AWS Lamba invoke function with parameters/payload - php

Question

I started with AWS Lambda today and I can't succeed in passing a payload to the function. On the server side I try to read all the event data but it is empty. What am I doing wrong here?
$client = LambdaClient::factory(array(
'profile' => 'default',
'key' => AWS_ACCESS_KEY_ID,
'secret' => AWS_SECRET_ACCESS_KEY,
'region' => 'eu-west-1'
));
$payload = array('key1' => '1');
$result = $client->invoke(array(
'FunctionName' => 'hello',
'InvocationType' => 'RequestResponse',
'LogType' => 'Tail',
'Payload' => json_encode($payload)
));
Returns:
Received event: {}
Function code on AWS:
console.log('Loading function');
exports.handler = function(event, context) {
console.log('Received event:', JSON.stringify(event, null, 2));
};

Answer 1

In python I send the payload like this:
from boto3 import client as botoClient
import json
lambdas = botoClient("lambda")
def lambda_handler(event, context):
response = lambdas.invoke(FunctionName="myLambdaFunct", InvocationType="RequestResponse", Payload=json.dumps(event));
where event is a dictionary and, json.dumps serialize event to a JSON formatted string