TECHNICAL BRIEFING DOCUMENT

GLOBAL SYSTEM MANAGER (NOVELL)

Global System Manager is a complete, portable environment for business applications, currently licensed for use at over 25,000 multi-user sites worldwide. Running on Windows NT, Unix, Novell and DOS/Windows, it controls user access, menus and file/record locking and offers multi-tasking of up to 9 concurrent programs per screen, as well as a complete set of utilities such as print spooling and on-screen calculator, calendar and data transfer.

Novell NetWare is one of the world's leading PC networking systems. Hitherto, it has enjoyed wide acceptance as a vehicle for office automation software, but has had less impact in the accounts and distribution arena which demands far more complex file and record locking facilities. Suppliers porting to Novell, whether adapting single-user DOS products or multi-user applications from another environment, have usually had to improvise special locking techniques which often cause substantial performance overheads.

Global System Manager has always incorporated platform-independent file/record locking techniques, and for this reason its previous Novell implementation offered superior performance and achieved considerable success. Nevertheless, at larger sites performance and reliability sometimes failed to meet the standards of other Global implementations.

Networking implementations of Global System Manager require one computer to function as the 'master computer'; i.e. to hold central 'lock tables' that keep track of which files or records are currently being updated by which users. For performance reasons, the Novell fileserver could not function as the master computer, and so access to data on the fileserver by a workstation user was always indirect.

The problem of additional network traffic was exacerbated by the unreliability of the IPX protocol used by previous releases of Global System Manager (Novell), which occasionally failed to deliver its 'packets' of network data in the order in which they were sent. The new release uses instead the far more resilient SPX (Sequenced Packet eXchange) network transmission protocol and thus offers far greater reliability than its predecessor.

Resolution of the performance problem has now been achieved by the adoption of the NetWare Loadable Module (NLM) facility, which was introduced by Novell in Netware 3.

An NLM is a third party software module which extends the standard functionality of the Network Operating System (NOS) that every Novell fileserver runs. Such modules must be 'well-behaved' as they run simultaneously and share memory with the NOS. Typically, an NLM provides a common service (such as print spooling) to applications running on the workstations, and SPX packets can indicate a particular NLM as the target process.

Global designers immediately recognised that NLMs represented the perfect solution to the performance problem. By producing a 'cut-down' Global System Manager, which combined just the disk and network controllers and lock tables in a single NLM, they could produce a new implementation which would offer outstanding performance, flexibility and reliability.

Global System Manager (Novell) V8.0 - and later variants - is the result. The NLM (which runs as a screenless process on the fileserver) functions as the Global master computer, and any workstation that needs to access shared data communicates directly with the fileserver. Workstations can log into System Manager as and when required (previously at least one workstation - the 'master computer' - had to be running System Manager continuously, and thus could not be used for DOS applications). Because the System Manager NLM makes minimal processor demands and is memory resident, fileserver performance is not affected by its running.

If required, any workstation can drive multiple serial screens (this is unique in the Novell world), though such a machine cannot run DOS applications at the same time. Furthermore, the SPX Workstation option enables single-user workstations to function as serial screens onto another - multi-user - workstation; this gives them the advantage of being able to hot-key between DOS and Global applications without having to end their System Manager session.

The significance of the new release for existing and prospective users of Global on Novell is immense. Global System Manager (Novell) V8.0 and later variants introduce new standards of flexibility and performance to the PC networking world. Its enhanced resilience means that, for the first time, users can confidently run mission-critical accounting and distribution applications on PC networks.

Furthermore, the adoption of the SPX protocol, with its extended addressing capabilities and its inherent reliability, makes the use of highly populated and geographically widely spread PC WANs (wide area networks) a practical proposition. Companies requiring real-time international accounting networks, with workstation users in different countries accessing a single fileserver, can now use Global 2000 or 3000 modules to achieve that end. Multi-national order processing systems are now feasible using industry-standard PC hardware.