Fetch Drupal nodes as json by url/title
In Service Module API, Some hooks are presents to help you.
You need to alter or add your own implementation of this service.

The second link is a file where you have the default service implementation.
You can try to alter this configuration with your own by using "hook_services_resources_alter".

I can't test but you can try and custom this snippet :

function YOUR_MODULE_services_resources_alter(&amp;$resources, &amp;$endpoint) {
    $['node']['operations']['retrieve']['callback'] = '_your_retreive_method';
    $['node']['operations']['retrieve']['args']     = array(
        'name' =&gt; 'node_alias',
        'optional' =&gt; FALSE,
        'source' =&gt; array('path' =&gt; 0), // Put your path index here
        'type' =&gt; 'string',
        'description' =&gt; 'The alias node to get',
    );
}

function _your_retreive_method($node_alias){
    // transform your alias to nid
    $path   = drupal_get_normal_path($node_alias);    
    if($path !== $node_alias &amp;&amp; ctype_digit($nid = str_replace('node/','',$path))){
        return _node_resource_retrieve($nid);
    }
    return false;
}


Links :


Service API Docs
File with an implementation of a service