Library holdings: RDFa with schema.org codelab

Turning library holdings into Product

schema.org adopted the existing GoodRelations vocabulary as a way of expressing products and services that are available for sale. As it turns out, although some of the property and type names reflect a commercial bias, you can use the same vocabulary elements can to express non-commercial offers--such as the offer to lend a library resource to a patron.

In this exercise, you will turn the existing Book entity into a multi-typed entity by adding Product to the type declaration. This enables the described resource to satisfy properties expecting a value of either Book or Product, and also makes a union of the properties from those types available to further describe the resource.

View the page source HTML

Open step1/rdfa_book.html in a text editor. You should see something like the following HTML source for the web page:

<!DOCTYPE html>
<html>
<head>
  <title>Las Vegas-Clark County Library District /All Locations</title>
</head>

<body vocab="http://schema.org/" typeof="Book" resource="#book">
  <link property="sameAs" href="https://www.googleapis.com/freebase/v1/rdf/m/01069fkb">
  <link property="sameAs" href="http://worldcat.org/entity/work/id/1782516719">
  <link property="sameAs" href="http://www.scholastic.ca/books/view/spirit-animals-book-three-blood-ties">
  <meta property="typicalAgeRange" content="8-12">
  <div id="coverImage">
...

Note: In a pinch, you can use the browser development tools to view and edit the source of the web page (CTRL-Shift-i in Chrome or Firefox, in the Elements or Inspector tab respectively).

Add `Product` to the type declaration

Add Product to the typeof attribute in the <body> element. Check the results with one or more of the structured data testing tools.

You should see that both the Book and Product types are recognized. You may note, however, that Google's SDTT only recognizes the first declared type; this is a limitation of their tool and does not necessarily represent the results of their actual search engine.

Check your markup

<!DOCTYPE html>
<html>
<head>
  <title>Las Vegas-Clark County Library District /All Locations</title>
  <style>...</style>
</head>

<body vocab="http://schema.org/" typeof="Book Product" resource="#book">
...

Declare each holding as a separate `Offer`

Products link to their offers via the offers property. The expected range of the offers property is an Offer entity.

Declare each holding in the catalog record as a separate Offer.

Check your markup

<!DOCTYPE html>
<body vocab="http://schema.org/" typeof="Book" resource="#book">
...
  <tr class="bibItemsEntry" property="offers" typeof="Offer">
    <td>Centennial Hills YPL</td>
    <td><a href="/search~S12?/hJ/hj/-3,-1,,B/browse">J</a></td>
    <td>ON HOLDSHELF</td>
  </tr>

  <tr class="bibItemsEntry" property="offers" typeof="Offer">
    <td>Centennial Hills YPL</td>
    <td><a href="/search~S12?/hJ/hj/-3,-1,,B/browse">J</a></td>
    <td>ON HOLDSHELF</td>
  </tr>
...

Identify the seller, offer terms, and price of the `Offer`

While sellers of bibliographic items have a fairly clear mapping to Offer, the applicability for libraries is a bit less obvious. To express individual items that are available to purchase or borrow, begin by mapping your holding properties to Offer properties as follows:

Library = seller: the attribute name is commercial, but it will be treated by schema.org processors as the organization or individual offering the item; the fact that it may be a loan instead of a sale can be handled as part of the Offer.
Borrowing terms = businessFunction: the closest match for "loan" is http://purl.org/goodrelations/v1#LeaseOut and this overrides the default value of "for sale".
Price = price; if your library does not charge for regular loans, set a price of 0.00 so that consuming applications can display a price accordingly.

