# Investigation of Microservice-Based Workflow Management Solutions for Industrial Automation
## 2 Background and Related Work
### Workflows and Business Processes  
Numerous devices are expected to communicate and share data with each other in modern production systems, as information-driven decisions are a vital advantage of Industry 4.0 organizations. Among the expected benefits that factory-wide communications will bring to companies are dynamic business processes and increased engineering flexibility [9]. In this scenario, WFMSs can support production by managing and organizing heterogeneous systems, their interactions, and their evolving behaviors.  
The Workflow Management (WFM) and BPM fields were created during the rise of information systems, when companies were searching for new tools to coordinate a growing number of resources and automate complex processes. Although these fields have evolved, generally accepted definitions of their primary terms, business process, and workflow are still lacking in the scientific literature [10]. In the scope of this work, business processes are described as the manner in which an organization's resources are used to provide an output, adding value by fulfilling certain business goals. In an effort to develop industry standards in this domain, the Workflow Management Coalition (WfMC) [11] was created, which defined workflows as the way business processes are automated according to a set of procedural rules. Another important contribution into the field was the workflow reference model (Figure 2), which has had a significant influence on the modular design of WFMSs for interoperability [12]. Nevertheless, the WfMC had decreased its activity in recent years, proceeding to its dissolution in 2019 [13], while development in the field is still ongoing.  
Of the different types of workflows in use today, this work explores the use of manufacturing workflows, which aim to be incorporated into the new generation of automation architectures. They are based upon business workflows and their emphasis on the control-flow perspective while focusing on coordinating software systems and relegating human tasks. Their advantage resides in the advanced control they offer over the factory shop floor operations by the execution of the workflow task through granular calls to machine services. The creation of manufacturing workflows would follow a Product Lifecycle Management (PLM) approach and be planned, scheduled, and executed by a Manufacturing Execution System (MES).  
The lack of well-established definitions for the basic terminology of workflows and business processes reflects the absence of standardization in the field. From the workflow modeling languages to the WFMSs, their basic functionality and properties are not harmonized across the range of commercial offerings. Providers should consider their conformance with related solutions more thoroughly before creating their own offerings. Standards have been published, but, as argued in [14], they have failed to reach widespread adoption as they were not built upon a comprehensive workflow theory. Aside from the communication problems that engineers face when designing new WFMSs, the lack of standardization in the field is also represented by volatile requirements. There is a broad market of WFMSs that focus on particular niches, prompting practitioners to re-assess the requirements for each project as market demands shift.