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<link title="Rdf_xml" rel="Chapter" href="Rdf_xml.html"><link title="Options" rel="Section" href="#2_Options">
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<title>OCaml-RDF : Rdf_graph</title>
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<h1>Module <a href="type_Rdf_graph.html">Rdf_graph</a></h1>
<pre><span class="keyword">module</span> Rdf_graph: <code class="code">sig</code> <a href="Rdf_graph.html">..</a> <code class="code">end</code></pre><div class="info">
Graph abstraction.
<p>
The graph provides an abstraction of the storage used (memory, database, ...).
The graph is modified in place.
<p>
Example of usage:
<pre class="codepre"><code class="code">let options =
[
"storage", "mysql" ;
"database", "mydb";
"user", "john" ;
]
in
let graph = Rdf_graph.open_graph ~options (Rdf_uri.uri "http://hello.fr") in
graph.add_triple
~sub: (Rdf_node.node_of_uri_string "http://john.net")
~pred: (Rdf_node.node_of_uri_string "http://relations.org/hasMailbox")
~obj: (Rdf_node.node_of_literal_string "john@john.net");
...
</code></pre><br>
</div>
<hr width="100%">
<br>
<h2 id="2_Options">Options</h2><br>
<pre><span id="TYPEoptions"><span class="keyword">type</span> <code class="type"></code>options</span> = <code class="type">(string * string) list</code> </pre>
<pre><span id="VALget_option"><span class="keyword">val</span> get_option</span> : <code class="type">?def:string -> string -> <a href="Rdf_graph.html#TYPEoptions">options</a> -> string</code></pre><div class="info">
<code class="code">get_options name options</code> returns the value associated to the
option with the given name, in option list.
If the option name is not found in the list, the function raises
the <code class="code">Failure</code> exception with a message about the missing option.<br>
</div>
<div class="param_info"><code class="code">def</code> : can be used to specify a default value; in this case, if
the option name was not found in list, the default value is
returned instead of raising <code class="code">Failure</code>.</div>
<br>
<h2 id="2_Creatingstorages">Creating storages</h2>
<p>
This is useful only to create your own storage.<br>
<pre><span class="keyword">module type</span> <a href="Rdf_graph.Storage.html">Storage</a> = <code class="code">sig</code> <a href="Rdf_graph.Storage.html">..</a> <code class="code">end</code></pre><div class="info">
A storage is a module with this interface.
</div>
<pre><span id="EXCEPTIONStorage_error"><span class="keyword">exception</span> Storage_error</span> <span class="keyword">of</span> <code class="type">string * string * exn</code></pre>
<div class="info">
This is the exception raised by the module we get when applying
<a href="Rdf_graph.Make.html"><code class="code">Rdf_graph.Make</code></a> on a storage.
<p>
Each call to a <a href="Rdf_graph.Storage.html"><code class="code">Rdf_graph.Storage</code></a> function is embedded so that the
<a href="Rdf_graph.html#EXCEPTIONStorage_error"><code class="code">Rdf_graph.Storage_error</code></a> exception is raised when an error occurs in
a storage function.
The exception provides the name of the storage, the error message
(obtained with <a href="Rdf_graph.Storage.html#VALstring_of_error"><code class="code">Rdf_graph.Storage.string_of_error</code></a>) and the original exception.
<p>
Refer to the documentation of <a href="Rdf_graph.Storage.html"><code class="code">Rdf_graph.Storage</code></a> for information about
the functions provided by the resulting module.<br>
</div>
<pre><span class="keyword">module type</span> <a href="Rdf_graph.Graph.html">Graph</a> = <code class="code">sig</code> <a href="Rdf_graph.Graph.html">..</a> <code class="code">end</code></pre><pre><span class="keyword">module</span> <a href="Rdf_graph.Make.html">Make</a>: <div class="sig_block"><code class="code">functor (</code><code class="code">S</code><code class="code"> : </code><code class="type"><a href="Rdf_graph.Storage.html">Storage</a></code><code class="code">) -> </code><code class="type"><a href="Rdf_graph.Graph.html">Graph</a></code><code class="type"> with type g = S.g</code></div></pre><br>
<h2 id="2_Registeringstorages">Registering storages</h2><br>
<pre><span id="VALadd_storage"><span class="keyword">val</span> add_storage</span> : <code class="type">(module Rdf_graph.Storage) -> unit</code></pre><div class="info">
Add a storage to the list of registered storages.<br>
</div>
<pre><code><span id="TYPEgraph"><span class="keyword">type</span> <code class="type"></code>graph</span> = {</code></pre><table class="typetable">
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code><span id="TYPEELTgraph.name">name</span> :<code class="type">unit -> <a href="Rdf_uri.html#TYPEuri">Rdf_uri.uri</a></code>;</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code><span id="TYPEELTgraph.add_triple">add_triple</span> :<code class="type">sub:<a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> -> pred:<a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> -> obj:<a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> -> unit</code>;</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code><span id="TYPEELTgraph.rem_triple">rem_triple</span> :<code class="type">sub:<a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> -> pred:<a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> -> obj:<a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> -> unit</code>;</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code><span id="TYPEELTgraph.add_triple_t">add_triple_t</span> :<code class="type"><a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> * <a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> * <a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> -> unit</code>;</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code><span