The application itself logs messages in Javascript console of your browser (developer tools). The network tab in developer tools shows all requests, the payload and responses. This is very helpful for debugging.

If you want to know what's happening on server-side. This is not enough. The server-side runs on a Java application server like Tomcat or Wildfly. To enable logging on server-side, simply do following:

Create the directory classes in your applications WEB-INF folder. The folder already contains lib, rad directories and web.xml file. In the newly created classes folder, create a file logging.properties with following content:

logging.properties
#####################################################################################################
# HANDLER definition
#####################################################################################################
 
# development handlers
#handlers = java.util.logging.ConsoleHandler
 
# tomcat handlers
handlers = java.util.logging.ConsoleHandler, org.apache.juli.FileHandler  
 
# application handlers
#handlers = java.util.logging.FileHandler 
 
#####################################################################################################
# HANDLER configuration
#####################################################################################################
 
java.util.logging.ConsoleHandler.level = ALL
java.util.logging.ConsoleHandler.formatter = com.sibvisions.util.log.jdk.JdkLineFormatter
 
java.util.logging.FileHandler.level = ALL
java.util.logging.FileHandler.pattern = application_%g.log
java.util.logging.FileHandler.limit = 10000
java.util.logging.FileHandler.count = 5
java.util.logging.FileHandler.formatter = com.sibvisions.util.log.jdk.JdkLineFormatter
 
org.apache.juli.FileHandler.level = ALL
org.apache.juli.FileHandler.directory = ${catalina.base}/logs
org.apache.juli.FileHandler.limit = 10000
org.apache.juli.FileHandler.count = 5
org.apache.juli.FileHandler.formatter = com.sibvisions.util.log.jdk.JdkLineFormatter
org.apache.juli.FileHandler.prefix = application_%g.
 
#####################################################################################################
# Package specifig log levels
#####################################################################################################
 
.level = SEVERE
 
org.restlet.level = OFF
#jvx.rad.util.level = SEVERE
 
# INFO logs request URL, FINE also logs json, ALL everything
com.sibvisions.rad.server.http.rest.ApplicationResource.level = FINE
 
# Websocket logging
#com.sibvisions.rad.server.http.rest.WebSocketListener.level = ALL

Use handlers to define where logged messages will be available.

ConsoleHandler logs messages in console (standard output).
FileHandler is used for file output.

If you enable logging for com.sibvisions.rad.server.http.rest.ApplicationResource, your requests will be logged and it dependes on the log level what you'll see. If you set INFO, only request URLs will be logged. The level FINE also logs json request messages and responses.