Sphinx: Link to outer non-sphinx document by using intersphinx. https://groups.google.com/d/topic/sphinx-users/P_FolrZVoNg/discussion

conf.py

extensions = ['sphinx.ext.intersphinx']

intersphinx_mapping = {
    'javaapi': ('http://api.example.com/', 'javaapi.inv'),
}

generate_javaapi_inv.py

# -*- coding: utf-8 -*-

import zlib

inventory_header = u'''\
# Sphinx inventory version 2
# Project: javaapi
# Version: 2.0
# The remainder of this file is compressed with zlib.
'''.encode('utf-8')

inventory_payload = u'''\
api1 std:label -1 api.html#api1 API 1
'''.encode('utf-8')

# inventory_payload lines spec:
#   name domainname:type priority uri dispname
#
# * `name`     -- fully qualified name
# * `dispname` -- name to display when searching/linking
# * `type`     -- object type, a key in ``self.object_types``
# * `docname`  -- the document where it is to be found
# * `anchor`   -- the anchor name for the object
# * `priority` -- how "important" the object is (determines placement in search results)
#
#   - 1: default priority (placed before full-text matches)
#   - 0: object is important (placed before default-priority objects)
#   - 2: object is unimportant (placed after full-text matches)
#   - -1: object should not show up in search at all
#

inventory = inventory_header + zlib.compress(inventory_payload)
open('javaapi.inv','wb').write(inventory)

index.html

<div class="section" id="example-link-to-outer-non-sphinx-by-using-intersphinx">
<h1>Example: Link to outer non-sphinx by using intersphinx<a class="headerlink" href="#example-link-to-outer-non-sphinx-by-using-intersphinx" title="Permalink to this headline">ﾂｶ</a></h1>
<p><a class="reference external" href="http://api.example.com/api.html#api1" title="(in javaapi v2.0)"><em class="xref std std-ref">Java API 1</em></a></p>
</div>

index.rst

Example: Link to outer non-sphinx by using intersphinx

Java API 1 <javaapi:api1>

index.txt

Example: Link to outer non-sphinx by using intersphinx
==========================================================================

:ref:`Java API 1 <javaapi:api1>`