Hybrid SUV example: provided/required DirectedFeatures (Internal Definition Diagram)

On the previous IBD with provided/required Interfaces all one could see was the name of the Interfaces, not the underlying operations. Not so with SysML DirectedFeatures! Note how in SysML the directed features can be exposed in an IBD in special compartments on the Ports (in this case :values and :operations) that expose the features of the underlying Types of the Ports. This capability is extremely powerful!

SysML-1.6: 'SysML permits any property shown on an internal block diagram to also show compartments within the property box. These compartments may be given standard or user-customized labels just as on block definitions.'

SysML-1.6: 'All features shown within these compartments shall match those of the block or value type that types the property.'

SysML-1.6: 'The label of any compartment shown on the property box that displays contents belonging to the type of the property is shown with a colon character (“:”) preceding the compartment label. The compartment name is otherwise the same as it would appear on ...'

It can, however, be a bit tricky activating this in the tool until you know where to look:

MagicDraw/Cameo: the (not so well named) "Enable Parts Compartment" feature on Ports is highly recommended and can make diagrams much easier to read.

The MagicDraw/Cameo feature "Enable Parts Compartments" really means "Enable SysML Compartments"

The SysML spec supports exactly what any engineer would wish, indeed it's actually a modeller's dream come true:

SysMLv1.6 Provided/required DirectedFeature contracts for ProxyPorts SHOULD be satisfiable Feature-wise (including as subsets of Features) not necessarily just at the level of entire Blocks (types)! [See also the SysMLv1.7 spec changes.]

Webel: SysML1.7: Port contract matching is Feature-based, not Type-based. There's nothing particularly magical or special about use of an ~InterfaceBlock on a "conjugating" SysML Port, it's just a convenient way of managing one-to-one Feature matching!

The tool support to fully match this promising capability is still lagging a bit:

MagicDraw/Cameo 19SP3: Does not yet handle Feature-wise validation of provided/required DirectedFeature contracts (it only handles them at the level of entire Block types). Webel asserts the spec is inconsistent w.r.t. ProxyPort connection compatibility.

However, from a pure drawing and modelling perspective the tool support for SysML DirectedFeatures is already excellent. Dr Darren says:

I was a big fan of provided/required Interfaces for UML-driven software engineering; SysML DirectedFeatures are better! And the notation is much better for communicating with a wide range of stakeholders. This is one of the best capabilities of SysML, and it will help revolutionise model-driven systems engineering.

Up next

UML provided/required Interfaces vs SysML DirectedFeatures on Ports

Notes

[MODELLING, STYLE]{RECOMMENDED} SysMLv1: Prefer not show Port symbols on the boundary of Block symbols in BDDs, just list them in compartments. One can't connect them in a BDD anyway. Recommend only show Port symbols in IBDs.

[NAMING, POLICY]{STRICT} For SysML Blocks and InterfaceBlocks used to type Ports with contracts use the naming convention 'I_UpperCamelCase' [may be combined with acronymn conventions]

[ASSERTION, TIP] You can't make connections in BDDs, only in IBDs. A BDD shows where connections may be made, an IBD shows where specific connections have been made in a specific context!

[CAPABILITY, DISPLAY, TOOL] MagicDraw/Cameo: the (not so well named) "Enable Parts Compartment" feature on Ports is highly recommended and can make diagrams much easier to read.

[CAPABILITY, DISPLAY, TOOL] The MagicDraw/Cameo feature "Enable Parts Compartments" really means "Enable SysML Compartments"

[ASSERTION, WISHLIST] SysMLv1.6 Provided/required DirectedFeature contracts for ProxyPorts SHOULD be satisfiable Feature-wise (including as subsets of Features) not necessarily just at the level of entire Blocks (types)! [See also the SysMLv1.7 spec changes.]

[ISSUE, TOOL] MagicDraw/Cameo 19SP3: Does not yet handle Feature-wise validation of provided/required DirectedFeature contracts (it only handles them at the level of entire Block types). Webel asserts the spec is inconsistent w.r.t. ProxyPort connection compatibility.

Snippets (quotes/extracts)

[SysML-1.6] [SysML1.6: PREFER SysML1.7] A DirectedFeature indicates whether the feature is supported by the owning block (provided), or is to be supported by other blocks for the owning block to use (required), or both ...