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The AppleTalk Network System

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Introduction

Applications development opportunities for the AppleTalk Network System (ANS) abound, and products that allow users to work effectively together-groupware applications-are likely to be successful in the years to come. Products such as single-user word processing applications integrate well with single-user spreadsheets and page-layout programs, and the functionality of these solutions can be extended to include multiuser support. Just a few examples of the new generation of products enabled by the services provided in ANS include multiuser calendaring and schedul­ing, and project management applications.

Developers who can maintain the unique Macintosh experience while creating multiuser solutions are the ones who will develop the winning products in a shared environment. Before we examine the specific details of developing applica­tions for the ANS, we'd like to provide some general directions that should give de­velopers the best opportunity to create products that will stand apart from the crowd.

The AppleTalk Network System - Developer Opportunities

While Apple concentrates on providing the standard mechanisms for ANS - protocols and basic services - developers should concentrate on solutions that build upon the network infrastructure. The AppleTalk Filing Protocol (AFP) has been implemented in a number of different environments to provide, for example, file-sharing solutions based on several types of minicomputers and file-server platforms. While the resulting product provides a basic service, it maintains the same functionality as the original AppleShare file server product and furthers the consistency of the user interface and the end user's experience.

On the hardware side, concepts worth investigating include providing AppleTalk support over alternative media types, uninterruptible power supply (UPS) support for AppleShare file servers, and network peripherals, such as plotters, facsimile modems, and modem and serial device servers.

With the introduction of AppleTalk Phase 2, in June 1989, developers of most AppleTalk-based services - multiuser databases, electronic-mail systems, and so on - do not have to modify their applications at all in order to remain compatible. The implementation of AppleTalk Phase 2 maintained the insulation of higher-level services that utilize AppleTalk from the underlying protocol layers that has been a hallmark of the AppleTalk network system since its inception.

Development Information: Required System Configuration, Documentation, and Tools

Once your product idea is clearly defined, you need to determine the minimum configuration of Apple equipment, as well as any third-party equipment needed, on which to develop and test your applications. We recommend that your products run on the broadest possible range of machines.

Apple Equipment and Software

  • One dedicated Macintosh Plus, Macintosh SE, Macintosh SE/30, Macintosh II, Macintosh IIx, or Macintosh IIcx computer to be used as an AppleShare file server. The file server must have one or more SCSI hard disks attached to it.
  • One Macintosh Plus, Macintosh SE, Macintosh SE/30, Macintosh II, Macintosh IIx, or Macintosh IIcx computer or Apple IIe or Apple IIGS computer to act as the development workstation. In the case of the Apple IIe, the Apple IIe Work­station Card is required; an Apple IIGS requires IIGS Workstation software.
  • For connection-oriented applications development on a Macintosh, the Ap­pleTalk Data Stream Protocol (ADSP) software is recommended, available from the Apple Software Licensing Department.
  • AppleShare File Server software, version 2.01.
  • [[LocalTalk[[ or EtherTalk network cables, connectors, and interface cards for each workstation, server, and printer.

Documentation and Tools

In addition to the most recent versions of the System and Finder files, you should have the following documentation and tools, available from APDA:

  • AppleTalk Filing Protocol, version 2.0 release notes
  • AppleTalk Data Stream Protocol preliminary note
  • EtherTalk and Alternate AppleTalk Connections Reference manual. (A new version of this document has been produced to reflect the changes necessary to support AppleTalk Phase 2. This document should be available from APDA in the third quarter of 1989.)
  • Foreground Applications Development for AppleShare manual
  • Inside Macintosh, Volumes IV and V, published by Addison-Wesley
  • Inside AppleTalk, published by Addison-Wesley
  • AppleTalk Network System Overview, published by Addison-Wesley
  • Software Applications in a Shared Environment manual

Apple's standard ADEV and Network CDEV are available for licensing for third parties who plan to develop EtherTalk or other alternate AppleTalk network adapters. Contact Apple's Software Licensing Department for more information.

Q&A: Background Information

The following are answers to commonly asked questions about Apple's networking strategy as it relates to the ANS:

Why does Apple refer to AppleTalk as a "network system"?

