Aspect] is a simple and practical aspect-oriented extension to Java With just a few new constructs, AspectJ provides support for modular implementation of a range of crosscutting concerns. In AspectJ's dynamic join point model, join points are well-defined points in the execution of the program; pointcuts are collections of join points; advice are special method-like constructs that can be attached to pointcuts; and aspects are modular units of crosscutting implementation, comprising pointcuts, advice, and ordinary Java member declarations. AspectJ code is compiled into standard Java bytecode. Simple extensions to existing Java development environments make it possible to browse the crosscutting structure of aspects in the same kind of way as one browses the inheritance structure of classes. Several examples show that AspectJ is powerful, and that programs written using it are easy to understand.

An overview of AspectJ

http://emamispnu.persiangig.com/Projects/Cloud%20Computing/science_2.pdf

Review: A survey on security issues in service delivery models of cloud computing

The Object Management Group's (OMG) Model Driven Architecture (MDA) strategy envisages a world where models play a more direct role in software production, being amenable to manipulation and transformation by machine. Model Driven Engineering (MDE) is wider in scope than MDA. MDE combines process and analysis with architecture. This article sets out a framework for model driven engineering, which can be used as a point of reference for activity in this area. It proposes an organisation of the modelling 'space' and how to locate models in that space. It discusses different kinds of mappings between models. It explains why process and architecture are tightly connected. It discusses the importance and nature of tools. It identifies the need for defining families of languages and transformations, and for developing techniques for generating/configuring tools from such definitions. It concludes with a call to align metamodelling with formal language engineering techniques.

Model Driven Engineering

Recent technology trends in the Web Services (WS) domain indicate that a solution eliminating the presumed complexity of the WS-* standards may be in sight: advocates of REpresentational State Transfer (REST) have come to believe that their ideas explaining why the World Wide Web works are just as applicable to solve enterprise application integration problems and to simplify the plumbing required to build service-oriented architectures. In this paper we objectify the WS-* vs. REST debate by giving a quantitative technical comparison based on architectural principles and decisions. We show that the two approaches differ in the number of architectural decisions that must be made and in the number of available alternatives. This discrepancy between freedom-from-choice and freedom-of-choice explains the complexity difference perceived. However, we also show that there are significant differences in the consequences of certain decisions in terms of resulting development and maintenance costs. Our comparison helps technical decision makers to assess the two integration styles and technologies more objectively and select the one that best fits their needs: REST is well suited for basic, ad hoc integration scenarios, WS-* is more flexible and addresses advanced quality of service requirements commonly occurring in enterprise computing.

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Restful web services vs. "big"' web services: making the right architectural decision

/pdf/a-survey-on-internet-of-things-architectures-57ioqohrvj.pdf

A survey on Internet of Things architectures

In SOA based application development, a plethora of architectural constructs such as processes, services and components need to be built. This requires modeling of the application at different levels of abstraction such as business architecture, application architecture and runtime architecture. Model driven development (MDD) is hence considered the primary development approach for building SOA applications. Existing MDD methodologies and tools only support searching and discovery of assets, and do not support their analysis in order to determine their suitability for reuse. This often results in selecting potentially incompatible assets among the various layers of the solution, resulting in redundant asset customizations. In order to address this issue, we present a novel framework and methodology that enables the integrated analysis of existing assets associated across multiple abstractions of the solution from different asset repositories. This approach helps in creating a consistent asset reusability view across all the phases of SOA development with multiple reusable asset options to compare and select. We present an experimental evaluation of our methodology on real-life SOA assets distributed across multiple repositories and illustrate how our integrated mechanism can help consistently maximize reuse of assets in SOA development.

/pdf/integrated-asset-analysis-framework-for-model-driven-5epn3xps5p.pdf

Integrated asset analysis framework for model-driven development of SOA based solutions

We provide a novel approach for specifying and relating non-functional properties for distributed component Web services that can be used to adapt a composite Web service. Our approach uses distributed aspect-oriented programming (AOP) technology to model an adaptive architecture for Web services composition and execution. Existing Web service adaptation mechanisms are limited only to the process of Web service choreography in terms of Web service selection/invocation vis-a-vis pre-specifled (Service Level Agreement) SLA constraints. Our system extends this idea by representing the non-functional properties of each Web service - composite and component - via AOP. Hence our system models a relation function between the aspects of the composite Web service, and the individual aspects of the component Web services. This enables mid-flight adaptation of the composite Web service - in response to changes in non-functional requirements - via suitable modifications in the individual aspects of the component Web service. From the end users' viewpoint, such upfront aspect- oriented modeling of non-functional properties enables on-demand composite Web service adaptation with minimal disruption in quality of service.

Aspect-oriented Approach for Non-functional Adaptation of Composite Web Services

Software service organizations typically develop custom solutions from scratch in each project engagement. This is not a scalable proposition, since it depends too heavily on labor alone. Rather, creating and reusing software "assets" is more scalable and profitable. One prevalent approach to building software solutions is to use service-oriented architecture (SOA) to compose software services to support business processes. In this context, the key to reusing assets is to discover (from existing assets in a portfolio) or derive service variants to meet the requirements of a stated business process specification. To that end, this paper presents our Variation-Oriented Service Design (VOSD) algorithm for the same. Via IBM's Rational Software Architect modeling tool, we also demonstrate the practical usefulness of our algorithm via a prototype implementation in the insurance domain.

/pdf/discovering-and-deriving-service-variants-from-business-5gd8nltgp7.pdf

Discovering and Deriving Service Variants from Business Process Specifications

A method, an apparatus and an article of manufacture for modeling a task-site allocation. The method includes generating a task-site allocation network based on at least one site-task pair and at least one site-centric constraint of at least two sites, wherein generating a task-site allocation network comprises generating a task-specific constraints model based on task context information and generating a task-site pair that satisfies at least one constraint based on the task-specific constraints model, and determining a preferred allocation of task to site by comparing estimated task-site allocation cost between a single site allocation and a distributed site allocation among the at least two sites.

Modeling task-site allocation networks

One approach to improve the reusability of business process-based solutions is to represent the business process as a combination of autonomous services via a service-oriented architecture (SOA) centric style. Such an approach would represent variations at service and business process level in terms of two key constructs - variation points (the placeholders in the solution model where variations can be introduced) and variation features (the actual variations that can be introduced at a subset of the listed variation points for that solution). One key research issue that has arisen out of the VOE project is how to actually identify and subsequently justify these variation points and variation features based on changed requirements. In this paper we propose our approach called Variation- Oriented Requirements Analysis (VORA) that addresses this issue. VORA is based on a traceability model that maps requirements to use cases, sequence diagrams, business processes and finally service specifications. We show how this mapping can also be used to (semi-) automatically map requirement changes down to variation points and variation features at service and business process level. We also demonstrate VORA via a simple yet realistic running example.

Karthikeyan Ponnalagu

Papers

Integrated asset analysis framework for model-driven development of SOA based solutions

Aspect-oriented Approach for Non-functional Adaptation of Composite Web Services

Discovering and Deriving Service Variants from Business Process Specifications

Modeling task-site allocation networks

Variation-Oriented Requirements Analysis (VORA)