To bind an API to the system providing it, the endpoint concept is used. Endpoint is described either by an address with a port, or MMT, hiding them. APIs are described by a machine-readable description (declaration), for example Java interface and WSDL document.

The API life cycle is close in stages to the software life cycle and the following cycle stages can be outlined: requirements gathering, interface design, implementation, testing, operation, and decommissioning stages: decommissioning warning (marked as obsolete to avoid new users), decommissioning (tracking the decrease of existing users), disposal (closing access to the API and removing it), and the stage of creating a new version. The new version of the API can be compatible and incompatible with the old one, for this you can differentiate them by semantic versioning into incompatible with the previous version, compatible with the previous version and bug fixes. By semantic versioning, the version can be written as "major.minor.patch", for example 1.9.0 – > 1.10.0 – > 1.11.0.

The solution integration layer is described in the conceptual architecture. The conceptual framework only indicates integration. It is intended for coordination with stakeholders: architects of the integrated solution, corporate architect responsible for the landscape, product owners, owner of the variable landscape, security service, resource provision service (infrastructure department) for its quick approval. The content is indicated in the target architecture (detailed architecture) of the solution. She participates in the early stages of creating a service and in the acceptance tests of the solution within the framework of architectural control. The conceptual architecture is the source of artifacts for implementing and developing a detailed solution architecture. We can distinguish the following stages of creating a conceptual architecture: planning, creation, development of an incremental draft (sketch), approval, revision. In order for the diagrams to be understood by both the developer and the owner of the product, a short description (Architecture Decision Records, ADR) is needed: the goal, the essence of the solution, rejected options, rationale, consequences, affected systems, a link to the diagram and the originator's contacts.

The corporate data bus is usually used to connect individual systems. For connections within the system – point-to-point network connection and their control using integration gateways. Integration gateways can and can be used between systems, but often, these systems are not protocol compatible and require their transformation, which is provided by the corporate data bus, but not provided by the integration gateway. And the use of a corporate data bus to connect the components of one system is expensive, since the asynchronous protocol will be loaded by other systems due to the fact that the message queue that implements it will be filled with messages from other systems and subsequent messages will wait for their sending, which causes delays in data transmission… For the exchange of large amounts of data between systems and within systems – distributed information storage.

With the layers we figured out, now, imagine the architecture as a layer cake. We can cut off a piece from it and narrow it down in more detail, but the number of layers in all pieces of this pie will be the same. By analogy, we can divide the corporate architecture into chunks. These pieces can be separate systems that are directly used on the business layer, or it can be a group of these applications developed by some department or department. The pie itself is the corporate architecture, and the piece is the solution (service) architecture. Enterprise architecture appears when we need to add new pieces to the pie, while the pieces are the architecture of the solution, and the rules according to which are made, for example, the number of layers – corporate architecture standards, cakes and cream – providing technologies for corporate architecture.