Views all aliases, or creates an alias to a resource. This simplifies queries by using qualified names instead of element references within constraints.
h2. Viewing Aliases Mulgara has a set of predefined aliases on startup. These can be viewed along with any user-defined aliases by using the *alias* command without any arguments: <pre> alias; </pre> This will print all aliases that are currently registered. h2. Adding Aliases The general form for adding an alias is: <pre> alias resource as namespace; </pre> Where @resource@ is the URI prefix to abbreviate and @namespace@ is an unquoted XML namespace prefix. h2. Examples Look at the default set of aliases: <pre> alias; mulgara: <http://mulgara.org/mulgara#> dc: <http://purl.org/dc/elements/1.1/> rdfs: <http://www.w3.org/2000/01/rdf-schema#> foaf: <http://xmlns.com/foaf/0.1/> krule: <http://mulgara.org/owl/krule/#> rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> skos: <http://www.w3.org/2004/02/skos/core#> owl: <http://www.w3.org/2002/07/owl#> </pre> Add aliases: <pre> alias <http://www.w3.org/1999/xhtml#> as xml; alias <http://www.w3.org/2001/XMLSchema#> as xsd; </pre> Updating an alias: <pre> alias <http://www.w3.org/2001/XMLSchema-datatypes#> as xsd; </pre> *Note:* _The interpreter does not know which namespaces are followed by paths and which are followed by fragments. For this reason the trailing # or / character must be included by the user. This is demonstrated in the above aliases._ In the following example, the where clause in the following select command uses a complete URI. <pre> select $obj $pred from <http://purl.org/dc/elements/1.1/> where <http://purl.org/dc/elements/1.1/title> $pred $obj; </pre> With the alias command, this can be simplified to: <pre> alias <http://purl.org/dc/elements/1.1/> as dc; select $obj $pred from <http://purl.org/dc/elements/1.1/> where <dc:title> $pred $obj; </pre>
Updated by Gregg - over 13 years ago · 4 revisions