Wei-Tek Tsai

• Ph.D.
• Professor (Full) at Arizona State University

With the rapid development of smart IoT technology, various innovative mobile applications improve many aspects of our daily life. End-edge-cloud collaboration provides data transmission in connecting heterogeneous IoT devices and machines with improvements in high quality of service and capacity. However, the end-edge cloud architecture still rema...

The stakes are increasing daily as more companies bet on object-oriented technology for military and commercial application development. Instead of being an academic exercise, making a commitment to use object-oriented technology is a grave managerial and technical decision—one which affects careers, projects, and entire organizations. On the posit...

This paper proposes a blockchain-based digital-currency model based on certificates, and uses stablecoins as an example to illustrate the model. A stablecoin is anchored on a fiat currency, and often backed by 100% fiat such as USD. Unlike traditional cryptocurrency models, the blockchain system using this model does not store the assets directly,...

With the rapid development of blockchain technology, smart contracts (SCs) applied in digital currency transactions have been widely used. However, SCs often have vulnerability in their code that allow criminals to exploit them to steal associated digital assets. Benefiting from the development of machine learning technology and the improvement of...

Traditional blockchain systems the consensus protocol and transaction management is performed together. In other words, the completion of the consensus protocol means the completion of a transaction. Furthermore, the transaction is considered as settled. This scheme is not compatible with modern financial transaction rules where transaction is dist...

The existing blockchain consensus protocol has reached the level of availability in replicas in small-scale scenarios. However, if the blockchain system is composed of hundreds or even thousands of replicas, the throughput and delay will significantly decrease as the number of replicas increases, which makes it difficult to apply it in large-scale...

This paper proposes a blockchain-based multi-level corporate digital wallet that meets financial regulatory requirements, including compliance with the Travel Rules, and identification of suspicious financial transactions. Unlike personal digital wallets, a corporate wallet is actually a large financial management system with internal blockchains,...

In a traditional blockchain system, the consensus protocol and the transaction management are coupled, i.e., transactions are performed during the consensus process. When the consensus protocol completes its process, the transaction is considered as completed. Such an integrated approach challenges the system scalability and regulatory issues. And...

Nowadays, Blockchain technology has received widespread attention because of its ability to effectively solve the trust problem in transactions. However, the throughput of crypto currency using Blockchain technology has never been comparable to that of centralized payment institutions. The fundamental reason is the architecture of the Blockchain it...

The cover image is based on the Original Article Verification Algebra for Multi-Tenant Applications in VaaS Architecture by Kan Luo et al., https://doi.org/10.1002/stvr.1763.

Anomaly detection for smart contracts can effectively prevent hidden security risks such as financial fraud, illegal financing, and money laundering. Ethereum is currently the largest platform for smart contracts, and anomaly detection is imminent. However, the data related to smart contracts is huge and contains complex objects and relationships....

This paper proposes a dynamic and scalable blockchain system framework for structuring a blockchain systems (BC). Traditionally a BC maintain multiple nodes with a smart-contract engine (SC) running on nodes, possibly with one or more Oracles Machines (OMs). However, many sophisticated applications require a much flexible yet still secure and scala...

This paper proposes an algebraic system, verification algebra (VA), for reducing the number of component combinations to be verified in multi‐tenant architecture (MTA). MTA is a design architecture used in SaaS (Software‐as‐a‐Service) where a tenant can customize its applications by integrating services already stored in the SaaS databases or newly...

The blockchain whitepaper contains detailed technical and business information, so its analysis is important for blockchain text mining. Previous works focuses on analyze homogeneous objects and relations. The main problem, however, is these works do not take into account the heterogeneity of information. This paper presents a new methodology for w...

Business processes often involve operational processes, contracts, and regulations. The modeling of such processes must address regulation monitoring and enforcement and maintain a reliable history of data for evidence. This study proposes modeling business processes as chaincode (CC) on permissioned blockchains (BCs). The challenges encountered by...

In recent years, artificial intelligence (AI) has played an increasingly important role in the medical field. AI based on big data analysis and deep learning algorithms has become the core driving force for the future development of the medical industry, but the biggest obstacle to its development is incompleteness and inaccuracy of medical data. T...

