(IJCSIS) International Journal of Computer Science and Information Security, Vol. 7, No. 2, February 2010 mechanism that selects the most relevant web service from all outputs. The approach is a combination of semantic and statistical metrics. 

A number of web services algorithm use service profile method for dynamic web services discovery. [16] proposed the discovery mechanism based on web services composition and service profile. The proposed algorithm does not describe the internal behavior for web services composition. 

Although a number of dynamic web services techniques have been introduced, there is a need of dynamic services discovery mechanism which eliminates the problems in current discovery approaches. This paper presents an approach towards these solutions and proposes a framework that is efficient, reliable, scalable, flexible and fault tolerant. 

## Iii. Preliminaries

This section describes the web services discovery mechanism and differentiates between different approaches used for service discovery. 

## A. Web Services Discovery

Web services discovery is the process of finding the appropriate services on the web that meets the user's desired requirements. All Service providers register their web services in registry called UDDI. Service requesters search the appropriate service providers available on the registry. Each service that is registered on UDDI has WSDL. WSDL is a description language which describes complete detail about web services for example its methods, protocols and ports etc. 

Web service interface is described in WSDL and used by the client to discover and invoke web services. SOAP message is sent to server asking for certain service and it replies with SOAP response message. Web service discovery and invocation process is shown in Fig 1. [14] 

B. Web Service Discovery Approaches 

![0_image_1.png](0_image_1.png)

Different approaches for discovery mechanism as discussed in [15] are: 
1. UDDI: It is a standard for web services registration, discovery and integration.
2. Service directories/portals: They provide the web services using focused crawlers and provide searching through HTML (Hyper Text Markup Language) interface. 

3. Web Search Engines: They are most widely used in today's web. They search the web services by retrieving information from WSDL descriptions. 

These approaches can be compared by focusing on following two aspects: 1) Number of services, 2) Quality of information associated with them. It is concluded from this research that browsers can give the desired results but one have to spend too much time for filtering the desired service which requires a lot of effort and it is a time consuming task. Only dedicated portal pages produce best results.

## Iv. Proposed Framework

Proposed framework of dynamic services discovery mechanism is shown in Fig 2. Web services discovery framework includes the following components: 
1. *Translator:* Most service discovery frameworks 

![0_image_0.png](0_image_0.png)

distinguish between external and internal specification languages. Translator is used for translation of user input to a form that can be efficiently used by the system. It is also used to translate the system response to a form that can be easily understandable for the user. 

2. *Matching Engine:* Key component that is used for dynamic discovery mechanism. It matches the input to registered services using keyword and fuzzy logic based 