Data-intensive Web Applications Research Articles

Enhancing Accessibility to Data in Data-Intensive Web Applications by Using Intelligent Web Prefetching Methodologies

Data-intensive Web Applications built using client–server architectures usually provide prefetching mechanisms to enhance data accessibility. Prefetching is a strategy of retrieving data before it is requested so that it can be ready when the user requests it. Prefetching reduces the load on the web server by making data available before the user requests it. Prefetching can be used for static content, such as images and web pages, as well as dynamic content, such as search results. Prefetching can also be used to improve the performance of web applications, as the data is available quickly. There are several scheduling methods, such as time-based scheduling, event-based scheduling and priority-based scheduling, for prefetching to ensure that essential data is always ready when the user requests it. In this study, we focus on time-based scheduling for prefetching. We introduce time-based scheduling methodologies using sequential pattern mining techniques and long-term short memory-based deep learning strategies. To show the usefulness of these strategies, we develop a prototype application. We conduct an extensive experimental study to evaluate the performance of the proposed time-based scheduling methodologies using both performance and accuracy metrics. Based on the computed metrics, using proposed prefetching methods provided a promising cache hit rate when using the optimal cache size. The results show that the proposed prefetching methodologies are useful in data-intensive web applications for enhancing data accessibility. Work remains to investigate the use of attention-based sequence-to-sequence models in the web prefetching domain.

E-MDAV: A Framework for Developing Data-Intensive Web Applications

The ever-increasing adoption of innovative technologies, such as big data and cloud computing, provides significant opportunities for organizations operating in the IT domain, but also introduces considerable challenges. Such innovations call for development processes that better align with stakeholders needs and expectations. In this respect, this paper introduces a development framework based on the OMG’s Model Driven Architecture (MDA) that aims to support the development lifecycle of data-intensive web applications. The proposed framework, named E-MDAV (Extended MDA-VIEW), defines a methodology that exploits a chain of model transformations to effectively cope with both forward- and reverse-engineering aspects. In addition, E-MDAV includes the specification of a reference architecture for driving the implementation of a tool that supports the various professional roles involved in the development and maintenance of data-intensive web applications. In order to evaluate the effectiveness of the proposed E-MDAV framework, a tool prototype has been developed. E-MDAV has then been applied to two different application scenarios and the obtained results have been compared with historical data related to the implementation of similar development projects, in order to measure and discuss the benefits of the proposed approach.

A Pattern-Based Development Approach for Interaction Flow Modeling Language

Development and deployment technologies for data-intensive web applications have considerably evolved in the last years. Domain-specific frameworks or model-driven web engineering approaches are examples of these technologies. They have made possible to face implicit problems of these systems such as quick evolving business rules or severe time-to-market requirements. Both approaches propose the automation of redundant development tasks as the key factor for their success. The implementation of CRUD operations is a clear example of repetitive and recurrent task that may be automated. However, although web application frameworks have provided mechanisms to automate the implementation of CRUD operations, model-driven web engineering approaches have generally ignored them, so automation has not been properly faced yet. This paper presents a pattern-based development approach for the Interaction Flow Modeling Language as a way to finally automate repetitive specification tasks. Our approach is illustrated by defining and applying IFML patterns for CRUD operations. Additionally, a supporting tool, which enables automation, is shown. The suitability of our approach and the utility of its tool have been evaluated by its application into several real projects developed by a software company specialized in model-driven web application development. The results obtained present evidence of a significant productivity improvement obtained by the automation of the IFML specification of CRUD operations.

Two-level task scheduling with multi-objectives in geo-distributed and large-scale SaaS cloud

With the exploding of data-intensive web applications and requests (tasks), geo-distributed and large-scale data centers (DCs) are widely deployed in Software as a Service (SaaS) cloud, but server failures continue to grow at the same time. In this context, task scheduling problems become more intricate and both scheduling quality and scheduling speed raise further concerns. In this paper, we first propose a virtualized & monitoring SaaS model with predictive maintenance to minimize the costs of fault tolerance. Then with the monitored and predicted available states of servers, we focus on dynamic real-time task scheduling in geo-distributed and large-scale DCs with heterogeneous servers. Multiple objectives, including the long-term performance benefits, energy and communication costs, are taken into consideration in order to improve scheduling quality. For inter-DC and intra-DC task scheduling, two dynamic programming problems are formulated respectively, but there exists the problem that both state and action spaces are too large to be solved by simple iterations. To address this issue, we introduce the idea of reinforcement learning theory into solving traditional stochastic dynamic programming problems in the large-scale SaaS cloud, and put forward a cascaded two-level (inter-DC and intra-DC level) approximate dynamic programming (ADP) task-scheduling algorithm. The computation complexity can be significantly reduced and scheduling speed can be greatly improved. Finally, we conduct experiments with both random simulation data and Google cloud trace-logs. QoS evaluations and comparisons demonstrate that two ADP algorithms can work cooperatively, and our two-level ADP algorithm is more effective under large quantity of bursty requests.

