Hi Folks,
An XML object is an element whose content is a collection of heterogeneous data items. For example, this
Book element contains a collection of heterogeneous data items and therefore is an XML object:
<Book>
<Title>The First and Last Freedom</Title>
<Author>J. Krishnamurti</Author>
<Date>1954</Date>
<ISBN>0-06-064831-7</ISBN>
<Publisher>Harper
& Row</Publisher>
</Book>
The fact that it is an object becomes more apparent with this graphic:
Recommendation:
Don’t create XML objects with duplicate keys. For example, this
Book object has duplicate Author keys:
<Book>
<Title>Parsing Techniques</Title>
<Author>Dick Grune</Author>
<Author>Ceriel Jacobs</Author>
<Date>2007</Date>
<ISBN>978-0387202488</ISBN>
<Publisher>Springer</Publisher>
</Book>
Instead, create a single
Authors element whose content is an array:
<Book>
<Title>Parsing Techniques</Title>
<Authors><Author>Dick Grune</Author><Author>Ceriel Jacobs</Author></Authors>
<Date>2007</Date>
<ISBN>978-0387202488</ISBN>
<Publisher>Springer</Publisher>
</Book>
Now the Book object contains a collection of
unique keys. The value of the Authors key is an array of
Author elements.
Why follow this recommendation? Here’s why:
1. It enables XML objects to evolve, using the Must-Ignore policy, as I described in yesterday’s message.
2. It enables conversion between XML and programming language objects and databases.
3. It is consistent with rfc 7493 (http://www.rfc-editor.org/rfc/rfc7493.txt) which recommends that no JSON object have duplicate keys.
/Roger
Cart
