Saturday, October 22, 2016

IT Compass

During a meeting, the terms "north" and "south" popped up again while discussing network zoning and DMZ. North is the "outside", typically the Internet. South are the internal, trusted systems.

North-South in networking (from PaloAlto networking)
How would IT people in South-Africa think about this, where the north is "hot" and very south Antarctica cold? Maybe also good fit: freezing in the data center, hot and dangerous on the Internet.

Saturday, October 15, 2016

Unikernel: microservices without an OS

As I continue to spend lots of time on the road and in traffic jams, podcasts are an efficient way to keep up-to-date in the fast moving IT world. Just finished listening SE-Radio Episode 271: Idit Levine on Unikernels. Very interesting.

Had never heard of Unikernel. Actually this is hardly a real OS: no multi-tasking, no security, no memory management. Memory directly mapped to the underlying hardware and some device drivers.

Unikernels become most relevant when used on top of a virtualization layer. A single application is combined with the Unikernel to become a super light-weight runtime unit. A fine alternative for microservices running in a container.

Unikernels are also a nice fit with server-less architectures: the Unikernel App is super-fast to start. So Unikernel Apps as a more efficient Function-As-A-Service approach.

When mapping this to my own world of integration, the Unikernel App could be a nice mechanism to handle all the async events going on in an integration environment. An incoming message or API call starts the Unikernel App which handles the message: transformation, routing, logging, forwarding...

Incredible at which pace the IT world keeps moving.

Sunday, October 9, 2016

Event-driven Microservices

A few weekends ago, I decided that it was time to catch up on Microservices. Hadn't been following the topic for a longer while. Starting point is often Safari: but instead of reading, I ended up watching the video tutorial "Event-Driven Microservices". By the way, the first part is freely accessible without a Safari subscription.

The video course is presented by Chris Richardson. I know Chris as a speaker at earlier Devoxx conferences. Very interesting is his approach to address the topic based on patterns, documented at
Microservices patterns (from, by Chris Richardson)

What was new to me and most interesting was the part about Event-Sourcing: instead of storing the state of each object as a database row, the sequence of changes is recorded and maintained. This an approach to tackle the issue of distributed transactions that do not fit with a Microservices architecture. This is also the topic Richardson personally focuses on as his latest startup is all about Event Sourcing.
List of events represents state (Source

Handling request by rebuilding state from list of events (Source:
Of course one needs to remain critical about Microservices:
  • We've been successfully building 3-tier web and mobile apps, why do it all different now?
  • How heterogeneous will all these microservices be?  
  • Not every organisation is like LinkedIn or Netflix
  • Transactions that are eventually consistent are not trivial
  • What will be the next thing after Microservices?
After 4h 47minutes, I understood that Microservices is as well a domain that is in full flux.