Microservices: Artifact Ejection2019-12-30 #microservices #artifacts #connection #ejection
As I was discussing about artifacts in microservices, I guess I forgot to discuss some important point: How those artifacts are "ejected" from the microservice?
"Ejected", in this case, means "pass it to the next necessary stage", which can mean a lot of stuff (sometimes, more than one). Also, I needed some catchy word for it 'cause simply "produces" isn't that fashionable.
For example, if your microservice is producing intermediate data -- say, it connects to an external service and retrieves information, which is then processed by different microservices -- then you probably want to use a message broker as the ejection route for the artifact. Using a message broker will allow another services to keep listening to the creation of those artifacts and do their thing -- producing new artifacts.
Another possibility is that this microservice is the end of the production line and, thus, it just keeps the artifact in order to by consumed in a non-asynchronous way. For example, the microservice may produce elements that are later requested by a web request, so what its needs is to produce said artifact and keep it around, responding requests later.
This, again, is akin to the way CQRS (command-query response segregation) works: You have one side of your microservice receiving data and processing its artifact, and another that allows querying the artifacts.
You can even do both: When the artifact is produced, the microservice ejects it through a message broker to be processed by other microservices and still stores it internally to be queried.
There is even the possibility of the query part be just another microservice: It gets the artifact from another microservice and stores it, with no processing (if you don't count as "saves in a permanent storage" a processing). This is interesting 'cause the "query" part of the microservice is just another microservice, instead of being some sort of specialized microservice that produces, ejects and stores artifacts.
When I mentioned we saved our artifacts in Firebase, we are basically building this split microservice: While we have microservices that produce the artifacts, the "storage and query" part is giving to Firebase -- but you can consider this as any other service.
(This whole post is just to give some pointers on what I want to discuss next, which are some thoughts about self-healing microservices -- and what I meant by that.)