External links
About this task
Map components and subsystem components are the fundamental building blocks of a system. The Integration Flow Designer uses links to display data flow relationships among these components. A link that is displayed between two system components is called an external link because the link is not an integral part of either component. An external link represents the fact that one of the components produces a data target and the other component uses this data as a source.
An external link can connect a map component to another map component, or a map component to a subsystem component, or a subsystem component to a subsystem component. External links are represented by a solid, directed line. An example follows. The map components are expanded, indicating that the internal links are visible. A visual clue that indicates a component is expanded is that the name is displayed in bold text. When the component is not expanded, the name text is regular, not bold.
Results
An external link conveys more information when the map components that it connects are expanded. In this example, you can explicitly view which targets of one component feed which sources of the other component. When a link is displayed between contracted map components, the link implicitly displays the data flow relationship between the two components.
The Integration Flow Designer automatically derives and displays an external link between two components that share common resources as sources and targets. As with internal links, the Integration Flow Designer uses information in the referenced source map or compiled map files together with any source and target overrides that you may have specified to determine if any two components in a system definition file have a data flow relationship.
The Integration Flow Designer automatically derives and displays database links, messaging links, and file links.
A database link is drawn between two map components when the Select statement defined in the database source of one of the maps references the table associated with the database target of another map. You can view the links explicitly if both map components are expanded.
A messaging link is drawn between two map components when the messaging source of one of the maps references the messaging target of another map.
A file link is created between two map components when the file named in the source of one of the maps references the same file in the target of another map.
Changing the default sources or targets defined within a source map or compiled map file using the Map Designer, or changing the source or target overrides by using the Integration Flow Designer has a direct effect on the external links that are drawn.
The Integration Flow Designer prevents you from deleting external links that it has automatically derived. You must either delete one of the components or change the source or target settings to remove an external link.