The ANS is made up of a number of different components, including physical network components, file- and print-sharing components, and network manage­ment features, as well as support for connections to Digital VAX environments.

The ANS is unique in many respects. First, it is virtually self-configuring. Each machine in an AppleTalk network "negotiates" with its peer machines for assignment of its node identifier; the network manager does not have to config­ure the network in terms of software address assignment. It is not necessary to "halt" an AppleTalk network to add additional nodes.

Second, AppleTalk is independent of physical media and speed. Ap­pleTalk has been implemented on Ethernet, Token Ring, shielded and unsh­ielded twisted-pair cable, Northern Telecom's LANSTAR (LANSTAR AppleTalk) local area network, and fiber-optic cable (from Du Pont). Third parties are de­veloping AppleTalk interfaces to DataPoint's ARCnet, as well.

Further, AppleTalk has built-in facilities for internetwork support that make network management extremely flexible and configuration extremely easy. AppleTalk has built-in support for the assignment of logical groups of systems into what are called AppleTalk zones. These zones may be subsets or supersets of physical networks, and can be used by network administrators to create workgroup arrangements of individuals or machines that may not be part of the same contiguous physical network. The ANS has built-in support for network printing, allowing Macintosh systems to select printers from a list of available printers, and print to them regardless of their physical location; therefore, expensive printing resources can be shared among larger groups of users. Most AppleTalk services are selected through the use of Apple's Chooser interface, which provides a simple, intuitive means for selecting printers, file servers, print servers, and other network resources, either from the local zone or from a zone in another building or city. Numerous other special characteristics of AppleTalk are described in more detail in Inside AppleTalk, which is available from APDA.

The latest development in the introduction of the AppleTalk Network System is AppleTalk Phase 2. AppleTalk Phase 2 allows AppleTalk networks to increase in size to support the requirements of very large organizations. A single AppleTalk internet could contain 16 million AppleTalk nodes. All of the features described earlier continue to work in AppleTalk Phase 2.

Would you describe LocalTalk and EtherTalk?

LocalTalk is a shielded twisted-pair cabling system that can connect to the Ap­pleTalk hardware built into every Macintosh computer, LaserWriter printer (except for the LaserWriter IIse), and Apple IIGS system. In addition, LocalTalk cards are available for the Apple IIe computer, ImageWriter II and Image Writer LQ printers, and even IBM PCs, PS/2s and compatibles.

More recently, Apple has introduced the EtherTalk Interface Card, which allows Macintosh II computers to utilize AppleTalk services over Ethernet media. In addition, cards available through third-party vendors allow the Macintosh II family of computers and the Macintosh SE and the Macintosh SE/30 to take advantage of Ethernet. Third parties also offer SCSI-to-Ethernet products that link Macintosh Plus systems to EtherTalk; and network routers that link LocalTalk networks and LaserWriter printers to EtherTalk networks.

How can AppleTalk services operate over Ethernet media?

Apple has developed a set of enabling technologies that manage link access (the LAP manager); address resolution between AppleTalk and Ethernet addressing schemes; and provide a user interface for selecting the type of network that the user wishes to utilize. This collection of facilities is described in the EtherTalk and Alternate AppleTalk Connection Reference manual, which is available through APDA. In order to develop an AppleTalk implementation on non­-LocalTalk media, developers must license the appropriate LAP manager compo­nents from the Apple Software Licensing Department.

Why did Apple decide to produce "AppleTalk Phase 2"?

AppleTalk Phase 2 is Apple's response to a number of customer requirements: larger AppleTalk networks, Token Ring support, support for MS-DOS PCs on EtherTalk networks, EtherTalk support for the A/UX operating system, and an internet router from Apple Computer, Inc.

In an AppleTalk Phase 2 network, the 254-nodes-per-network limitation is eliminated. Networks of up to 16 million nodes can be built to serve the needs of the largest organizations.

EtherTalk 2.0 changed Apple's AppleTalk-over-Ethernet media offering. EtherTalk 2.0 is implemented to the IEEE 802.3 standard. This allows lower-level media access bridges to support large EtherTalk networks. This update is an example of the specific changes requested by Apple's customer base that were implemented in AppleTalk Phase 2. EtherTalk 2.0 is supported by a number of third parties, and is compatible with third-party routers and Apple's AppleTalk Internet Router.

