The use of Metadata within web pages to provide a ‘richer’ and more tailored data structure is not new. The term metadata is defined as "data about data". The term is however slightly ambiguous, as it can be used for two fundamentally different concepts (types). Structural metadata is about the design and specification of data structures and is more properly called "data about the containers of data"; descriptive metadata, on the other hand, is about individual instances of application data, the data content. In our context we are really talking about ‘data about data content’.
We say it is not new because many years ago we worked upon implementing some of the ‘Dublin Core’ metadata into some specific sites that we were working with. The focus now seems to be the use of the vocabularies as defined by ‘schema.org. This is no doubt influenced by the fact that it was promoted by Microsoft and Google themselves.
Deciding to implement it is not for the faint hearted especially if the ‘intended’ target is composed of entities that do not easily fit into one of the defined ‘standards’. As an example we have looked at our ‘Problem/Issue/Bug Tracking’ application. At first glance it looks to be a ‘Product’, but the products are those that are sold, or available to hire etc. The output from our ‘Issue Tracker’ is a set or series of ‘reports’ which describe reported problems or improvement tasks for a ‘product’ hence perhaps they should instead be an ‘Article’. Here again they do not really fit into the current ‘standard’. The best we can come up with would be a ‘CreativeWork’, and more specifically a ‘SoftwareApplication’, but even here we would need to add some specific custom extensions, which is possible with ‘schema.org’ to more accurately reflect information that should be in the meta tags. We require the metadata to describe the output from the application and not the application itself.
At the moment the jury is still out as to whether we wish or desire to add an automated mechanism to our application to generate the meta data automatically. We will probably continue to monitor the situation before deciding whether to implement it as a feature or not, especially as it is not certain whether including it will improve the page rankings within Google, since the exact details of the algorithm used by Google is their secret.