Hodur is a descriptive domain modeling approach and related collection of libraries for Clojure.
By using Hodur you can define your domain model as data, parse and validate it, and then either consume your model via an API making your apps respond to the defined model or use one of the many plugins to help you achieve mechanical, repetitive results faster and in a purely functional manner.
For a deeper insight into the motivations behind Hodur, check the motivation doc.
Hodur has a highly modular architecture. Hodur Engine is always required as it provides the meta-database functions and APIs consumed by plugins.
Therefore, refer the Hodur Engine's Getting Started first and then return here for GraphViz-specific setup.
After having set up hodur-engine
as described above, we also need to
add hodur/graphviz-schema
, a plugin that creates diagrams in
GraphViz out of your model to the deps.edn
file:
{:deps {hodur/engine {:mvn/version "0.1.7"}
hodur/graphviz-schema {:mvn/version "0.1.1"}}}
You should require
it any way you see fit:
(require '[hodur-graphviz-schema.core :as hodur-graphviz])
Let's expand our Person
model from the original getting started by
"tagging" the Person
entity for GraphViz. You can read more about
the concept of tagging for plugins in the sessions below but, in
short, this is the way we, model designers, use to specify which
entities we want to be exposed to which plugins.
(def meta-db (hodur/init-schema
'[^{:graphviz/tag-recursive true}
Person
[^String first-name
^String last-name]]))
The hodur-graphviz-schema
plugin exposes a function called schema
that generates your model as a GraphViz dot payload:
(def graphviz-schema (hodur-graphviz/schema meta-db))
When you inspect graphviz-schema
, this is more or less what you
have:
digraph G {
fontname = "Bitstream Vera Sans"
fontsize = 8
dpi = 300
node [
fontname = "Bitstream Vera Sans"
fontsize = 8
shape = "record"
]
edge [
fontname = "Bitstream Vera Sans"
fontsize = 8
arrowhead = "open"
labelangle = 45
labeldistance = 1.1
]
Person [
label="{Person|first-name: String\llast-name: String\l}";
]
}
You can then spit
this content on to a dot file, for isntance:
(spit "diagram.dot" graphviz-schema)
And then run dot directly with:
$ dot -Tpng -odiagram.png diagram.dot
This will give you a diagram like this:
All Hodur plugins follow the Model Definition as described on Hodur Engine's documentation.
You can select the color of a specific entity by using the marker
:graphviz/color
:
[^{:graphviz/tag-recursive true
:graphviz/color "navajowhite1"}
Person
[^String name]
^{:graphviz/tag-recursive true
:graphviz/color "lightsalmon"}
Business
[^String total-revenue]]
GraphViz colors can be found here.
You can always choose whether an entity and any of it's fields or
parameters get generated by either tagging it for GraphViz with
:graphviz/tag
or not. However, sometimes you need finer control to
create more bespoke diagrams.
One such situations is called grouping. You can mark an entity as part
of a certain group with the marker :graphviz/group
:
[^{:graphviz/tag-recursive true
:graphviz/group "people-stuff"}
Person
[^String name]
^{:graphviz/tag-recursive true
:graphviz/color "business-stuff"}
Business
[^String total-revenue]]
The schema
function takes a map as its second argument where you can
specify which groups you want to generate. In the following example
you would generate just the Person
entity above as it is the only
one marked as part of the "people-stuff"
group:
(hodur-graphviz/schema meta-db {:groups ["people-stuff"]})
Another situation is when you want to generate just what has been tagged for some plugin. For instance, you want a diagram of all the entities that are going to be used by your SQL schema plugin. In that situation you can use the same map but specifying a collection of tags:
(hodur-graphviz/schema meta-db {:tags [:sql]})
Of course, both systems can be mixed and matched. The system generates
anything that hits (i.e. if an entity is tagged with :foo
and
another with :bar
and you use {:tags [:foo :bar]}
, both will be
generated.
You may want to configure what DPI will be used when generating an image from dot file. Per default 300 dpi will be used, but you can set it:
(hodur-graphviz/schema meta-db {:dpi 600})
This will mark dot file to generate 600 dpi image files.
If you find a bug, submit a GitHub issue.
This project is looking for team members who can help this project succeed! If you are interested in becoming a team member please open an issue.
Copyright © 2019 Tiago Luchini
Distributed under the MIT License (see LICENSE).