Example: 

stage("Stage A" ) {
node { echo "Task of A"}
}
stage("Stage B") {
parallel ('Parallel B.1':{
node { echo "Step of Parallel B.1"
echo "Expect only Stage B or ok, since parallel is not wrapped in a stage Parallel B.1"
}
}, 'Parallel B.2':{
node { echo "Step of Parallel B.2"
echo "Expect only Stage B or ok, since parallel is not wrapped in a stage Parallel B.2"
}

})
}
stage("Stage C" ) {
node { echo "Task of C"}
}

Blue  Ocean show's see attachment ex1.png

I would be ok with only Stage B, but since not stage word is enclosed ok.

Example: 

stage("Stage A" ) {
node { echo "Task of A"}
} 
parallel ('Parallel B': {
stage ("Stage B") { node { echo "Task of Stage B" 
echo "Would expect Stage B instead of Parallel B"
} }
}, 'Parallel C':{
stage ("Stage C"){node { echo "Task of Stage C"}
echo "Would expect Stage C instead of Parallel C"
}
})
stage("Stage D" ) {
node { echo "Task of D"}
}

Blue Ocean show here see attachment ex2.png

Here i would clearly expect Stage B and Stage C instead of Parallel B and Parallel C.

Example : 

stage("Stage A" ) {
node { echo "Task of Stage A"}
}
parallel ('Parallel B': {
stage ("Stage B") { node { echo "Task of Stage B"
echo "Would at least expect to see Stage B Parallel to Stage C"
} }
}, 'Parallel C':{
stage ("Stage C"){
stage ("Stage C.1") {node { echo "Task of Stage C.1"
echo "Would at least expect to see Stage C Parallel to Stage B, if not Stage C.2 in sequence to C.1"
}
} 
stage ("Stage C.2 ") {node { echo "Task of Stage C.2"
echo "Would at least expect to see Stage C Parallel to Stage B, if not Stage C.2 in sequence to C.1"
}
} 
}
})
stage("Stage D" ) {
node { echo "Task of Stage D"}
}

Blue Ocean show here see attachment ex3.png

Would at least expect to see Stage C Parallel to Stage B, if not Stage C.2 in sequence to C.1 parallel to B. For me the fact that Parallel B and Parallel C are shown is clearly a conceptional break with regard to Stage A and Stage B: the keyword parallel and stages are two completely different conceptional entities. 

Somewhat more complicated : 

stage ("Stage A") { node { echo "Task of Stage A"} }
parallel ('Parallel A ': {
stage ("Stage A") { node { echo "Task of Stage A"
echo "Expect to see Stage A in Parallel with Stage B"
} 
}
}, 'Parallel B':{
stage ("Stage B"){
stage ("Stage B.1 ") {node { echo "Task of Stage B.1.1"
echo "Expect to see Stage A in Parallel with Stage B at least"
echo "Possibly Stage A in Parallel with a Sequence of B.1, B.2, B.3"
}} 
stage ("Stage B.2") {node { echo "Task of Stage B.1,2"
echo "Expect to see Stage A in Parallel with Stage B at least"
echo "Possibly Stage A in Parallel with a Sequence of B.1, B.2, B.3"
}} 
stage("Stage B.3") {
parallel ('Parallel B.3.1':{
node { echo "Task of Stage B.3, Parallel B.3.1"
echo "Expect to see Stage A in Parallel with Stage B at least"
echo "Possibly Stage A in Parallel with a Sequence of B.1, B.2, B.3"
echo "Possibly Stage A in Parallel with a Sequence of B.1, B.2 in Parallel with a sequence of B.3.1, B.3.2 "
}
}, 'Parallel B.3.2':{
node { echo "Task of Stage B.3, Parallel B.3.2"
echo "Expect to see Stage A in Parallel with Stage B at least"
echo "Possibly Stage A in Parallel with a Sequence of B.1, B.2, B.3"
echo "Possibly Stage A in Parallel with a Sequence of B.1, B.2 in Parallel with a sequence of B.3.1, B.3.2 "
}
}) 
}
}
stage ("Stage C") { node { echo "Task of Stage C"} }

})
stage("Stage D" ) {
node { echo "Task of Stage d"}
}

See attachment ex4.png

 Here the conceptional break of visualizing stages and parallel is even clearer from my point of view. At the least i would expect to see Stage A in parallel with Stage B. The visualization of  Parallel A being parallel with B.3.1 and B.3.2 is misleading, resp. is pure coincidence if it is. 

Hi Christoph Henrici,

I had a very similar thought a few months ago. I pulled this document out of our internal wiki and made it publicly available.

Let me know what you think.

Thanks,
James

very interesting Christoph Henrici

James Dumay that's a very valid proposal. If i understand correctly the key word parallel would be in the long run ignored in Blue Ocean visualization except for before stages also for scripted pipelines. 

"Parallel execution is used to speed up the execution of the pipeline by having different parts run in parallel. They have little or no bearing on the stage flow graph and in generally not useful to visualise." Absolutely agreed. 

And with this approach , if a developer finds parallel processing important to visualize he can use the proposed syntax

Christoph Henrici great to hear that you concur!

Parallel Stage syntax from Declarative is made available for scripted Pipelines.

does not make sense. Scripted is a superset of Declarative so of course you can already decide in a scripted Pipeline whether to introduce a stage in each branch or not. No changes to the parallel step are required or advisable.

This doesn't make sense to me – the parallel construct is heavily used and works in its intended role.  What isn't fully supported is nesting, but parallel branches are labelled for a reason. 

The better solution is to fully support nesting, or ensure that for Scripted pipelines Blue Ocean does the same hack on Parallels with nested Stages that it does with Declarative. 

Better yet, let the UI support nesting fully, but with the UX showing "Parallel A { Stage A {" as one branch if there are no other stages/parallels nested inside the parallel (to reduce visual clutter).   The lower-level APIs are all written to permit nesting of any stage/parallel combo – it just isn't propagated up to the UI because that lacks support.

I see justification for both argumentations of Sam Van Oort and James Dumay. The difference is a matter of emphasis, priorisations and feasibility. The main point being though what you want to vizualize. And here i my opinion is unchanged. Parallel is a adjective:  it's  parallel somethings ,  parallel stages , parallel steps , parallel tasks,  parallel processes, whatever... so you want to vizualize stages, steps as node and additionally the fact that they are parallel in ralation to other stages , tasks. You do NOT what to vizualize parallel as a node itself, which is want currently is happening in Ocean View.