Use global persistence connection to enhance performance

[s8sg]

All call to function and for next node execution are submitted via Gateway. In the current code

• A http client was being created for each incoming message in the handler. this is a overkill, cause for every new request there will be a Handshake.
• The http client created was using default transport. default http client does have a keep-alive setting.

We can reuse a connection instead of creating new one. We can do so by creating a global client as:

var client *http.Client

func init() {
    tr := &http.Transport{
           MaxIdleConnsPerHost: 1024,
     }
   client = &http.Client{Transport: tr }
}

When we are using common client, we also need to make sure that we

• Read until Response is complete (i.e. ioutil.ReadAll(rep.Body))
• Call Body.Close()