This document describes relevant information about the code structure of JabRef precisely and succinctly. Closer-to-code documentation is available at [[Code HowTos]].
We are currently transitioning from a spaghetti to a more structured architecture with the model in the center, and the logic as an intermediate layer towards the gui which is the outer shell. There are additional utility packages for preferences and the cli. The dependencies are only directed towards the center. We have JUnit tests to detect violations of the most crucial dependencies (between logic, model, and gui), and the build will fail automatically in these cases.
The model represents the most important data structures (BibDatases, BibEntries, Events, and related aspects) and has only a little bit of logic attached. The logic is responsible for reading/writing/importing/exporting and manipulating the model, and it is structured often as an API the gui can call and use. Only the gui knows the user and his preferences and can interact with him to help him solve tasks. For each layer, we form packages according to their responsibility, i.e., vertical structuring. The model should have no dependencies to other classes of JabRef and the logic should only depend on model classes. The cli package bundles classes that are responsible for JabRef's command line interface. The preferences represents all information customizable by a user for her personal needs.
We use an event bus to publish events from the model to the other layers.
This allows us to keep the architecture but still react upon changes within the core in the outer layers.
You can view up-to-date diagrams for model, gui, and logic packages here.
Permitted dependencies in our architecture are:
gui --> logic --> model
gui ------------> model
gui ------------> preferences
gui ------------> cli
gui ------------> global classes
logic ------------> model
global classes ------------> everywhere
cli ------------> model
cli ------------> logic
cli ------------> global classes
cli ------------> preferences
All packages and classes which are currently not part of these packages (we are still in the process of structuring) are considered as gui classes from a dependency stand of view.
Both GUI and CLI are started via the JabRefMain which will in turn call JabRef which then decides whether the GUI (JabRefFrame) or the CLI (JabRefCLI and a lot of code in JabRef) will be started. The JabRefFrame represents the Window which contains a SidePane on the left used for the fetchers/groups Each tab is a BasePanel which has a SearchBar at the top, a MainTable at the center and a PreviewPanel or an EntryEditor at the bottom. Any right click on the MainTable is handled by the RightClickMenu. Each BasePanel holds a BibDatabaseContext consisting of a BibDatabase and the MetaData, which are the only relevant data of the currently shown database. A BibDatabase has a list of BibEntries. Each BibEntry has a key, a bibtex key and a key/value store for the fields with their values. Interpreted data (such as the type or the file field) is stored in the TypedBibentry type. The user can change the JabRefPreferences through the PreferencesDialog.