Store application data between pages

[ulitol97]

A mechanism for data persistence between the client pages and tools has been setup using React's Context API and Session Storage.

Currently, the following user data is not lost between pages:

• RdfData (more than a single data instance can be stored, i.e.: for data merges)
• Validation schema
• ShapeMap
• SPARQL Query (+ query target/endpoint)
• XMI (UML) data