Is ZK(ZKoss) framework a kind of web content management system like wordpress, joomla and others? Or it is more complicated and needs more advanced programming skills to use?
By using ZK you are able to write your own Java enterprise web applications. You need great skill in Java and some about a database framework like Hibernate. But the important point is you do not need to have skill in AJAX and Javascript. There are many useful components you can use.
ZK is not a CMS. By installing ZK you are not able to write posts and articles, similiar to Joomla or Wordpress.