TokenTalk 2.0 allows NuBus-based Macintosh systems to utilize Ap­pleTalk services over Token Ring media. TokenTalk 2.0 is compatible with Ap­pleTalk Phase 2, and with the AppleTalk Internet Router. Like EtherTalk 2.0, Token Talk 2.0 is implemented to the IEEE specifications for Token Ring, and uses the 802.2 Type 1 (connectionless) service for its packet format. TokenTalk 2.0 supports IBM source routing bridges, and includes the full 802.2 LLC implem­entation of IBM's Token Ring.

AppleShare PC 2.0 features a full implementation of AppleTalk Phase 2 for MS-DOS PCs. It includes support for LocalTalk, EtherTalk 2.0, and Token­Talk 2.0, and supports the OLI (Open Link Interface) that Apple and others jointly developed with Novell. AppleShare PC 2.0 requires a third-party Ethernet or Token Ring card with an appropriate OLI driver to connect PCs to EtherTalk or TokenTalk networks.

EtherTalk 2.0 for A/UX brings the benefits of AppleTalk Phase 2 to Macintosh systems running the A/UX operating system. EtherTalk 2.0 for A/UX supports toolbox printing directly from applications. A LocalTalk card is no longer required for A/UX systems to access AppleTalk.

One major area of the ANS that changes in AppleTalk Phase 2 is network router implementation. AppleTalk Phase 2 contains a number of performance enhancement fe atures for routers, in addition to support for larger networks.

The AppleTalk Internet Router is a software-based router that can run in the background of a Macintosh. It is data-link independent; it can support nonextended (LocalTalk) and extended (EtherTalk 2.0, TokenTalk 2.0) net­works. The router supports up to eight ports simultaneously, and is admini­stered through a desk accessory. The router administration screen displays routing table and statistical information about the internet. Third parties that plan to offer alternate data link support for Macintosh computers can build drivers for the AppleTalk Internet Routers to internetwork the alternate links with the three standard data links supported by the router.

The AppleTalk Internet Router is not meant to replace third-party routers. It is meant to provide a benchmark for router performance and reliabil­ity. It serves as a springboard for future network management support.

How do I upgrade to AppleTalk Phase 2?

Apple has provided upgrade utilities and associated documentation for network administrators to use to upgrade their networks to AppleTalk Phase 2. The first, the "AppleTalk Phase 2 Upgrade Utility," is an INIT resource that is installed in AppleTalk Internet Routers. If a Phase 1 router is detected at startup time, the router will translate Phase 2 routing packets back to Phase 1 on that specific network. This allows incremental upgrade of the routers on the internet. However, some of the features specific to AppleTalk Phase 2, including network ranges and zone lists, are not available on the internet until all routers are upgraded to AppleTalk Phase 2 compatibility.

The "Phase 2 Node Identifier" is another utility that assists the adminis­trator in identifying the Phase 1 and Phase 2 nodes on a specified network. The utility can be targeted to select nodes through selection of various criteria, and the resulting list can be saved to disk or printed, in addition to display on the Macintosh screen.

The Apple Talk Phase 2 Introduction and Upgrade Guide documents the benefits of AppleTalk Phase 2, and details the installation and use of the Ap­pleTalk Phase 2 Upgrade Utility.

What do you mean by "network servers" in the ANS?

Currently, two network servers are part of ANS. The first is the AppleShare File Server (AFS); the second is the AppleShare Print Server (APS). AppleShare provides a shared resource-a Macintosh running AppleShare software with one to seven hard disk volumes attached-that can be shared by users in the workgroup, or by other users in other groups, simply by selecting the desired file server through the familiar Chooser interface. If the user wished to use AFS services, he or she would sign on to the file server with an authorized user code and password and select the volume on that server that contains the desired information. When the volume appeared on the user's desktop, it could be accessed as though it were any ordinary disk file.

The AppleShare File Server contains additional features that make it an ideal system for workgroups. For example, it allows the network administrator to group individual users in one arrangement to represent their membership within the organization and in another arrangement for a particular project or task force. The network administrator may, for security and privacy reasons, limit the access to particular files and folders. One typical use of this facility is to create a "drop box" folder, into which all users can insert files, but which can only be opened by the owner of the folder. Most AppleShare administrative tasks can be performed from the Macintosh acting as the file server while the file server is operating.

