Writing new front ends

Lino can have many faces

Lino is designed to have many possible front ends. It comes with an extensible collection of out-of-the-box front ends. You can write a Lino application once and then deploy it via different web interfaces.

There are currently only two realistic choices for the front end: lino.modlib.extjs (the classic front end based on ExtJS) and the React front end (the new front end that will replace ExtJS step by step). The Demo sites page shows both front ends for some applications.

The React front end is already used in production on several sites. But there are more conservative customers who still prefer the clasic front end. Both front ends are currently maintained.

Alternative front ends

There are several proofs of concept for alternative front ends.

  • The ExtJS 6 front end front end was almost ready for production but went asleep because the ExtJS library is unfortunately no longer free. More precisely its free community version is not maintained.

  • OpenUI5 is developed by SAP, conceptually quite similar to ExtJS. We developed the lino_openui5 front end, which was almost ready for production, but stopped this project when we discovered React front end.

  • The lino.modlib.bootstrap3 web interface optimized for read-only access and publication of complex data (something like The belref project). We acknowledgethat this needs more work before becoming really usable.

  • One might consider Lino's TextRenderer (used for writing tested functional specifications) as a special kind of front end.

  • a more lightweight web interface using some other JS framework than ExtJS. e.g. Angular or Vue

  • A console UI using ncurses would be nice. Not much commercial benefit, but a cool tools for system administrators.

  • We once started working on an interface that uses the Qooxdoo library.

  • A desktop application using PyQt. There is a first prototype of the qtclient command.

  • Something similar could be done for wxWidgets.

  • Support OData to provide an XML or JSON based HTTP interface.

Elements of a front end

In Separate business logic and front end we say that Lino separates business logic and front end. That's a noble goal, but the question is where exactly you are going to separate. The actual challenge is the API between them.

The general elements of every Lino application are:

  • the main menu : a hierarchical representation of the application's functions. In multi-user applications the main menu changes depending on the user permissions.

  • a highly customizable grid widget for rendering tabular data.

  • form input using detail windows which can contain slave tables, custom panels, ...