If we assume the different parts of a cross-system business application and their interactions are “hard-coded” on the individual systems that the process spans, then every change at the technical implementation level (such as changing a server address) entails a change to the whole business process. This is time consuming, error prone, and does not scale for complex business processes and large system landscapes. Therefore, one basic principle of SAP NetWeaver PI is to de-couple the business semantics from the technical details of the concrete system landscape.
Business semantics are, for example, the business flow of a process and its separation into individual application components, as well as the structure of exchanged data. These aspects of a business process are merely determined by business considerations rather than by details of the implementation or of the concrete system landscape.
Design Time, Configuration Time, and Runtime
Based on this de-coupling, it is possible to describe the integration-relevant aspects of a business process at an abstract level first – irrespective of the details of a particular system landscape. We call the corresponding phase of an integration project the design time. In other words, at design time, you can specify an integration scenario independent from any technical details that are implementation-relevant or system landscape-relevant.
In a later phase – at configuration time – the integration scenario will be configured such that it runs in a specific system landscape. The phase when the integration scenario is executed is referred to as runtime. You can consider one and the same integration scenario being deployed on completely different system landscapes. For example, in one case there is a material management integration scenario that spans only a few systems within a midsize company, whereas in another case the same integration scenario spans several hundreds of systems located in the different departments of a large enterprise. The same scenario in this case involves the execution of the same business logic – just on a different scale. The scenario is finally executed at runtime and can be monitored by an administrator.
The following figure illustrates the relationship of the design time and runtime view:
Comparison of Design Time and Runtime View
The upper part of the figure shows an interaction of two application components as modeled at design time. As an example, the left application component sends a request to the right one. You can consider this interaction as one little part of an integration scenario.
At configuration time, this interaction is configured in a way that it runs in a specific system landscape.
The lower part of the figure shows the runtime view which results out of the configuration time activities. The system landscape in general is composed of many business systems.
For the request-response interaction outlined in the figure, the business logic of the requester application component is deployed on (one or more) sender systems, and the business logic of the responding application component is deployed on (one or more) receiver systems. The communication of sender and receiver systems is mediated by the SAP NetWeaver PI runtime.
The three phases introduced here can be considered to be phases of an integration project.