id="TYPEELTgraph.rem_triple_t">rem_triple_t</span> :<code class="type"><a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> * <a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> * <a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> -> unit</code>;</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code><span id="TYPEELTgraph.subjects_of">subjects_of</span> :<code class="type">pred:<a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> -> obj:<a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> -> <a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> list</code>;</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code><span id="TYPEELTgraph.predicates_of">predicates_of</span> :<code class="type">sub:<a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> -> obj:<a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> -> <a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> list</code>;</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code><span id="TYPEELTgraph.objects_of">objects_of</span> :<code class="type">sub:<a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> -> pred:<a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> -> <a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> list</code>;</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code><span id="TYPEELTgraph.find">find</span> :<code class="type">?sub:<a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> -><br> ?pred:<a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> -> ?obj:<a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> -> unit -> <a href="Rdf_node.html#TYPEtriple">Rdf_node.triple</a> list</code>;</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code><span id="TYPEELTgraph.exists">exists</span> :<code class="type">?sub:<a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> -><br> ?pred:<a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> -> ?obj:<a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> -> unit -> bool</code>;</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code><span id="TYPEELTgraph.exists_t">exists_t</span> :<code class="type"><a href="Rdf_node.html#TYPEtriple">Rdf_node.triple</a> -> bool</code>;</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code><span id="TYPEELTgraph.subjects">subjects</span> :<code class="type">unit -> <a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> list</code>;</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code><span id="TYPEELTgraph.predicates">predicates</span> :<code class="type">unit -> <a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> list</code>;</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code><span id="TYPEELTgraph.objects">objects</span> :<code class="type">unit -> <a href="Rdf_node.html#TYPEnode">Rdf_node.node</a> list</code>;</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code><span id="TYPEELTgraph.transaction_start">transaction_start</span> :<code class="type">unit -> unit</code>;</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code><span id="TYPEELTgraph.transaction_commit">transaction_commit</span> :<code class="type">unit -> unit</code>;</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code><span id="TYPEELTgraph.transaction_rollback">transaction_rollback</span> :<code class="type">unit -> unit</code>;</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code><span id="TYPEELTgraph.new_blank_id">new_blank_id</span> :<code class="type">unit -> <a href="Rdf_node.html#TYPEblank_id">Rdf_node.blank_id</a></code>;</code></td>
</tr>
<tr>
<td align="left" valign="top" >
<code> </code></td>
<td align="left" valign="top" >
<code><span id="TYPEELTgraph.namespaces">namespaces</span> :<code class="type">unit -> (<a href="Rdf_uri.html#TYPEuri">Rdf_uri.uri</a> * string) list</code>;</code></td>
</tr></table>
}
<div class="info">
This is the structure returned by <a href="Rdf_graph.html#VALopen_graph"><code class="code">Rdf_graph.open_graph</code></a>. It contains
the same functions as in <a href="Rdf_graph.Graph.html"><code class="code">Rdf_graph.Graph</code></a>, except the graph data is hidden,
like in a class interface.
Refer to the documentation of <a href="Rdf_graph.Storage.html"><code class="code">Rdf_graph.Storage</code></a> for information about
the functions in the fields.<br>
</div>
<br>
<h2 id="2_Graphcreation">Graph creation</h2><br>
<pre><span id="VALopen_graph"><span class="keyword">val</span> open_graph</span> : <code class="type">?options:(string * string) list -> <a href="Rdf_uri.html#TYPEuri">Rdf_uri.uri</a> -> <a href="Rdf_graph.html#TYPEgraph">graph</a></code></pre><div class="info">
<code class="code">open_graph ~options uri_name</code> creates a new graph. The storage used
is specified by the "storage" option. For example, having <code class="code">("storage", "mysql")</code>
in the options indicates to use the storage "mysql".
<p>
If the specified storage is not registered, the function raises <code class="code">Failure</code>.
Other options may be used by each storage.
<p>
To make sure the storage you want to use is registered, beware of linking the
corresponding module in your executable, either by using the <code class="code">-linkall</code> option
or by adding a reference to the module in your code.<br>
</div>
<pre><span id="VALmerge"><span class="keyword">val</span> merge</span> : <code class="type"><a href="Rdf_graph.html#TYPEgraph">graph</a> -> <a href="Rdf_graph.html#TYPEgraph">graph</a> -> unit</code></pre><div class="info">
<code class="code">merge g1 g2</code> add triples from <code class="code">g2</code> to <code class="code">g1</code>.<br>
</div>
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