Compare Workflow Engines

Blog: Imixs Workflow Blog

The term “workflow engine” is not clearly defined in software development and therefore we would like to give a brief overview of different aspects and types of workflow engines below.

If you take a look at the Github page awesome-workflow-engines, you will find an impressive number of open source workflow engines. But not all of these engines solve the same problem because the idea behind the term ‘workflow’ can be very different. In general a workflow is a series of tasks or activities that are required to complete a specific process. It can involve multiple people, teams, microservices or other systems. Workflows can be used in a variety of contexts, including business, manufacturing, software development, and many more.

Types of Workflows

For example, a workflow in a business context might involve tasks such as creating a proposal, getting an approval from a manager, making a decision by a human expert or routing important information through an organization. On the other hand in software deployment process (DevOps), a workflow might involve tasks such as committing code, testing the code, building an artefact and deploying the results to a server. There are therefore different types of workflows depending on a specific requirement and context.

Modelling

Workflows are often visualized as flowcharts or diagrams, which can help to clearly communicate the steps involved and the dependencies between tasks. The Business Process Model and Notation (BPMN) is a modelling standard that provides a graphical notation how to specify a business processes in a Business Process Diagram. BPMN is easy to understand by all project members and a good starting point to talk about a business process with technician as also with management people. In addition to the graphical notation, BPMN also offers the possibility of a machine-readable format. This makes BPMN well suited for workflow engines and has become a de facto standard for business workflows.

Frameworks

Workflow Engines can be based on a specific framework or technology stack. A framework is a set of libraries, tools, and conventions that provide a structure for developing software applications. For example there are frameworks for Java like the Jakarta EE specification that simplifies the development of enterprise applications, or the Kubernetes API standardizing the way how to implement a workflow into Kubernetes. The main advantage of using a framework in case of a workflow engine is, that it provides a clear way how to integrate the solution into a specify technology stack. A workflow engine based on a framework makes the development process more efficient and consistent.

Security

Data security has become one of the essential factors in modern Software Development. Due to the clearly structured way in which data is processed by a workflow engine, corresponding solutions offer a high degree of security in data processing. But also the access to data can be secured by a workflow engine. For example, human-based workflow engines offer the possibility to control access to certain data depending on previously defined roles or business rules in a more fine grade way that this is possible with common security solutions.

Open Source

Open source refers to a type of software whose source code is available for anyone to view, modify, and distribute freely. Open Source is developed and maintained by a community in a open and transparent way. Workflow engines based on open source result in a more diverse and robust product, as those engines are developed and improved by many different users.

Open Source also allows adopters to customize the workflow engine to fit their specific needs. This is particularly useful for organizations that need to modify the software to integrate with their existing systems or processes. Since the source code for an open source workflow engine is available for anyone to view, it is also easier for security vulnerabilities to be identified and fixed. This makes open source software more secure than proprietary software, which may have undisclosed vulnerabilities.

One of the main advantages of open source is that it is generally free to use. This can be a significant cost savings for individuals and organizations that need to use software on a regular basis.

The list below gives a brief overview of some workflow engines used in different application scenarios:

Feature	Type	Language	Framework	Modelling	Security
Imixs-Workflow	Business Workflow	Java	Jakarta EE	BPMN	ACL based
Activiti	Automation	Java	Spring	–	–
Apache Airflow	Automation	Python	–	–	–
Argo Workflow	Deployment	Kubernetes CRD	Kubernetes	–	role based
Bonita	Business Workflow	Java	–	BPMN	–
Dolphin Scheduler	Orchestration	Python	–	Graphical UI	–
Kubeflow Pipeline	Deployment ML	YAML	Kubernetes	–	role based
metaflow	ML	Python	–	–	–

There are many other aspects that can be important when choosing a workflow engine. Therefore, we recommend aligning the criteria with your own goals and thus selecting the optimal product for the next software project. If you have any comments or ideas, we look forward to your feedback.