Check your markup

<!DOCTYPE html>
<body vocab="http://schema.org/" typeof="Book" resource="#book">
...
  <tr class="bibItemsEntry" property="offers" typeof="Offer">
    <td property="seller">Centennial Hills YPL</td>
    <td><a href="/search~S12?/hJ/hj/-3,-1,,B/browse">J</a></td>
    <td>ON HOLDSHELF
      <link property="businessFunction" href="http://purl.org/goodrelations/v1#LeaseOut">
      <meta property="price" content="0.00">
    </td>
  </tr>

  <tr class="bibItemsEntry" property="offers" typeof="Offer">
    <td property="seller">Centennial Hills YPL</td>
    <td><a href="/search~S12?/hJ/hj/-3,-1,,B/browse">J</a></td>
    <td>ON HOLDSHELF
      <link property="businessFunction" href="http://purl.org/goodrelations/v1#LeaseOut">
      <meta property="price" content="0.00">
    </td>
  </tr>

  <tr class="bibItemsEntry" property="offers" typeof="Offer">
    <td property="seller">Centennial Hills YPL</td>
    <td><a href="/search~S12?/hJ/hj/-3,-1,,B/browse">J</a></td>
    <td>DUE 06-10-14
      <link property="businessFunction" href="http://purl.org/goodrelations/v1#LeaseOut">
      <meta property="price" content="0.00">
    </td>
  </tr>

  <tr class="bibItemsEntry" property="offers" typeof="Offer">
    <td property="seller">Enterprise YPL</td>
    <td><a href="/search~S12?/hJ/hj/-3,-1,,B/browse">J</a></td>
    <td>AVAILABLE
      <link property="businessFunction" href="http://purl.org/goodrelations/v1#LeaseOut">
      <meta property="price" content="0.00">
    </td>
  </tr>
...

Show the availability

The item holding status best maps to the availability property, which can take one of the following values:

Available for loan: <link property="availability" href="http://schema.org/InStock">
Checked out: <link property="availability" href="http://schema.org/OutOfStock">
On order: <link property="availability" href="http://schema.org/PreOrder" />
Reference: <link property="availability" href="http://schema.org/InStoreOnly">

If you have chosen to publicly display due dates in your system, you can also use the availabilityStarts property to provide an estimate of when the item will be available. The property expects a date/time value in ISO8601 format following the pattern YYYY-MM-DDThh:mm:ss (with an optional positive or negative time appended to indicate a time zone offset). Reminder: use the content attribute to supply the machine-readable counterparts for human-readable values.

Reflect the availability of each holding in the markup of the page.

Check your markup

<!DOCTYPE html>
<body vocab="http://schema.org/" typeof="Book" resource="#book">
...
  <tr class="bibItemsEntry" property="offers" typeof="Offer">
    <td property="seller">Centennial Hills YPL</td>
    <td><a href="/search~S12?/hJ/hj/-3,-1,,B/browse">J</a></td>
    <td>ON HOLDSHELF
      <link property="availability" href="http://schema.org/OutOfStock">
      <link property="businessFunction" href="http://purl.org/goodrelations/v1#LeaseOut">
      <meta property="price" content="0.00">
    </td>
  </tr>

  <tr class="bibItemsEntry" property="offers" typeof="Offer">
    <td property="seller">Centennial Hills YPL</td>
    <td><a href="/search~S12?/hJ/hj/-3,-1,,B/browse">J</a></td>
    <td>ON HOLDSHELF
      <link property="availability" href="http://schema.org/OutOfStock">
      <link property="businessFunction" href="http://purl.org/goodrelations/v1#LeaseOut">
      <meta property="price" content="0.00">
    </td>
  </tr>

  <tr class="bibItemsEntry" property="offers" typeof="Offer">
    <td property="seller">Centennial Hills YPL</td>
    <td><a href="/search~S12?/hJ/hj/-3,-1,,B/browse">J</a></td>
    <td property="availabilityStarts" content="2014-06-10T00:00:00">DUE 06-10-14
      <link property="availability" href="http://schema.org/OutOfStock">
      <link property="businessFunction" href="http://purl.org/goodrelations/v1#LeaseOut">
      <meta property="price" content="0.00">
    </td>
  </tr>

  <tr class="bibItemsEntry" property="offers" typeof="Offer">
    <td property="seller">Enterprise YPL</td>
    <td><a href="/search~S12?/hJ/hj/-3,-1,,B/browse">J</a></td>
    <td>AVAILABLE
      <link property="availability" href="http://schema.org/InStock">
      <link property="businessFunction" href="http://purl.org/goodrelations/v1#LeaseOut">
      <meta property="price" content="0.00">
    </td>
  </tr>
...

