CODEWITHSUNDEEP
microservices
Robert Powell
Robert Powell

Reputation: 11

linking Microservices and allowing for one to be unavailable

I'm new to the microservices architecture and am seeing that it is possible under the model to call a microservice from another via HTTP request. However, I am reading that if a service is down all other services should still operate. My question is, how is this generally achieved?

Example, a microservice that handles all Car record manipulation may need access to the service which handles the Vehicle data. How can the Car Microservice complete it's operations if that service is down or doesn't respond?

Upvotes: 0

Views: 375

Answers (1)

techagrammer
techagrammer

Reputation: 1306

You should generally consider almost zero sync communication between microservices(if still you want sync comminucation try considering circuit breakers which allow your service to be able to respond but with logical error message , if no circuit breaking used dependent services will also go down completly).This could be achieved by questioning the consistency requirement of the micorservice.

Sometimes these things are not directly visible , for eg: lets say there are two services order service and customer service and order service expose a api which say place a order for customer id. and business say you cannot place a order for a unknown customer

one implementation is from the order service you call the customer service in sync ---- in this case customer service down will impact your service, now lets question do we really need this.

Because a scenario could happen where customer just placed an order and somebody deleted that customer from customer service, now we have a order which dosen't belong to customer.Consistency cannot be guaranteed.

In the new sol. we are saying allow the order service to place the order without checking the customer id and do one of the following:

  1. Using ProcessManager check the customer validity and update the status of the order as invalid and when customer get deleted using ProcessManager update the order status as invalid or perform business logic
  2. Do not check at all , because placing a order dosen't count a thing, when this order will be in the process of dispatch that service will anyway check the customer status

Statement here is try to achieve more async communication between microservices , mostly you will be able find the sol. in the consistency required by the business. But in case your business wants to check it 100% you have to call other service and if other service is down , your service will give logical errors.

Upvotes: 2

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