web services - Systems architecture for small business ISP -

i'm programmer of pretty small isp in rural area around 2000 customers. have finished couple of semesters in university have couple of years of experience in field i'm uncertain of architectural decisions i'm making , hoping me pick right path.

most of our internal apps created 8-10 years ago , severely outdated , have been given job replace systems. of basic underlying systems solid apps use manage our customers , connecting our internal systems are...lacking least.

most of these applications created in php in day , using mysql databases. decided going create couple of rest apis using nodejs on top of these databases , create central app take care of connecting systems , making sure stay date 1 another.

now question. i've been looking bit enterprise architecture , i've gathered going sort of micro service architecture seems solid plan. i've seen couple articles talking message buses , question if should instead set message bus, example apache activemq these services can talk amongst instead of using central app handle managing of them.

are there specific patterns should reading on or i've come solid enough?

an enterprise service bus add lot of complexity design, need @ pro/con see if it's necessary. here article can upgrade architecture in future , migrate services.

i run complex services on apache tomcat , work great. supports user pool of 70,000. if build in connection pooling , redundancy should fine.