Editing EPrints4 Roadmap

[[Category:Eprints4]]
[[Category:Contribute]]
Some general ideas for the development of the next major release of EPrints. 

Also read [[EPrints4_Status]]

==Main Objectives==

* Separation of the Core API and UI (/rendering) components - that mainly means that core objects (Repository, MetaField*, DataObj*) won't have any render_* method. this could also imply that the core or the UI could be upgraded separately. It would also make re-use of the eprints core easy for other purposes (e.g. data repository, OER etc.)

* Remove the spaghetti code (esp (1) rendering methods (2) Dataobj-Metafield relations)

* Drop support for internal search in favour of specialist tools such as Xapian or Solr - we might however need to keep some aspects of the internal search (cf List/data retrieval) for exact matching - perhaps that's more a (SQL) "QueryBuilder" than a (user) search.

* Drop support for Windows?

* Implement object locking at the core level (for any objects, perhaps without using database fields at all). Actually this is done via: DB Transactions, ETag and If-None-Match headers. The current (3.2/3.3) object locking is a UI feature not a core one.

* Implement object state at the core level (at the moment EPrint object might be in one of 4 states: inbox, buffer, archive, deletion via the field eprint_status) <DONE>

* code normalisation:
** use new class name (e.g. EPrints::Session => EPrints::Repository)
** use "new way" of doing things (e.g. EPrints::Dataobj::X->new(12) => repo->dataset( 'x' )->dataobj(12))
** remove v2.x features deprecated in v3+ (cf. EPrints::BackCompatibility)

* define clear API for core functions (e.g. Database, object handling) and for UI purposes. The API must present a unique way of doing something.

* It might be worth separating the code into 3 packages to ease the development: eprints4-core, eprints4-ir and eprints4-ir-ui.

==Core==

* Revisit Apache request Handler aka Apache::Rewrite (lots of hard-coded paths, many obsolete paths) - URL handling should be done by Controllers called/prioritised via a trigger. <TESTED OK>

* Remove EPrints::Session from anywhere in favour of EPrints::Repository

* Test using memcached (http://code.google.com/p/memcached/) - Cache::Memcached::Fast to cache data objects, perhaps could work to cache XML fragments too. <TESTED OK>

* Use Multipart rather than Compound - Compound creates 1 table per subfield whilst Multipart creates 1 column per subfield. <TESTED OK>

* Finer grain permissions (using User, Groups, perhaps ACL concepts) - also security should be handled at the core level not at the UI level

* Core should be able to run without IR extensions nor UI elements (might require to extend the SWORD layer for interactions with the core) <TESTED OK>

* Built-in locking mechanisms for objects (improved edit_lock)

* No hard-coded exceptions for IR extensions (e.g. eprint_status hard-coded in places) <TESTED OK>

* Generalise concept of "files" to allow the storage of arbitrary files against any data objects (e.g. a profile picture for a User) <TESTED OK>

* (coding-style) don't use objects via hash-value directly e.g. my $repo = $object->{repository} - use method instead: my $repo = $object->repository.

* Metafield/DataObj::set_value should re-enforce the database type - i.e. $object->set_value( 'int_field', 'abc' )should fail at the Application layer - not silently at the DB layer as it currently happens. Same goes with any field type (e.g. ->set_value( 'set_field', 'invalid_set_value' ) should fail). <TESTED OK>

* Extra dataset properties to allow global, consistent behaviour. Considered: "states", "revision" (TESTED OK), "lastmod" (TESTED OK), "read-only" (TESTED OK), "cache" (i.e. use memcached), "history" (keep revision history, implies revision=true), "datestamp", "acl"

==Extensions for IR-type of Repositories==

* Authors/names stored in a separate dataset - should help integrate with various UID systems like OrcID.

* Extra metadata to describe a User - cf. MePrints.


==UI elements==

* jQuery over Prototype

* jQueryUI widgets used to render fields 

* Javascript/Ajax concepts built-in

* CSS3 Responsive design to support small screens (mobile, tablets etc) - http://alistapart.com/article/responsive-web-design

* Consider http://getbootstrap.com/javascript/ -  http://getbootstrap.com/components/

==Misc==

* an internal messaging system would be nice (similar to the current Message data object but with more options) - this would help system/user and user/user interactions. A logged-in user could then see messages and act accordingly. For instance: publication just went live, items have been imported from remote sources, user commented on a resource etc.

==Current Dev tasks (stuff in progress)==

* Complex UI elements such as forms with validations - Currently using a mix of Mustache (server-side templates) and AngularJS (client-side) - btw some cool stuff here: http://angular-ui.github.io/bootstrap/
* (Deep) integration of Xapian into the core:
** but keeping it generic enough to allow other implementation of other search engines
** must find a way to (1) conduct a user search via Xapian and (2) merge the results with a DB-bound search to restrict to items that the user can effectively search (think ACL here)
** Must find a way to generate API pages from the code/POD