HVAC Control in the New Millennium.pdf - HVAC.Amickracing

Advanced HVAC Control, Information Technology and Open Systemsunderlying security infrastructure in MSMQ makes it possible to developthe message infrastructure.Message StructureMSMQ mirrors much of the Internet. Internet e-mail uses DomainName Service (DNS) as a directory service for name lookups. Directoryservices operate within a defined scope, much as a telephone directoryis valid only for a given town or city.Multiple copies of the MSMQ are stored in different computersthroughout the system. In a busy network, the directory service caneasily be overwhelmed by lookup requests into multiple sites. Each sitehas its own copy of the site controller, which provides load-balancingand fail-over schemes.MessagingDistributed applications pass messages between computers, eithersynchronously or asynchronously. With a synchronous exchange, boththe sender and the receiver must be running at the same time.Examples of queues occur in e-mail in-boxes. Messages arrive periodically,and you can respond to each as you see fit. You can view themin this queue.In MSMQ’s recoverable delivery option a message is copied to adisk queue, guaranteeing the message will not be lost. The MSMQ infrastructureis responsible for delivering the message. Transactionalthroughput is controlled by keeping transactions as brief as possible.SecurityMSMQ supports secure transmission of messages. This involveslimiting access to that information. Authentication verifies the identityof the sender. Encryption ensures that the message cannot be read byauthorized receivers. MSMQ supports authenticated and encryptedmessages.The two general encryption schemes in use today are symmetricand asymmetric. Symmetric encryption schemes use the same key for©2001 by The Fairmont Press, Inc. All rights reserved.