Errata: January 31, 2019

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Unless otherwise noted, errors have been corrected or are pending in all versions.


Page 29, figure 2.1

The oval on the right under #B should be http://lukeruth.com/me.ttl#Me; however, this link is no longer active.

Page 65, Section 3.3.2, SameAs.org

The Sindice search entry point is no longer available from SameAs.org. The first paragraph should read:

Another avenue for discovery of Linked Data is SameAs.org, http://www.sameas.org. The objective of SameAs.org is to identify equivalent URIs to the Linked Data URI entered.

Page 113, Section 5.5, SPARQL results formats (XML, JSON)

The colloquial term "Tag" was used instead of the technically correct term "Element." While we believe the message could still be understood this correction will be clearer in the long run. The second and third paragraphs should read as follows (changed words are bolded):

The XML format is, as the name suggests, an XML representation of a SPARQL result set. It is a W3C Recommendation and thus implemented by all SPARQL endpoints. Listing 5.18 provides an example of the results for the query in Listing 5.2 in the XML format. Note that the <head> element contains a list of all the variables named in the SELECT clause of the query. This facilitates parsing, even though the variable names may also be found in the <results> element content. The <results> element contains zero or more <result> element, each of which contains a result.

A <binding> element appears for each variable in a result. The name attribute indicates the variable's name and the enclosed tag indicates the binding's data type (e.g. "literal" or "uri" as shown here; other data types include "date", "integer", etc).

The comments for Listing 5.18, SPARQL Results in XML format for the query in Listing 5.2

#A This is an XML document and so starts with an XML header.
#B This is a SPARQL results document. The element provides the SPARQL results namespace.
#C The <head> element contains a listing of the variables from the SELECT clause of the preceding query.
#D The <results> element contains zero or more <result> element, each of which contains a result.
#E A <binding> element appears for each variable in a result. The "name" attribute indicates the variable's name and the enclosed tag indicates the binding's data type (e.g. "literal" or "uri" as shown here).

Page 139, Listing 6.6, Sample listing 6.5 using GoodRelations

This error hasn't been corrected in any version.

The RDFa in the listing is missing the namespace for the GoodRelations vocabulary. The namespace should be inserted in the list of namespaces between lines 12 and 18. The namespace line should look like this:

gr: http://purl.org/goodrelations/v1#