Skip to content
Software Architecture Guide

Application Interface Diagram

Explanation

Section titled “Explanation”

An application interface diagram shows how the applications in an organization work together. Applications appear as boxes. The interfaces between them appear as lines. Each line names the technology the interface uses, for example REST or FTP.

Where the idea appears. Other frameworks use other names. TOGAF has an application communication view. ArchiMate has an application cooperation viewpoint. Both show how applications cooperate. Dependencies between applications are often drawn in one of these two views. (See the articles TOGAF and Architecture Viewpoint.)

Why the technology label matters. A plain cooperation view says only that two applications work together. Showing the technology interface, such as REST or FTP, is a useful addition. Readers then see how the applications talk, not just that they do.

Why it exposes dependencies. A dependency means one element is used to support another. Drawing these links between applications shows which ones rely on which. That makes integration dependencies visible.

How it differs from a C4 container diagram. A container diagram also shows technology choices and how its parts communicate. But it covers one software system. An application interface diagram looks across the applications of the whole organization. (See Container Diagram (C4 Level 2).)

Example

Section titled “Example”

A company has a web shop, an order system, and a warehouse system. The diagram draws one box for each. A line from the web shop to the order system is labeled “REST”. A line from the order system to the warehouse system is labeled “FTP”. A reader sees which application relies on which. They also see that two different technologies are in use.

Trade-offs

Section titled “Trade-offs”

The diagram shows connections and their technologies. It does not replace a view of one system’s internals. For that, a C4 container diagram is scoped to a single software system. Choose the view that matches the question you need to answer.

Generic application interface diagram: three applications, with each interface labeled by its technology.

Diagram source 
flowchart LR
  A[Web shop] -->|REST| B[Order system]
  B -->|FTP| C[Warehouse system]

Checks

Section titled “Checks”
  • Interfaces between applications are labeled with the technology used, such as REST or FTP.
  • The diagram shows dependencies between applications, not only a list of applications.
  • The view is scoped to the application landscape, not to the internals of one software system.
Section titled “Related”

Sources

Section titled “Sources”