Provide finer grained location information

Earlier, you identified with which library each item is associated; however, that may not be enough to identify the location of a given copy of a resource. There are a number of other Offer properties that are suitable for providing more granular location information for items:

Call number = sku: the attribute name stock keeping unit is overly specific, but the intended role as an inventory identifier and physical locator for a specific organization is a reasonable match for a call number.
Barcode = serialNumber: as a unique identifier for a single item, serialNumber is a good match for barcodes.
Shelving location = availableAtOrFrom: ideally, one would use a Place -> containedIn -> Place relationship to identify a location within a given building, but in practice most sites will likely supply a simple text value like "Stacks" or "Reference"

Add markup for the call number in the holdings page.

Check your markup

<!DOCTYPE html>
<body vocab="http://schema.org/" typeof="Book" resource="#book">
...
  <tr class="bibItemsEntry" property="offers" typeof="Offer">
    <td property="seller">Centennial Hills YPL</td>
    <td property="sku"><a href="/search~S12?/hJ/hj/-3,-1,,B/browse">J</a></td>
    <td>ON HOLDSHELF
      <link property="availability" href="http://schema.org/OutOfStock">
      <link property="businessFunction" href="http://purl.org/goodrelations/v1#LeaseOut">
      <meta property="price" content="0.00">
    </td>
  </tr>

  <tr class="bibItemsEntry" property="offers" typeof="Offer">
    <td property="seller">Centennial Hills YPL</td>
    <td property="sku"><a href="/search~S12?/hJ/hj/-3,-1,,B/browse">J</a></td>
    <td>ON HOLDSHELF
      <link property="availability" href="http://schema.org/OutOfStock">
      <link property="businessFunction" href="http://purl.org/goodrelations/v1#LeaseOut">
      <meta property="price" content="0.00">
    </td>
  </tr>

  <tr class="bibItemsEntry" property="offers" typeof="Offer">
    <td property="seller">Centennial Hills YPL</td>
    <td property="sku"><a href="/search~S12?/hJ/hj/-3,-1,,B/browse">J</a></td>
    <td property="availabilityStarts" content="2014-06-10T00:00:00">DUE 06-10-14
      <link property="availability" href="http://schema.org/OutOfStock">
      <link property="businessFunction" href="http://purl.org/goodrelations/v1#LeaseOut">
      <meta property="price" content="0.00">
    </td>
  </tr>

  <tr class="bibItemsEntry" property="offers" typeof="Offer">
    <td property="seller">Enterprise YPL</td>
    <td property="sku"><a href="/search~S12?/hJ/hj/-3,-1,,B/browse">J</a></td>
    <td>AVAILABLE
      <link property="availability" href="http://schema.org/InStock">
      <link property="businessFunction" href="http://purl.org/goodrelations/v1#LeaseOut">
      <meta property="price" content="0.00">
    </td>
  </tr>
...

Checkpoint: Your original HTML page should now look like step1/check_a.html.

Lessons learned

In this exercise, you learned how to express library holdings using the GoodRelations agent-promise-object model, adapting commercial properties to non-commercial usage where necessary.

RDFa with schema.org codelab: Library holdings

About this codelab

Turning library holdings into Product

View the page source HTML

Add `Product` to the type declaration

Declare each holding as a separate `Offer`

Identify the seller, offer terms, and price of the `Offer`

Show the availability

Provide finer grained location information

Lessons learned

About the author

RDFa with schema.org codelab: Library holdings

About this codelab

Turning library holdings into Product

View the page source HTML

Add Product to the type declaration

Declare each holding as a separate Offer

Identify the seller, offer terms, and price of the Offer

Show the availability

Provide finer grained location information

Lessons learned

About the author

Add `Product` to the type declaration

Declare each holding as a separate `Offer`

Identify the seller, offer terms, and price of the `Offer`