Application Deployments define the package of software components that make up an application in a particular environment, e.g. development or production. A layered application is to deploy everything to a single server. This is called the single-tier or monolithic approach.
Application layer Architecture
User Interface (or Presentation Layer)
Responsible for showing information to the user and interpreting the user’s commands. The external actor might sometimes be another computer system rather than a human user.
Application Layer
Defines the jobs the software is supposed to do and directs the expressive domain objects to work out problems. The tasks this layer is responsible for are meaningful to the business or necessary for interaction with the application layers of other systems. This layer is kept thin. It does not contain business rules or knowledge, but only coordinates tasks and delegates work to collaborations of domain objects in the next layer down. It does not have state reflecting the business situation, but it can have state that reflects the progress of a task for the user or the program.
Domain Layer (or Model Layer)
Responsible for representing concepts of the business, information about the business situation, and business rules. State that reflects the business situation is controlled and used here, even though the technical details of storing it are delegated to the infrastructure. This layer is the heart of business software.
Infrastructure Layer
Provides generic technical capabilities that support the higher layers: message sending for the application, persistence for the domain, drawing widgets for the UI, and so on. The infrastructure layer may also support the pattern of interactions between the four layers through an architectural framework.
