Replace server.url with server.host

[fmvilas]

Problem

Currently, AsyncAPI servers have a property called url. In many cases, we're showing examples of the url field as a host instead (without the protocol part of the URL) which is incorrect. On top of that, what's the point of having the protocol included in the url field if we already have the protocol field? This is an example of what I'm talking about:

asyncapi: 3.0.0
servers:
  localhost:
    url: mqtt://localhost
    protocol: mqtt
  production:
    url: kafka://my-production-server.com
    protocol: kafka

It can also create inconsistencies where the protocol in the URL and the protocol field don't match:

asyncapi: 3.0.0
servers:
  localhost:
    url: kafka://localhost
    protocol: mqtt

Proposal

My proposal is that we rename the url field as host, which would be more correct. Example:

asyncapi: 3.0.0
servers:
  localhost:
    host: localhost
    protocol: mqtt
  production:
    host: my-production-server.com
    protocol: kafka

---

We may also have to consider adding other parts of the URL like the path and query variables.

This is a proposal to fix #274

[dedoussis]

Thanks for putting the issue together!

This is indeed a glitch of the existing spec (2.0.0) and I think the root cause of the glitch is the url field of the Server Object supporting both absolute and relative URLs. One cannot simply determine whether the url value is relative or not, as the scheme of the URL is expected to be defined in the separate protocol field.

The OpenAPI Server Object does not have a protocol field, which makes sense since the protocol can be inferred from the url field. If the url value is absolute, then it includes the protocol. If relative, then the protocol/scheme can be inferred from the URL that was used to access the OpenAPI document.
This allows OpenAPI to support relative URLs, since the only protocol one can use is http (and https), which conveniently is the protocol though which one is serving their API documentation. However, this is not the case in the AsyncAPI world where in most scenarios: server protocol != API docs endpoint protocol.

So this proposal is essentially dropping support for relative server URLs.

[dedoussis]

Instead of dropping the url field and introducing new fields (for the different parts of the url), I would suggest the inverse approach:
Drop the protocol field and enforce the value of the existing url field to be an absolute URL.

The enforcement of the absolute url will provide support for all possible URL parts (even for niche parts such as fragment or userinfo)

To me, this feels like the most simple and future proof approach.

[fmvilas]

🤔 Enforcing the URL to be always absolute would go against our plans to support any kind of APIs in the future (REST too).

Just thinking out loud: another option is that we decide to take both approaches and do something like "use url or protocol + host + path + ...". In other words, they'll be mutually exclusive. Not a fan of polymorphism here but definitely an option.

[dedoussis]

Enforcing the URL to be always absolute would go against our plans to support any kind of APIs in the future (REST too).

I see. In that case, I think I lean towards your proposal: drop the URL field, and replace it with fields for all the possible URL parts.

[dedoussis]

Happy to champion this RFC by the way. Will be putting together a Stage 1 proposal.

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[jonaslagoni]

I think this makes sense to include in 3.0.0.

My only concern is that it becomes difficult for tooling to access the full URL. As you rarely need to access the individual components of the full URL, tooling would have to remember how to glue together the pieces of information.

Added a clarification issue for the parser-api to ensure we don't forget to solve this for tooling - asyncapi/parser-api#37

[jonaslagoni]

Is there any of you who wants to champion this? 🙂 Or can we consider this issue as needs champion? 🤔

[gibson042]

Anything addressing this issue should be required to also resolve #274, which basically stems from the fact that any bare host name is also syntactically a valid URI reference (e.g., in the absence of documented priority for interpreting the data, it is ambiguous whether url: api.example.com refers to "https://example.com/path-to-AsyncAPI-spec/api.example.com" or to "https://api.example.com/").

[smoya]

@dedoussis are you happy championing this one as you mentioned in the past?

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity 😴

It will be closed in 120 days if no further activity occurs. To unstale this issue, add a comment with a detailed explanation.

There can be many reasons why some specific issue has no activity. The most probable cause is lack of time, not lack of interest. AsyncAPI Initiative is a Linux Foundation project not owned by a single for-profit company. It is a community-driven initiative ruled under open governance model.

Let us figure out together how to push this issue forward. Connect with us through one of many communication channels we established here.

Thank you for your patience ❤️

[smoya]

@fmvilas what about this one? Do we want to move it forward or rather stale it finally?

[fmvilas]

I think this should be addressed in the next major version, otherwise, it will produce a breaking change. Or! We leave it for 4.0.0 and see how well the parser intent-driven API behaves 😄

[fmvilas]

I made a proposal for this issue: #888.

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity 😴

It will be closed in 120 days if no further activity occurs. To unstale this issue, add a comment with a detailed explanation.

There can be many reasons why some specific issue has no activity. The most probable cause is lack of time, not lack of interest. AsyncAPI Initiative is a Linux Foundation project not owned by a single for-profit company. It is a community-driven initiative ruled under open governance model.

Let us figure out together how to push this issue forward. Connect with us through one of many communication channels we established here.

Thank you for your patience ❤️

[fmvilas]

Be patient, dear Github Actions. The PR is done and it will make it to 3.0.0. Just give us some more time :)

[github-actions]

This issue has been automatically marked as stale because it has not had recent activity 😴

It will be closed in 120 days if no further activity occurs. To unstale this issue, add a comment with a detailed explanation.

There can be many reasons why some specific issue has no activity. The most probable cause is lack of time, not lack of interest. AsyncAPI Initiative is a Linux Foundation project not owned by a single for-profit company. It is a community-driven initiative ruled under open governance model.

Let us figure out together how to push this issue forward. Connect with us through one of many communication channels we established here.

Thank you for your patience ❤️