VoiceXML Host Server

The VoiceXML Host Server (VXMLHostSvr) is a server process that initially receives all VoiceXML interpret document requests and forwards the requests to a VoiceXML Interpreter Server for processing. The VoiceXML Interpreter Server makes requests back to the VoiceXML Host Server to upload resources, such as prompts and grammars, to the CIC server.

The VoiceXML Host server resides on the CIC server and performs the following tasks:

• Accepts a logon from a VoiceXML Host Server and creates an Interpreter session

• Stops an Interpreter session

• Reserves a file name for use by the requesting VoiceXML Host Server

• Uploads files from the requesting VoiceXML Host Server to the VXML Host Server's cache

• Downloads files from the VXML Host Server's cache to the requesting VoiceXML Host Server

• Releases files from the VXML Host Server's cache

• Passes all VoiceXML interpret document requests to a VoiceXML Interpreter Server determined by a load balancing algorithm

Load balancing

The VoiceXML Host Server uses a simple form of load balancing to determine which VoiceXML Interpreter Server to use for a specified request to interpret a document. When a request is received, the VoiceXML Host Server looks through all of the interpreters currently accepting requests and determines how many requests each is processing. The VoiceXML Host Server then selects the interpreter which is processing the fewest number of requests to process the document. The selection does not account for how complicated any particular request is or for how much CPU load the interpreter is using.

Logging/tracing

The VoiceXML Host Server generates log and trace messages to help you to track down and troubleshoot issues.

ININ tracing

The VoiceXML Host Server generates diagnostic trace messages in the “voicexml host server.ininlog” file located in the ININ logging directory of the CIC server.

System event log

The VoiceXML Host Server can generate the following messages in the Windows System Event log of the CIC server system:

Message	Category
MSG_VXML_HOST_NO AVAILABLE_VOICEXML_INTERPRETERS_ERROR  (44703)	VoiceXML Host Server (IC 3.0 100 / IC 4.0 -101)
MSG_VXML_HOST_STARTED_INFO (43600)	VoiceXML Host Server (IC 3.0 100 / IC 4.0 -101)
MSG_VXML_HOST_START_ERROR (43601)	VoiceXML Host Server (IC 3.0 100 / IC 4.0 -101)
MSG_VXML_HOST_STOPPED_INFO (43602)	VoiceXML Host Server (IC 3.0 100 / IC 4.0 -101)
MSG_VXML_HOST_STD_EXCEPTION (43610)	VoiceXML Host Server (IC 3.0 100 / IC 4.0 -101)
MSG_VXML_HOST_MFC_EXCEPTION (43611)	VoiceXML Host Server (IC 3.0 100 / IC 4.0 -101)
MSG_VXML_HOST_UNKNOWN_EXCEPTION (43612)	VoiceXML Host Server (IC 3.0 100 / IC 4.0 -101)
MSG_VXML_HOST_NO_AVAILABLE_VOICEXML_LICENSES_ERROR (44615)	VoiceXML Host Server (IC 3.0 100 / IC 4.0 -101)
MSG_VXML_HOST_NOTIFIER_ERROR (43613)	VoiceXML Host Server (IC 20.2)

VoiceXML Host Server Notifier messages

The VoiceXML Host Server interacts with the Notifier process of a CIC system where it both services a number of Notifier messages and uses a number of Notifier messages.

Serviced Notifier messages

The VoiceXML Host Server services the Notifier messages described in the following table:

Notifier Message	Description
eVoiceXMLRequest_InterpreterLogin	Handles a request to log in an interpreter.
eVoiceXMLRequest_InterpreterLogout	Handles a request to log out an interpreter.
eVoiceXMLRequest_ExchangeStreamEndpoints	Handles a request to exchange Notifier stream endpoints.
eVoiceXMLRequest_AcceptSessions	Handles a request to set an interpreter as accepting sessions or as not accepting sessions.
eVoiceXMLRequest_ReserveFileName	Handles a request to reserve a file name on the local cache.
eVoiceXMLRequest_UploadFile	Handles a request to upload a file name to the local cache.
eVoiceXMLRequest_ReleaseFile	Handles a request to release a file from the local cache.
eVoiceXMLRequest_InterpretURL	Handles a request to process the VoiceXML document at a specified URL.
eVoiceXMLRequest_InterpretDocument	Handles a request to process the VoiceXML document in a specified string.
eVoiceXMLRequest_Cancel	Handles a request to cancel prompt/input operations.

Utilized Notifier messages

The VoiceXML Host Server uses the following Notifier messages:

Notifier Message	Description
eVoiceXMLRequest_InitiateSessionURL	Handles a request with the URL specifying the document.
eVoiceXMLRequest_InitiateSessionDocument	Handles a request containing the initial VoiceXML document as (XML) data.

Determining connected VoiceXML Interpreter Servers

The only way to determine which VoiceXML Interpreter Servers are currently connected to the VoiceXML Host Server and are active is through the ININ trace log. Look under InterpreterMgrTopic in the log viewer.

License management

In addition to these other tasks, the VoiceXML Host Server process manages the usage of VoiceXML licenses. Each running VoiceXML session uses one VoiceXML license, no matter which VoiceXML interpreter is selected to process that session.