HOPEX IT Architecture V2 > Architecture Specification > Modeling Applications and System Architectures > Describing System architecture > Describing an Application System Environment with HOPEX IT Architecture
Describing an Application System Environment with HOPEX IT Architecture
*An application system environment allows presenting the other application systems, applications or micro-services with which this application system can interact.
Accessing the list of application system environments
To access the list of application system environments from the Application navigation pane:
1. Select Hierarchical View.
2. Expand the Application System Environments folder.
The tree of application system environments appears in the edit area.
Creating an application system environment
To create an application system environment:
1. From the Applications navigation pane, select Application Hierarchy.
2. Expand the Application System Environments folder.
The tree of application system environments appears in the edit area.
3. Select the Application System Environment folder and click New > Application System Environment.
The Add of Application System dialog box appears.
4. Select the application system that is the subject of the environment and click OK.
The new application system environment appears in the list, it has the name of the application system followed by "Environment".
Application system environment properties
The Characteristics properties page for an application system environment provides access to:
• its Owner, by default during creation of an application system environment, the current library.
• its Name,
• the text of its Description.
• The Owned Realization section is used to connect the described application system environment to element representing needs or constraints.
For example,the application system environment can be connected to a functionality map.
*For more details on the realization concept, see Using fulfillment mechanisms
With HOPEX IT Architecture an application system environment is described by other property pages. See HOPEX IT Architecture properties pages content.
Application system environment diagrams 
An application system environment is described by several types of diagram:
• an Application System Environment diagram describes the exchanges between the subject application system and its partners in a specific context.
• a scenario of application system environment flows presents the flows exchanged between the application services or the micro-services used by the described application system in a specific context.
Describing an application system environment diagram 
An application system environment is described by an application system environment diagram that describes the interactions between the internal application systems, its users and the partner application systems.
*For more details on use of a structure diagram, see Application structure diagram
Application system environment diagram for the Purchasing Requests
Purchase requests are formulated by clients or employed using the "Purchasing Management Platform".
The "Purchasing Management Platform” application system uses an internal application system for the “Payment management” and a partner application system for the “Delivery”.
The elements of an application system environment diagram are:
• the main application system principal described by the environment.
*An application system is an assembly of other application systems, applications and end users interacting with application components to implement one or several functions.
• partner application systems that represent the other application system with which the main application system described by the environment interacts.
In this example, this concerns two loan services offered to individuals and companies.
*A partner application system is an application system external to the environment of the described application service. The partner application system can be a service supplier or a service consumer with respect to application system users.
• The categories of users of services provided by the environment are represented either by an Org-Unit or by a Position Type.
*An org-unit represents a person or a group of persons that intervenes in the enterprise business processes or information system. An org-unit can be internal or external to the enterprise. An internal org-unit is an organizational element of enterprise structure such as a management, department, or job function. It is defined at a level depending on the degree of detail to be provided on the organization (see org-unit type). Example: financial management, sales management, marketing department, account manager. An external org-unit is an external entity that exchanges flows with the enterprise. Example: customer, supplier, government office.
*A position type represents a status assigned to an individual or a group of individuals with the aim of defining an organization or a hierarchy.
This concerns two user categories: individuals and companies.
• interactions between components
*An interaction represents a contract established in a specific context between autonomous entities that are internal or external to an enterprise. These entities can be enterprise org-units, applications, activities or processes, as well as external org-units. The content of this contract is described by an exchange contract.
Describing a Scenario of Application System Environment Flows 
A scenario of application system environment represents the flows exchanged between the components of the application system environment.
*For more details on use of a scenario of flows, see Using a Scenario of Application Flows Diagram
The elements of a scenario of application system environment are:
• the main application system principal described by the environment.
*An application system is an assembly of other application systems, applications and end users interacting with application components to implement one or several functions.
• partner application systems that represent the other application system with which the main application system described by the environment interacts.
*A partner application system is an application system external to the environment of the described application service. The partner application system can be a service supplier or a service consumer with respect to application system users.
• End User Participants that represent the categories of users of application system provided by the environment.
• The categories of users of services provided by the environment are represented either by an Org-Unit or by a Position Type.
*An org-unit represents a person or a group of persons that intervenes in the enterprise business processes or information system. An org-unit can be internal or external to the enterprise. An internal org-unit is an organizational element of enterprise structure such as a management, department, or job function. It is defined at a level depending on the degree of detail to be provided on the organization (see org-unit type). Example: financial management, sales management, marketing department, account manager. An external org-unit is an external entity that exchanges flows with the enterprise. Example: customer, supplier, government office.
*A position type represents a status assigned to an individual or a group of individuals with the aim of defining an organization or a hierarchy.
• interactions between components
*An interaction represents a contract established in a specific context between autonomous entities that are internal or external to an enterprise. These entities can be enterprise org-units, applications, activities or processes, as well as external org-units. The content of this contract is described by an exchange contract.