Networks 

The WBAR program is compatible with the built in networking capabilities of the Microsoft operating system as well as the Novell, and IBM network operating systems.  WBAR does not run on  Unix or Linnux networks.

With network hardware and software installed, WBAR allows the sharing of files and printers between two or more computers. The ability to share files and run multiple programs has many advantages over single application processing. The are however, more complex procedures and programming considerations in a shared use environment. This manual addresses some of the more common do's and don'ts of a network setup.

Understanding Networks
Networks have their own language and terminology which is used to identify the equipment, software, strategies, and architecture of the network. All networks work on the same basic principal. Files and "resource" devices are stored on or attached to a machine that "shares" access to those files and devices with other machines. In a network, the machine with the files being shared is called a SERVER. The computers that access the server and use the shared files are called CLIENTS. A small network will usually have only one server and only a few clients. A large network may have dozens of servers and hundreds of clients.   

                                                          Server

Simple Network  :                                                                       

 

                                 Client 1                                                  Client 2

                                                                                                                                               

 

In this example, the machine in the middle is the Server and the two machines at the bottom are Clients. The computers on a network are connected either by wire or by a radio frequency connection (called wireless networking). If you are new to networking, you will probably need the assistance of a skilled computer  technician to set up the hardware and software for your network. Each computer must be equipped with a network adapter (sometimes referred to as a NIC card). The network adapter allows signals to pass from the computer over the wire (or radio wave) to the other computers in the network.

Each machine on your network must have a unique machine name or identifier. If your computer is part of a workgroup, a simple name can be used. If your computer is part of a larger network, it will probably be identified by the domain it belongs to and will use a set of numbers called an IP address. The identifiers allow the network to tell the machines apart when several computers are running.

Peer to Peer vs Application Server

The Server is usually the largest (most powerful) computer in the network. Since the Server is going to be sharing files and possibly other resource devices, it makes sense for it to be the most powerful computer in the group.

Some network Servers are designed to run software applications which are then shared with less powerful computers or terminals. In this type of network, programs actually run on the server and only the information the programs produce is delivered to the Client machine. Such programs are sometimes referred to as server side applications because all of the processing is done on the server. In some cases, the Client machines do not even have hard drives because the programs and data are all stored on the Server.

The other type of network which is becoming popular is called the peer to peer network. In this setup, each computer can be both a Server and a Client. In other words, each machine can access shared files and resources on the other machines and can share its own files and resources with other users. Peer to peer networking is convenient because it allows the sharing of multiple devices that may be connected to other computers on the network. It also means that each computer uses its own memory and central processor to run programs. Each computer can be set up to share, or not share, files and devices with other users. Sharing can also be set up to allow some users access based on passwords you assign.

WBAR was designed to run on networks that allow a shared drive and folder. The shared drive must be mapped by the Client machines and full read/write sharing rights must be allowed. The shared drive must be mapped to a drive letter. WBAR uses that drive to locate the program and the data it needs. When WBAR is started, it loads the program and support library from the shared drive. When WBAR needs to access data, it looks for it on the shared drive. The program and data is loaded into the memory of the Client machine and runs on the Client, but the program itself is installed on the Server. Because WBAR writes some temporary files to the Client, each Client machine must be equipped with its own hard drive. WBAR does not need each Client machine to be in a peer to peer environment unless you intend to let network users have access to files and devices located on other machines.

                                                                              Server                    Shared Resources

Network Sharing  :                                                                    ---------Shared Hard Drive

                                                                                                   ----------Shared Laser Printer

                                 Client 1     Shared Resources                                           Client 2            Shared Resources

                                                     ----Shared Drive                                                                   -----Dot Matrix Printer

 

 

In this example, the Server has been setup to share its hard drive and a laser printer, which is physically attached to the Server. Both Client 1 and Client 2 will be able to access the WBAR program that will be installed onto the Server's shared drive. Both will be able to use the laser printer as well, provided that they have been given access rights. Access rights are setting controlled by the network software and are used to allow or denied access to files and devices attached to each machine.

