HTTPClient.md

Call the other services on the Platform project

You can call any service or any endpoint defined on the Platform project, obtaining and using a proxy object.

For example, if you need to connect to a CRUD, you have to use a Proxy towards the crud-service.

You can get a proxy calling these methods both on Request(the first argument of handler) and Service (the Fastify instance):

• getServiceProxy(options) - returns a proxy passing through the Microservice Gateway.
  • options - is an object with the following optional fields:
    • port - an integer that identifies the port of the service to be queried.
    • protocol - a string that identifies the protocol to use (only http and https are supported, the default value is http).
    • headers - an object that represents the set of headers to send to the service;
    • prefix - a string representing the prefix of the service call path.
• getDirectServiceProxy(serviceName, options) - returns a direct proxy to the service.
  • serviceName - The name of the service to call. You can't specify the port here, you have to do in options.port.
  • options - The same options described above.

Potentially, the getDirectServiceProxy method allows you to also query services outside the Platform. In this case, however, it is necessary to bear in mind that the platform headers will be automatically forwarded.

Both proxies, by default, forward the four Mia headers to the service called. In addition, other headers of the original request can also be forwarded to the named service. To do this it is necessary to define an additional environment variable, ADDITIONAL_HEADERS_TO_PROXY, whose value must be a string containing the keys of the headers to be forwarded separated by a comma.

Both proxies expose the methods to perform a specific HTTP request to service.

• get(path, querystring, options)
• post(path, body, querystring, options)
• put(path, body, querystring, options)
• patch(path, body, querystring, options)
• delete(path, body, querystring, options)

The params to be passed to these functions are:

• path - a string that identifies the route to which you want to send the request.
• body - optional, the body of the request which can be:
  • a JSON object
  • a Buffer
  • one Stream
• querystring - optional, an object that represents the querystring.
• options - optional, an object that admits all the options listed above for the getServiceProxy and getDirectServiceProxy methods (which will eventually be overwritten), plus the following fields:
  • returnAs - a string that identifies the format in which you want to receive the response. It can be JSON, BUFFER or STREAM. Default JSON.
  • allowedStatusCodes - an array of integers that defines which status codes of the response are accepted. If the response status code is not contained in this array, the promise will be rejected. If this parameter is omitted, the promise is resolved in any case (even if the interrogated server answers 500).
  • isMiaHeaderInjected - a boolean value that identifies whether Mia's headers should be forwarded in the request. Default true.

All methods return a Promise object.

Examples

// Example of a request towards `tokens-collection` endpoint passing through Microservice Gateway
async function tokenGeneration(request, response) {
  const crudProxy = request.getServiceProxy()
  const result = await crudProxy
    .post('/tokens-collection/', {
      id: request.body.quotationId,
      valid: true
    })
  // ...
}

// and bypassing Microservice Gateway
async function tokenGeneration(request, response) {
  const crudProxy = request.getDirectServiceProxy('crud-service')
  const result = await crudProxy
    .post('/tokens-collection/', {
      id: request.body.quotationId,
      valid: true
    })
  // ...
}