Data IntElliGence and knOwledge

New paper “Discovering Guard Stage Milestone Models Through Hierarchical Clustering” at CoopIS 2023

Authors: Leyla Moctar M’Baba, Mohamed Sellami, Nour Assy, Walid Gaaloul, and Mohamedade Farouk Nanne


Processes executed on enterprise Information Systems (IS), such as ERP and CMS, are artifact-centric. The execution of these processes is driven by the creation and evolution of business entities called artifacts. Several artifact-centric modeling languages were proposed to capture the specificity of these processes. One of the most used artifact-centric modeling languages is the Guard Stage Milestone (GSM) language. It represents an artifact-centric process as an information model and a lifecycle. The lifecycle groups activities in stages with data conditions as guards. The hierarchy between the stages is based on common conditions. However, existing works do not discover this hierarchy nor the data conditions, as they considered them to be already available. They also do not discover GSM models directly from event logs. They discover Petri nets and translate them into GSM models. To fill this gap, we propose in this paper a discovery approach based on hierarchical clustering. We use invariants detection to discover data conditions and information gain of common conditions to cluster stages. The approach does not rely on domain knowledge nor translation mechanisms. It was implemented and evaluated using a blockchain case study.

New paper “Request relaxation based-on provider constraints for a capability-based NaaS services discovery” at CAISE 2023

Authors: Imen Jerbi, Hayet Brabra, Mohamed Sellami, Walid Gaaloul, Sami Bhiri, Boualem Benatallah, Djamal Zeghlache, and Olivier Tirat


Network as a Service (NaaS) enables cloud customers to connect their distributed services across multiple clouds without relying exclusively on their infrastructures. The discovery of NaaS services remains challenging not only because of their scale and diversity but also because of the hidden constraints that cloud providers impose on these services at the networking layer. NaaS services are usually offered in the form of service bundles containing underlying services and constraints not requested by the customers. This creates undesirable dependencies and constraints that hamper portability, compatibility and interoperability across providers. The problem of service discovery becomes more challenging when these constraints are the main and first cause that prevents a customer’s request from being fulfilled. Without a mechanism that enables customers to identify these constraints and to adjust their requests accordingly, existing service discovery solutions are likely to fall short. We propose to complement existing service discovery solutions by not only identifying unmatched constraints but also recommending relaxing discovery requests to retrieve optimal and compliant services.

New article “Process mining for Artifact-Centric Blockchain Applications” in the SIMPAT journal

Authors: Leyla Moctar M’Baba, Nour Assy, Mohamed Sellami, Walid Gaaloul and Mohamedade Farouk NANNE


Process mining can provide valuable insights into user behavior, performance, and security for blockchain applications. In return, process mining benefits from the trustworthiness of blockchain data. One obstacle to realizing these benefits is that blockchain data is inadequate for process mining. This issue has been previously explored in literature, but mainly with regards to workflow-centric processes, leaving out the more common artifact-centric applications. This article introduces ACEL (Artifact-Centric Event Log), an extension to the OCEL (Object-Centric Event Log) standard, specifically designed for artifact-centric processes. Additionally, we present a method for extracting ACEL logs from the Ethereum blockchain platform and demonstrate its effectiveness and the perspectives of process discovery through two case studies of public Ethereum applications.

New paper “Blockchain logging for process mining: a systematic review” at HICSS’2022

Authors: Leyla Moctar M’Baba, Mohamed Sellami, Walid Gaaloul and Mohamedade Farouk NANNE


Considerable progress was forcasted for collaborative business processes with the rise of blockchain programmable platforms. One of the saliant promises was auditable traces of business process execution, but practically it has posed challenges specially with regard to blockchain logs’ structure who turned out to be inadequate for process mining techniques. Approaches to answer this issue have started to emerge in the literature; some focusing on the creation process of event logs, and others dealing with their retrieval from the blockchain. This work outlines the generic steps required to solve these challenges and analyzes findings in these approaches with a consideration for efficiency and future research directions.