If you are unfamiliar with networking, you will probably need the assistance of a network administrator or technician to initially set up the access rights and sharing properties on your network.

Notice that Client 2 also has a printer attached. Client 1 will be able to to use the dot matrix printer attached to Client 2 if access rights are granted. Client 2 can also use the printer because it is physically attached to that machine. Notice also that Client 1 has a shared drive. This could be a hard drive, diskette drive, Zip drive, or CD-ROM drive. If Client 2 is given access rights, the it can use the shared drive on Client 1 to retrieve and store information.

In addition to computers and printers, a network may consists of peripheral devices such as modems,  fax machines, CD-ROM drives and scanners. These devices are referred to as network RESOURCES since they can also be shared with other users of the network. As with printers, sharing can occur even if the device is not physically attached to the computer which is using it. For instance, a scanner can be shared by several people even though the scanner is only physically attached (by cable) to one of the computers. This sharing of devices is one of the reasons computer networks are becoming more and more attractive. It is less expensive to share than to purchase separate RESOURCES for each user.

Exclusive and Multi-User Sharing

When a command is issued to read a file located on another computer, the network software determines where the file is, opens it on the other computer, and carries the information back to the user's computer display.

The network handles FILE and RECORD LOCKING to protect files from two or more users trying to change data at the same time. This is done automatically within WBAR as well. File locking is a way to temporarily freeze a file from being altered until some change is completed. Record locking is the same thing except it affects only one record within a file that may contain many records. When two or more people are sharing a file, the network controls when the file can be changed, viewed, deleted, added to, and copied. For example, if the file is being used by two people and one attempts to delete the file, the network will return a message saying that the file is shared and cannot be deleted at this time.

Virtually any type of file can be "accessed" across a network. Not all file types can be "shared".

There are two forms of sharing that can occur on a network. Exclusive file sharing is when a file resides on one machine but can be "accessed" from another machine on the network. For example, a document created with a word processor might contain a form letter. The document is stored on the hard drive of the server. Karla uses a client machine down the hall to open the file using the word processing software on her computer. The file is "read into" the memory of her computer so that she can work with it. She makes some changes and then saves the file back to the server. In this situation, the "access" to the file is shared but the file itself was only used by one person. Since the file was changed, when it was saved, the changes she made would be written to the file back on the server.

Now let's assume that Tom in another location also uses his word processor to open the file on the server. Tom does not know that Karla is also using the file. Tom makes some changes to the letter and saves it to the server. If Tom saves his file after Karla saves hers, Tom's version will be the one Karla sees the next time she opens the file. In other words, the last person to save the file gets his/her version copied over any previous version.

The other type of sharing is multi-user or non-exclusive sharing. In this situation, two people need to be able to look up or change information in the same file. WBAR is a multi-user sharing system. Its files can be opened by many people at the same time and the software controls the flow of data in and out of the files.

Avoiding Data Collision

WBAR uses file and record locking to protect information from data collision. Data collision is when two or more people are attempting to access the same piece of data at the same time. For example, if Tom looks up information on account 03-1245, and then attempts to change the address while Karla is attempting to change the zip code of the same account, data collision could occur. WBAR  handles this situation by "locking out" the second person temporarily until the first change has been recorded. WBAR waits for the first change to take place and for the person to move off of the record before allowing the second person to begin making a change.

Data collision is NOT A PROBLEM when users are in DIFFERENT records of the same FILE. Suppose Tom is changing information about 03-1245 and Karla wants to change 05-1220. There is no problem because both records can be changed without interference from the other user.

Data collision is NOT A PROBLEM when users are VIEWING information. When an account is viewed or a table of records is displayed, a file is in a state called READ ONLY. This means that the information is able to be viewed but not changed. Only programs that allow information in a record to be changed requires data collision protection.

Data collision is NOT A PROBLEM when users are ADDING new records to a file. Adding data from one or more machines at the same time is fine because the records are not being accessed at the same time. There is a FILE being shared into which the records are being added, but the new data coming from each machine is not in conflict.

