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This is not so much a programming question as it is a question about modelling. But you could argue that modelling is an integral part of programming.

In SDL it is possible to annotate "communication lines" between blocks (processes, services) with signal list. This is very convenient for developers because it informs them about which types of signals (messages in my case) a block either sends or accepts. (see also wikipedia on SDL and communication between blocks)

I can't find a similar notion in SysML. Either I've to introduce a new class for each signal and use a class (interface) to represent a list, or I need to define an interface class with methods, each representing a signal?

I was a bit surprised it is so difficult to find, because in the development of SysML, the ITU (i.e. the original makers of SDL) purportedly were a stakeholder in the definition of SysML.

I'm looking not for "something that works", but for a readily and widely accepted (say, canonical) way of defining signal lists for SysML blocks.

Anyhow, anyone any idea?

Thanks!

BTW: a suggestions for redirects to more appropriate SO sites is welcome.

nanitous
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In SysML block element is consists of various compartments, one of such compartments is signal compartment where both input and output signals can be defined.

In a case where you need to define a concrete subset of signals for a purpose of concrete communication case, you need to define an interface block and a corresponding port (proxy or not) that includes input and output signal that supposed to appear when a communication is occurred via the channel that block represents.

In general, if you want to simplify a model and if you can afford such a simplification, an interface and a port could be omitted, then the whole block element can be treated as a "port" with an "interface" defined by its compartments. Such blocks then can be connected directly on IBD in a way to transmit only a subset of signals.

I would like to recommend A Practical Guide to SysML, The Systems Modeling Language – Sanford Friedenthal, Alan Moore, Rick Steiner books as a massive source of practical explanations and examples of modeling approaches in a scope of SysML applications.

masted
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  • Hi @masted, thanks. That could work indeed. I didn't realise that blocks also could be used to represent an interface. That is a key idea I missed. – nanitous May 21 '20 at 09:04
  • @nanitous yeah, blocks are pretty generic modelling elements, you can think about plain block as of a "thing" or an "object" composed of structural and functional features (the difference between these thing is a topic of systems theory itself, so let me omit this aspect in the comment) , where both a structure and a function could be trivial or empty. So that, in fact, blocks can represent anything: systems, structures, behaviours, interfaces, protocols, contexts, projects, actions, etc. etc., you name it... by stereotypes. :) – masted May 22 '20 at 12:21