# Investigation of Microservice-Based Workflow Management Solutions for Industrial Automation
## 3 Challenges and Requirements Set by the Industry for the Workflow Lifecycle  
Several reports have been published with valuable insights into the challenges faced by companies looking to adopt workflow technology [49], derived from the work in European research projects, Productive 4.0 ([[https://cordis.europa.eu/project/id/737459](https://cordis.europa.eu/project/id/737459)]([https://cordis.europa.eu/project/id/737459](https://cordis.europa.eu/project/id/737459)), accessed on 10 December 2022), and Arrowhead Tools ([[https://cordis.europa.eu/project/id/826452](https://cordis.europa.eu/project/id/826452)]([https://cordis.europa.eu/project/id/826452](https://cordis.europa.eu/project/id/826452)), accessed on 10 December 2022), where companies and research institutes have worked together. This information has been supplemented with a scientific literature survey of past WFM requirements [25; 50]. Finally, the main barriers for industry have been grouped into four focus areas:  
**Architecture:** From the architectural perspective, a company needs to decide how the WFMS is going to interact with the rest of the company's applications and devices. It needs to decide whether the steps of a workflow are controlled by a central system (orchestration) or else the control is passed at each step of the workflow to the next system executing it (choreography). A comparison of both approaches, orchestration vs. choreography, is presented in [51]. Another architectural constraint is the type of workflow considering the entity in charge of dispatching the model. The workflow can follow the traditional automation hierarchy and be PLM-based; the workflow recipe can be carried out by the products themselves through a smart product approach or can consider a hierarchical architecture that relies on a set of manufacturing equipment connected together that works as a production unit. **Engineering Life Cycle:** Integrated into this area are a myriad of different lifecycles, from the overall project lifecycle to each individual shop floor equipment, which is used as resources when implementing the workflows. Although they will all have some impact on the suitability of the WFMS, it will be too complex to study them all. Therefore, a good way to start will be to approach the two most crucial phases of a general engineering process lifecycle when creating and managing workflows [52]. Design time workflow engineering encompasses the time spent designing the workflow, combining the functionality of different services in a specified order to achieve the desired business goal. Run-time workflow engineering, which refers to the period during which the workflow is executed in the deployed environment, corresponds to the operation & management step in the engineering process. Companies should consider how much dynamism is required in their workflows and at which stages. **Process-Task Relation:** This area analyzes the characteristics of the workflows and their individual tasks. When considering the process-task relation, an organization must determine the aspects that are related to the workflow nature, such as parallel or sequential flow structure, nature of tasks (including human interaction or exclusively machine services), communication between tasks, interoperability, and the nature of services (reliability, dynamism, or concurrency). **Context:** The new Industry 4.0 approach toward WFM also impacts the features that companies demand from new solutions. Thus, aspects such as scalability (replicability), security and privacy, collaborative process management (cross organization), and service management (service discovery) introduce new constraints, such as the addition of new infrastructure (message brokers, interoperability converters, firewalls, etc.). The following subsections identify the individual requirements of WFMSs throughout the phases of the workflow lifecycle introduced in this paper.