<p>I need to validate an XML string (and not a file)
against a DTD description file. </p>

<p>How can that be done in <code>python</code>?</p>

Another good option is
lxml's validation
which I find quite pleasant to use.
A simple example taken from the lxml site:
```
```
from StringIO import StringIO

from lxml import etree

dtd = etree.DTD(StringIO("""<!ELEMENT foo EMPTY>"""))
root = etree.XML("<foo/>")
print(dtd.validate(root))
# True

root = etree.XML("<foo>bar</foo>")
print(dtd.validate(root))
# False
print(dtd.error_log.filter_from_errors())
# <string>:1:0:ERROR:VALID:DTD_NOT_EMPTY: Element foo was declared EMPTY this one has content
```
```