Assignment 3
Creating and Using an RNG File

Read everything before doing anything.

The objects of this assignment are:

• create an RNG file using many of RNG's features
• validate a document with respect to that grammar

See instructor's sample files
See a note about <interleave>
See a solution allowing nested <ul>
See a solution not allowing nested <ul>

Specification of the Language

The catalog example used in part two of Assignment 1 had no specification for its “grammar.” Here is an English-language description of that grammar, which you should turn into an RNG specification. We've expanded upon it to use features of RNG that aren't available in a DTD. New information has a vertical bar at the side.

• A <catalog> consists of a <company> element followed by one or more <department> elements.

• A <company> element contains plain text.

• A <department> contains one or more <item> elements. It must have a name attribute and a unique code attribute.

• An <item> element contains <name> followed by, in any order, a <price>, an optional <manufacturer>, a color specification (see below), a <summary>, and an optional <description>

• The <name> and <manufacturer> elements contain plain text. The <summary> and <description> may contain a small subset of HTML, as described below.

• The <price> is an empty element which has a required amt attribute that specifies the price as a decimal number, and it must be in the form of a decimal number. It also has an optional units attribute, which may have a value of either USD or CDN.

• A color specification is either a single <color> element (for those items that come in only one color), or a <color-list> (for items that come in multiple colors), or an <sku> element (for items that have no color). These are further defined as:

  • A <color> element contains text, and has a required sku attribute and an optional hex attribute. The sku attribute must begin with one or two capital letters followed by 3 or 4 digits, and (optionally) a hyphen followed by two alphabetic characters. Thus, XY123 and X123-ab are fine; X123ab and XY123- are not. The hex attribute must be in the form of a # followed by six hexadecimal digits, upper or lowercase.

  • The <color-list> element contains one or more <color> elements.

  • An <sku> element contains text which must begin with one or two capital letters followed by 3 or 4 digits, and (optionally) a hyphen and two alphabetic characters.

HTML Subset

First, we define inline elements as the <em> and <strong> elements, which may contain text and other inline elements. Given that definition, the <summary> and <description> elements may contain:

• Text with inline elements

• The <p> (paragraph) element, which may contain text with inline elements.

• The <ul> element, which contains <li> elements.

• Each <li> element may contain text with inline elements and <p> (paragraphs).

• You may have <ul> elements within an <li> if you wish. This is not a requirement, but it might make your RNG a bit easier to write if you allow this nesting.

Notice that this is a highly recursive definition. Here's an example of a valid <description>

<description xmlns:xh="http://www.w3.org/1999/xhtml">
The <xh:strong><xh:em>Sup-R Frying Pan</xh:em></xh:strong> is such a deal!
<xh:p>
Made of <xh:strong>heavy-duty</xh:strong> aluminum alloy, it assists
food preparation with:
</xh:p>
<xh:ul>
<xh:li>A non-conductive handle.</xh:li>
<xh:li><xh:p>Non-stick coating</xh:p> (it's vitamin-enriched, too!)</xh:li>
</xh:ul>
<xh:p>Buy one <xh:em>right now!</xh:em></xh:p>
</description>

Please use namespaces to implement this subset of XHTML, as in the example above. The namespace URI for XHTML is http://www.w3.org/1999/xhtml.

You will also need to produce mixed content with <interleave>. See information about a problem you might encounter.

Note: You will want to add some of this XHTML to your file to test that your RNG file handles it properly. I will test your RNG against one of my own sample files.

Naming Your Files

Your files should be saved as plain ASCII text, but that does not mean that they must both end with the extension .txt. If your name is Joe Doakes, your RNG file should have a name like doakes_j_3.rng and the XML file should have a name like doakes_j_3.xml. You may remove the <!DOCTYPE> from the XML file, as it is no longer needed.

Checking Your Work

Use the msvalidate.bat file on Windows, or msvalidate.sh shell script on Unix/Linux. The validator will give no error messages if everything is OK. If you've named your files as shown above, you would type:

msvalidate doakes_j_3.rng doakes_j_3.xml