Basics of Automation Orchestration in SAP DM: Web Servers, Services, and Production Processes

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SAP Digital Manufacturing (DM) increases industrial productivity by converging business capabilities (IT) with connectivity and automation capabilities (OT):

• Top-Floor-to-Shop-Floor Connectivity: Using the Production Connectivity Model, you can connect various systems, assets, and web servers for seamless data and service exchange from top floor business applications to shop floor machine operations.
• End-to-End Automation: Using the Production Process Designer, you can orchestrate services from various web servers to model production processes, then deploy them to automate manufacturing operations from raw material to finished goods, including the automation of physical assets, such as complete robot cells, machineries, conveyor belts, and other equipment.

A production process is a chain of actions that aims to complete a business purpose through a series of service calls. You can create a production process with service calls across the landscape of systems on the top floor and shop floor. The following graphic shows production processes for automating engraving activities.

Note: With production processes, you can also control the flow of operations based on your business logic using control elements such as Script Task, Condition, and Error Catch. For more information, please refer to the official Help Portal Production Process Designer documentation.

Figure 1: Routings, cloud-based production processes, and shop-floor-based automation sequences.

Connectivity is the foundation of automation. To automate processes across your cloud-based systems, on-premise systems, and shop floor systems, you must connect the systems with each other so that they can call each other’s services. In Setting up Shop Floor Connectivity, we’ve explained how to establish a secure connection between a shop floor system and SAP DM using the Production Connector and the Cloud Connector, and how to connect a device on the shop floor using the asset model to read its tags.

Note: There are built-in services for both reading and writing indicators. For more information, refer to Available Services and Subprocesses.

After connecting systems and assets, you can create and connect various web server objects, register the services provided by them, and use the services across your system landscape to create production processes.

In this blog, we’ll explain the conceptual basics of services, web servers, and production processes, the building blocks of automation orchestration.

1 - Service Registry

The service registry hosts all necessary (meta-)information on services across the customer’s system landscape, including shop floor, top floor, on-premise, and in the cloud. This information is essential for calling a service and includes details such as its endpoint, input and output payloads, and failure codes. To make a service available for orchestration in the Production Process Designer, you must register it in the service registry by providing its (meta-)information.

Figure 2: A screenshot of the Manage Service Registry app showing a registered service’s meta-information.

2 - Web Servers

Web servers are systems that offer REST-based and ODATA-based services.

Setting Up Web Servers

In the Manage Web Servers app, you can create digital twins of your physical web servers by providing their (meta-)information and the services they host. The app distinguishes different types of web server objects.

You can manually create web server objects of types “Cloud services” and “On Premise services”:

• Cloud services:
  This type of web server object represents cloud-based web servers. They offer REST-based services in the cloud (e.g., SAP S/4HANA Cloud).
• On Premise services:
  This type of web server object represents on-premise-based web servers. They offer REST-based services in the local on-premise network (e.g., an on-premise EWM system, a LIMS system, or a local AGV control offering its functionality via REST)

Some web servers can also host a process runtime, a component that enables the execution of production processes. Process runtimes are offered on DM in the cloud and on the edge, known as the “Process Engine”. They are also offered on Production Connectors, which can be edge-based or standalone MS Windows-based.

These process runtime web servers (hereafter referred to as runtime servers) are represented by web server objects of types “SAP Digital manufacturing services”, “SAP Digital Manufacturing for edge computing services”, “Production Connector services”, and “PCo services” (legacy). They are automatically created when you onboard these systems.

Figure 3: A screenshot of the Manage Web Servers app showing different types of web server objects.

Assigning Services to Web Server Objects

You can assign services to web server objects in the Manage Service Registry app. You can also deactivate services in a web server object in the Manage Web Servers app.

Figure 4: An example of available web servers and services. You can assign services to the web servers that provide them.

Connecting Runtime Servers with Web Servers

A runtime server can call services offered by itself, as well as services offered by web servers directly connected to this runtime server. To call services from a runtime on a remote dedicated web server, you must connect this runtime server object to the web server object in the Manage Web Servers app.

Figure 5: An example network of connected web server objects. The web servers that host process runtimes are DM, Production Connector A, and Production Connector B. In this scenario, DM can call services offered by itself, Production Connector A and B, and the 3rd party web server. Production Connector B can call services offered by DM, ME, and the 3rd party web server.

Note: When the runtime server is a Production Connector, you can explicitly select which services you want to call from it and then deploy them to the Production Connector. For more information, refer to Adding and Deploying Services from a Connected Web Server.

Note: As service providers, web server objects are counterparts of OPC server objects in the Configure Production Connectivity app. OPC servers use OPC discovery to detect available services. For more information, refer to Configuring Services in Service Provider.

3 - Production Processes Designer

You can use the Production Process Designer to create production processes and deploy them to their designated runtimes.

Note: A process deployed to the Process Engine on Cloud or Edge is typically called a production process, while a process deployed to the Production Connector is referred to as an automation sequence.

Creating and Deploying Production Processes

To create a production process, you first select the runtime environment where the production process will be executed. You can only use services offered by the runtime server itself, or services offered by web servers directly connected to this runtime server. For more information, refer to Available Services and Subprocesses.

The available services are shown in the Services and Processes toolbox section of the Design Production Processes app. Services with web server assigned are grouped in root nodes while services without web server assigned are put under one independent folder.

Figure 6: A screenshot of the design interface of the Design Production Processes app.

Figure 7: In this scenario, we create three production processes “PP” for the DM runtime, “Sub PP 1” for the Production Connector A runtime, and “Sub PP 2” for the Production Connector B runtime. Because “PP” is to be deployed to DM runtime, we can only use services offered by DM itself, Production Connector A and B, and the 3rd party web server to create it.

Figure 8: After creating the production processes, we deploy them to their designated runtimes for execution.

Next Steps

In the following blogs in our series, we’ll showcase how to create and call production processes in different ways to automate manufacturing processes.

For more information, refer to the user assistance for SAP Digital Manufacturing on the SAP Help Portal.

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