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Subject: Re: [xdi] New XDI graph diagram layout technique

On Sat, Nov 23, 2013 at 12:58 AM, Markus Sabadello <markus.sabadello@gmail.com> wrote:
Okay. To me this is just a matter of taste, doesn't really make a difference.

I never saw a "top-down hierarchy" in any of the diagram formats we have had so far.
And I think a "left-right hierarchy" still applies even in this new format.

Good point. But at least it's not "top-down".

But yes maybe this is more helpful for beginners.

And that's the primary driver. Because at this point in time, 99.9999999% of humanity are XDI "beginners" ;-)


On Sat, Nov 23, 2013 at 9:24 AM, Drummond Reed <drummond.reed@xdi.org> wrote:
On Fri, Nov 22, 2013 at 12:55 AM, Markus Sabadello <markus.sabadello@gmail.com> wrote:
Ah yes, didn't see it! I would have expected it to be in the top left corner.

I know. But the fact that you expected it there illustrates the VERY DELIBERATE reason that it's not in the top left corner:

   Because XDI graphs are not hierarchical!

To me, that was part of the revelation about why to switch to this new orientation for drawing the graph. It wasn't just that it reads from left to right just like XDI statements. It was equally that a pure left-to-right orientation would help remove any suggestion of "top-down" hierarchy (which is how hierarchy is typically drawn and thought about).

So by convention I think we should place the start node (note that I'm no longer calling it the "root node") of an XDI graph diagram (technically the "outer start node") in the middle of the left border (or someplace conveniently close to the middle), as I did in this example diagram. That way it's clear that it this node is the start of all the XDI statements in the graph, without looking hierarchical.

I have to go to catch a plane shortly, but as soon as I get time I'll send another message proposing why I think we should switch all of XDI terminology from using the term "root" or "root node" to "start" or "start node".


On Fri, Nov 22, 2013 at 9:47 AM, Drummond Reed <drummond.reed@xdi.org> wrote:
On Thu, Nov 21, 2013 at 1:48 AM, Markus Sabadello <markus.sabadello@gmail.com> wrote:
I like it.. I think writing an automatic diagram generator for this technique would also be significantly easier than for the old one.


One input I have is that the outer root should probably also be drawn as a circle, even though it has no address.

It is drawn as an open circle. It's the circle at the far left edge. It's the starting point for all arcs. 


On Thu, Nov 21, 2013 at 9:14 AM, Drummond Reed <drummond.reed@xdi.org> wrote:
As I prepare diagrams for the XDI Core spec, using the updated notation we agreed on, I just wanted to share a new way of laying them out that makes drawing them much easier and more uniform, as well as making them easier to read. An example is below, with notes following that.

Inline image 1
  • What makes it easier to read is:
    • Everything except relational arcs reads left-to-right, just like XDI statements.
    • The outer root node is always the far left edge—the starting point (with no address)—exactly like an XDI statement.
    • For contextual arcs, labels are directly above each horizontal line.
    • Relational arcs stand out because they are the only curved lines.
    • It is easier to see the transition points between roots, entities, attributes, and values.
  • What makes it easier to draw is:
    • All contextual arcs are straight lines—either directly horizontal, or vertical+horizontal—which means in most drawing tools like Powerpoint or Visio there is a connector shape that does this automatically.
    • It is easy to vertically align nodes to see "levels" of contextual nesting.
    • It is easy and fast to adjust sections of the graph up or down to make room for new statements.
Please post any thoughts about further ideas or improvements -- this is the format I plan to use for XDI Core spec illustrations.

Also, I can post the Powerpoint file I'm using to make these, but the format is trivially easy (the only secret is to made the circle and diamond shapes exactly the same height so that everything snaps to grid easily).

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