python-inema: Python module implementing Deutsche Post 1C4A Internetmarke API

At sysmocom we maintain a webshop with various smaller items and accessories interesting to the Osmocom community as well as the wider community of people experimenting (aka 'playing') with cellular communications infrastructure. As this is primarily a service to the community and not our main business, I'm always interested in ways to reduce the amount of time our team has to use in order to operate the webshop.

In order to make the shipping process more efficient, I discovered that Deutsche Post is offering a Web API based on SOAP+WSDL which can be used to generate franking for the (registered) letters that we ship around the world with our products.

The most interesting part of this is that you can generate combined address + franking labels. As address labels need to be printed anyway, there is little impact on the shipping process beyond having to use this API to generate the right franking for the particular shipment.

Given the general usefulness of such an online franking process, I would have assumed that virtually anyone operating some kind of shop that regularly mails letters/products would use it and hence at least one of those users would have already written some free / open source software code fro it. To my big surprise, I could not find any FOSS implementation of this API.

If you know me, I'm the last person to know anything about web technology beyond HTML 4 which was the latest upcoming new thing when I last did anything web related ;)

Nevertheless, using the python-zeep module, it was fairly easy to interface the web service. The weirdest part is the custom signature algorithm that they use to generate some custom soap headers. I'm sure they have their reasons ;)

Today I hence present the python-inema project, a python module for accessing this Internetmarke API.

Please note while I'm fluent in Pascal, Perl, C and Erlang, programming in Python doesn't yet come natural to me. So if you have any comments/feedback/improvements, they're most welcome by e-mail, including any patches.