The OP addresses this as one of the three options: The final option is to share resources such as a tax calculating library between the services. This can be u

The OP addresses this as one of the three options: The final option is to share resources such as a tax calculating library between the services. This can be useful, but it won't always work in a polyglot environment and introduces coupling which may mean that services have to be released in parallel to maintain the implicit interface between them. This coupling essentially mitigates a lot of the benefits of Microservices approaches.