Which Workflow Engine(s) for which workflow solution?

[SBach]

Here is an update on a blog post published in 2019 by Alan Rickayzen about which of SAP's workflow engines is the choice for which workflow project. Thanks to all colleagues who gave input and reviewed my text/changes. I will differentiate new workflows from existing ones, also process monitoring requirements, migration of workflows to SAP S/4HANA, and the inbox topic.

SAP's strategic Workflow Engine for approvals and process execution is SAP Build Process Automation on SAP Business Technology Platform and part of SAP Build.

Here you can get a detailed overview of all product capabilities. Also, explore more on the community page for SAP Build Process Automation. New functionality is added on a weekly basis (e.g. modeling option for sub-flows). Check also the roadmap explorer to get the latest information on upcoming features/capabilities.

SAP Build Process Automation has been introduced for SAP customers and SAP Solutions to provide a citizen developer workflow environment to automate faster. It uses an easy-to-use process designer in which you can integrate RPA functionality with full process visibility on top. Keep your eyes open for further enhancements, including in SAP S/4HANA, to further simplify and enhance standard workflows.

SAP BTP is the platform to consider when a central strategy demands one single environment for workflow & API management, especially taking into account the broader capabilities that SAP Integration Suite & SAP Build Process Automation offer. For a more holistic enterprise automation approach in combination with SAP Signavio new capabilities are available.

There are some cases where certain individual requirements can be handled differently as described in the subsequent paragraphs.

New Workflow Project 

Type	Environment	Advice
Enterprise automation approach	Involving Cloud or On-Premise	For a holistic process management approach from process insights to improvements use SAP Build Process Automation, SAP Integration Suite, and SAP Signavio; Look at SAP Business Accelerator Hub for Workflow Content Packages to jumpstart your project.
Workflows with RPA / AI  requirements	Cloud or On-Premise	SAP Build Process Automation combines the offerings from SAP Workflow Management and iRPA for Citizen Developers Intelligent recommendations - out-of-the-box machine learning capabilities in SAP Task Center user decisions are available for SAP Build Process Automation Tasks (confidence level for positive outcome). Over Side-by-Side Extensions (availability see below) for SAP S/4HANA Cloud and SAP S/4HANA.
Single Cross-system (orchestration) processes	Where on-premise deployment of the workflow is essential	If legal requirements forbid still the use of Cloud services for process automation then use SAP Business Process Management for cross-system processes, including environments where third-party systems need to be integrated in the process. This software has proven itself as a robust, flexible, and powerful tool available as part of SAP Process Orchestration. Please take a look at the upcoming hybrid deployment option of the SAP Integration Suite and be aware of end of maintenance timeline of NetWeaver AS and consider Migration of your On-Premise SAP BPM applications to the cloud -> SAP Build Process Automation.
Standard local processes such as an approval	Cloud products, including SAP S/4HANA Cloud, public edition	Use the workflow tooling embedded in the Cloud solution, be it SAP S/4HANA Cloud, SAP Ariba, SAP SuccessFactors, or others to automate simple standard processes. This is usually tightly coupled with the application and offers design and control of the business processes without a learning curve. Stay alert from the beginning to detect signs of a non-standardized process or the need to break out and extract or propagate information from other software. That is a sure sign that your process requires extensibility offered by SAP BTP / SAP Build Process Automation. In SAP S/4HANA Cloud for custom objects, you can use a custom communication scenario to implement a workflow solution on SAP BTP. See also this blog.
Single customer-specific local processes	SAP S/4HANA and SAP S/4HANA Cloud, private edition	In SAP S/4HANA you have the choice between developing classic SAP Business Workflows or adding more flexibility with scenarios using flexible workflows. Here we recommend using the Add-On flexible workflow for empowering your business process experts. This is the workflow tool selected by the embedded applications in SAP S/4HANA, such as procurement or sales. Only resort to the classic workflows if the capabilities that flexible workflow provides are not sufficient/required – but keep an eye on the release updates, particularly the Cloud releases, which are an indication of what will be available in the next On-Premise release. Here you find the actual documentation. Stay alert from the beginning to detect signs of a need to break out and extract or propagate information from other software or cloud services. That is a sure sign that your process requires extensibility via the Integration to SAP BTP / SAP Build Process Automation. If you plan to move to the Cloud in general, consider using SAP BTP from the start.
Single cloud process	SAP BTP, ABAP Environment	SAP Build Process Automation; See documentation.

Extensions of existing workflow solutions

Type	Environment	Advice
Standard local processes such as an approval	SAP S/4HANA	In-App Extensions via BAdIs are available for Custom conditions, custom agent rules available in the Responsibility Management framework, Scenario Specific Extension (e.g. Procurement) Side-by-side extensions with SAP Build Process Automation (SAP Workflow Management)  via extension steps for Standard Scenarios are planned innovations.
Single customer-specific local processes	SAP ECC / SAP S/4HANA	Beneath the APAB Platform capabilities to enhance and build custom solutions, you can extend existing workflows with cloud services using Side-by-Side Extensibility for Custom Classical and Flexible Workflows for User Decision Steps (Outcome Driven Extension Steps) and/or also for context-driven background steps (Context Driven Extension Steps) with SAP Workflow Management / and for SAP S/4HANA (since 2022 FPS03) SAP Build Process Automation.
Single Cross-system (orchestration) processes	SAP BPM	You can extend existing workflows with cloud services using Side-by-Side Extensibility with SAP Workflow Management in SAP BPM (See here the documentation).

Availability of BTP Workflow Extensions with SAP Build Process Automation

The actual availability of extensions for ERP solutions you see here:

Business Event based Side-by-Side Extensions with SAP Build Process Automation for SAP S/4HANA Cloud 2408 with Extensibility Wizard

For event-driven worfklow extensions with SAP Build Process Automation for additional processes on SAP BTP for SAP S/4HANA Cloud (available with 2408) please see the following blogs:

SAP Build Extensibility Wizard for SAP S/4HANA Cloud Public Edition

Creating side-by-side process extensions from SAP S/4HANA Cloud

Process Monitoring Requirements

Use the Process Visibility Capability of SAP Build Process Automation to monitor and control your running process instances (Documentation) Here the actual availability:

Here an overview with example of an integration of a SAP Business Workflow in process visibility on SAP BTP.

SAP Workflow Management retirement and transition to SAP Build Process Automation

Here you find the path forward for SAP Workflow Management customers and in this Blog how to transition to SAP Build Process Automation.

Migration project of existing workflows to SAP S/4HANA / SAP BTP

For Migration projects to SAP S/4HANA please use the following decision tree to decide for each of the existing workflow scenarios you have in SAP ECC / SAP BPM / SAP Business Suite in place.

Generic Approval Inbox

You should choose SAP Task Center as the newest available approval Inbox running on SAP BTP within SAP Build Work Zone [Check here for the actually available task providers and more information] -  or MyInbox in SAP S/4HANA / SAP ECC (in case you need a deep dive look at this training).