Converting Docs via HTTP

The included WSGI app provides access to unoconv and filters in this package via HTTP. More specificially we provide a RESTful WSGI app that can be served by HTTP servers and optionally caches result docs.

Setting Up the WSGI App With Paste

To run the included RESTful doc converter WSGI app we can use Paste. The required paster script can be installed locally with:

(py27) pip install PasteScript

Then we need a PasteDeploy compatible config file like the following sample.ini:

# sample.ini
# A sample config to run WSGI components with paster
[app:main]
use = egg:ulif.openoffice#docconverter
cache_dir = /tmp/mycache

[server:main]
use = egg:Paste#http
host = localhost
port = 8008

In the [app:main] section we tell to serve the ulif.openoffice WSGI app docconverter. We additionally set a directory where we allow cached documents to be stored. This entry (cache_dir) is optional. Just leave it out if you do not want caching of result docs.

The [server:main] section simply tells to start an HTTP server on localhost port 8008. host can be set to any local hostname or an IP number. Set it to 0.0.0.0 to be accessible on all IPs assigned to the current machine (but read the security infos below, first!).

You now can start a conversion server:

(py27) $ paster serve sample.ini

and start converting real office documents via HTTP on the configured host and port (here: localhost:8008).

While we use the Paste HTTP server here for demonstration, you are not bound to this choice. Of course you can use any HTTP server capable of serving WSGI apps you like. This includes at least Apache and nginx (with appropriate modules loaded).

Securing the Document Converter (optional)

As told above, you can set the listening port of the Paste HTTP server to 0.0.0.0 which will make it accessible for everyone and from everywhere (given you’re not protected by local firewalls, etc.). This might not be what you want.

Therefore with ulif.openoffice we provide simple authentication (another WSGI app) that requires HTTP basic auth authentication for incoming requests and checks sent credentials against a local htaccess-like file.

To activate it, you can create a sample.ini like this:

# An sample config to run WSGI components with paster
[app:main]
use = egg:ulif.openoffice#docconverter
filter-with = auth_htaccess
cache_dir = /tmp/mycache

[server:main]
use = egg:Paste#http
host = localhost
port = 8008

[filter:auth_htaccess]
use = egg:ulif.openoffice#htaccess
realm = Sample Realm
htaccess =  %(here)s/htaccess
# possible values: plain, sha1, crypt
auth_type = plain

This setup is basically the same as the one above, but with an additional auth_htaccess filter injected that is configured in the [filter:auth_htaccess] section.

The htaccess filter requires three options:

realm - The authentication realm.

Some text. Might be shown by webbrowsers when asking the user for credentials in the basic-auth dialog (normally some popup).

htaccess - The path to some password file.

Here we set the path to some file called htaccess in the local directory.

auth_type - The encryption type of passwords in the password file.

Possible values are plain (clear text passwords), sha1, or crypt for the respective encryption types. Different to regular Apache htaccess files, md5 is not supported. All passwords in the chosen password file are expected to be encrypted with the encryption type set here. You cannot mix-up plain, crypt, and SHA1 encrypted passwords.

The password file set by the htaccess option can be some regular Apache htaccess file (given you avoid md5 encryption). It can even be edited using the htpasswd commandline tool (if installed).

A typical plain text password file could look like this:

# htaccess
# A password file for the document converter.
# Supported encryption types: plain, crypt, sha1
# Not supported: md5
# You can use htpasswd to edit me.
# All passwords must have same encryption type.
bird:bebop
ornette:wayout

would allow user bird access when authenticating with plain password bebop. With this setup anonymous doc conversions are not possible.

Of course you can pick a different WSGI filter to protect your document conversion server, but this one is already included in ulif.openoffice and might serve for simple use-cases.

Converting Documents

Once the server runs, we can start converting docs via HTTP.

The ulif.openoffice WSGI app supports the following HTTP-based protocol to create, update, and remove documents:

HTTP method	Path	Params	Semantics
GET	/docs/new	none	Get an HTML form to trigger a new conversion.
POST	/docs	doc, [other...]	Create a new conversion.
GET	/docs/<docid>	none	Get a cached conversion.

Currently, removal and updating are not supported.

Creating New Resources

Via GET to /docs/new you can get an HTML form usable in a browser to send new documents to the server. This form provides a very limited set of options you can set for the conversion.

>>> url = 'http://localhost/docs/new'
>>> print(browser.GET(url))          
200 OK
Content-Type: text/html; charset=UTF-8
Content-Length: ...

<html>
  <head>
    <title>Create a new doc</title>
  </head>
  <body>
    <form method="POST" action="/docs"
          enctype="multipart/form-data">
    ...
    </form>
  </body>
</html>

Via a POST to /docs you can send a document to the server that will be converted. The result will be the converted document.

>>> url = 'http://localhost/docs'
>>> form = {'doc': ('sample.txt', 'Some Content'),
...         'oocp-out-fmt': 'html'}
>>> response = browser.POST(url, **form)
>>> response.status
'201 Created'

>>> for key in sorted(response.headers.keys()):
...     print("%s: %s" % (key, response.headers.get(key)))
Content-Length: ...
Content-Type: application/zip
ETag: "...-...-..."
Last-Modified: ...
Location: http://localhost:80/docs/78138d2003f1a87043d65c692fb3a64b_1_1

>>> response.body.startswith(b"PK")
True

Here we converted a sample.txt file to HTML. To do that we POSTed a request to the server with two parameters:

doc

the file to be converted.

oocp-out-fmt

the output format we want the document to be converted to.

While the doc parameter is mandatory, other parameters are optional. The oocp-out-fmt parameter, for instance, is set to html by default and you don’t have to send it with the request. See ulif.openoffice.processor for the options of different document processors.

With the response we not only get the converted document (packed into a ZIP file), but also some helpful information:

Stating 201 Created the server indicates that the converted document was cached after creation and can be retrieved in future from the URI given in the Location header.

Note

The cached location for later retrieval of the generated document works only, if caching is enabled for the REST server. If it is not, you will get status 200 OK and no Location header instead.

To get a complete list of supported document processing options you can run:

(py27) $ oooclient --help

The WSGI document converter accepts all short options (the ones with a leading single dash) with the leading dash removed. For example while oooclient accepts

-oocp-out-fmt and --oocp-output-format,

the WSGI app accepts only

oocp-out-fmt

without the leading dash. The same applies to all other options listed by oooclient --help.