Add Service Call capability

[jaguardo]

Should be similar to Topic?

[flynneva]

that would definitely be something if we could enable services and actions. would have to do some research how difficult this would be...

[jaguardo]

so, ros services is just an array, whereas topics is an object with an array (RobotWebTools/roslibjs#363)... so stay true to roslibjs and just pass through the array, or add the functionality so that topics and services act the same? (I chose the later to get it to work):

  function getServices() {
    const servicesPromise = new Promise((resolve, reject) => {
      ros.ROS.getServices((services) => {
        const serviceList = services.map((serviceName) => {
          return {
            path: serviceName,
            type: "service",
          }
        });
        resolve({
          services: serviceList
        });
        reject({
          services: []
        });
      }, (message) => {
        console.error("Failed to get services", message)
        ros.services = []
      });
    });
    servicesPromise.then((services) => setROS(ros => ({ ...ros, services: services.services })));
    return ros.services;
  }

so instead of [... , ... , ... ] you get [{...}, {...}, {...}] returned... either way is probably fine, OCD in me likes the later to match the topic return... but you are not really getting any more information, since we are just arbitrarily adding type:"service" as another key:value element... but you already "know" that because of the react-ros variable is called "services"!

[jaguardo]

I tested the function above and it seems to work... this "may" work if we want to be purists and just return the array:

  function getServices() {
    const servicesPromise = new Promise((resolve, reject) => {
      ros.ROS.getServices((services) => {
        const serviceList = services.map((serviceName) => {
          return {
            serviceName,
          }
        });
        resolve({
          services: serviceList
        });
        reject({
          services: []
        });
      }, (message) => {
        console.error("Failed to get services", message)
        ros.services = []
      });
    });
    servicesPromise.then((services) => setROS(ros => ({ ...ros, services: services })));
    return ros.services;
  }

[jaguardo]

This works for a simple "clear" command to the turtlesim... not sure how to "universalize it" within react-ros:

      var cleanTurtle = new ROSLIB.Service({
         ros : ros,
         name : '/clear',
      });

      var request = new ROSLIB.ServiceRequest({});

      cleanTurtle.callService(request, function(result){console.log((result))});

instead of "listeners", could create an array of "servicers"? would be nice if react-ros returned a function call, so to send the service call, you would just call it, i.e. ( cleanTurtle())... I'm sure there are service calls that get a bit more complex though.

[jaguardo]

for a "/kill" service to the turtlesim, the request becomes

var request = new ROSLIB.ServiceRequest({name: 'turtle1'})

so it will get challenging to incorporate something "easy"... maybe a function that accepts arguments (defaults to none) and leave it to the user to figure out how to use it... because the arguments can get pretty complex! http://wiki.ros.org/roslibjs/Tutorials/Writing%20a%20dynamic_reconfigure%20client%20with%20roslibjs

  38     var request = new ROSLIB.ServiceRequest({
  39         config: {
  40             bools: [
  41                 // {name: '', value: false}
  42             ],
  43             ints: [
  44                 // {name: '', value: 0}
  45             ],
  46             strs: [
  47                 // {name: '', value: ''}
  48             ],
  49             doubles: [
  50                 {name: 'Kp_scale', value: 10.0},
  51                 {name: 'Kp', value: 0.1},
  52                 {name: 'Ki_scale', value: 0.1},
  53                 {name: 'Ki', value: 0.2},
  54                 {name: 'Kd_scale', value: 1.0},
  55                 {name: 'Kd', value: 0.3},
  56             ],
  57             groups: [
  58                 // {name: '', state: false, id: 0, parent: 0}
  59             ]
  60         }
  61     });

[flynneva]

@jaguardo this one too?

[jaguardo]

No issue, actually making a service call is going to be pretty involved (getting the list is not bad)... not sure if it is worth it.