Hi,
reusing the same connection to the same url is delegated to liburl, so you can have that when using http_async_client.
More workers will increase the capacity at the price of resources (shared memory).
I wrote a wrap up about building the request payload here: https://lists.kamailio.org/pipermail/sr-users/2016-December/095454.html - please double check escaping.
The function methods have been reviewed in version 5 and removed, replaced by pseudovariable settings which is more common practice in kamailio. 
Instead of http_append_header() use 
$http_req(hdr) = "X-theheader: the value";

Instead of http_set_method() use
$http_req(method) = "POST";

The latest documentation requires a little review for some mentions of the old functions. Will try to fix as soon as possible.

Best Regards,
Giacomo

On 25 April 2017 at 19:02, Pranathi Venkatayogi <pvenkatayogi@cyracom.com> wrote:

I recently successfully used http_async_client for POST. Will try to help you out here -

 

From: sr-users [mailto:sr-users-bounces@lists.kamailio.org] On Behalf Of Ramachandran, Agalya (Contractor)
Sent: Tuesday, April 25, 2017 10:17 AM
To: giacomo.vacca@gmail.com; sr-users@lists.kamailio.org
Subject: [SR-Users] Query with regard to http_client and http_async_client

 

Hi Giacomo,

 

I have few questions with regard to rest client in kamailio.

 

1)     I see there are two modules in kamailio for rest client. http_client, http_async_client.

I hope http_client does the http transfer in synchronous  way.

http_async_client does the http transfer in asynchronous manner.

Correct me if am wrong here.

Correct.

2)     I want to achieve https transfers in async way, so choosing http_async_client.

Is there a way that kamailio maintains persistent TCP connection  pooling for http transfer.

I see there is a “workers” parameter in http_async_client. By increasing this number does it result it more http request’s handling?

Let the author reply here.

3)     Also, I have some questions regarding documentation for module http_async_client in 5.0 version.

In the API exposure, it says “http_async_query(url, route_name)”.

But the example if I want to use POST, it says “http_async_query("http://example.com/test.php", "{'r_uri':'$rU', 'f_uri':'$fU'}", "HTTP_REPLY");”

There is a parameter mismatch between the example and the actual function.

 

If I try to use GET query, kamailio service is starting. But if I try to give the POST query with payload, kamailio service is not started.

It says, sctp_core_destroy(): SCTP API not initialized.

 

Also I have noticed that, functions like http_append_header(),http_set_method() are removed in 5.0 version, whereas we have this API’s is 4.x versions.

Is there some issue with the documentation for 5.0  ?

 

I used it like this and it works - http_async_query("http://TEXT_BROKER/api/events/CallAnswered", 
                                                                                          "{'CallId':'$ci', 'Time' : '$TF'}", 
                                                                                           "HTTP_REPLY");

Issue may be with quotes. Make sure you don’t have “ in the second parameter content. If you send Kamailio log it will be easier to debug.

 

Please let me the know the details for the above queries.

 

Regards,
Agalya