Web Services

Abstract

Web services are part of the business logic component that is programmatically written to serve as black boxes to provide access to functionality via the Internet using standard protocols such as HTTP. Web Services are based on the usage of XML called the Simple Object Access Protocol (SOAP). SOAP defines a standardized format for enveloping the XML exchanged between two entities over the standard protocols such as HTTP. The consumers of a web service are therefore completely shielded from any implementation details about the platform exposing the web service – they simply send and receive XML over HTTP protocol (Homer and Anderson, 2004).

Homer and Anderson (2004) also explained that Web services allow distributed applications to share business logic over a network. By using standard web protocols such as HTTP, and data description languages such as XML, to exchange data over common ports, web services can utilize the HTTP infrastructure support that is already in place. The following are the common features of the web services:

  • Web services are non-specific to implementation. The application logic can be implemented by components such as script languages or by any other mechanism that supports XML.

 

  • Web Services use Internet transport protocols such as HTTP or SMTP. The combination of XML and HTTP forms Simple Object Access Protocol (SOAP).

 

  • Consumers of a web service don’t need to know anything about the platform, object model, or programming language used to implement the service, they only need to understand how to send and receive SOAP messages.

Why Web Services?

VK Infotek Inc. (2009) explained that other technologies were available by Microsoft before the arrival of the web services such as Component Object Model (COM), and Distributed COM (DCOM). With such technologies the TCP/IP protocol was used to implement these technologies. Also, Common Object Request Broker (CORBA) was developed by vendor called Object Management Group to compete with Microsoft projects. However, all the above technologies have different limitations, some of these limitations are:

  • DCOM works well with binaries where it’s written with Microsoft languages, and also running under Microsoft Platforms. Also, the protocol used with such technologies is TCP/IP protocol over a LAN or WAN. With such technique, the Firewalls represented serious problems in blocking traffics where the data is passed as binary messages on non-standard ports which represented a poor performance.
  • On the client side, to use the above technologies on a remote computer, both client and the server should have the appropriate DCOM or CORBA libraries installed.

VK Infotek Inc. (2009) also explained that with the introduction of the web services, service-based model architecture was implemented where the client computer can request and consume the web service and terminate such service as desired, the client needs to be provided with the Web services URL only. With such model the following are the new features implemented by the web services:

  • Client applications don’t have to be developed with the same tools as the web services or running under the same platform as the Web services are (I.e. clients can be running with different technology such as Sun Microsystems or IBM technology, while the web services are developed with Microsoft technology, and there is no need to meet any compatibility issues).
  • The web services are written separately from any application logic, and communicate with different entities without affecting the existence of such entities.
  • Web services made the communication flows among applications easy since an application programming interface (API) is used to allow applications to expose its functionalities to other applications via API mechanism.
  • Web Services improve the flow of information among applications since web services are using the Extensible mark-up language (XML) (a text based protocol) to all the applications to communicate with.
  • No license cost is required for the applications to communicate with each other via Web services.
  • Web services don’t rely on specific protocol to do the job. Web services use standard protocols such as HTTP and SOAP and messages are transmitted over port 80 which is an open port for web server firewalls. Web services are transmitted as SOAP-formatted messages in XML format i.e. simply text and not a binary data.
  • Web services are a low cost technology that can be used among businesses compared to the EDI solutions. Web services can also be implemented over reliable transport mechanisms such as FTP and others.

The framework of Web Services

In the same way that SQL provided a standard way to allow software to communicate with the database, the web services provide a standard way to package information from one entity to communicate with another entity. That opened a new level of communications among business that can implement different technology and different platforms. XML and SOAP are the most important protocols behind the web Services. SOAP (Simple Object Access Protocol) represents a standard way to access different objects, and also any systems that support such protocol. XML represents the standard way that structuring the text that will pass among objects. In the same way browsers understand HTML, SOAP understand XML. However, the structure of such XML messages has to be defined between businesses, and follow certain standard to maintain accessibility between businesses (Berlind, 2002).

