Zero-knowledge proofs (zkp) have been used to address several blockchain limitations (e.g. privacy, scalability). Recent work has proposed its usage to improve blockchain interoperability solutions, aiming to help software architects and developers reduce barriers to blockchain adoption. However, more studies are needed to understand the full potential of zkp in this context. In this paper, we empirically analyse how zkp may improve a gateway-based solution for blockchain interoperability. The results showed that it was possible to improve the selected solution in terms of privacy and data confidentiality limitations, by incorporating anonymous cross-chain authentication and private data exchange. A prototype was developed and evaluated using three strategies: 1) its application in a use case scenario, 2) performance tests, and 3) cost analysis. The evaluation showed that the approach is technically feasible, but not suitable for every use case. Furthermore, the private data exchange approach confirmed the results of other studies: zkp is not mature enough for some scenarios, and more work is required in this area.

Distributed ledger technologies (DLT) usage is currently limited to a single platform as they do not have design-based interoperability capabilities. In general, it's challenging for a DLT to communicate with another one. Although several DLT solutions have been proposed and applied in specific application areas, building a general-purpose interoperability solution for any DLT remains a challenge. In previous work, we proposed a tailor-made interoperability solution between Hyperledger Fabric and Corda. This paper extends that work to enable interoperability between Hyperledger Fabric and Ethereum. The main contribution of this paper is to provide a new approach to enable interoperability between these two DLT. The approach follows a new request-response interaction model and future payments to enable the payments of services. A prototype was developed and evaluated through a case scenario, performance tests and cost analysis. Performance tests showed bottlenecks under heavy load scenarios due to Ethereum's design. Costs analysis showed that the approach is suitable for purchasing high-priced services. These promising results constitute a step forward in developing a general-purpose solution for DLT interoperability.

During the last years, interoperability has become one of the main challenges within blockchain research as blockchains increasingly require integration between each other. Indeed, blockchains work by design in silos of information as interoperability is not a native feature. The main efforts in the field target permissionless blockchains, such as Bitcoin and Ethereum. However, interoperability in permissioned blockchains remains as an almost untouched area of work as they introduce additional requirements focusing on privacy and identity. Although there are some interoperability solutions for permissioned blockchains, they are either high-level design proposals not providing concrete implementations or focus on interoperability issues between business applications and blockchain platforms. In this paper we propose a gateway-based platform-to-platform interoperability solution for permissioned blockchains, which comprises a detailed solution design and a reference implementation. The proposal was assessed through the development of a social security case scenario, based on the reference implementation and using two blockchain platforms: Hyperledger Fabric and Corda.

The development of large-scale software systems is usually supported by integration platforms, which provide connectivity and mediation capabilities to facilitate the integration of heterogeneous and distributed applications. Integration platforms have traditionally been built as monolithic systems which, in some of the current contexts (e.g. market's high pace of demand, large amount of users and data), present issues in terms of scalability, maintainability and fault tolerance, among others. In turn, microservices architecture is an approach for developing applications as a set of small independent services, which may contribute to address such limitations (e.g. maintaining and scaling services independently, according to their specific needs). Indeed, various integration platform proposals leveraging this approach have emerged during the last years. However, those proposals are domain-specific and/or they do not provide insights regarding the architecture and implementation of the platform. This paper proposes a general-purpose microservice-based integration platform, which aims to address limitations of monolithic solutions and of the aforementioned existing proposals. Our work comprises the definition of the platform and its main functionality, a description of its microservice-based architecture, and implementation alternatives as well as prototypes for some of its main components.

Blockchain is a decentralized transaction and data management technology firstly developed for the Bitcoin cryptocurrency. In recent years, the interest in this technology has increased and its use has extended to other scenarios to address, for example, traceability and transparency issues in different application domains (e.g. health, government, art). On the other hand, there is a growing offer of platforms that support this technology with different characteristics (e.g. smart contracts, permissioned). Therefore, the task of identifying which platform is the most suitable for a given scenario is not usually easy. This paper proposes a requirement-driven process for the identification and selection of Blockchain platforms. The process takes as input the business requirements of a particular scenario in order to determine, firstly, the set of characteristics required by the scenario and, secondly, the most suitable Blockchain platforms based on a taxonomy also proposed in this work. The process was assessed through existing projects in the industry that use Blockchain platforms, which allowed validating the adequacy of the proposal.

Performing Bioinformatic's experiments involve an intensive access to distributed services and information resources through Internet. Existing tools facilitate the implementation of workflow-oriented applications, however they lack of capabilities to integrate services beyond low-scale applications, particularly integrating services with heterogeneous interaction patterns and in a larger scale. On the other hand, such integration mechanisms are provided by middleware products like Enterprise Service Buses (ESB). This paper proposes an integration platform, based on enterprise middleware, to integrate Bioinformatics services. It presents a multi-level reference architecture and focuses on ESB-based mechanisms to provide asynchronous communications, event-based interactions and data transformation capabilities.

The Uruguayan e-government agency has made available an Interoperability Platform (InP) with the purpose of facilitating the implementation of e-government services. By leveraging the Web Services technology, public agencies have implemented various atomic services which are usually hosted at the agencies but have to be accessed through proxy services in the InP. Given that the implementation of e-government processes involves invoking multiple services, the mechanisms to implement service orchestrations are increasingly required. Although there are well-known solutions for orchestrating Web Services, their application within the InP presents challenges, in particular, regarding the integration with its Security System. This paper proposes alternatives for implementing orchestrations of secure Web Services within the InP. The proposal consists of a base architecture that can be configured to implement different solution alternatives, enabling its application in other similar scenarios. The proposal was completely prototyped which allowed evaluating some operational aspects of the solution.