doc: add component description

README.md

 Directories
 ===========
 
-* `/timeline`: Goals and results for each week.
+* `/doc`: Project documentation.
 
-* `/ulo`: Playing around w/ the results of the ULO paper [1, 2]
+* `/timeline`: Goals and results for each week.
 
 * `/graphdb`: Playing with the RDF4J [3] API of GraphDB [4].
 
+* `/ulo`: Playing around w/ the results of the ULO paper [1, 2]
+
 References
 ==========
 

doc/components.md

+Components
+==========
+
+This is a rough sketch of the involved components of this project.
+Look at `componets.png` for a little illustration of the involved
+components.
+
+`Collector`
+-----------
+
+* Given some source of ULO/RDF files (Git repository, HTTP server,
+  local file system), the `Collector` processes/cleans up these files
+  and forwards them to the `Importer`.
+
+* Implement core functionality as library with command line and web
+  front end.
+
+* Can be implemented in any language. I'll probably pick Go as I'm
+  pretty productive in it.
+
+
+`Harvester`
+-----------
+
+* Low Priority. Just an idea I had. But it might go against the idea
+  of using MathHub as a centralized place for data.
+
+* Converts arbitrary source data (e.g. Coq) to ULO/RDF.
+
+* The generated RDF is *volatile*, it does not need to be stored to
+  any repository. Rather it is directly forwarded to a `Collector`.
+
+* I'm not sure if this makes any sense actually as it might be
+  difficult to track changes and so on.
+
+* Can be implemented in any language that makes sense for the given
+  source format.
+
+`Importer`
+----------
+
+* Essentially a wrapper around a database. Written in the language
+  that best fits the database. In particular, GraphDB only has good
+  Java/JVM programming support.
+
+* Accessed w/ a simple file upload API. You upload a file and get a
+  path returned that shows you the current state of the import.
+
+`Endpoint`
+----------
+
+* Again, like the `Importer`, this is a wrapper around the database.
+
+* Might be optional if applications accesses the database directly.
+  Certainly when it comes to querying I will not introduce a custom API
+  as querying is a problem way way more complicated than a simple
+  import.