+
As part of my involvement with the
+Nikita
+Noark 5 core project, I have been proposing improvements to the
+API specification created by The
+National Archives of Norway and helped migrating the text from a
+version control system unfriendly binary format (docx) to Markdown in
+git. Combined with the migration to a public git repository (on
+github), this has made it possible for anyone to suggest improvement
+to the text.
+
+
The specification is filled with UML diagrams. I believe the
+original diagrams were modelled using Sparx Systems Enterprise
+Architect, and exported as EMF files for import into docx. This
+approach make it very hard to track changes using a version control
+system. To improve the situation I have been looking for a good text
+based UML format with associated command line free software tools on
+Linux and Windows, to allow anyone to send in corrections to the UML
+diagrams in the specification. The tool must be text based to work
+with git, and command line to be able to run it automatically to
+generate the diagram images. Finally, it must be free software to
+allow anyone, even those that can not accept a non-free software
+license, to contribute.
+
+
I did not know much about free software UML modelling tools when I
+started. I have used dia and inkscape for simple modelling in the
+past, but neither are available on Windows, as far as I could tell. I
+came across a nice
+list
+of text mode uml tools, and tested out a few of the tools listed
+there. The PlantUML tool seemed
+most promising. After verifying that the packages
+is available in
+Debian and found its
+Java source under a GPL license on github, I set out to test if it
+could represent the diagrams we needed, ie the ones currently in
+the
+Noark 5 Tjenestegrensesnitt specification. I am happy to report
+that it could represent them, even thought it have a few warts here
+and there.
+
+
After a few days of modelling I completed the task this weekend. A
+temporary link to the complete set of diagrams (original and from
+PlantUML) is available in
+the
+github issue discussing the need for a text based UML format, but
+please note I lack a sensible tool to convert EMF files to PNGs, so
+the "original" rendering is not as good as the original was in the
+publised PDF.
+
+
Here is an example UML diagram, showing the core classes for
+keeping metadata about archived documents:
+
+
+@startuml
+skinparam classAttributeIconSize 0
+
+!include media/uml-class-arkivskaper.iuml
+!include media/uml-class-arkiv.iuml
+!include media/uml-class-klassifikasjonssystem.iuml
+!include media/uml-class-klasse.iuml
+!include media/uml-class-arkivdel.iuml
+!include media/uml-class-mappe.iuml
+!include media/uml-class-merknad.iuml
+!include media/uml-class-registrering.iuml
+!include media/uml-class-basisregistrering.iuml
+!include media/uml-class-dokumentbeskrivelse.iuml
+!include media/uml-class-dokumentobjekt.iuml
+!include media/uml-class-konvertering.iuml
+!include media/uml-datatype-elektronisksignatur.iuml
+
+Arkivstruktur.Arkivskaper "+arkivskaper 1..*" <-o "+arkiv 0..*" Arkivstruktur.Arkiv
+Arkivstruktur.Arkiv o--> "+underarkiv 0..*" Arkivstruktur.Arkiv
+Arkivstruktur.Arkiv "+arkiv 1" o--> "+arkivdel 0..*" Arkivstruktur.Arkivdel
+Arkivstruktur.Klassifikasjonssystem "+klassifikasjonssystem [0..1]" <--o "+arkivdel 1..*" Arkivstruktur.Arkivdel
+Arkivstruktur.Klassifikasjonssystem "+klassifikasjonssystem [0..1]" o--> "+klasse 0..*" Arkivstruktur.Klasse
+Arkivstruktur.Arkivdel "+arkivdel 0..1" o--> "+mappe 0..*" Arkivstruktur.Mappe
+Arkivstruktur.Arkivdel "+arkivdel 0..1" o--> "+registrering 0..*" Arkivstruktur.Registrering
+Arkivstruktur.Klasse "+klasse 0..1" o--> "+mappe 0..*" Arkivstruktur.Mappe
+Arkivstruktur.Klasse "+klasse 0..1" o--> "+registrering 0..*" Arkivstruktur.Registrering
+Arkivstruktur.Mappe --> "+undermappe 0..*" Arkivstruktur.Mappe
+Arkivstruktur.Mappe "+mappe 0..1" o--> "+registrering 0..*" Arkivstruktur.Registrering
+Arkivstruktur.Merknad "+merknad 0..*" <--* Arkivstruktur.Mappe
+Arkivstruktur.Merknad "+merknad 0..*" <--* Arkivstruktur.Dokumentbeskrivelse
+Arkivstruktur.Basisregistrering -|> Arkivstruktur.Registrering
+Arkivstruktur.Merknad "+merknad 0..*" <--* Arkivstruktur.Basisregistrering
+Arkivstruktur.Registrering "+registrering 1..*" o--> "+dokumentbeskrivelse 0..*" Arkivstruktur.Dokumentbeskrivelse
+Arkivstruktur.Dokumentbeskrivelse "+dokumentbeskrivelse 1" o-> "+dokumentobjekt 0..*" Arkivstruktur.Dokumentobjekt
+Arkivstruktur.Dokumentobjekt *-> "+konvertering 0..*" Arkivstruktur.Konvertering
+Arkivstruktur.ElektroniskSignatur -[hidden]-> Arkivstruktur.Dokumentobjekt
+@enduml
+
+
+
The format is quite
+compact, with little redundant information. The text expresses
+entities and relations, and there is little layout related fluff. One
+can reuse content by using include files, allowing for consistent
+naming across several diagrams. The include files can be standalone
+PlantUML too. Here is the content of
+media/uml-class-arkivskaper.iuml:
+
+
+@startuml
+class Arkivstruktur.Arkivskaper {
+ +arkivskaperID : string
+ +arkivskaperNavn : string
+ +beskrivelse : string [0..1]
+}
+@enduml
+
+
+
This is what the complete diagram for the PlantUML notation above
+look like:
+
+
+
+
A cool feature of PlantUML is that the generated PNG files include
+the entire original source diagram as text. The source (with include
+statements expanded) can be extracted using for example
+exiftool. Another cool feature is that parts of the entities
+can be hidden after inclusion. This allow to use include files with
+all attributes listed, even for UML diagrams that should not list any
+attributes.
+
+
The diagram also show some of the warts. Some times the layout
+engine place text labels on top of each other, and some times it place
+the class boxes too close to each other, not leaving room for the
+labels on the relationship arrows. The former can be worked around by
+placing extra newlines in the labes (ie "\n"). I did not do it here
+to be able to demonstrate the issue. I have not found a good way
+around the latter, so I normally try to reduce the problem by changing
+from vertical to horizontal links to improve the layout.
+
+
All in all, I am quite happy with PlantUML, and very impressed with
+how quickly its lead developer responds to questions. So far I got an
+answer to my questions in a few hours when I send an email. I
+definitely recommend looking at PlantUML if you need to make UML
+diagrams. Note, PlantUML can draw a lot more than class relations.
+Check out the documention for a complete list. :)
+
+
As usual, if you use Bitcoin and want to show your support of my
+activities, please send Bitcoin donations to my address
+15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b.
+
+
+
+
+
+
+
+