The scope of this Case study is the complete design of the registration process for the University of Nicosia LAMS (Learning Activity Management System) which is the Online Learning System of Unic. The implementation of the case study is based on the Web Services technology which is allow to communication and the exchange of data regardless of the platform operating system, the programming language or the type of the information system.
A web service is basically a software interface that describes a collection of operations that they can be approached by the network through standard XML messages. It uses standard XML messages to describe an operation and the data for the exchange with another application.
Basic Technologies of Web Services:
- XML: Identical form and exchange of data
- SOAP: Standard communication channel
- WSDL: Standard descriptive language for the description of the given services
- UDDI: Registration and localization of the given services.
An internet web service is constituted by a lot of connected technologies that they are placed in different level. Beginning from bottom to top, we report the models that are used and we analyze it more extensively with the subjects of safety and management in the first chapter. Initially, it is required protocol on transport of information via network, as http (Hypertext Transfer Protocol), the SMTP (Simple Mail Transport Protocol) or the FTP (File Transfer Protocol). Each call and response of service should "be packed" in message SOAP (Simple Object Access Protocol), which can exist treatment by certain extensions SOAP (SOAP Extensions) front it is dispatched from applicant service (request agent) and it is delivered in the provider of service (provider agent) and reversely. The messages that are exchanged and the way that becomes exchange they are described at greater length in file WSDL (Web Services Description Language). Next step is the discovery of services, for which they exist three approaches: the existence of list of recording and publication services with the form of service of recording (registry), as the UDDI (Universal Description, Definition and Integration) and the DISCO (Microsoft Discovery), where constitutes the widespreadest solution, the existence of web pages of reference in services, type http://www.amazon.com and model SOAP, WSDL, UDDI and DISCO have it writes in language of pointing out XML (Extensible Markup Language) and potentially follow in some written DTD (Document Type Definition) or XML Schema
Application Integration(or Enterprise Application Integration)
"EAI (enterprise application integration) is a business computing term for the plans, methods, and tools aimed at modernizing, consolidating, and coordinating the computer applications in an enterprise. Typically, an enterprise has existing legacy applications and databases and wants to continue to use them while adding or migrating to a new set of applications that exploit the Internet, e-commerce extranet, and other new technologies. EAI may involve developing a new total view of an enterprise's business and its applications, seeing how existing applications fit into the new view, and then devising ways to efficiently reuse what already exists while adding new applications and data".
Enterprise application integration is being used by many companies to interconnect their major e-business applications. EAI also provides middleware in order to perform major actions such as data conversion, application communication, messaging services, and access to the application interfaces.
So by taking into account the above processes and operations that are take place in EAI it can be said EAI software can integrate the front-office and back-office operations of a business so they work together in an integrated way. This is an important capability that provides a real business value to an enterprise that can respond more efficient to their customer's demands.
Approaches to application integration
Integration architecture is the most important factor for the reliability and the performance of an information system. The design and the way of integrating the system must allow the extension and addition of new technologies and new applications without the need to change the structure development of the existing system architecture.
Such architectures are:
Point-to-Point Integration architecture
P2P (Point-to-Point) communication is the direct availability and exchange of data or resources without any centralized processor. The peers are both suppliers and consumers of the available resources in comparison with the client-server model which only the server shares the resources.
Features of a P2P applications:
- A p2p application should be able to find and locate other peers in the network
- It should be able to communicate with those peers and exchange messages with them
- After the connection, information and resources could be exchanged.
Convergence of P2P and web services
By studying those two technologies it could be realized that there are common features between them. P2P computing gives processing power, sharing information and applications on a distributed system but doesn't give much emphasize on message format or communication protocols.
Web Services are a kind of P2P technology because for example XML standards give the opportunity to p2p applications handling registration and content information under a very strong security protection.
The name point-to-point architecture gives the exact definition of this type of architecture; it means that there is a direct communication between the applications and the simplicity that we can see. The communication is made by sending and receiving messages between the peers. Also it has middleware centralized component. Those specifications give speed and reliability. Besides that, the system can be complex and cost effective as the number of application increases because of maintenance and lack of flexibility. Furthermore the higher use of one application the lowest ability to use and develop other aspects of the system. For example Business Activity Monitoring (BAM) which is the software that monitors and analyze the main operations and activities of the business.
Hub and Spoke integration architecture
This architecture constitutes of a central hub that control and directs the application requests that are connected to it. Inside the hub validation and routing algorithms are takes place for the correct and asynchronous message delivery. In addition Hub and Spoke solutions give process management capability and they have software for the monitoring for the workings that are takes place in hub.
Advantages of Hub and Spoke Architecture
With Hub and Spoke technology the integration procedure becomes simplest and more efficient. It remains simple because all the connections are passing through the hub which control and manage them. Furthermore the small number of "routes" gives the opportunity of more efficient transfer of the messages and data.
Disadvantages of Hub and Spoke Architecture
If we have too much traffic through the hub and a lot of disk usage then the processing power of the hub decreases and as a result the performance of the hub suffer and then is difficult for it to maintain and manage the connections.
Since the hub must control and integrate the processes, it's applicable only when there is an agreement which hub must be used between sender and receiver. This is not a problem for companies that the integrating procedure takes place internally in the company, but it is a serious problem for companies that use Business 2 Business and even-cross departmental projects.
If the hub is broken then the entire system goes down and furthermore the hub constitutes a bottleneck in the network because the total traffic of the network is limited by the hub's total capacity so this results delays for the efficient communication.
Distributed integration Architecture
This architecture was designed as a solution for the hub and spoke scalability issue to perform translation, routing and splitting actions closer to the source and target systems by "agents". Agents are smaller computers and they are used to reduce the processing work on that system. Agent takes the information from the application they are connected, process it and they send it only to target applications that make the request to the agent. This architecture is also known as Peer to Peer architecture.
Advantages of Distributed Integration Architecture
Distributed architecture is controlled by centralized processes and rules. Most of the processes are placed in the agents so it relives the processing work load from the central hub. By distributing the work load to the agents can be an important factor for the easy of the expansion of the system without the need to redesign it.
Distributed Architecture works only where the internal and external operations and facilities operated under the same technology.
- Whatis.com: Application integration definition Enterprise Information Systems, 13th edition, McGraw Hill International Edition