Setting a breakpoint:
breakpoint_set -t [type] -f [filename] -n [lineno]
 -a [classname] -m [functionname]
breakpoint_set -i 4 -t line -f dbgp-example.php -n 3
breakpoint_set -i 5 -t call -m level1

response:
<response command="breakpoint_set" transaction_id="4"
    id="31400001"></response>

Retrieving and deleting breakpoints:
breakpoint_list -i 6
breakpoint_get -i 7 -d 3140002
breakpoint_remove -i 7 -d 3140001

response:
<response command="breakpoint_get" transaction_id="7">
  <breakpoint type="call" function="level1"
      state="enabled" id="31400002"></breakpoint>
</response>