IBM Redbooks (2005) stated that the existing trend for companies to integrating systems to implement IT support for business processes started with electronic data Interchange (EDI) interaction and that demand increasing and asking for new technologies that can support the connections between systems over the web, and also sharing resources and data in flexible and standardized manner. The web services introduced a service-oriented architecture that can replace the existing EDI systems with less cost and more comprehensive technology and easy to use concept to many businesses. The services-oriented architecture of the web services consist of three basic components:

  • Service provider – Creates the Web services and publishes the interface that makes it accessible to the service broker. Each provider must decide which the service to expose, and consider the security and easy availability to the service broker. 
  • Service broker – Also known as service registry is responsible in creating the web services interface and implement the accessibility of the information to be available to the potential service requester.  
  • Service requester – Locates entries to the service broker in order to invoke one of its Web services.

Barry, D. (n.d.) explained that the core language of the Web services is the Web Services Description Language (WSDL). The following are the steps required to provide and consume a service:

  • The description of the service using the WSDL via a service provider.
  • Issuing one or more queries by a service consumer.
  • Inform the service consumer what the requests and responses required by service provider via WSDL.
  • Using the WSDL by the service consumer to send a request to the service provider.
  • The expected response to the service consumer is provided by the service provider.

IBM Redbooks (2004) explained that there are a certain standards are in used in web services; one of the most common standards is the HTTP. HTTP is used in web services for transporting and requesting services between the provider and the consumer. There are several advantages of using HTTP as a transport layer for the web services interaction, some of these advantages are:

  • HTTP is widely used protocol, and implemented by any organization that is using Web servers and web browsers.
  • HTTP protocol is widely open, and used under many platforms.
  • Most organizations allow HTTP to travel through firewalls protocol.

Conclusion

By using web services, different applications can talk to each other, share data, and services. Web services use standard protocol for the communication. Web service uses SOAP over the HTTP protocol for the communication, and that provides a low cost communication between different applications. Other reliable protocol that Web services can implement is Web Service over FTP protocol. Using the Web Services reduce the software development time since it’s a self describing applications that can help business save time and money by cutting development time (JavaBeat, 2008).

Web services reducing cost of the development and the implementation process by developing a standardizing internal system interfaces to communicate between applications. Also, promote the maximizing of interface reuse. Web services provide simplicity, abstraction, reusability, and provide the required performance and reliability that any business needs (Blank, 2003).

References

Barry, D. (n.d.) Web Services Explained [Online]. Available from: http://www.service-architecture.com/web

services/articles/web_services_explained.html (Accessed: 20 March 2010).

Berlind, D. (2002) What are Web services anyway? [Online]. Available from: http://news.zdnet.com/2100-10532_22-296359.html (Accessed: 20 March 2010).

Blank, M. (2003) Knowing When to Use Web Services [Online]. Available from: http://soa.sys-con.com/node/39872 (Accessed: 20 March 2010).

Homer, A. & Anderson, R. (2004) Professional ASP.NET 1.1. 2nd ed. Indianapolis: Wiley Publishing, Inc.

IBM Redbooks (2005) Web services Handbook and Deployment [Online]. Available from: http://site.ebrary.com.ezproxy.liv.ac.uk/lib/liverpool/docDetail.action?docID=10112467 (Accessed: 20 March 2010).

IBM Redbooks (2004) Using Web Services for Business Integration [Online]. Available from: http://site.ebrary.com.ezproxy.liv.ac.uk/lib/liverpool/docDetail.action?docID=10112742 (Accessed: 20 March 2010).

JavaBeat (2008) Benefits of using Web Services [Online]. Available from: http://www.javabeat.net/tips/144-benefits-of-using-web-services.html (Accessed: 20 March 2010).

VK Infotek Inc. (2009) Why use Web services [Online]. Available from: http://www.vkinfotek.com/webservice/whycreatewebservice.aspx (Accessed: 20 March 2010).

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