Blockchain(BC), as an emerging distributed database technology with advanced security and reliability, has attracted much attention from experts who devoted to e-finance, intellectual property protection, the Internet of Things (IoT) and so forth. However, the inefficient transaction processing speed, which hinders the BC’s widespread, has not been...

Purpose This paper aims to apply blockchains (BCs) for trade clearing and settlement in a realistic clearinghouse. The purpose is to demonstrate the feasibility and scalability of this approach. Design/methodology/approach The study uses account BCs and trading BCs as building blocks for trade clearing and settlement. Careful design is made to ens...

This chapter discusses combinatorial testing in multi-tenancy Software-as-a-Service (SaaS) system. SaaS often uses multi-tenancy architecture (MTA) where tenant developers compose their applications online using the components stored in the SaaS database. Tenant applications need to be tested, and combinatorial testing can be used. While numerous c...

This chapter proposes a new algebraic system, test algebra (TA) for identifying faults in combinatorial testing for Software-as-a-Service (SaaS) applications. In the context of cloud computing, SaaS is a new software delivery model, in which mission-critical applications are composed, deployed, and executed on cloud platforms. Testing SaaS applicat...

A new integrated testing framework is proposed to use adaptive reasoning algorithm with automated test cases generation (ARP) and test algebra (TA) for increasing SaaS testing efficiency in faulty combination identification and elimination. The ARP algorithm has been evaluated by both simulation and real experimentation using a MTA SaaS sample runn...

Software-as-a-Service (SaaS) application plays an important role in daily life and needs to have high reliability and availability before publishing. Testing SaaS applications become important, as the large number of testing prior to their deployment. TA identifies faults in combinatorial testing for SaaS applications using existing test results an...

This chapter gives an introduction to combinatorial testing. In particular, it describes the applications and challenges of combinatorial testing in cloud environment and briefly introduces solutions to address challenges. It also discusses and compares existing faulty location analysis solutions of combinatorial testing.

Testing-as-a-Service (TaaS) in a cloud environment can leverage the computation power provided by the cloud. Specifically, testing can be scaled to large and dynamic workloads, executed in a distributed environment with hundreds of thousands of processors, and these processors may support concurrent and distributed test execution and analysis. TaaS...

Testing-as-a-Service (TaaS) is a software testing service in a cloud that can leverage the computation power provided by the cloud. Specifically, a TaaS can be scaled to large and dynamic workloads, executed in a distributed environment with hundreds of thousands of processors, and these processors may support concurrent and distributed test execut...

Testing SaaS applications are challenging, because a large number of configurations need to be tested. Faulty configurations should be identified and corrected before the delivery of SaaS applications. TA proposes an effective way to reuse existing test results to identify test results of candidate configurations, and it also defines rules to permi...

With the development of cloud infrastructure, more and more transaction processing systems are hosted in cloud platform. Log, that usually saves production behaviors of a transaction processing system in cloud, is widely used for triaging production failures. Log analysis of a cloud-based system faces challenges as the size of data increases, unstr...

A gesture-based interaction system for smart homes is a part of a complex cyber-physical environment, for which researchers and developers need to address major challenges in providing personalized gesture interactions. However, current research efforts have not tackled the problem of personalized gesture recognition that often involves user identi...

This paper presents a blockchain definition independent of any digital currency, and describes its characteristics including consensus protocols, design patterns, scalability, databases, and chaincode. The paper then presents a permissioned blockchain, called Beihangchain, with its unique consensus algorithms, interfaces, and design. It also propos...

We introduce in this work a new software architecture design, based on well-established web communication protocols and scripting languages, for implementing spatially-indexed media in smart environments. We based our approach on specific design guidelines. Our concept of spatially-indexed media enables users to readily instantiate mappings between...

This paper characterizes Boolean expression faults as changes of the topological structures in terms of shrinking and/or expanding regions in K-map. A cell-covering is a set of cells (test cases) in K-map to cover the fault regions such that faults guarantee to be detected. Minimizing cell covering can be formulated as an Integer Linear Programming...

This book introduces readers to an advanced combinatorial testing approach and its application in the cloud environment. Based on test algebra and fault location analysis, the proposed combinatorial testing method can support experiments with 250 components (with 2 * (250) combinations), and can detect the fault location based on the testing result...

