| Branches and connections - a neverending story [message #79] |
Fri, 11 June 2004 11:05  |
Volker Knollmann
Messages: 32
Registered: October 2003
|
Member |
|
|
Hello,
I just was preparing some RailML-example-code and had a close look at
the current schema (0.94_18) when I came across some difficulties
related to switches, branches and connection. The problems refer to
Matthias' posting from April 13.
Like Matthias, I don't understand the neccesarity for <singleCrossOver>.
In fact, it is a switch, so why don't we use the <switch>-element?
Additionally I found that using the current syntax, we always have to
include two <branchConnection>-elements with the same contents (one in
each <track> of the branch). This creates unneccessary redundancy.
My suggestion to reduce the complexity of branches and connections is:
* skip <singleCrossOver>
* use <switch> for every kind of branch
* rename <connections> to <switches> and make it an ordinary container
element
* make <branchConnection> a child of <tracks> to include it only once
per branch. Introduce an appropriate container element.
I think, the last point makes sense. Since a branch connects TWO tracks,
it should NOT be a child of a track. It should be a sibling of <track>.
Here's a very simple example (ASCII-art):
------------------------------ Track 1 of Line A
\ /
\ /
------------------------------ Track 2 of Line A
<line lineID="A">
<tracks>
<track trackID="1" length="42.000">
<trackTopology>
<switches>
<switch connectionID="SW1" pos="1.000">
<switch connectionID="SW2" pos="1.500">
</switches>
</trackTopology>
</track>
<track trackID="2" length="42.000">
<trackTopology>
<switches>
<switch connectionID="SW3" pos="1.060">
<switch connectionID="SW4" pos="1.440">
</switches>
</trackTopology>
</track>
<branchConnections>
<branchConnection fromElemID="SW1" toElemID="SW3"
branchDist="0.065" />
<branchConnection fromElemID="SW2" toElemID="SW4"
branchDist="0.065" />
</branchConnections>
</tracks>
</line>
I skipped many attributes which are required "in real life"; my
intention was to show the idea and the structure.
Using the attribute-names "fromElemID" and "toElemID", the branch has an
implicit direction (like a vector), so the usage of the "dir"-attribute
would be possible.
So what do think? I'm looking forward to your suggestions and comments!
Best regards from Braunschweig,
Volker Knollmann
|
|
|
|
Members
Search
Help
Login
Home
