Web Engineering for Workflow-based Applications: Models, Systems and Methodologies

This dissertation presents novel solutions for the construction of Workflow-based Web applications: The Web Engineering DSL Framework, a stakeholder-oriented Web Engineering methodology based on Domain-Specific Languages; the Workflow DSL for the efficient engineering of Web-based Workflows with strong stakeholder involvement; the Dialog DSL for the usability-oriented development of advanced Web-based dialogs; the Web Engineering Reuse Sphere enabling holistic, stakeholder-oriented reuse

Verifying the Interplay of Authorization Policies and Workflow in Service-Oriented Architectures (Full version)

A widespread design approach in distributed applications based on the service-oriented paradigm, such as web-services, consists of clearly separating the enforcement of authorization policies and the workflow of the applications, so that the interplay between the policy level and the workflow level is abstracted away. While such an approach is attractive because it is quite simple and permits one to reason about crucial properties of the policies under consideration, it does not provide the right level of abstraction to specify and reason about the way the workflow may interfere with the policies, and vice versa. For example, the creation of a certificate as a side effect of a workflow operation may enable a policy rule to fire and grant access to a certain resource; without executing the operation, the policy rule should remain inactive. Similarly, policy queries may be used as guards for workflow transitions. In this paper, we present a two-level formal verification framework to overcome these problems and formally reason about the interplay of authorization policies and workflow in service-oriented architectures. This allows us to define and investigate some verification problems for SO applications and give sufficient conditions for their decidability.Comment: 16 pages, 4 figures, full version of paper at Symposium on Secure Computing (SecureCom09

A web services choreography scenario for interoperating bioinformatics applications

BACKGROUND: Very often genome-wide data analysis requires the interoperation of multiple databases and analytic tools. A large number of genome databases and bioinformatics applications are available through the web, but it is difficult to automate interoperation because: 1) the platforms on which the applications run are heterogeneous, 2) their web interface is not machine-friendly, 3) they use a non-standard format for data input and output, 4) they do not exploit standards to define application interface and message exchange, and 5) existing protocols for remote messaging are often not firewall-friendly. To overcome these issues, web services have emerged as a standard XML-based model for message exchange between heterogeneous applications. Web services engines have been developed to manage the configuration and execution of a web services workflow. RESULTS: To demonstrate the benefit of using web services over traditional web interfaces, we compare the two implementations of HAPI, a gene expression analysis utility developed by the University of California San Diego (UCSD) that allows visual characterization of groups or clusters of genes based on the biomedical literature. This utility takes a set of microarray spot IDs as input and outputs a hierarchy of MeSH Keywords that correlates to the input and is grouped by Medical Subject Heading (MeSH) category. While the HTML output is easy for humans to visualize, it is difficult for computer applications to interpret semantically. To facilitate the capability of machine processing, we have created a workflow of three web services that replicates the HAPI functionality. These web services use document-style messages, which means that messages are encoded in an XML-based format. We compared three approaches to the implementation of an XML-based workflow: a hard coded Java application, Collaxa BPEL Server and Taverna Workbench. The Java program functions as a web services engine and interoperates with these web services using a web services choreography language (BPEL4WS). CONCLUSION: While it is relatively straightforward to implement and publish web services, the use of web services choreography engines is still in its infancy. However, industry-wide support and push for web services standards is quickly increasing the chance of success in using web services to unify heterogeneous bioinformatics applications. Due to the immaturity of currently available web services engines, it is still most practical to implement a simple, ad-hoc XML-based workflow by hard coding the workflow as a Java application. For advanced web service users the Collaxa BPEL engine facilitates a configuration and management environment that can fully handle XML-based workflow

A Constrained Object Model for Configuration Based Workflow Composition

Automatic or assisted workflow composition is a field of intense research for applications to the world wide web or to business process modeling. Workflow composition is traditionally addressed in various ways, generally via theorem proving techniques. Recent research observed that building a composite workflow bears strong relationships with finite model search, and that some workflow languages can be defined as constrained object metamodels . This lead to consider the viability of applying configuration techniques to this problem, which was proven feasible. Constrained based configuration expects a constrained object model as input. The purpose of this document is to formally specify the constrained object model involved in ongoing experiments and research using the Z specification language.Comment: This is an extended version of the article published at BPM'05, Third International Conference on Business Process Management, Nancy Franc

