Hi Sergey, You probably looked already at the already existing json logging support in Kamailio, recently there was also common event expression syntax added: https://www.kamailio.org/wiki/cookbooks/devel/core#log_engine_cli_parameter Maybe you can add some post-processing to format it in a way you would like to ingress it. Regarding your requirements, the first two categories look more like accounting requests, have you looked into facility the accounting module for transactions and/or dialogs? The last category is probably highly specific to the particular Kamailio configuration file. Maybe its easier to just use some script language json operations together with http_client or the like? Of course, a module can be added if there is demand, for the transactions and dialogs one need to use the internal callbacks. Cheers, Henning From: Sergey Safarov &lt;s.safarov(a)gmail.com&gt; Sent: Sonntag, 9. Juli 2023 20:42 To: Kamailio (SER) - Devel Mailing List &lt;sr-dev(a)lists.kamailio.org&gt; Subject: [sr-dev] Re: tracing, zipkin Zipkin schema for JSON body can be found at https://zipkin.io/zipkin-api/#/default/post_spans Required to select "Model -> Span". [cid:image001.png@01D9B30F.8B714D40] On Sun, Jul 9, 2023 at 8:59 PM Sergey Safarov <s.safarov@gmail.com<mailto:s.safarov@gmail.com>> wrote: When used different application servers like: 1) kamailio; 2) freeswitch; 3) crm Required correlate logs and events between all daemons. For such purposes can be used tracing (OpenTelementry, Zipkin). An example for Envoy tracking can look like POST /api/v2/spans HTTP/1.1 host: zipkin content-type: application/json x-envoy-internal: true x-forwarded-for: 217.12.247.98 x-envoy-expected-rq-timeout-ms: 5000 transfer-encoding: chunked 2ad [{"tags":{"upstream_cluster":"dynamic_forward_proxy_cluster","component":"proxy","response_flags":"DC","peer.address":"127.0.0.1","http.method":"CONNECT","http.protocol":"HTTP/1.1","downstream_cluster":"-","user_agent":"curl/7.85.0","request_size":"842","guid:x-request-id":"0456e862-4cf7-9ee2-b280-e6f59965a70d","upstream_cluster.name<http://upstream_cluster.name>":"dynamic_forward_proxy_cluster","http.status_code":"200","response_size":"3750"},"name":"ifconfig.net:443<http://ifconfig.net:443>","annotations":[{"timestamp":1688924085239932,"value":"ss"}],"kind":"SERVER","localEndpoint":{"port":0,"ipv4":"217.12.247.98"},"timestamp":1688924084352715,"shared":true,"traceId":"67480febdcdd48dc","duration":886997,"id":"67480febdcdd48dc"}] 0 HTTP/1.1 202 Accepted content-length: 0 server: Armeria/1.17.2 date: Sun, 9 Jul 2023 17:34:47 GMT where json body looks like [ { "tags": { "upstream_cluster": "dynamic_forward_proxy_cluster", "component": "proxy", "response_flags": "DC", "peer.address": "127.0.0.1", "http.method": "CONNECT", "http.protocol": "HTTP/1.1", "downstream_cluster": "-", "user_agent": "curl/7.85.0", "request_size": "842", "guid:x-request-id": "0456e862-4cf7-9ee2-b280-e6f59965a70d", "upstream_cluster.name<http://upstream_cluster.name>": "dynamic_forward_proxy_cluster", "http.status_code": "200", "response_size": "3750" }, "name": "ifconfig.net:443<http://ifconfig.net:443>", "annotations": [ { "timestamp": 1688924085239932, "value": "ss" } ], "kind": "SERVER", "localEndpoint": { "port": 0, "ipv4": "217.12.247.98" }, "timestamp": 1688924084352715, "shared": true, "traceId": "67480febdcdd48dc", "duration": 886997, "id": "67480febdcdd48dc" } ] I looking to create a task for the team developer to develop a module like "tracing_zipkin". This module should allow trace transactions and dialogs 1. request and response timing; 2. dialog start-stop events; 3. business logic like call hold/unhold, media added//removed (video, text, message, audio), request multipart content raw or filtered. I will appreciate it if you share your thoughts about how JSON POST should look. Sergey Safarov