Srinath Perera

Multi-tenant SOA Middleware for Cloud Computing

Enterprise IT infrastructure incurs many costs ranging from hardware costs and software licenses/maintenance costs to the costs of monitoring, managing, and maintaining IT infrastructure. The recent advent of cloud computing offers some tangible prospects of reducing some of those costs; however, abstractions provided by cloud computing are often inadequate to provide major cost savings across the IT infrastructure life-cycle. Multi-tenancy, which allows a single application to emulate multiple application instances, has been proposed as a solution to this problem. By sharing one application across many tenants, multi-tenancy attempts to replace many small application instances with one or few large instances thus bringing down the overall cost of IT infrastructure. In this paper, we present an architecture for achieving multi-tenancy at the SOA level, which enables users to run their services and other SOA artifacts in a multi-tenant SOA framework as well as provides an environment to build multi-tenant applications. We discuss architecture, design decisions, and problems encountered, together with potential solutions when applicable. Primary contributions of this paper are motivating multi-tenancy, and the design and implementation of a multi-tenant SOA platform which allows users to run their current applications in a multi-tenant environment with minimal or no modifications.

Axis2, Middleware for Next Generation Web Services

Axis2, the next generation of Apache Web services middleware, is an effort to re-architecture Apache Web service stack to incorporate the changes in Web services. Among many improvements, Axis2 provides first class messaging and SOAP extension supports together with a novel lightweight streaming based XML processing model. The architecture is build on top of a simple and extensible core that provides the basic abstractions for the rest of the system. We present the design and the thought process behind the key abstractions by breaking down the architecture into three topics, XML processing model, extensible SOAP processing model and messaging framework. This paper explains the overall architecture while concentrating on the three topics, and demonstrate how they all fit together to yield Axis2

Apache airavata: a framework for distributed applications and computational workflows

In this paper, we introduce Apache Airavata, a software framework to compose, manage, execute, and monitor distributed applications and workflows on computational resources ranging from local resources to computational grids and clouds. Airavata builds on general concepts of service-oriented computing, distributed messaging, and workflow composition and orchestration. This paper discusses the architecture of Airavata and its modules, and illustrates how the software can be used as individual components or as an integrated solution to build science gateways or general-purpose distributed application and workflow management systems.

Case-based design: A review and analysis of building design applications

This paper presents a review of CBD and its application to building design in particular. Case-based design is the application of case-based reasoning to the design process. Design maps well to case-based reasoning because designers use parts of previous design solutions in developing new design solutions. This paper identifies problems of case representation, retrieval, adaptation, presentation, and case-based maintenance along with creativity, legal, and ethical issues that need to be addressed by CBD systems. It provides a comprehensive review of CBD systems developed for building design and provides a detailed comparison of the CBD systems reviewed.

A Multi-tenant Architecture for Business Process Executions

Cloud computing, as a concept, promises cost savings to end-users by letting them outsource their non-critical business functions to a third party in pay-as-you-go style. However, to enable economic pay-as-you-go services, we need Cloud middleware that maximizes sharing and support near zero costs for unused applications. Multi-tenancy, which let multiple tenants (user) to share a single application instance securely, is a key enabler for building such a middleware. On the other hand, Business processes capture Business logic of organizations in an abstract and reusable manner, and hence play a key role in most organizations. This paper presents the design and architecture of a Multi-tenant Workflow engine while discussing in detail potential use cases of such architecture. Primary contributions of this paper are motivating workflow multi-tenancy, and the design and implementation of multi-tenant workflow engine that enables multiple tenants to run their workflows securely within the same workflow engine instance without modifications to the workflows.

Siddhi: a second look at complex event processing architectures

Today there are so much data being available from sources like sensors (RFIDs, Near Field Communication), web activities, transactions, social networks, etc. Making sense of this avalanche of data requires efficient and fast processing. Processing of high volume of events to derive higher-level information is a vital part of taking critical decisions, and Complex Event Processing (CEP) has become one of the most rapidly emerging fields in data processing. e-Science use-cases, business applications, financial trading applications, operational analytics applications and business activity monitoring applications are some use-cases that directly use CEP. This paper discusses different design decisions associated with CEP Engines, and proposes some approaches to improve CEP performance by using more stream processing style pipelines. Furthermore, the paper will discuss Siddhi, a CEP Engine that implements those suggestions. We present a performance study that exhibits that the resulting CEP Engine--Siddhi--has significantly improved performance. Primary contributions of this paper are performing a critical analysis of the CEP Engine design and identifying suggestions for improvements, implementing those improvements through Siddhi, and demonstrating the soundness of those suggestions through empirical evidence.

A hierarchical case representation using context guided retrieval

This paper presents a hierarchical case representation using a context guided retrieval method. The performance of this method is compared to that of a simpler flat file representation using standard nearest neighbour retrieval. The estimation of construction costs of light industrial buildings is used as the test domain. Each case in the system has approximately 400 features. These are structured into a hierarchical case representation that holds more general contextual features at its top and specific building elements at its leaves. Problems are decomposed into sub-problems and solutions recomposed into a final solution. Comparative results show that the context guided retrieval method using the hierarchical case representation is significantly more accurate than the simpler flat file representation using standard nearest neighbour retrieval.

Collaborative case-based estimating and design

Abstract Information Technology (IT) solutions to problems in construction design need to consider the perspectives of all the participants in the process; only then can IT provide a platform for integration. The research described examines issues involved in the integration of construction disciplines by using Case-Based Reasoning (CBR). It describes a hierarchical case memory structure and a context-based indexing method for retrieval and reuse of previous designs and their costs. Estimating and design cases selected for reuse are adapted with the use of sub-cases and domain specific adaptation rules. A prototype system, NIRMANI, was successfully implemented to support collaborative design.

Enabling Web Service extensions for scientific workflows

Web services have become an integral part of workflow orchestration in scientific applications and many tools used by scientists including Kepler, Taverna and Triana incorporate Web services. However orchestration of complex workflows that involve services that exploit standards like WS-Addressing or WS-Security are not easily managed by these tools. Most complex use cases that involve ldquoadd onrdquo service standards use implementation specific assumptions, and as a result, the services and workflow composers become tightly coupled. This leads to stove-piped, noninteroperable implementations. This paper describes an effort to implement complex use cases that include asynchronous messaging and WS-Security, for a large application project called LEAD, while maintaining standard conformance and composer simplicity. The primary contribution of the paper is design of a Mediator and a generic Web service actor that allow the addition of new Web service standards to services in a workflow, without the need to make the workflow composer or enactor explicitly aware that these standards are being used. These concepts are demonstrated by an implementation that allows large workflows to be constructed using two different scientific workflow systems that were not designed with these extensions in mind.

Wihidum: Distributed complex event processing

Abstract In the last few years, we have seen much interest in data processing technologies. Although initial interests focused on batch processing technologies like MapReduce, people have realized the need for more responsive technologies such as stream processing and complex event processing. Complex event processing has been historically used within a single node or a cluster of tightly interconnected nodes. However, to be effective with Big Data use-cases, CEP technologies need to be able to scale up to handle large use-cases. This paper presents several approaches to scale complex event processing by distributing it across several nodes. Wihidum discusses how to balance the workload among nodes efficiently, how complex event processing queries can be broken up into simple sub queries, and how queries can be efficiently deployed in the cluster. The paper focuses on three techniques used for scaling queries: pipelining, partitioning and distributed operators. Then it discusses in detail the distribution of few CEP operators: filters, joins, pattern matching, and partitions. Empirical results show that the techniques followed in Wihidum have improved the performance of the CEP solution.