Marko A. Rodriguez created TINKERPOP-1277:
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Summary: Write a Gremlin traversal machine variant tutorial
Key: TINKERPOP-1277
URL: https://issues.apache.org/jira/browse/TINKERPOP-1277
Project: TinkerPop
Issue Type: Improvement
Components: documentation
Affects Versions: 3.1.2-incubating, 3.2.0-incubating
Reporter: Marko A. Rodriguez
We have discussed "Gremlin language variants" which teach people how to embed
Gremlin in non-JVM languages (e.g. Python, Ruby, PHP, etc.). Developers in
these non-JVM languages can then communicate with JVM-based Gremlin via
GremlinServer. This all assumes that the ultimate graph system (OLTP or OLAP)
is JVM-based. How about when a graph system isn't on the JVM and the graph
system designers want to use Gremlin as their query language?
Like building a Gremlin language variant, building a Gremlin machine variant is
not too difficult. The Gremlin traversal machine is relatively simple with only
a few constructs needed -- traversals, traversers, steps, bulking. Its all
pretty straightforward.
I think it would be smart to demonstrate how to build the Gremlin machine in
another language. Perhaps in a "high performance" language like C or C# or
...?. (Or perhaps just do it in like Ruby as its easy for people to build and
run the code without having to do {{gcc make}}-crap) The tutorial does not need
to go into all step implementations, but perhaps a few that demonstrate a
filter, flatmap, map, sideEffect, branch -- as well as ones that take
{{by()}}-modulators and {{TraversalParents}}. We would need to create a
"TinkerGraph" in that language as well so that the implemented machine would
work for it. Finally, to complete the picture, Apache TinkerPop's Gremlin-Java
should be used to communicate with the non-JVM machine via a
{{RemoteConnection}}! Classy.
This would complete the "Gremlin as a standard"-push. Not only can it be
embedded in a host language (non JVM), but its machine can be implemented in
another language as well. Thus, Gremlin is not just a JVM construct. Though
Apache TinkerPop would stick to only supporting a JVM implementation of the
Gremlin traversal machine.
NOTES:
* Unlike creating a Gremlin language variant, its hard to programmatically
create a Gremlin machine variant. However, if the Gremlin machine variant
supported {{RemoteConnection}}, then we could use Gremlin-Java's
{{ProcessXXXTest}} as a way to verify that the machine variant is compliant.
* Supporting OLAP is not that difficult either. A naïve implementation of
{{TraversalVertexProgram}} is only, maybe 100 lines of code. The more
complicated part is the "TinkerGraphComputer"-implementation in the other
language.
* The specification articulated in http://arxiv.org/abs/1508.03843 is what we
should go by as its mathematically clean. We should not just try and map over
the concepts 1-to-1 from Apache TinkerPop's Gremlin traversal machine.
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