L4 – Logical Activities

The L4 Logical Activities View specifies solution-independent operational activities that are normally conducted in the course of achieving a mission or a business goal. L4 also specifies the logical flows produced and consumed by the activities.

Concerns Addressed

  • Process Modelling.
  • Operational Planning.
  • Concept of Operations.
  • Service Orchestration.

Background

The L4 View describes the operational activities that are being conducted within the mission or scenario. These activities are defined at a logical, solution-neutral level so as to enable different solutions in the Physical layer.

The L4 View describes the activities associated with the logical architecture, as well as the:

  • Relationships or dependencies among the operational or business processes.
  • Information exchanged between operational or business processes.
  • External interchanges (from/to operational or business processes that are outside the scope of the architecture).

An operational activity is a logical process, specified independently of how it is carried out. To maintain this independence from implementation, logical nodes in the L2 View are used to represent the structure which carries out the operational activities. Operational activities are realised as resource functions (P4) which are the “how” to the Operational Activities’ “what” – i.e. they are specified in terms of the resources that carry them out.

Usage

  • Requirements capture.
  • Description of business processes and workflows.
  • Operational planning.
  • Logistics support analysis.
  • Information flow analysis.
  • Support task analysis to determine training needs.

Representation

  • Hierarchy chart.
  • IDEF0 Diagram.
  • UML activity diagram.
  • UML activity diagram (with swim-lanes)

Detailed View Description

Standard Operational Activities from C4 may be re-used in L4. Standard operational activities are those defined in doctrine, but which are not tailored to a specific requirement, i.e. they may be used across multiple logical architectures.

There are two basic ways to depict activity models:

  • The activity hierarchy shows activities depicted in a tree structure, as shown in Figure 3-312. It helps provide an overall picture of the activities involved and a quick reference for navigating the L4 input/output flow model.

    FIg 3-312

  • The activity flow diagram shows activities connected by information flow arrows, see Figure 3-323. Input/outputs of operational activities relate to information elements of L3, Node Interactions, and are further characterised by the information exchange attributes.

Figure 3-323

Operational activities may consume or produce information / resources. When these cross node boundaries, they are carried by logical flows shown in the L2, Logical Scenario. In this way the L4 can contribute to information exchange requirements analysis. Annotations to the activities may also identify the costs (actual or estimated) associated with performing each activity. The business rules that govern the performance of the activities can be keyed to each activity - the business rules may be described in L8, Logical Constraints. In addition, a process flow model may be annotated with the names of the nodes responsible for conducting those activities, in swimlanes. As with L2, Logical Scenario, and L3, Node Interactions, flows on the L4 may also carry materiel, human resources or energy.

If the UML method is used, the activity model can include decision points and branching.

Fig 3-34

If the architect is developing a service-oriented architecture, the L4 may be used to show which services are required to support the conduct of operational activities. It helps define what services are needed to support an operation and when they are needed.

Figure 3-335: Example P4 View with Services (TBD)

Key Elements and Their Relationships

Figure

Meta-Model

The detailed meta-model and element list for L4, Logical Activities, is at paragraph 4.4.4.