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MESSAGE HANDLING SERVICES

Global Message Handling Services

Novell’s NetWare Message Handling Services (MHS) product family provides a messaging infrastructure service. Because messaging is, by nature, a fully distributed service used on a networkwide basis, the concept of a directory is very important. NetWare Global MHS is Novell’s NetWare Loadable Module (NLM)-based messaging product that includes messaging-specific directory support designed to: service environments without NetWare 4.0, integrate NetWare 3.x messaging environments with NetWare 4.0, and propagate message routing information. This approach allows NetWare Global MHS to provide the complete messaging solution customers and MHS application developers need.

NetWare Global MHS is a store-and-forward messaging technology that provides messaging and directory services to any desktop that has file access to a NetWare server (e.g., DOS, Windows, Macintosh, Unix, and OS/2), and to disconnected laptops. MHS is typically used in conjunction with such messaging applications as E-mail, calendaring, and network fax applications. Commercial third-party products include da vinci’s eMAIL and Coordinator, Coordinate.com’s BeyondMail, Reach’s MailMAN and WorkMAN, Powercore’s WinMail, Infinite’s ExpressIT!, Notework’s Notework, Futurus’ Team, MicroSystems Software’s CaLANdar, Campbell Services’ OnTime, Castelle’s FaxPress, Optus’ FACSys, CE Software’s QuickMail, Transend’s CompletE-mail, and many others. In addition, MHS comes with a starter E-mail package, FirstMail, to enable users to get started with messaging.

Submitting a message to MHS is as easy as creating a text file with appropriate headers and giving MHS access to the new file. The simplicity of this process makes it easy for third parties to develop applications and for system integrators and corporate developers to use the messaging system. For example, an E-mail message may look like this:

    smf-71To:
    Bob Smith@marketing.acme
    From: Tim Johnson@engineering.acme
    Subject: Q1 Results?

    Are the quarterly results in yet?

Once a message has been submitted, MHS determines how to route it through the messaging system. Global MHS implements various messaging protocols, including standard MHS protocols, as well as other industry standards (e.g., SMTP, SNADS, and X.400). After sending a message through the messaging system, MHS delivers the message into a file that the recipient’s application may access. In addition to the messaging service, Global MHS provides a directory system for use by MHS and its applications. Access to directory information is gained by opening a shared file on the NetWare server containing information about individual users on the messaging system. E-mail applications typically use this information to provide point-and-click lists to the users. The naming scheme for MHS is hierarchical, as shown in Exhibit 5-4-1.


Exhibit 5-4-1.  MHS Naming Scheme.

For example, Bob Smith’s MHS name is formed from this tree: BobSmith@marketing.acme. The nodes in the naming tree that are not leaf nodes are called workgroups. Therefore, Acme is a workgroup that contains two other workgroups: marketing.acme, and engineering.acme. This hierarchical naming scheme allows a single unique global name for all MHS messaging users to ensure that no two MHS messaging users in the world have the same MHS name. In addition, this naming scheme is structurally identical to that in NetWare directory services (NDS) and X.500. Applications can also gain access to the directory information. They typically use this information to provide point-and-click lists to users. MHS provides this information in the form of an extract file that contains sorted records in a fixed-length format. Each record contains information about a user of the messaging system (e.g., mail address, phone number, title, and department). Directory information is shared between servers through a subscription mechanism. This mechanism is another characteristic of the NetWare Global MHS directory that logically relates to NDS functions.

The NetWare Global MHS product provides scalable, fully integrated MHS services to NetWare 3.x users. Implemented as a set of NLMs for NetWare 3.x and NetWare 4.x, NetWare Global MHS enables the network operating system to support a complete messaging infrastructure. This approach allows messaging services to be easily installed and also capitalizes on existing NetWare investments. NetWare Global MHS provides built-in directory support, routing, and workgroup-to-workgroup connectivity and it offers optional protocol modules for messaging interoperability with users on SMTP, SNADS, and X.400 systems.

Users and their associated mailboxes can be added to a server in a NetWare 3.x environment through the administrative utility in Global MHS. That server becomes the owner of that user object, and it commands the right to modify or delete the object. MHS propagates the fact that this object exists to other MHS systems by creating MHS directory synchronization messages. In addition to user information, distribution lists and workgroup information are also propagated the same way. To minimize synchronization traffic, only changes in the directory are propagated immediately. MHS also periodically synchronizes the entire directory to ensure that all servers have the same directory information (this is useful to guard against undelivered directory synchronization messages that may have resulted from servers being down for a long period of time or a loss of a communications link). Global MHS also uses directory synchronization messages to synchronize routing information, including server connectivity.

Global MHS uses the user information in the directory for routing purposes. Global MHS routing is a two-step process. The first step is to determine on which server the recipient’s mailbox is located. The second step is to examine the connectivity of the network to determine the best path to that server. Messages are then routed accordingly.

NetWare 4.1 implements a variety of new services and functions. The feature that is particularly relevant to MHS is NDS. NDS implements a distributed directory database that takes over the role performed by the Bindery in previous NetWare releases. NDS’s schema conforms to the X.500 international standard and is similar to the NetWare Global MHS directory. Names in the directory are hierarchical as shown in the diagram in Exibit 5-1. This is very similar to the MHS naming scheme, with the exception that NDS permits nodes in the directory tree to have a type associated with them (e.g., organization or common name).


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