Send request to service endpoint

[Kinrany]

Since NATS offers a first-class concept of services, I would expect the library to offer a way to send requests to endpoints directly. I can't find one though. It looks like the service module is designed only for implementing services, not for consuming them?

[jnmoyne]

You simply use the 'request' call on your NATS connection object, not part of the service module (which automatically creates an 'inbox' subject, subscribes to it and publishes the request message on the specified subject (i.e. what your service end point subscribes to) with that inbox subject in the 'reply' field of the message. The request call is synchronized and will block until the reply is received, or time out.

[Kinrany]

I get that I can do that. But I can implement a service manually as well since this is just a layer on top of Core's request-reply.

[jnmoyne]

Correct. The services library doesn't implement the distributed request/reply as that is already in Core NATS what it does is simplify your life as a service implementer by taking care of (and standardizing) all the other stuff around and beyond the basic request/reply functionality (eg service description, stats, how to expose the stats, etc...). But as a client just making a request all you have to do is just call the Core NATS request call to make the request, which is why there isn't a request call in the services part of the client library. To do things like service discovery or getting stats for a service however that's going to be functionality in the services part of the client library.

[Kinrany]

One thing that I think this misses is the construction of subjects: a service with many endpoints will have a prefix, a collection of services will have another. The client will then have to repeat the logic instead of using the same configured router.