The Jukebox IAP

This document describes the specifics of the Jukebox IAP. For a general description of an IAP, refer iap.html.

The Jukebox IAP is a proxy for the Ninja Jukebox Service. The Ninja Jukebox service provides a SecureRMI interface for accessing mp3 songs in a repository. The Jukebox IAP was built as a exercise in extending services to Iceberg end-points. The IAP itself does not include any security mechanisms and hence is not currently set up as a long-running service.

The specifics of the Jukebox_Iap are as follows:

• It supports only incoming calls, no outgoing calls
• It only supports incoming DTMF, no outgoing DTMF
• It collects DTMF tones one by one, and on detecting a '#' or '*', computes the song-number from the digits collected so far. Then it issues a ca.changePath() with the new song information. This causes the Call Agent to call a changePath on the APC service. The APC service changes the current path so that the new song is pulled (the APC actually kills the old path and instantiates a new one).
• The calls from the APC are all dummy ones since there is no source operator at the Jukebox_Iap. The source is simply a HTTP location and the song is pulled by the first operator of the APC created path.

The files

• Jukebox_Iap.java -- this is the main file that implements the interface for calls from the CA and the APC.
• songs.java -- this maintains a hashtable of mappings between song name and song number. This is required because across invocations of the Jukebox IAP, the song numbers at the Jukebox service may not remain the same. The mappings maintained translate the old song number to the song name and then the song name back to the new song number.
• jb_thr_class.java -- this used to be the per-session thread that exec'ed proceses and waited on them. A whole bunch of processes had to be invoked when the APC service was not yet ready. This is no longer required since all data transformation is taken care of by the APC service. Although the thread is never used, the thread class is still used to maintain per-session state (like the DTMF tones that have come in for this session).

Running the Jukebox IAP

The Jukebox IAP runs with the switch dbg set to true by default and in this mode, plays a default hardcoded mp3 file always (this mp3 file needs to be present at the APC service -- a hack for demo/testing purposes). To make it run in its original intended mode, you have to set the dbg variable to true and receompile. Of course, this would require you to have a Jukebox service running.

The Jukebox IAP operates as follows. It fetches the list of songs from the Jukebox service and writes this information onto a file. This file assigns each song a song-number. This list is intended to be given to the users. The song-number is used by the users to interactively pull songs, by keying in the song-number using DTMF tones.

The Jukebox IAP needs to be run as follows to fetch the list of songs and write onto a file:

jukebox_iap.Jukebox_Iap music-dir-host -w songs-file-name

This fetches the list of songs from the Jukebox service at music-dir-host and writes onto the file songs-file-name.

The Jukebox IAP can now be run as an iSpace service with the iSpace configuration file having the following line:

iceberg.iap.jukebox_iap.Jukebox_Iap music-dir-host songs-file-name ipop-host[:port]

The ipop-host is the location of the machine where the iPOP is running, and port is the iSpace port of the iPOP (defaults to 1099).

On an incoming call, the Jukebox_Iap starts playing the first song. The user can key in a song request by pressing the digits of the song number followed by the '#' or '*' sign. There is no interactive-voice system and this is an obvious area of extension.

Naming service and preference registry entries

Since the Jukebox IAP has an identity of its own (that is, users may try to reach the mediamanager IAP as an entity), it needs a naming service entry and preference registry entry. This is very similar to the voice-mail IAP, refer here.