If we look only at the name, we can see that there are two separate entities — the client and the server — working together to accomplish some task. Client/server computing is a relationship between the separate machines: the server providing services and the client consuming those services. The key word to describe this relationship may be interoperability, which means two (or more) systems working together in a cooperative manner, such that they appear to the user to be a single system. An early name used to describe client/server computing was cooperative processing. However we choose to define client/server, we may be able to agree on some characteristics:

•  In client/server computing, the intelligence is distributed across a network — it is not in a single location.

•  Servers provide resources that are shared among many clients. These resources are both hardware and software.

•  The location of the shared resources is transparent to end users. The resource may be on the same system as the client or on a different system elsewhere in the network.

•  Clients always initiate the operations by requesting a service. A server waits for the requests from the clients.

•  Clients and servers exchange information via messages. The connection between clients and servers is either a local or a remote communications network.

•  The system is viewed from the perspective of the user.

Client/server computing holds out the promise of making a business and its people more efficient and more productive by distributing business data and computing throughout the organization. To accomplish this goal requires more than just dropping in a new application; it requires changes to the business processes. In the past couple years, many businesses have successfully implemented client/server applications by restructuring parts of their business to take advantage of the client/server computing model.

Other businesses who didn’t restructure but just installed client/server applications have not fared as well. Client/server computing is probably more expensive, from a business standpoint, than any other form of computing. Consequently, these businesses generally found the new application model increased their costs of doing business with no tangible value.

Still other businesses cannot get to a client/server model for a variety of reasons. One study of businesses by the Standish Group showed that the success rate for client/server projects was only one in six. According to this study, 31 percent of the client/server projects were canceled, 16 percent were successful, and the rest just gave up. Those numbers are not very encouraging for someone embarking on a client/server project; but then, who said it would be easy?

Because client/server computing is difficult and expensive to deploy, many AS/400 businesses still have only host-based applications, using 5250s or PCs as terminals. While many of these customers say they intend to move to a client/server model, they are taking a wait-and-see attitude until the benefits and chances for success are more certain.

The AS/400 division’s goal is to simplify the client/server model by reducing the complexity of creating, installing, and maintaining client/server applications. We have developed and integrated several products into the AS/400 to achieve this goal. Foremost among these is the Client Access family of products.

I introduced Client Access briefly in Chapter 5. Client Access was originally announced in 1994 as the replacement to IBM’s PC Support/400 product. Although PC Support/400 was a very successful product, installed on nearly 80 percent of all AS/400s, after 11 years it needed to be restructured. In short, we needed to infuse new technology into this product, and Client Access was the answer.

Client Access is a family of products to support various clients, including Windows 95/NT clients, OS/2 clients, Windows 3.1 clients, Unix clients, and Macintosh clients. Each Client Access product is a single integrated package that includes

•  Connectivity support with protocol independence

•  Graphical user interface (GUI)

•  5250 display emulation

•  Print services

•  Mail and office services

•  Multimedia

•  Security

•  System management

•  Database access

•  File transfer

•  Application enablers and APIs

Enhancements to the Client Access family of products will continue at every release of Version 4. The purpose of this section is simply to introduce some of the functions that are offered to simplify client/server computing, not to cover all the Client Access features in detail. Two of the more recent enhancements need elaboration, however, because they can have a big impact on managing a client/server installation and creating client/server applications.

When IBM added a new graphical system administration interface to Client Access for the Windows 95/NT clients, the usability of the AS/400 was enhanced for those customers who like the look and feel of the PC desktop. Called Operations Navigator, this new AS/400 interface simplifies many user tasks through a Windows panel. For example, adding a new user to the system in a single step automatically creates the user profile, adds the user to the system directory, and even adds the user as a Notes or NetWare user. This graphical Windows interface provides many other administrative operations for the AS/400, such as database administration, backup support, security and auditing policies, printer support, and job support. Operations Navigator provides a consistent interface to both PC and AS/400 resources, which greatly simplifies system administration in a client/server environment with Windows clients, because end users need to learn only a single interface.

Still another enhancement to make the creation of client/server applications easier has the code name Project Lightning. This product provides efficient access into the AS/400 database and makes it easier to build 32-bit Windows applications. It is designed to work across different products in the Windows environment by conforming to the COM/OLE (discussed later in the chapter) and ActiveX specifications. Visual Basic add-ins allow programmers easy access to stored procedures, databases, programs, data queues, and commands. The menu items on the Windows screen are wizards that guide the programmer through a series of steps for linking to different functions on the AS/400. The wizards actually generate the code needed to link to each function on an AS/400. Programmers can then modify the code themselves or continue to use the wizards to generate the code for them.