Hunting Sample App using ECharts

In this example I show how to build a more complex sample using the ECharts state machine language. Details about ECharts can be found in http://echarts.org/ and also in one my previous posts in screening sample app with ECharts . The sources for the sample are available in cvs using cvs -d:pserver:[your java.net account]@cvs.dev.java.net:/cvs co sailfin/sailfin-tests and then can be found then in community/samples/hunting, or send an email to me to get them.

It provides the functionality to define a list of alternative Sip URI's in a database which are tried in sequence to connect when a call is received until a successful connection is established.

• The application is triggered only in terminating case via the ECharts application router if the To address matches the specfied pattern in the app router.
• It then connects the call to a mediaserver (MRF) which plays a dialtone or other announcement to the caller.
• When the dialtone is established it sends a INVITE to the original called party of the call.
• When the called party answers with 200 OK it disconnects from the mediaserver and reconnects via REINVITE to the caller. How to setup a mediaserver I will show in a future blog entry.
• If the called party returns a 486 BUSY or 487 NOT REACHABLE it retrieves the next alternative Sip URI from the database and sends INVITE again.
• If no alternative called party is available it stops the dialtone and signals a failure to the caller.

Sip Callflow for Redirect on Busy

The following callflow shows a scenario where the B Party is busy and the call is forwarded to C-Party.

A-Party......Sailfin......B-Party......MRF......C-Party

-INVITE SDPa->.....................................
.............-INVITE-------------------->..........
.............<-200 OK SDPm---------------..........
<-200 OK SDPm-.....................................
-ACK--------->.....................................
.............-ACK----------------------->..........
.............-INVITE SDPa--->......................
.............<-486 BUSY------......................
.............-ACK----------->......................
.............-INVITE SDPa------------------------->
.............<-200 OK SDPc-------------------------
.............-BYE----------------------->..........
<-200 OK SDPc-.....................................
.............<-200 OK--------------------..........
-ACK--------->.....................................
.............-ACK--------------------------------->
..................t a l k i n g....................
-BYE--------->.....................................
.............-BYE--------------------------------->
.............<-200 OK------------------------------
<-200 OK------.....................................

State Machines

A graphical description of the state machines can be found in the downloaded sources in hunting/src/echarts/hunting/ech/doc-files

• The MainFSM machine connects to the MRF to play the dialtone using the ConnectFSM machine. When the dialtone is established it transitions to the HuntingFSM which performs the search and connect for the called party. Finally when the call is successfully established it transitions to the TransparentFSM which handles the talking state of the call and also the turndown at the end.
• The HuntingFSM runs three paralles states.
  The PLAY_DIALTONE state uses the TransparentFSM and monitors the connection to the MRF.
  The CALL state uses the CallFSM to make a connection the called party until it has a successful connection.
  The REINVITE state uses the ReinviteFSM to handle the reinvite to the caller after a successful connection to the B-Party has been established.
• The ConnectFSM machine handles the conenction to the MRF.
• The CallFSM handles connect attempts to the B-Party.
• The SendReinviteFSM handles the reinvite to the caller.
• The TransparentFSM handles the talking state and turndown together with the TransparentHandleRequestFSM.