Multi-tenancy architecture (MTA) is often used in Software-as-a-Service (SaaS) and the central idea is that multiple tenant applications can be developed using components stored in the SaaS infrastructure. Recently, MTA has been extended to allow a tenant application to have its own sub-tenants, where the tenant application acts like a SaaS infrast...

Testing-as-a-Service (TaaS) is a software testing service in a cloud that can leverage the computation power provided by the cloud. Specifically, a TaaS can be scaled to large and dynamic workloads, executed in a distributed environment with hundreds of thousands of processors, and these processors may support concurrent and distributed test execut...

Context-aware applications often consist of a middleware and a collection of services, and run autonomously adaptive to changing environments with sensors installed in physical facilities and end-users moving around. Testing such applications is challenging due to the complex interactions with the environments. This paper proposes a model-based tes...

Hierarchical multi-tenancy, which enables tenants to be divided into subtenants, is a flexible and scalable architecture for representing subsets of users and application resources in the real world. However, the resource isolation and sharing relations for tenants with hierarchies are more complicated than those between tenants in the flat Multi-T...

Formal methods and verification technique are often used to develop mission-critical systems. Cloud computing offers new computation models for applications and the new model can be used for formal verification. But formal verification tools and techniques may need to be updated to exploit the cloud architectures. Multi-Tenant Architecture (MTA) is...

Monitoring is widely applied in problem diagnosis, fault localization, and system maintenance. And since the cloud infrastructure is complex, the applications on the cloud are therefore complex, which makes monitoring in cloud more difficult. Rich monitors that contain composite and heterogeneous probes are often used in service-oriented system mon...

Large scale software systems with increasing complexity, variability and uncertainty, brings about grand challenges for traditional software engineering. Recently, crowdsourcing practices in the domain of software development such as Apple App Store and TopCoder have exhibited a promising and viable solution to the issues. The use of a crowd for de...

Recently software crowdsourcing has become an emerging development paradigm in software ecosystems. This paper first introduces a software crowdsourcing framework in the context of software ecosystems. The framework includes a game-theoretical model for peer software production to describe the competitive nature of software crowdsourcing. The analy...

Testing-as-a-Service (TaaS) is a software testing service in a cloud that can leverage the computation power provided by the cloud. Specifically, a TaaS can be scaled to large and dynamic workloads, executed in a distributed environment with hundreds of thousands of processors, and these processors may support concurrent and distributed test execut...

Performance monitoring tools have received a great significant attention. On the one side, it is necessary to support managing increasingly complex hardware and software infrastructures; on the other side, it can provide user system load and application running information in real time so as to guide user's resource request scheme and program optim...

Sub-Tenancy Architecture (STA), is an extension of Multi-Tenancy Architecture (MTA), allows tenants to offer services for subtenant developers to customize their applications in the SaaS infrastructure [1]. In a STA system, tenants are autonomous decentralized entities who can create subtenants, and grant their resources (including private services...

Following development of Software-as-a-Service (SaaS), combinatorial testing technologies are used in SaaS testing. It is difficult to handle the exponential growth of SaaS testing workloads. This paper proposes a new integrated testing framework using Adaptive Reasoning algorithm with automated test cases generation (ARP) and Test Algebra (TA) to...

AADL (Architecture Analysis and Design Language) is often used to model safety-critical real-time systems. Model transformation is widely used to extract a formal speci�cation so that AADL models can be veri�ed and analyzed by existing tools. Timed Abstract State Machine (TASM) is a formalism not only able to specify behavior and communication but...

Cloud computing introduces a new paradigm for software deployment, hosting, and service renting. Based on the XaaS architecture, a large number of users may share computing resources, platform services, and application software in a multi-tenancy approach. To ensure service availability, the system needs to support an advanced level of massive scal...

This book presents the latest research on the software crowdsourcing approach to develop large and complex software in a cloud-based platform. It develops the fundamental principles, management organization and processes, and a cloud-based infrastructure to support this new software development approach. The book examines a variety of issues in sof...

Safety-critical real-time systems need to be modeled and simulated early in the development of lifecycle. SIGNAL is a data-flow synchronous language with clocks widely used in modeling of such systems. Due to the synchronous features of SIGNAL, clock calculus is essential in compilation and simulation. This paper proposes a new methodology for cloc...

