Since we don't use different view types much these functions have been dropped.

I think viewtypes are automatically detected based on the folders in /views. If you wish to check if a view exists in a viewtype you can use elgg_view_exists('someview', 'your_viewtype');

@RvR Thanks for reply, i already did this, but i am getting page not found when i am going to open mysite.com/article/all
let me show you how i written code.
 
elgg_register_plugin_hook_handler('route:rewrite', 'blog', 'blog_rewrite_handler');

function blog_rewrite_handler($hook, $type, $value, $params) {
    $value['identifier'] = 'article';
    return $value;
}
also i have put this hook handler out of 'init','system' hook.

It should go the other way around, you want to 'article' routes to be handled by the blog plugin.

so your rewrite hook should be on 'artilce' and then return 'blog'. that way all requests will be handled by the blog plugin

@Jerome Bakker Thanks for reply, changed as per your guidance its working now.

GraphQL is a query language, which allows you to specify, which fields you want returned in the actual query. Read the GraphQL docs - this questions is completely unrelated to Elgg, so seek help on StackOverflow.