Kanchana Rajaram

Template based SOA framework for dynamic and adaptive composition of web services

Automated Web service composition is currently one of the major research problems in the area of service oriented computing. Web services facilitate seamless business-to-business integration. Whenever it becomes difficult to find a single service for a particular task, a composition of services that can together perform the given task, is required. In general, this is accomplished using Service Oriented Architecture (SOA). However, the requirements of the users are frozen before the system locates, composes and executes the required services. The response is not personalized to the user environment. Further, conventional web services cannot handle the context and the context aware web services need to contain the context processing logic. Hence, we propose a framework for dynamic composition of Web services using templates in SOA. This framework allows maximum flexibility for the users to change their requirements at runtime and provides adaptive composition irrespective of whether a web service is context enabled or not.

Deriving reliable compositions using cancelable web services

Reliability is one of the main challenges while composing web services. Due to the inherent heterogeneity of web services, it is important to predict the behaviour of the overall composite service. Existing works that deal with reliable web service composition consider only three basic transactional properties such as pivot, retriable, and compensatable. When a service fails, its results can be ignored if it is pivot; it can be retried until it succeeds if it is retriable; or the previously completed services must be rolled back if they are compensatable, in order to achieve reliable execution. In general, business applications involve long running services. Service execution must be interrupted to adapt to dynamically changing user preferences since execution of the service to completion with the older requirements is no longer meaningful. Hence, service composition requires additional transactional support beyond the three transactional properties. To address this need, we introduce cancelable services and investigate the transactional properties of composite services that involve cancelable component services. The valid compositions, which result in a reliable execution are identified and formally verified.

Specification of Transactional Requirements for Web Services using Recoverability

In Service-Oriented Computing SOC, a business transaction comprises of several web services provided by multiple enterprises. The transactional behaviour of individual web services must be considered for service selection so that the composition of web services results in a reliable execution. It is difficult for a business analyst to envisage the desired business policies of a process in terms of transactional properties of the corresponding service. Hence, an abstract mechanism that enables the business analyst to specify the transactional properties in a simple manner must be introduced. Towards this objective, it is proposed to express the transactional properties in terms of the recoverability of services. The transactional web services are grouped into different levels of recoverability based on their recovery cost. The estimated recovery costs are empirically verified and validated.

Emulation of IoT gateway for connecting sensor nodes in heterogenous networks

An Internet of Things (IoT) are ‘things’ that com-municate in different networks. An IoT gateway which provides device connectivity and protocol translation is often expensive in case of small scale academic projects. In view of this, an Emulated IoT gateway is proposed that emulates the IoT gateway using a local computer in a cost effective way. The sensor data sent from sensor nodes connected in cellular network (GPRS), WiFi, RF, Bluetooth or in LAN using Ethernet are collected and successfully processed in cloud server.

Dynamic Transaction Aware Web Service Selection

Web service composition, that recursively constructs a composite web service out of the existing services based on a business workflow has been acknowledged as a promising approach to meet the user...

Tx-policy: transactional policies for reliable web service composition

In Web services paradigm, whenever a single service cannot meet the requirements of a user, many services need to be composed that can collectively satisfy the user expectations. Existing research focuses on service selection based solely on non-functional properties for composition, whenever there is more than one service provider who is offering services with similar functionality. However, the transaction behavioral aspects of a service, which ensure the reliability of a composite service has not been considered till now. Currently, the transactional properties cannot be represented as a part of service definition. To address this need, it is proposed to specify transactional properties using WS-Policy language and integrate it with the service definition. The transactional requirements of service consumer are matched with transactional policies of service providers and the correct set of services is selected for composition that will result in reliable execution. This approach is experimented with a case study of Scan Report Generation process in health care domain.

Utilization based prediction model for resource provisioning

Resource provisioning refers to the selection, deployment and management of resources to ensure guaranteed performance for the applications. Efficient resource provisioning is a challenging problem since it is dynamic in nature and requires supporting applications with different performance requirements. In order to provide adequate resources for applications with different requirements that must satisfy expected performance, it is required to predict correct set of resources. Towards this objective, a prediction model for resource provisioning has been developed in this work. The prediction model is trained by the dataset that is created using a benchmark e-Commerce application namely TPC-W that is deployed in Amazon EC2 environment. The experimental results show that the prediction model based on Linear regression exhibits 70 percentage of accuracy, Support Vector Regression shows 68 percentage of accuracy, whereas Multilayer perceptron exhibits 90 percentage of accuracy for the same dataset.

Monitoring flow of web services in dynamic composition using event calculus rules

Monitoring composition of web services is important to ensure provisioning of a valid business process. Most of the existing works on service monitoring focused either on QoS violations or service interactions during execution of services that are statically composed. However, dynamic composition of services wherein the services are discovered and composed at runtime based on user requirements and outcome of previously composed services is significant for business applications with frequently changing user requirements and business policies. In such scenarios, the order in which the services are composed must be monitored to comply with business polices. Otherwise, the composition leads to incorrect and inconsistent results. To address this issue, a runtime monitoring framework is proposed in this paper that monitors composition order of services that are dynamically composed, validates it using predefined rules and initiates corrective actions in case of violations from rules. The web services and the rules for composition flow have been expressed as event calculus axioms that are useful in validating the composition order. The performance of the proposed framework has been assessed and it is found out that it introduces only a marginal overhead on turnaround time of the user request as compared to absence of monitoring.

Dynamic generation of transactional contracts for hierarchical workflows

Service orientation is gaining momentum in distributed software applications, mainly because it facilitates interoperability. Service composition has been acknowledged as a promising approach to meet the user demands, whenever a single service cannot fulfill the needs. It is essential to ensure the reliability of the composed service, as the component services are offered by multiple providers from different organizations. The behavioral or transactional properties of component services determine the reliability of the composite service. The guaranteed values on transactional properties of every service must be recorded in a contract as agreed by a consumer and a provider, in order to avoid unpredictable performance in service provisioning. The approach proposed in this paper enables generation of contracts at runtime along with transactional guarantees, based on the frequently changing business requirements of service consumers. The approach is experimented with a case study of Scan Report Generation in healthcare domain.

A model for predicting resources for on-premise applications

Accurate prediction of resources is a cliallenging problem in any environment. Effective provisioning of resources for on-premise applications with varied performance requirements requires an accurate prediction of resources. Towards this objective, a prediction model, namely. Multilayer Perceptron has been proposed in this work. The prediction model is trained using a dataset generated from TPC-W benchmark based online application and tested for new requirements. Its prediction accuracy has been compared with that of two other prediction models such as Linear Regression and Support Vector Regression. The Multilayer perceptron model is found to exhibit a better accuracy of 91.8 percentage.