Doctor, Doctor, my docs aren’t doing well. Can I get some Asciidoctor pills?

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
    "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd">
<book lang="en">
    <bookinfo>
        <title>Document Title</title>
        <date>2013-01-01</date>
        <author>
            <firstname>Doc</firstname>
            <surname>Writer</surname>
            <email>doc@asciidoc.org</email>
        </author>
        <authorinitials>DW</authorinitials>
        <revhistory>
            <revision>
                <revnumber>1.0</revnumber>
                <date>2013-01-01</date>
                <authorinitials>DW</authorinitials>
                <revremark>Initial version</revremark>
            </revision>
        </revhistory>
    </bookinfo>
    ...

    ...
    <preface>
        <title></title>
        <simpara>
           <ulink url="http://asciidoc.org">AsciiDoc</ulink> is a
           lightweight markup language.
        </simpara>
        <simpara>
            This is the optional preamble (an untitled section body).
            Useful for writing simple sectionless documents consisting
            only of a preamble.
        </simpara>
        <note>
            <simpara>
                The abstract, preface, appendix, bibliography, glossary
                and index section titles are significant
                (<emphasis>specialsections</emphasis>).
            </simpara>
        </note>
    </preface>
    <chapter id="_first_section">
        <title>First section</title>
        <simpara>
            ...

            ...
            Document sections start at <emphasis role="strong">level
            1</emphasis> and can nest four levels deep.
        </simpara>
        <itemizedlist>
            <listitem>
                <simpara>Item 1</simpara>
            </listitem>
            <listitem>
                <simpara>Item 2</simpara>
            </listitem>
        </itemizedlist>
    </chapter>
</book>

# Document Title

[AsciiDoc](http://asciidoc.org) is a lightweight markup language.

This is the optional preamble (an untitled section body). Useful for
writing simple sectionless documents consisting only of a preamble.

<div class="note">
  <h5>Note</h5>
  <p>The abstract, preface, appendix, bibliography, glossary and index
  section titles are significant (<em>specialsections</em>).</p>
</div>

## First section

Document sections start at **level 1** and can nest four levels deep.

* Item 1
* Item 2

{% highlight ruby %}
puts 'Hello, World!'
{% endhighlight %}

= Document Title
Doc Writer <doc@asciidoc.org>
v1.0, 2013-01-01: Initial version

http://asciidoc.org[AsciiDoc] is a lightweight markup language.

This is the optional preamble (an untitled section body), useful for
writing simple sectionless documents consisting only of a preamble.

NOTE: The abstract, preface, appendix, bibliography, glossary and
index section titles are significant (_specialsections_).

== First section

Document sections start at *level 1* and can nest four levels deep.

* Item 1
* Item 2

[source,ruby]
puts 'Hello, World!'

import static org.asciidoctor.AttributesBuilder.attributes;
import static org.asciidoctor.OptionsBuilder.options;

...

Attributes attributes = attributes().backend("docbook").get();
Options options = options().inPlace(true).attributes(attributes).get();

String render = asciidoctor.renderFile("sample.asciidoc", options);

...