Service-oriented architecture (SOA) is characterized by dynamic service discovery and composition. For user-centric SOA, not only services, workflows, and application templates can be published and discovered for composition. Furthermore, a user can publish an application template and let providers supply the needed services. A key issue in user-ce...

In computer and network security education, hands-on laboratories are essential to help students understand the course content. However, hands-on laboratories are difficult to implement due to the complicated setup and location restrictions of a physical laboratory, which limits their use in online education. Using a remotely accessible, physically...

Hands-on experiments are essential for computer network security education. Existing laboratory solutions usually require significant effort to build, configure, and maintain and often do not support reconfigurability, flexibility, and scalability. This paper presents a cloud-based virtual laboratory education platform called V-Lab that provides a...

Testing-as-a-Service (TaaS) in a cloud environment can leverage the computation power provided by the cloud. Specifically, testing can be scaled to large and dynamic workloads, executed in a distributed environment with hundreds of thousands of processors, and these processors may support concurrent and distributed test execution and analysis. TaaS...

Context-aware applications often consist of a middleware and a collection of services, which run autonomously adaptive to the changing environments, where a variety of sensors are installed in physical facilities, with end-users moving around. Testing such context-aware applications is challenging due to the complex interactions among the component...

In addition to providing large-scale, highly available computational resources, clouds also enable a new methodology for software development via crowdsourcing, in which crowd participants either collaborate or compete to contribute software. Using a crowd to develop software is predicted to take its place alongside established methodologies, such...

Software-as-a-service (SaaS) has received significant attention recently as one of three principal components of cloud computing, and it often deals with applications that run on top of a platform-as-a-service (PaaS) that in turn runs on top of infrastructure-as-a-service (IaaS). This paper provides an overview of SaaS including its architecture an...

This paper explores the application of Self-Organizing Learning (SOL) to software crowdsourcing so that people can learn software design. SOL principles include communication, reflection, collaboration, community, creative tools, and amplification. Based on these principles, this project proposed a cloud-based environment to support people to learn...

SaaS (Software-as-a-Service) as a part of cloud computing is a new approach for software construction, evolution, and delivery. This paper proposes HLA-based SaaS-oriented simulation frameworks where simulation services will be organized into a SaaS framework running in a cloud environment. This SaaS-oriented frameworks can be applied to multiple a...

Recently many companies have featured their applications as SaaS (Software as a Service) applications where applications will be treated as services and provided online for thousands and millions of users. Social Networking SaaS (SNS) is one of the most popular kinds of SaaS. The key to the success of a SNS heavily relies on the scale of users. Wit...

Software-as-a-Service (SaaS), a new software delivery model, plays an important role in daily life. In SaaS, mission-critical applications are composed, deployed, and executed on cloud platforms. SaaS applications needed to have high reliability and availability before publishing. Testing SaaS applications becomes important, as the large number of...

A algebraic system, Test Algebra (TA), identifies faults in combinatorial testing for SaaS (Software-as-a-Service) applications. SaaS is a software delivery model that involves composition, deployment, and execution of mission application on cloud platforms. Testing SaaS applications is challenging because a large number of configurations needs to...

A mobile cloud is a cloud infrastructure connecting to mobile devices with a variety of applications (apps). This paper proposes utilizing bigraphical reaction systems (BRSs) to model and analyze a mobile cloud including its contexts such as mobile location, power consumption, network bandwidth, and latency. Simulations and evaluations are performe...

Multi-tenancy architecture (MTA) is often used in Software-as-a-Service (SaaS) and the central idea is that multiple tenant applications can be developed using components stored in the SaaS infrastructure. Recently, MTA has been extended where a tenant application can have its own sub-tenants as the tenant application acts like a SaaS infrastructur...

The distinguished features of mobile computing bring both opportunities and challenges to the development of Mobile Social Networking (MSN) applications. Learning the successful experiences from existing MSN applications is valuable to both industry and academy. The paper aims at identifying the success factors of Instagram, a well-known MSN applic...

To cope with frequent upgrades of mobile devices and technologies, engineers need a reusable and cost-effective environment for testing mobile applications and an elastic infrastructure to support large-scale test automation.

Modern software operates in highly dynamic and often unpredictable environments that can degrade its quality of service. Therefore, it is increasingly important having systems able to adapt their behavior. However, the achievement of software adaptability ...