Creating a Testing Framework and Workflow for Developers New to Web Application Engineering

Web applications are quickly replacing standalone applications for everyday tasks. These web applications need to be tested to ensure proper functionality and reliability. There have been substantial efforts to create tools that assist with the testing of web applications, but there is no standard set of tools or a recommended workflow to ensure speed of development and strength of application. We have used and outlined the merits of a number of existing testing tools and brought together the best among them to create what we believe is a fully- featured, easy to use, testing framework and workflow for web application devel- opment. We then took an existing web application, PolyXpress, and augmented its development process to include our workflow suggestions in order to incorporate testing at all levels. PolyXpress is a web application that “allows you to create location-based stories, build eTours, or create restaurant guides. It is the tool that will bring people to locations in order to entertain, educate, or provide amazing deals.”[10] After incorporating our testing procedures, we immediately detected previously unknown bugs in the software. In addition, there is now a workflow in place for future developers to use which will expedite their testing and development

Automating distributed workflow for electronic commerce: A model for building meta-workflow components

Business software development environments for web- based applications are at a very early stage in their potential lifecycle. The purpose of this research agenda is to develop a model for how business processes can be interpreted into primitive computer codes for web applications. We have taken a transaction perspective adapted from the distributed database approach to maintenance of integrity assuming the concepts of ACIDity (Atomicity, Consistency, Isolation, and Durability) and serializability. This perspective is consistent with emerging literature on “workflow agents” [e.g., Huhns and Singh, 1998]. In this paper, we design, develop, and show an example of a meta-level set of building blocks for a direct mapping between electronic commerce and workflow processes. To validate the sufficiency and completeness of the meta-level components proposed, a complete mapping of an electronic commerce application to meta-workflow components is proposed

An Innovative Workspace for The Cherenkov Telescope Array

The Cherenkov Telescope Array (CTA) is an initiative to build the next generation, ground-based gamma-ray observatories. We present a prototype workspace developed at INAF that aims at providing innovative solutions for the CTA community. The workspace leverages open source technologies providing web access to a set of tools widely used by the CTA community. Two different user interaction models, connected to an authentication and authorization infrastructure, have been implemented in this workspace. The first one is a workflow management system accessed via a science gateway (based on the Liferay platform) and the second one is an interactive virtual desktop environment. The integrated workflow system allows to run applications used in astronomy and physics researches into distributed computing infrastructures (ranging from clusters to grids and clouds). The interactive desktop environment allows to use many software packages without any installation on local desktops exploiting their native graphical user interfaces. The science gateway and the interactive desktop environment are connected to the authentication and authorization infrastructure composed by a Shibboleth identity provider and a Grouper authorization solution. The Grouper released attributes are consumed by the science gateway to authorize the access to specific web resources and the role management mechanism in Liferay provides the attribute-role mapping

Usability Metrics of Web-based Mapping Applications

In academic libraries, the rise of web-based mapping applications or web geographic information systems (web GIS) brings great opportunities for information seeking. Users can search spatial information, create customized maps, as well as perform simple spatial analysis with these tools. In this presentation, we report results from an empirical usability evaluation of major web-based mapping applications, including ESRI Business Analyst Online, PolicyMap, SimplyMap, and Social Explorer. Eighteen university students participated in the evaluation in which they completed tasks of creating a customized map about business-related information (e.g., unemployment rate of an area), changing map display options (map unit, data range, and center location), and exporting maps. These tasks represent the typical workflow of using a web-based mapping application for users without GIS background and experience. We measured task successfulness, time to task completion, number of times help was needed, number of errors, and participants’ ratings of the System Usability Scale (SUS). Participants’ comments were also analyzed for the evaluation. Results of the evaluation indicated a number of usability issues for each application. Furthermore, we examined the effectiveness of task measures in terms of their predictive power of users’ task performance and usability issues. Our results show that task successfulness and task time are good indicators of potential performance and workflow issues, while number of errors made by participants could provide additional evidence of potential interface design issues. The number of help needed from participants and the SUS rating is less indicative of the differences of applications’ usability. To the best of our knowledge, this is the first study to evaluate web-based mapping applications from a usability and task performance perspective. Results of the study will be a valuable tool for librarians as well as general users who don’t have a background of GIS and usability to evaluate web GIS resources