Pinging google sitemap after every new article submission?

Question

Yes, that method is allowed by google.

1. Issue your request to the following URL:

   www.google.com/webmasters/tools/ping?sitemap=sitemap_url

   For example, if your Sitemap is located at http://www.example.com/sitemap.gz, your URL will become:

   www.google.com/webmasters/tools/ping?sitemap=http://www.example.com/sitemap.gz

2. URL encode everything after the /ping?sitemap=:

   www.google.com/webmasters/tools/ping?sitemap=http%3A%2F%2Fwww.yoursite.com%2Fsitemap.gz

3. Issue the HTTP request using wget, curl, or another mechanism of your choosing.

ADDED:

Based on the link I just given, there is an info in there, google says:

We recommend that you resubmit a Sitemap no more than once per hour.

Take a look at the code for the Google Sitemap Generator Plugin for Wordpress. A lot of people use that and it does not seem to slow things down enough to notice. Whatever methodology they are using should be a good place to start.

As of 2015, Google no longer suggests a rate limit in their documentation.

It is in Google's best interest to know when fresh articles are created so it is worth pinging them with your sitemap, or at least some kind of "Fresh Articles" sitemap when new articles are published.

Googlebot will request your sitemap every time your ping it. It sends requests headers to check the newness of the resource. So if you plan on submitting a sitemap frequently, make sure your server will handle the request correctly. Otherwise, you might return a 304 (Not Modified) and Googlebot won't actually get the file.