rdf_edit.pl -- RDF edit layer

This library provides a number of functions on top of the rdf_db module:

• Broadcast modifications
• Provide undo/redo

See also

- rdf_persistency.pl provides reliable persistency, but without changes boardcasting and undo/redo.

To be done

- This library must be rewritten using rdf_monitor/3. This allows using edit layer without having to choose between rdf_ and rdfe_ predicates.

 rdfe_update(+Subject, +Predicate, +Object, +Action)

Update an existing triple. Possible actions are:

! subject(+Subject) ! predicate(+Predicate) ! object(+Object) ! source(+Source)

 rdfe_delete(+Subject)

Delete a subject and all we know about it. This is a bit tricky. If we are involved in transitive relations, should we re-joint these in this module?

 rdfe_load(+File) is det

 rdfe_load(+File, +Options) is det

Load an RDF file and record this action including version information to facilitate reliable reload.

 rdfe_snapshot_file(-File)

Enumerate the MD5 snapshot files required to restore the current journal file. Using this call we can write a routine that packages the journal file with all required snapshots to restore the journal on another computer.

 rdfe_register_ns(Id, URI)

Encapsulation of rdf_register_ns(Id, URI)

 rdfe_transaction(:Goal)

Run Goal, recording all modifications as a single transaction. If Goal raises an exception or fails, all changes are rolled-back.

 rdfe_undo

Undo a (toplevel) transaction. More calls do further undo. The `Undone' actions are re-added to the undo log, so the user can redo them. Fails if there are no more undo/redo transactions.

 rdfe_redo

Start a redo-session

 rdfe_can_redo(-TID) is semidet

 rdfe_can_undo(-TID) is semidet

Check if we can undo and if so return the id of the transaction that will be un/re-done. A subsequent call to rdfe_transaction_name can be used to give a hint in the UI.

 rdfe_transaction_name(+TID, -Name)

Return name if the transaction is named.

 rdfe_set_transaction_name(+Name)

Set name of the current transaction

 rdfe_transaction_member(+TID, -Action)

Query actions inside a transaction to allow for quick update of visualisers.

 rdfe_set_file_property(+File, +Options)

Set properties on the file. Options is one of

• access(ro/rw)
• default(all/fallback)

 rdfe_get_file_property(+FileOrURL, ?Option)

rdfe_get_file_property(-URL, ?Option)

Fetch file properties set with rdfe_set_file_property/2.

 rdfe_is_modified(?Source)

True if facts have been added, deleted or updated that have Source as `payload'.

 rdfe_clear_modified(+Graph) is det

Consider the current state of Graph as unmodified.

 rdfe_set_watermark(Name)

Create a watermark for undo and replay journal upto this point. The rest of the logic needs to be written later.

 rdfe_reset

Clear database, undo, namespaces and journalling info.

 rdfe_open_journal(+File, +Mode) is det

Open a journal writing to File in Mode. Mode is one of

read

Open and replay the journal

write

Delete current journal and create a fresh one

append

Read and replay the existing journal and append new modifications to the File.

 rdfe_close_journal

Close the journal. Automatically called from at program termination from at_halt/1.

 rdfe_current_journal(-Path)

Query the currently open journal

 rdfe_replay_journal(+File)

Replay a journal file. For now this is our cheap way to deal with save/load. Future versions may be more clever when dealing with the version information stored in the journal.

Re-exported predicates

The following predicates are exported from this file while their implementation is defined in imported modules or non-module files loaded by this module.

 rdfe_can_redo(-TID) is semidet

 rdfe_can_undo(-TID) is semidet

Check if we can undo and if so return the id of the transaction that will be un/re-done. A subsequent call to rdfe_transaction_name can be used to give a hint in the UI.

 rdfe_load(+File) is det

 rdfe_load(+File, +Options) is det

Load an RDF file and record this action including version information to facilitate reliable reload.

Undocumented predicates

The following predicates are exported, but not or incorrectly documented.

 rdfe_assert(Arg1, Arg2, Arg3, Arg4)

 rdfe_retractall(Arg1, Arg2, Arg3)

 rdfe_assert(Arg1, Arg2, Arg3)

 rdfe_retractall(Arg1, Arg2, Arg3, Arg4)

 rdfe_update(Arg1, Arg2, Arg3, Arg4, Arg5)

 rdfe_transaction(Arg1, Arg2)

 rdfe_unregister_ns(Arg1, Arg2)