Introduce dynamic parameter order for the websubhub:Service remote methods

[ayeshLK]

Current Limitation

In the current implementation, the parameter order for websubhub:Service methods is static. Consider the following example:

service /websubhub on securedListener {

    remote function onRegisterTopic(websubhub:TopicRegistration message, http:Headers headers)
                                returns websubhub:TopicRegistrationSuccess|websubhub:TopicRegistrationError {
        
        // logic to be executed
    }

    // other methods
}

Here, the http:Headers parameter is optional, meaning users can choose to omit it. However, if we introduce another optional parameter, such as websubhub:Controller, the method signature would need to be modified as follows:

service /websubhub on securedListener {

    remote function onRegisterTopic(websubhub:TopicRegistration message, http:Headers headers, websubhub:Controller hubController)
                                returns websubhub:TopicRegistrationSuccess|websubhub:TopicRegistrationError {
        
        // logic to be executed
    }

    // other methods
}

With this approach, users must define the http:Headers parameter even if they do not use it, since the method parameters follow a fixed order.

To enhance flexibility, parameter ordering should not be strictly enforced. Instead, a more dynamic approach should be introduced to determine parameter order at runtime, allowing optional parameters to be omitted without affecting method invocation.

Suggested Improvement

Introduce dynamic parameter order which provides the flexibility to omit optional parameters as needed and define parameters in any order.

Version

Ballerina SL 2201.11.0 / Ballerina Websubhub v1.13.0

[ayeshLK]

This feature is an required improvement to implement the Subscription autoverification feature.