AutoCRUD: Automatic generation of CRUD specifications in interaction flow modelling language

Data-intensive Web applications are usually developed by means of specific Web application frameworks, which provide, among other features, the proper tools to automate redundant tasks, e.g. the implementation of CRUD operations. However, although Model-Driven Web Engineering (MDWE) approaches have defined specific languages and tools to significantly reduce development efforts, the provision of such automation tools has been traditionally neglected. This paper presents AutoCRUD, a WebRatio plug-in automating the generation of CRUD operations in OMG Interacting Flow Modelling Language (IFML). It has been developed as a joint effort by academia and industry to assess its validity in a real scenario. • A MDWE tool (WebRatio plugin) to automatically generate CRUD operations specification in IFML by pattern instantiation. • New patterns may be defined to enlarge its default repository. • For teaching purposes, a step-by-step generation of IFML may be performed. • Easy and guided visual instantiation of patterns. • It may significantly increase development team productivity.

Analysing the cognitive effectiveness of the WebML visual notation

WebML is a domain-specific language used to design complex data-intensive Web applications at a conceptual level. As WebML was devised to support design tasks, the need to define a visual notation for the language was identified from the very beginning. Each WebML element is consequently associated with a separate graphical symbol which was mainly defined with the idea of providing simple and expressive modelling artefacts rather than by adopting a rigorous scientific approach. As a result, the graphical models defined with WebML may sometimes prevent proper communication from taking place between the various stakeholders. In fact, this is a common issue for most of the existing model-based proposals that have emerged during the last few years under the umbrella of model-driven engineering. In order to illustrate this issue and foster in using a scientific basis to design, evaluate, improve and compare visual notations, this paper analyses WebML according to a set of solid principles, based on the theoretical and empirical evidence concerning the cognitive effectiveness of visual notations. As a result, we have identified a set of possible improvements, some of which have been verified by an empirical study. Furthermore, a number of findings, experiences and lessons learnt on the assessment of visual notations are presented.

Integrating trust management and access control in data-intensive Web applications

The widespread diffusion of Web-based services provided by public and private organizations emphasizes the need for a flexible solution for protecting the information accessible through Web applications. A promising approach is represented by credential-based access control and trust management. However, although much research has been done and several proposals exist, a clear obstacle to the realization of their benefits in data-intensive Web applications is represented by the lack of adequate support in the DBMSs. As a matter of fact, DBMSs are often responsible for the management of most of the information that is accessed using a Web browser or a Web service invocation. In this article, we aim at eliminating this gap, and present an approach integrating trust management with the access control of the DBMS. We propose a trust model with a SQL syntax and illustrate an algorithm for the efficient verification of a delegation path for certificates. Our solution nicely complements current trust management proposals allowing the efficient realization of the services of an advanced trust management model within current relational DBMSs. An important benefit of our approach lies in its potential for a robust end-to-end design of security for personal data in Web scenario, where vulnerabilities of Web applications cannot be used to violate the protection of the data residing on the database server. We also illustrate the implementation of our approach within an open-source DBMS discussing design choices and performance impact.

Managing the evolution of data-intensive Web applications by model-driven techniques

The adoption of Model-Driven Engineering (MDE) in the development of Web Applications permitted to decouple the functional description of applications from the underlying implementation platform. This is of paramount relevance for preserving the intellectual property encoded in models and making applications, languages and processes resilient to technological changes. This paper proposes a model-driven approach for supporting the migration and evolution of data-intensive Web applications. In particular, model differencing techniques are considered to realize a migration facility capable of detecting the modifications a model underwent during its lifecycle and to automatically derive from them the programs that are capable of migrating/adapting also those aspects which are not directly derivable from the source models, as for instance the data persistently stored in a database and the page layout usually written using graphic templates. The approach is validated by considering applications described with the beContent and WebML modeling languages.

