A standard web service to me means a RESTful one. That's what Google, Microsoft, Dropbox, Twitter, Facebook etc use to expose their services to the web. You can create RESTful web services in B4J. It has good JSON support and it's very easy to create end points that return JSON.
You can call a RESTful web service using cURL in PHP or save a lot of time and use one of the REST client libraries that have been developed.