CommandableHttpClient

Extends: RestClient

Description

The CommandableHttpClient class allows you to create commandable services. Commandable services are generated automatically for ICommandable objects.

Important points

• Each command is exposed as a POST operation that receives all parameters in the body object.

Configuration parameters

• base_route: base route for a remote URI
• connection(s):
  • discovery_key: (optional) key to retrieve the connection from IDiscovery
  • protocol: connection protocol (http or https)
  • host: host name or IP address
  • port: port number
  • uri: resource URI or connection string with all parameters in it
• options:
  • retries: number of retries (default: 3)
  • connect_timeout: connection timeout in milliseconds (default: 10 sec)
  • timeout: invocation timeout in milliseconds (default: 10 sec)

References

• *:logger:*:*:1.0 - (optional) ILogger components to pass log messages
• *:counters:*:*:1.0 - (optional) ICounters components to pass collected measurements
• *:traces:*:*:1.0 - (optional) ITracer components to record traces
• *:discovery:*:*:1.0 - (optional) IDiscovery services to resolve a connection

Constructors

Creates a new instance of the client.

CommandableHttpClient(String baseRoute)

• baseRoute: String - base route for a remote service.

Instance methods

callCommand

Calls a remote method via the HTTP commadable protocol. The call is made via a POST operation and all parameters are sent in the body object. The complete route to the remote method is defined as baseRoute + “/” + name.

Future callCommand(String name, String? correlationId, params)

• name: String - name of the command to call.
• correlationId: string - (optional) transaction id used to trace execution through a call chain.
• params: dynamic - command parameters.
• returns: Future - that receives result or error.

Examples

class MyCommandableHttpClient extends CommandableHttpClient implements IMyClient {
   ...
   Future<MyData> getData(String? correlationId, String id) async {
       var result = await callCommand(
           "get_data",
           correlationId,
           { 'id': id });
      if (result == null) return null;
      return MyData.fromJson(json.decode(result));
    }
    ...
}

var client = MyCommandableHttpClient();
client.configure(ConfigParams.fromTuples([
    "connection.protocol", "http",
    "connection.host", "localhost",
    "connection.port", 8080
]));

var result = await client.getData("123", "1")
...