capabilities. To realize this vision, Web content, particularly Web service content and capabilities, may need to be described in a language that goes beyond XML. This problem is well addressed in the Semantic Web vision of the next-generation Web[9].

5 Conclusion

In this article, first we discuss on the topic that what are web services,and what are the benefits, then some related technology are introduced, like SOAP, XML, WSDL and UDDI. As web service technology came to be systematism and mature, more and more companys provide web services. Then we focus on surveying three web service providers- eBay, Google and FedEx, we look at how these companys provide their web services, how to use these web services and how they work. Three kinds of application aren’t enough to explain the whole web service’s actuality and development, but it’s not hard to find out its characteristics and benefits, briefly speaking, web service is a vague term that refers to distributed or virtual applications or processes that use the Internet to link activities or software components. And applications using web services are open to be developed without much limit, they own a great ability on interactivity and they can use much more information which are shared by different companys and organizations. Web services became to be a trend of our internet, and it’s a potential technology in the future too.  

References

[1] Vangie 'Aurora' Beal, Understanding Web Services, October 07, 2005

[2] Prentic Hall Sanjiva Weerawarna, Francisco Curbera, Frank Leymann, Tony Storey, Donald F. Ferguson, Web Services Platform Architecture, 

[3] Lawrence Wilkes, The Costs and Benefits of Web Services and Service Oriented Architecture

[4] Web Services for Enterprise Application Integration.

[5] Rob Chappelle, Build a marketplace with the eBay SDK and Web services, 15 Oct 2004

[6] Scott Mitchell, Searching Google Using the Google Web Service

[7] Peter Bernhardt, Using the Google Web Service, 31 October 06

[8] Information from FedEx’s web site: http://fedex.com/ca_english/businesstools/webservices/index.html

[9] Hongbing Wang, Joshua Zhexue Huang, Yuzhong Qu and Junyuan Xie, Web services: problems and future directions