Hello,
it looks like two jsons one after other, which is what happens over tcp stream. If you write them at the slow pace and the consumer reads constantly, then it is likely that it will read one document at a time. If you write faster than consumer reads, then it will get them accumulated in the tcp buffer, one after the other. The consumer needs to be a stream parser and detect when there first json document ends, process it, then read the next one.
We do the same for sip, that's why the code for reading sip over tcp is rather complex, with lots of states (given there can be any kind of broken sip message).
Alternative for evapi is to use the netstring encoding, which is easier to read a json document at once, because the size is given first.
Cheers, Daniel
On 09/01/15 22:01, Alex Balashov wrote:
Hi,
I'm using evapi to emit JSON blobs to share presence event transitions with a TCP client:
loadmodule "evapi"
modparam("evapi", "workers", 4) modparam("evapi", "bind_addr", "0.0.0.0:8010") modparam("evapi", "netstring_format", 0)
if($hdr(Event) eq 'dialog' && $cl > 0) { $xml(u=>doc) = $rb; $var(state) =$xml(u=>xpath:/di:dialog-info/di:dialog/di:state/text());
evapi_relay("{ \"type\": \"state_transition\", " "\"sip_user\": \"$(fU{s.escape.common})\", " "\"sip_domain\":"$(fd{s.escape.common})", " ""state": "$var(state)" }"); }
Every once in a while, however, my consumer service's JSON.parse() throws a parsing exception. There seems to be no particular pattern. When I investigated the actual string being sent, I found two objects concatenated:
JSON parsing exception: SyntaxError: Unexpected token { Raw received string was: { "type": "state_transition", "sip_user": "6789540671", "sip_domain": "sip.evaristesys.com", "state": "" }{ "type": "state_transition", "sip_user": "6789540671", "sip_domain": "sip.evaristesys.com", "state": "" }
Any ideas as to why this might happen?
Thanks,
-- Alex