This is the second step in building Maps for hopp. In the article Target Map, we desc how the Target Map, based on metadata from the target system, exposes an interface that describes the required data for delivering it to the target system.
Now, let's delve into the Source Map to understand how it transforms and delivers data, conforming to the interface provided by the target system.
The Source Map consists of metadata describing the source system at the top, while at the bottom, we have the target interface exposed by the target map. This hierarchical structure contains various business objects, each with its own set of interface fields.
The task at hand is to assign values to each of these fields. We work on source objects for each business object in the target interface. What does that mean? Well, for a Business Object in the source map, you create a corresponding source map specific to that Business Object.
This Source Map is associated with the respective business object and connects to the metadata in the source system. For example, if we aim to generate one instance of the business object hierarchy for each role in a table, we create a root source object on the source map linked to this metadata structure. There's flexibility to modify this approach, such as applying predicates or other conditions to determine which rows will generate instances of the business object hierarchy.
Additionally, if we need to access data within this structure in the source system, we create another source object on the source map for the corresponding business entity or object. Once added, we must link this source object to the root source object. This linkage determines which fields in the parent source object will be used to look up a role in the child source object. This hierarchical linking can be repeated, defining the relationships from parent to child through source objects.
Connecting a source object to a structure in the source system provides access to the source fields residing within that structure. These source field values can be utilized to calculate the values for the interface fields.
So far, we've covered the process of creating root business objects. But what if it's a child object, like the one mentioned? Well, the initial steps remain the same. We create a source map for the child business object, establishing a root source object connected to a table in the source system.
However, as this is a child object, we now need to specify the link between the parent and child. From the root source object in the child's source map, we connect it to one of the source objects in the parent's source map. Any suitable connection can be established. In this case, let's connect it to the mentioned child source object. Consequently, on this link, we define which fields in the source data metadata structure are used to look up rows in the same structure, allowing us to create instances of the child business object.
Remember, this hierarchy enables the child object to extract data from other structures in the source system.
This article's subject - the Source Map - is also illustrated in this video.