Using a request/response pair to share data between logic apps
There are times when the opposite is true – you want to send a message and you are expecting a return in good time. Here, you may just want a child logic app at the heart of it all, or an Azure Function as the engine for your processing. In my example and sticking with contacts, now I know that an action has taken place, and which Contact this affects, I have created a GetContact logic app that will perform an HTTP API POST call back to the legacy system to obtain the contact records. From here, I can pick out the new field, reformat the data, and then pass it into my new system (in my case, the contact's record in D365).
In the middle of my child logic app, which is designed to create a contact detail line, I have an HTTP action to the GetContact logic app. This performs the record lookup in the legacy system: