# Indexer Based Dynamic Web Services Discovery

Saba Bashir, M.Younus Javed,Farhan Hassan Khan National University of Science & Technology Rawalpindi, Pakistan 
, 
 
Aihab Khan, Malik Sikandar Hayat Khiyal Fatima Jinnah Women University Rawalpindi, Pakistan Abstract-Recent advancement in web services plays an important role in business to business and business to consumer interaction. Discovery mechanism is not only used to find a suitable service but also provides collaboration between service providers and consumers by using standard protocols. A static web service discovery mechanism is not only time consuming but requires continuous human interaction. This paper proposed an efficient dynamic web services discovery mechanism that can locate relevant and updated web services from service registries and repositories with timestamp based on indexing value and categorization for faster and efficient discovery of service. The proposed prototype focuses on quality of service issues and introduces concept of local cache, categorization of services, indexing mechanism, CSP (Constraint Satisfaction Problem) solver, aging and usage of translator. Performance of proposed framework is evaluated by implementing the algorithm and correctness of our method is shown. The results of proposed framework shows greater performance and accuracy in dynamic discovery mechanism of web services resolving the existing issues of flexibility, scalability, based on quality of service, and discovers updated and most relevant services with ease of usage. 

Keywords-component: Classification of services; Dynamic discovery; Indexing; UDDI registry; Web services. 

## I. Introduction

As an enabling technology, web services are software components that are used to present services on internet. Each web service has standard interface through which it communicates with other web services in order to provide different functionalities. Service providers register their web services in registries, typically in UDDI (Universal Description Discovery and Integration). HTTP (Hyper Text Transfer Protocol) protocol is used for communication of SOAP (Simple Object Access Protocol) messages exchanged between service providers and consumers. 

With the increasing technology it is becoming more critical to find a service that satisfies user requirements. Service discovery is a mechanism used to find the appropriate service that meets desired criteria. Three main roles in web services are providers, consumers and registries. Service providers publish their web services in registries and clients discover their desired services by querying them using SOAP message protocol [1]. 

In manual discovery process a human uses a discovery service, which involves the input of user requirements and through matchmaking process, output the desired results [2]. 

The main obstacle in this mechanism is heterogeneity problem [3]. Different types of heterogeneities are: 
- Technological heterogeneities (different platforms or different data formats). 

- Ontological heterogeneity (difference in domain specific terms and concepts). 

- Pragmatic heterogeneity (different development of domain-specific processes) 
This makes the technology limited in terms of efficiency and availability. Whereas in dynamic discovery process an agent performs the above task either at design or run time, but there are different constraints of this process for example interface requirements, standardization of protocols and trust of stakeholders etc. This paper focuses on the dynamic web services discovery approach. 

With the increasing number of web services, it is becoming more difficult to manage description on distributed environment such as on web. Key limitations of current approaches for dynamic web services discovery are: 1. Lack of fully dynamic web services discovery mechanism. 

2. Lack of mechanism that solves heterogeneity problems. 3. Clients cannot learn from past experiences to improve future decisions. 

4. Need of mechanism which store and retrieve up to date information on consumer's request. 

5. Need of mechanism which gives in time response of query in case of searching services from web.