[Back]

C. Prybila:
"Runtime Verification for Business Processes utilizing the Blockchain";
Supervisor: S. Schulte; Institute of Information Systems, Distributed Systems Group, 2016; final examination: 2017-02-16.

To address the scalability limitations of orchestration-oriented workflow management systems, scientific contributions propagate workflow choreographies. The control over a workflow instance is shared between independent participants. Accordingly, an independent
mechanism to document and verify the execution of a workflow instance is required.
In the unrelated scientific field of cryptocurrencies, the Bitcoin project utilizes the Blockchain technology as distributed ledger to record payment transactions. This thesis explores the suitability of the Blockchain to create a novel approach to runtime verification.
Existing approaches to distributed runtime verification are discussed. Next, the properties of different operating Blockchains are highlighted. Based on these findings a novel approach to runtime verification that utilizes the Bitcoin Blockchain is developed.
The developed prototype is evaluated in a functional comparison. Based on selected criteria, runtime verification approaches are categorized and discussed. Findings show that our Blockchain-based approach enables a seamless execution monitoring while at the same time preserving anonymity and independence of the participants. Some downsides remain. Our proposed prototype enables flexible on-demand participant selection but is not able to provide data confidentiality or to enforce an execution sequence.
At last, the prototype is evaluated in a performance analysis. The usage of the runtime verification prototype can significantly increase workflow duration. The greatest influence factor is the transaction confirmation time (TCT) in the Bitcoin Blockchain. A median TCT of 7.741 minutes is recorded in the evaluation. The TCT also exhibits a very high standard deviation, indicating that single transactions take even longer to confirm.
While it is possible to reduce the induced execution overhead of the framework with a less safe but greedy approach, the results suggest that the prototype is most suited for business processes with long running activities like logistic or supply chain processes.

Choreographies / Blockchain / Business Process Management / Runtime Verification / Bitcoin