====== Link Resolver Drivers ======

This page contains details on writing a custom driver for an OpenURL Link Resolver not already supported by VuFind®.

Note that Link Resolver Drivers are only used when the "embed" setting is turned on in the [OpenURL] section of [[configuration:files:config.ini]].  This setting allows link resolver results to be directly embedded in the VuFind® search page rather than opening in a separate window.

===== Key Plugin Details =====

**Default Namespace:** \VuFind\Resolver\Driver

**Interface:** [[https://github.com/vufind-org/vufind/blob/dev/module/VuFind/src/VuFind/Resolver/Driver/DriverInterface.php|\VuFind\Resolver\Driver\DriverInterface]]

**Service Locator Configuration Section in module.config.php:** ['vufind']['plugin_managers']['resolver_driver']

**Service Manager Name for Service Locator:** VuFind\ResolverDriverPluginManager (VuFind® 2.x-4.x), VuFind\Resolver\Driver\PluginManager (VuFind® 5.0+)

See the [[development:plugins:general_information|General Plugin Information]] page for more details on VuFind® plugins.

===== Basic Structure =====

  * The PHP driver class must be registered in the service locator with the value used as the the resolver setting in the [OpenURL] section of [[configuration:files:config.ini|config.ini]].  (i.e. "sfx").
  * The driver class must implement the VuFind\Resolver\Driver\DriverInterface. For convenience, starting in release 4.0, most drivers will achieve this by extending VuFind\Resolver\Driver\AbstractBase.

===== Key Methods =====

==== fetchLinks ====

This method takes an OpenURL as a parameter and retrieves details from the link resolver.

==== getResolverUrl ====

:!: Introduced in VuFind® 4.0

This method takes an OpenURL as a parameter and returns a URL for accessing that item in the link resolver's native interface.

==== parseLinks ====

This method takes the output of fetchLinks and parses it into an array of associative arrays with the following keys:

  * href - the link to access the resource
  * title - a text description of the resource
  * coverage - coverage range applicable to the resource
  * service_type - used to categorize links (getHolding = local print holding, getWebService = special service related to item, getDOI = DOI link, getFullTxt = electronic holding)
  * access - used to style links according to their access-status (if supported by the link resolver driver - available status: open, limited, denied, unknown), style classes are named access-{status} in template ajax/resolverLinks.phtml; //this feature was added in VuFind® 2.5//

==== supportsMoreOptionsLink ====

:!: Introduced in VuFind® 4.0

This method returns true when the direct link provided by getResolverUrl offers a human-friendly interface; it should return false if the link resolver offers a data-only interface (for example, in the case of JOP).