[almighty] Cache solution for Almighty core

[Thomas Mäder]

Hi Alexey,

If you're talking about a "cache server" are you talking about a 
separate process, possibly on a different machine or an in-process 
service like groupcache?

How I understand microservices, they DON'T have a shared DB behind them. 
They have a relatively simple datamodel that is loosely coupled to the 
other microservices via a well defined API (no peeking at the 
internals!). Multiple instances of the same service may share a common 
DB, but not different microservices. As a consequence of this, it 
doesn't make sense for multiple different services to share the same 
cache in my opinion. Instead of asking any shared cache service, you 
might as well ask the original service and let that one take care of 
caching.

/Thomas

On 11/08/2016 01:15 AM, Alexey Kazakov wrote:
> Hi all,
>
> At some point we will probably need some universal cache solution 
> which we could use different types of objects in almighty core. I'm 
> going to spend some time on researching in this area but there are a 
> few questions I would like to discuss with the team.
> There are some solutions like Memcached or Redis which could be used 
> but they require to have a server with the cache service (on a 
> dedicated container?) where we could keep WIT, WI and any other 
> artefacts which we want to access some value by a key. Some solutions 
> like Memcached are pure in-memory some like Redis can be persistent 
> but my biggest concern for now is what approaches are best for 
> microservices world.
> In monolith world we could have a shared cache server. One DB - one 
> cache service. But I'm not sure if it's worth having an internal 
> dedicated cache server for each relevant microserver.
> Currently we are kinda building a monolith and a cache server could 
> work. But how our cache system should evolve when we start 
> splitting/introducing microservices in almighty-core? Is there any 
> concept of shared cache between microservices or it's always hidden by 
> the microservice implementation and the microservice just takes care 
> of synchronization of its internal model/DB and uses some internal 
> fully independent cache if needed.
>
> Any thoughts?
>
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