Frequently Asked Questions
==========================

What Is DECmessageQ?

	DECmessageQ is Digital's message queuing middleware product.
	Message queuing is a technique for sending messages from one
	program to another by directing messages to a memory- or
	disk-based queue as an intermediate storage point.  The
	queue stores the messages until they can be processed by the
	receiver program.  By queuing messages, programs can execute
	independently---they do not need to wait for an application
	to process a message before continuing.

What platforms does DECmessageQ run on?

	DECmessageQ runs on all industry leading systems including
	Windows, Windows NT, IBM AIX, Hewlett-Packard HP-UX, Sun
	Microsystem's SunOS and Solaris, 64-bit Digital UNIX, NCR
	SystemV and on OpenVMS VAX and Alpha systems.  It offers
	connectivity to IBM environments through LU6.2 Services.
	Version 3.2 of DECmessageQ will expand support to IBM OS/2
	and MVS systems and will offer interoperability with IBM
	MQSeries message and queuing product.

How does DECmessageQ work?

	The following example describes how applications communicate
	using DECmessageQ:

	1.   Application A attaches to the message queuing bus using
	     the DECmessageQ pams_attach_q function.

	2.   Once attached, Application A uses the pams_put_msg
	     function to tell the message queuing system that a message
	     is ready to be sent to Application B.

	3.   The message queuing system sends the message to the
	     system where Application B resides and places it in
	     Application B's queue.

	4.   In time, Application B reads the message in its queue
	     using the pams_get_msg function.

	5.   When Applications A and B are finished exchanging
	     information, they detach from the message queuing bus using
	     the pams_detach_q or the pams_exit function calls.

What's the difference between a DECmessageQ server and a client?

	DECmessageQ offers two types of implementations: message
	servers, and messaging clients.  DECmessageQ message servers
	provide full message routing throughout the DECmessageQ
	network.  Using a DECmessageQ Client Library software
	running on a DECmessageQ message server, the DECmessageQ
	client implementations provide applications with the full
	support of DECmessageQ features while using significantly
	fewer system resources than the server implementations.

	All DECmessageQ environments require the use of at least one
	message server implementation to offer full message routing
	to all other DECmessageQ systems in the network.  Both
	client and server applications can be deployed on systems
	running DECmessageQ client implementations which offer full
	DECmessageQ functionality through the Client Library Server.
	Therefore, when designing a DECmessageQ network, software
	developers and system managers can choose to minimize the
	number of message servers to reduce the amount of system
	configuration required.

How is DECmessageQ priced?

	DECmessageQ offers two types of user licenses for full
	message server products; development and runtime.  Pricing
	for each license type is determined by the type of server
	system on which DECmessageQ is run.  The server catagories
	are called Workgroup Server, Departmental Server, and
	Enterprise server.  Messaging clients carry a lower
	licensing price.

What kinds of connections does DECmessageQ offer to IBM systems?

	DECmessageQ Version 3.2 offers the following new products
	that allow applications to send and receive information from
	IBM systems:

	o    DECmessageQ MQSeries Connectionenables applications to
	     exchange messages between DECmessageQ and IBM's messaging
	     and queuing product called MQSeries

	o    DECmessageQ MVS Clientenables applications running on
	     IBM MVS systems to support all major DECmessageQ message
	     queuing features.

	o    DECmessageQ for OS/2provides a full message server and
	     messaging client to integrate applications running on IBM
	     OS/2 desktop systems.

	o    DECmessageQ LU6.2 Servicesprovides a means of
	     communications between OpenVMS applications and applications
	     running on IBM mainframes using LU6.2 networking software.

Why should I use message queuing middleware?

	Message queuing middleware can be used in new or existing
	applications to provide the mechanism for information exchange in
	a distributed multivendor environment.  Using message queuing,
	application developers no longer need to worry about the
	underlying transport to send and receive information between
	applications.  In addition, applications do not require constant
	maintenance to accommodate changes in operating system and
	network software and are portable between systems from different
	vendors.

Is there an industry standard for message queuing?

	Currently there is no industry standard for message queuing.
	However, the Message Oriented Middleware Association (MOMA)
	has been formed to advance the use of message passing and
	message queuing technologies within the software industry.

Why should I use DECmessageQ?

	Digital's DECmessageQ is the industry's leading message
	queuing middleware product.  It offers the widest array of
	supported environments, the fastest messaging throughput (at
	up to 500 messages per second) and the most robust set of
	features including recoverable messaging, message selection,
	message broadcasting, and tools for developers to build and
	test applications.  DECmessageQ is also the most proven
	message queuing technology with over 12 years of production
	history at over 400 companies worldwide.