LEVEL 5: Models are produced by business analysts and provide an informal description of the problem at a high-level of abstraction, that is, with no notion of applications, message flows or technology like software ecosystems. Models are specified in natural language and normally suffer from imprecisions, omissions and ambiguities.
LEVEL 4: Here models are considered CIMs. They are refinements of models from level 5, produced manually by business analysts and expressed in standards like BPMN. The notions of participating applications (source and consumer of data) and message flow appear at this level; yet the model does not capture core domain specific design concepts like the internal structure of the solution or the communication with its applications. The absence of these concepts prevents their programmatic transformation into executable models.
LEVEL 3: Models of this level are produced from models of level 4 manually by system analysts with expertise in EAI solutions. They precisely specify the functionality and structure of the solution in a manner that it can be programmatically converted into PSMs of level 2. So they deal with concepts at the granularity of applications, processes, tasks, message flow, integration links, ports, wrappers, etc. These models are expressed in a DSL with built-in constructs to describe all the EAI specific concepts listed above.
LEVEL 2: Models of this level result from automatic conversion of models from level 3; they are PSM and can be mapped into executable code of the chosen technology.
LEVEL 1: Models of this levels are the actual executable code of the solution and are programmatically generated from models from level 2.