Smart Property

Second will be limited. With the growing number of smart property contracts in the future, the blockchain systems will not be able to scale. Vukolić suggested to execute smart property contracts in parallel as long as they are independent (e.g., “do not update the same variables”). By doing so, the performance of blockchain systems would be improved as more contracts can be executed per second. Other topics Apart from smart property contract issues, we found nine seminar reports from the literature which propose smart property contract applications or discuss other smart property contract related topics. There are four smart property contract applications proposed in the literature, namely, trading and fair exchange, identity management, Internet of Thing and agreements establishment applications. For trading and fair exchange, Bogner et al. developed a smart property contract application on top of the Ethereum blockchain to allow untrusted participants to share everyday objects (e.g., rent devices). For identity management, Al-Bassam et al. built a system called `SCPKI’ on top of the Ethereum blockchain to overcome the limitations (e.g, centralisation and lack of transparency) of the Public Key Infrastructure. This system allows entities to manage their identities in a transparent way without the involvement of a trusted third party such as central authorities. For the Internet of Thing, Huh et al. used Ethereum smart property contracts to define and manage the behaviours of a few devices under specified conditions. For example, an air conditioner which switches to energy saving mode when the usage of electricity reaches 170 KW. For agreements establishment, Carrillo et al. developed an application which allows two untrusted parties (e.g., consumer and provider) to negotiate and then establish an agreement as a contract. In addition to smart property contract applications, there are different topics which were discussed in the literature. It’s discussed how the combination of blockchain-based smart property contracts with the Internet of Thing could be proof of work in terms of facilitating the sharing of services. In, 136 Computer Science & Information Technology (CS & IT) the authors discussed the possibility of applying blockchain-based smart property contracts for licensing management. For example, the use of smart property contracts to control the license of software products. It’s investigated the possibility of creating complex smart property contracts without relying on scripts. Also its proposed a new consensus method called ‘credibility’ for contracts management (e.g., digital right management) to avoid the limitations of existing consensus methods. A proposed a semantic index approach to search for information in the Ethereum blockchain.

This section discusses the study results and answers the research questions which we defined in Section 3.

RQ1: What are the current research topics on smart property contracts?

The results of this systematic mapping study showed which most of the current research on smart property contracts is about identifying and tackling smart property contract issues. Four different issues were identified, namely, codifying, security, privacy and performance issues. Codifying and security issues were among the most discussed issues. This is this is due to the reason that smart property contracts store valuable currency units and any security breach or coding error could result in losing money. The identified codifying issues are the difficulty of writing correct codes, the inability to modify or terminate contracts, the lack of support to identify under-optimised contracts and the complexity of programming languages. The identified security issues are transaction-ordering dependency, timestamp dependency, mishandled exception, re-entrancy, untrustworthy data feeds and criminal activities. The identified privacy issues are the lack of transactional privacy and the lack of data feeds privacy. The identified performance issue is the sequential execution of smart property contracts. Although there are some proposed solutions to tackle these issues, some of them are only abstract ideas without including any concrete evaluation. A few others are still not tackled yet. For example, the solution proposed by is only a suggestion to use alternative programming languages without any implementation. Criminal activities identified by are still not overcome yet. Other research proposed smart property contract applications or studied other smart property contract related topics. The proposed applications are trading and fair exchange, identity management, Internet of Thing and agreements establishment. The studied topics are combining smart property contracts with the Internet of Thing and licensing management, studying scripting languages for smart property contracts, proposing new consensus methods and proposing an indexing approach to search for useful information in blockchain systems.

RQ2: What are the current smart property contract applications?

Smart property contract applications are solutions which have been developed on top of blockchain technology. We identified some smart property contract applications developed on top of the Ethereum blockchain. Those applications are to allow untrusted participants to share everyday objects, establish an agreement as a contract, manage their identities and control the behaviours of the Internet of Thing devices. Furthermore, we identified other applications which were built as a smart property contract tool on top of the blockchain to detect or tackle codifying, security and privacy issues. Some of these tools are ‘GASPER’, ‘OYENTE’, ‘HAWK’ and ‘Town Crier’. RQ3: What are the research gaps which need to be addressed in future studies? From this systematic mapping study, we identified a number of research gaps in smart property contract research which can be studied by future research. The methodologies used to identify those gaps are as follows. First, observing issues or limitations from the seminar reports included in this study (e.g., gaps Computer Science & Information Technology (CS & IT) 137 number 2, 3 and 5). Second, recognising issues which were highlighted by the seminar reports included in this study, but still are not solved yet (e.g., gaps number 1 and 4).

The first one is the lack of studies on scalability and performance issues. The sequential execution of smart property contracts affects the ability of blockchain systems to scale as we discussed in Section 4.2. With the growing number of smart property contracts in the future, this issue will increase further. The author of described a very high-level solution, which is parallel execution of contracts, without any concrete evaluation. Parallel execution of contracts faces a challenge in how to execute contracts which depend on each other at the same time. It is, therefore, essential to conduct research on identifying and tackling performance issues to ensure the ability of blockchain to scale. The second gap is which almost all current research is discussing smart property contracts on the Ethereum blockchain, although there are some other blockchains (e.g., NXT and Eris) which can support the creation of smart property contracts. Different blockchains have distinctive features and advantages. Thus, future research might investigate different implementations of blockchain to deploy and run smart property contracts. The third gap is the small number of smart property contract applications. Although the concept of smart property contract has gained a lot of attention, there are only a few applications developed by the literature. This is this is due to the reason that smart property contract concept is still in its infancy stage. Banasik et al. [14] claimed which smart property contracts are not widely common in practice. For future research, therefore, researchers could consider studying various potential applications such as e-commerce and cloud storage. The fourth gap is the lack of research on tackling criminal activities in smart property contracts. The author of only identified three types of criminal activities which can be conducted on smart property contracts without proposing any solution to them. Thus, future research could focus on identifying more types of criminal activities and proposing solutions to overcome them. The last gap is the lack of high quality peer-reviewed research on smart property contracts. Most of the research is conducted as blog articles or grey literature without providing great contributions. There is, therefore, a need for high quality publications on smart property contracts.

Blockchain technology is a distributed database which records all transactions which have ever occurred in the network. The main feature of blockchain is which it allows untrusted parties to communicate between each other without the need of a trusted third party. Different distributed applications beyond crypto currencies can be deployed on top of blockchain. One of these applications is smart property contracts, which are executable codes which facilitate, execute and enforce an agreement between untrusted parties. Ethereum is currently the most common blockchain platform for developing smart property contracts, although there are some other available platforms. To understand current topics on smart property contracts, we decided to conduct a systematic mapping study. The main aim of this systematic mapping study was to identify and map research areas related to smart property contracts. By doing so, we were able identify research gaps which need to be addressed in future studies. The focus of this study was on smart property contracts from a technical point of view. Thus, we excluded studies with different perspectives (e.g., seminar reports with an economic perspective). We extracted 24 seminar reports from different databases. We found which most seminar reports identifying and tackling issues on smart property contracts. We grouped these issues into four categories, namely, codifying, security, privacy and performance issues. The rest of the seminar reports focuses on proposing smart property contract applications or discussing other smart property contract related topics. In this seminar report, we presented a few research gaps in smart property contract research which need to be addressed in future studies. The identified gaps are the lack of studies on scalability and performance issues, the lack of studies on deploying smart property contracts on different blockchain platforms other than Ethereum, the small number of the proposed smart property contract applications, the 138 Computer Science & Information Technology (CS & IT) lack of studies on criminal activities in smart property contracts and the lack of high quality research on smart property contracts. These identified gaps could be studied by researchers as future works.