Interactive Web Documents

Documents allow end-users to encapsulate information related to a collaborative business process into a package that can be saved, emailed, digitally signed, and used as the basis for interaction in an activity or an ad hoc workflow. While documents are used incidentally today in web applications, for example in HTML presentations of content stored otherwise in back-end systems, they are not yet the central artifact for developers of dynamic, data intensive web applications. This paper unifies the storage and management of the various artifacts of web applications into an Interactive Web Document (IWD). Data, presentation, behavior, attachments, and digital signatures collected throughout the business process are unified into a single composite web resource. We describe a standards-based approach to packaging multiple resources into IWD archives based on the Open Document Format, a REST-based protocol for interacting with IWDs, and an extensible interaction controller architecture.

A NOVEL APPROACH FOR IDENTIFYING ENTITY TYPES FOR CONCEPTUAL DATA MODELING IN DEVELOPING DATA-INTENSIVE WEB APPLICATIONS

Creating effective and efficient databases requires that we thoroughly identify and clearly define entity types, attributes, and relationships. That is why conceptual data modeling is one of the most important tasks in developing applications. This paper introduces a new method for identifying entity types for entity-relationship conceptual data modeling in developing data-intensive web applications. The method is founded on the very elements of web applications including pages, links, web application architecture, and business logic modules.

Model-driven development of context-aware Web applications

Context-aware, multi-channel Web applications are more and more gaining consensus among both content providers and consumers, but very few proposals exist for their conceptual modeling. This article illustrates a conceptual framework that provides modeling facilities for context-aware, multichannel Web applications; it also shows how high-level modeling constructs can drive the application development process through automatic code generation. Our work stresses the importance of user-independent, context-triggered adaptation actions, in which the context plays the role of a “first class” actor , operating independently of users on the same hypertext the users navigate. Modeling concepts are based on WebML (Web Modeling Language), an already established conceptual model for data-intensive Web applications, which is also accompanied by a development method and a CASE tool. However, given their general validity, the concepts of this article shape up a complete framework that can be adopted independently of the chosen model, method, and tool.

Model-driven design and deployment of service-enabled web applications

Significant effort is currently invested in application integration, enabling business processes of different companies to interact and form complex multiparty processes. Web service standards, based on WSDL (Web Service Definition Language), have been adopted as process-to-process communication paradigms. However, the conceptual modeling of applications using Web services has not yet been addressed. Interaction with Web services is often specified at the level of the source code; thus, Web service interfaces are buried within a programmatic specification.In this article, we argue that Web services should be considered first-class citizens in the specification of Web applications. Thus, service-enabled Web applications should benefit from the high-level modeling and automatic code generation techniques that have long been advocated for Web application design and implementation. To this end, we extend a declarative model for specifying data-intensive Web applications in two directions: (i) high-level modeling of Web services and their interactions with the Web applications which use them, and (ii) modeling and specification of Web applications implementing new, complex Web services.Our approach is fully implemented within a CASE tool allowing the high-level modeling and automatic deployment of service-enabled Web applications.

Conceptual modeling of data-intensive Web applications

Many of the Web applications around us are data-intensive; their main purpose is to present a large amount of data to their users. Most online trading and e-commerce sites fall into this category, as do digital libraries and institutional sites describing private and public organizations. Several commercial Web development systems aid rapid creation of data-intensive applications by supporting semiautomatic data resource publishing. Automatic publishing is typically subject to the constraints of database schemas, which limit an application designer's choices. Thus, Web application development often requires adaptation through programming, and programs end up intricately mixing data, navigation, and presentation semantics. Presentation is often a facade for elements of structure, composition, and navigation. Despite this frequently unstructured development process, data-intensive applications, based on large data sets organized within a repository or database, generally follow some typical patterns and rules. We describe these patterns and rules using WebML as a conceptual tool to make such notions explicit. WebML is a conceptual Web modeling language that uses the entity-relationship (ER) model for describing data structures and an original, high-level notation for representing Web content composition and navigation in hypertext form.

Tools and approaches for developing data-intensive Web applications

The exponential growth and capillar diffusion of the Web are nurturing a novel generation of applications, characterized by a direct business-to-customer relationship. The development of such applications is a hybrid between traditional IS development and Hypermedia authoring, and challenges the existing tools and approaches for software production. This paper investigates the current situation of Web development tools, both in the commercial and research fields, by identifying and characterizing different categories of solutions, evaluating their adequacy to the requirements of Web application development, enlightening open problems, and exposing possible future trends.