An  Application is a Business Software System that provides a set of  Functionality(ies) that End Users see as a single unit.

Essentially  Applications are architectural constructions resulting from the combinaison of the following four criteria:

1) A group of  Functionality that End Users see as a single unit.

2) A managed asset (Managed Application) associated with a budget line in the context of an Application Portfolio.

3) A body of code that is seen by developers as a single unit.

4) A group of deployable software units (Deployable Application Packages) that must be installed together on one or multiple execution nodes (Computing System).

 Application is a Mezzo enterprise asset  that sits between Application System and Application Component in the decomposition of Business Software Systems.

Example: " Payroll" is an  Application that is part an " HR System" which is an Application System.

The "Payroll"  Application includes, among other things, the "Salary and Wage Calculation" Application Component.

An  Application Component is a functionnal unit of software (java class, COBOL Program, Batch) that is  a consistent, indivisible unit of processing of an Application producing and consuming its Information Outcome Events though APIs (Application Interface).

a)  Application Components are assembled and orchestrated in Applications.

b)  Application Components cannot be directly deployed to Computing Systems: they need to be organized in Deployable Application Packages.

 Application Component is a Micro enterprise asset that sits at the lowest level of Business Software System decomposition.

Example: the "Salary and Wage Calculation" component is an  Application Component that is part of the "Payroll" Application.

A  MicroService is a small autonomous unit of software, emphasizing self-management and lightweightness as the means to improve software agility, scalability, and autonomy.

1)  MicroServices are automous or assembled and orchestrated as components of Applications.

2)  MicroServices can be directly deployed to Computing Systems.  MicroServices are both a logical unit of software and a Deployable Package.

3)  MicroServices owns their own data store and dot not have any shared stores with other components.

 MicroService is a Micro enterprise asset that sits at the lower level of Business Software System decomposition.