irc-books/docs/services.dot

digraph Services {
   node [shape=rect];
   rankdir=LR;
   IRCClient
   FileFetcher
   Unpacker
   WebAPI
   BulkInserter
   DB

   WebAPI -> IRCClient -> FileFetcher -> Unpacker
   FileFetcher -> BulkInserter

   WebAPI -> DB[label="Search" style=dashed];
   BulkInserter -> DB[label="Save cache" style=dashed];
}