AppleShare allows one other application, typically operating in the fore­ground, to coexist on the same Macintosh. [Note: Apple does not recommend the development of background applications for AppleShare at this time (see the Documentation and Tools section of this note for documents that discuss foreground operation in more detail).] This application is typically the AppleShare Print Server (APS). The APS provides print spooling and printer queue management facilities for one to five LaserWriter or ImageWriter printers (ImageWriter II and ImageWriter LQ printers must have the optional LocalTalk card installed to be attached to the network) and supports color printing on the ImageWriter. Like the AppleShare File Server, APS is configured while spooling is taking place, so changes can be made without halting the print-spooling function.

If only one foreground application can be coresident with AppleShare, what opportunities are there for developing applications compatible with AppleShare?

Customers are asking for applications that allow end users to share data easily and, in many cases, simultaneously. AppleShare provides the enabling tech­nologies and protocols to support these needs. AppleShare is based on the AppleTalk Filing Protocol (AFP), Apple's standard for file service. AFP provides facilities to support multilaunch applications. In addition, AFP provides byte­range-locking facilities for multiuser applications such as database systems, accounting packages, calendaring and scheduling packages, and any other applications that allow multiple users to update the same file at the same time.

Do MS-DOS PCs have a place in ANS?

Apple provides AppleTalk services for MS-DOS PCs. The LocalTalk PC Card allows these systems to connect to AppleTalk networks, and to print to network LaserWriter and ImageWriter printers. Apple also offers AppleShare PC 2.0, which allows MS-DOS PCs equipped with the LocalTalk PC Card or third-party cards with appropriate OLI drivers to utilize AppleShare file servers. The OU standard was developed by Novell, Apple, and others to allow developers to implement protocol stacks for network adapters (cards) in a standard, compatible fashion.

In addition to the normal benefits of AppleShare file service, many de­velopers can take advantage of the fact that their applications share common file formats between their MS-DOS and Macintosh versions. Where possible, Apple has provided a facility that automatically maps the DOS file extension to the Macintosh creator and type. The Macintosh user sees the DOS file on the desktop as though it were an ordinary Macintosh file, complete with the file icon; double-clicking the mouse on the icon launches the application and opens the file on the Macintosh.

What about networking and the Apple II?

Apple is committed to the education market and to the Apple II product line. As a result, the company supports Apple IIe and Apple IIGS participation in the ANS, including file and print service. Apple II systems can boot remotely from the AppleShare server, eliminating the need for individual disks for each system, and the AppleShare Print Server supports printing from Apple II systems. In addition, Apple II users enjoy a special menu facility called Aristotle, which allows educators to create special menus for networked classroom environ­ments. As new features are introduced for AppleShare, the needs of Apple II users and the education community will continue to be addressed.

Is Apple encouraging third parties to enhance AppleTalk and AppleShare?

Apple supports those developers who have introduced products that allow AppleTalk network connectivity over alternate media, such as unshielded telephone wiring or fiber-optic cabling. Apple also supports those developers who are providing APP-based file services on minicomputers and mainframes. However, Apple considers products that do not adhere fully to the AFP standard to be detrimental to the user's experience, as well as to the overall performance of the network system. A key strength of the Macintosh has been its consistent user interface and high-quality performance of compatible products.

Developers interested in developing products, such as network routers (sometimes called bridges), network management products, network modems and serial servers, and other peripherals that utilize the network depend on a standard environment. Apple will keep those developers informed as AppleTalk standards evolve so that the installed base of products and networks, now approaching 3 million nodes, can migrate along with the standards. Apple discourages developers from promoting alternatives that conflict with the Apple­-endorsed ANS standards.

Apple encourages developers to utilize the LAP manager and other facilities of the ANS to bring AppleTalk into new environments. Specialized media types, alternative transport systems such as infrared and packet-radio transmission, AFP servers on minicomputers and mainframes, and very high­-performance network routers that interface to T-carrier facilities are a few examples of developer opportunities that Apple endorses in the network infrastructure arena.

See Also