The recent Amazon S3 outage should make a strong argument that centralized services have severe issues, technically but from a business point of view as well(you don’t own the destiny of your own product!) and I whole heartily agree with “There is no cloud, it’s only someone else’s computer”. Still from time to time I like to see beyond my own nose (and I prefer the German version of that proverb!) and the current exploration involves ReactJS (which I like),…
A long time ago I wrote the OpenEmbedded User Manual and back then the obvious choice was to make it a docbook. In my community there were plenty of other examples that used docbook and it helped to get started. The great thing of docbook was with one XML input one could generate output in many different formats like HTML, XHTML, ePub or PDF. It separated the format from the presentation and was tailored for technical documents and articles with advanced features like generating…
Going from 2G/3G requires to learn a new set of abbreviations. The network is referred to as IP Multimedia Subsystem (IMS) and the HLR becomes Home subscriber server (HSS). ITU ASN1 to define the RPCs (request, response, potential errors), message structure and encoding in 2G/3G is replaced with a set of IETF RFCs. From my point of view names of messages, names of attributes change but the basic broken trust model remains. Having worked on probably the best ASN1/TCAP/MAP stack…
Introduction Previously I have written about connectivity options for IoT devices and today I assume that a cellular technology (e.g. names like GSM, 3G, UMTS, LTE, 4G) has been chosen. Unless you are a big vendor you will end up using a module (instead of a chipset) and either you are curious what the module is doing behind its AT command interface or you are trying to understand a real problem. The following is going to help you or at least…
As part of the Osmocom.org software development we have a Jenkins set-up that is executing unit and system tests. For OpenBSC we will compile the software, then execute the unit tests and finally run a bunch of system tests. The system tests will verify making configuration changes through the telnet interface, the machine control interface, might try to connect to other parts, etc. In the past this was executed after a committer had pushed his changes to the repository and…
As part of running infrastructure it might make sense or be required to store logs of transactions. A good way might be to capture the raw unmodified network traffic. For our GSM backend this is what we (have) to do and I wrote a client that is using libpcap to capture data and sends it to a central server for storing the trace. The system is rather simple and in production at various customers. The benefit of having a central server…
Many of us deal or will deal with (connected) M2M/IoT devices. This might be writing firmware for microcontrollers, using a RTOS like NuttX or a full blown Unix (like) operating system like FreeBSD or Yocto/Poky Linux, creating and building code to run on the device, processing data in the backend or somewhere inbetween. Many of these devices will have sensors to collect data like GNSS position/time, temperature, light detector, measuring acceleration, see airplanes, detect lightnings, etc.The backend problem is work but mostly “solved”….
Berlin continues to gain a lot of popularity, culturally and culinarily it is an awesome place and besides increasing rents it still remains more affordable than other cities. In terms of economy Berlin attracts new companies and branches/offices as well. At the same time I felt the itch and it was time to leave my home town once again. In the end I settled for the bicycle friendly (and sometimes sunny) city of Amsterdam. My main interest remains building reliable…
In the past I have written about my usage of Tufao and Qt to build REST services. This time I am writing about my experience of using the TreeFrog framework to build a full web application. You might wonder why one would want to build such a thing in a statically and compiled language instead of something more dynamic. There are a few reasons for it: Performance: The application is intended to run on our sysmoBTS GSM Basestation (TI Davinci DM644x). By modern…
Imagine you run a GSM network and you have multiple systems at the edge of your network that communicate with other systems. For debugging reasons you might want to collect traffic and then look at it to explore an issue or look at it systematically to improve your network, your roaming traffic, etc. The first approach might be to run tcpdump on each of these systems, run it in a round-robin manner, compress the old traffic and then have a…