New paper “Towards higher-level description of SLA-aware reconfiguration strategies based on state-machine” at ICEBE’2021

Authors: Jeremy Mechouche, Roua Touihri, Mohamed Sellami and Walid Gaaloul


High number of European projects and international initiatives show an increased interest in the multi-cloud paradigm. One key need identified in these studies is an SLA-driven service model for multi-cloud environment. While offering a multi-cloud application, cloud consumer define reconfiguration strategies to avoid violating SLAs established with their customers. In this context, this paper presents an approach for enriching multi-cloud SLA representations with reconfiguration strategies. Advantages of this approach are twofold: (i) simplify SLA administration and (ii) limit SLA violations caused by reconfiguration strategies. We represent reconfiguration strategies based on state-machine formalism. Furthermore, we define thresholds to guarantee their compliance with multi-cloud SLAs and anticipate SLA violations. An implementation of the approach is presented in the paper and illustrates how these thresholds are computed.

New paper “A Transactional Approach to Enforce Resource Availabilities – Application to the Cloud” at RCIS’2021

Authors: Zakaria Maamar, Mohamed Sellami and Fatma Masmoudi


This paper looks into the availability of resources, exemplified with the cloud, in an open and dynamic environment like the Internet. A growing number of users consume resources to complete their operations requiring a better way to manage these resources in order to avoid conflicts, for example. Resource availability is defined using a set of consumption properties (limited, limited-but-renewable, and non-shareable) and is enforced at run-time using a set of transactional properties (pivot, retriable, and compensatable). In this paper, a CloudSim-based system simulates how mixing consumption and transactional properties allows to capture users’ needs and requirements in terms of what cloud resources they need, for how long, and to what extent they tolerate the unavailability of these resources.

New article “Real-Time Tracking and Mining of Users’ Actions over Social Media ” at Computer Science and Information Systems

Ejub Kajan, Noura Faci, Zakaria Maamar, Mohamed Sellami, Emir Ugljanin, et al.. Real-time tracking and mining of users’ actions over social media. Computer Science and Information Systems, ComSIS Consortium, In press, pp.2-2. ⟨10.2298/CSIS190822002K⟩⟨hal-02514060⟩

Abstract. With the advent of Web 2.0 technologies and social media, companiesare actively looking for ways to know and understand what users think and say about their products and services. Indeed, it has become the practice that users go online using social media like Facebook to raise concerns, make comments, and share recommendations. All these actions can be tracked in real-time and then mined using advanced techniques like data analytics and sentiment analysis. This paper discusses such tracking and mining through a system called Social Miner that allows companies to make decisions about what, when, and how to respond to users’ actions over social media. Questions that Social Miner allows to answer include what actions were frequently executed and why certain actions were executed more than others.

New paper “Towards an Approach for Validating the Internet-of-Transactional-Things” at AINA’2020

Z. Maamar, M. Sellami, N.C. Narendra, I. Guidara, E. Ugljanin, and B. Banihashemi. Towards an Approach for Validating the Internet-of-Transactional-Things. In the 34-th International Conference on Advanced Information Networking and Applications (AINA-2020)


Abstract. This paper examines the impact of transactional properties, known as pivot, retriable, and compensatable, on Internet-of-Things (IoT). Despite the ever-growing number of things in today’s cyber-physical world, a limited number of studies examine this impact while considering things’ particularities in terms of reduced size, restricted connectivity, continuous mobility, limited energy, and constrained storage. To address this gap, this paper proceeds first, with exposing things’ duties, namely sensing, actuating, and communicating. Then, it examines the appropriateness of each transactional property for each duty. During the performance of transactional things, (semi)-atomicity criterion is adopted allowing to approve when these things’ duties could be either canceled or compensated. A system that runs a set of what-if experiments is presented in the paper allowing to demonstrate the technical doability of transactional things.