Data collision CAN BE A PROBLEM when attempting to UPDATE a group of records in a file. When WBAR performs an update of payments, meter readings, billing charges, etc., it uses the information in one file to change the information in another.

Updates take place as the information in the SOURCE file is read and then copied or added to the information in the DESTINATION file. The update program attempts to find and lock the record in the DESTINATION file so that the change can occur. If another person has placed a prior lock on the record because they are attempting a different type of change, then the update may not be able to continue the process.

Data collision CAN BE A PROBLEM when attempting to DELETE records or files. Because information in a network is SHARED, there are certain rules about when information can be removed. It would be chaos if one user were to remove records from a file while another person was using that same information.

Deletion within WBAR has two forms. A record may be MARKED for deletion, in which case it no longer appears in the file. The physical record is still there, but the program is told to ignore it. The second process is to actually (physically) remove the record from the file. To do this, the computer must be sure that the file is available to be in EXCLUSIVE use. That means the file is used by only one machine and that no sharing is allowed. If the computer detects that the file is EXCLUSIVE, it will remove those records marked for deletion, then it will re-size and re-sort the file.

Since UPDATES also involve removing records after the update is completed, they need to be done at a time when the file can be EXCLUSIVE. If an update is performed while the files are shared, no physical removal can take place.

* It is important to realize which programs and files on your computer are multi-user and which are shared access. Before attempting to install a new program for use on a network, check with the developer to find out whether it was designed to be shared over a network.

In order to avoid error and confusion over the update process, the following checklist should be observed.

  1. Make sure you have printed out the data ie. daily cash report, billing register, etc. BEFORE attempting an update.
  2. Back up your data files using the files before you update. Backing up your files prior to an update allows you to restore your accounts to their original position if the update fails or produces unwanted results.
  3. Make sure that CLIENT machines are not running the WBAR program. CLIENTS share the data on the SERVER and will prevent the removal of records AFTER the update is run.
AFTER an update is done, check one or more of the customer account records to verify that the information has changed. 

Selecting Printers With WBAR Network

WBAR uses the API controls in Windows to allow printing to any installed printer. When you install a printer within Windows, you also install special software called a driver. The driver tells Windows the make and model of the printer and includes all of the printing options supported by the printer. Windows allow you to have several printers installed at the same time. Once installed, you can print to local printers, those physically connected by cable to your computer,  or shared printers, those connected to other computers but shared.

WBAR's print engine reads the information in Windows to determine which printers are available for you to print to and what features each print has. When you run a report, WBAR will automatically be set to print to the printer you have selected as the "default printer". Your default printer is selected in the Printers dialog box of the Windows Control panel. When you change the default printer selection, WBAR will then begin using the new printer for each report.

You may also select a different printer prior to sending a report to print. WBAR's print engine allows you to select from the printers available. Click on the Options button and then the specific printer button.

 

This dialog box appears when the WBAR print engine is started. You can click on the Options button to select a different printer.

 

 

The drop down list will show the printers you have access to. You may also select either portrait or landscape mode, paper size, and paper source. Click on the Secondary Options tab to set the number of copies and range of pages to print. (Not all printers support multiple copies).

When you print a report, the printer's dialog box will appear allowing you further options. In this example, the print job is being sent to a laser printer that is attached to a machine called Fileserver. The printer is a shared printer physically connected to the Fileserver machine by a USB cable.

Network print jobs will usually be set to spool at the machine where the printer is located. Spooling is a way of managing multiple print jobs sent to the same printer. If spooling is allowed in Windows, WBAR's reports will be created as spooled files and then released to the printer as the printer become available. The printer administrator (one who has access and control rights to the printer) can use the printer's control list to pause, cancel, or change the order of print jobs sent to the printer.

 

 Windows Spooled Print Jobs Will Appear in the Printer Control Box

 

 

 

 

 

 
The printer spooling options are located in the Properties dialog box of the printer. Go to the Windows Control panel, click on Printers, and then right click on the printer you want to set properties for. Click on Properties.

 

 

 

 

 

This printer is set to spool print jobs and to start printing as soon as a print job begins spooling.

 

 

 

 

 

 

You  can also set up a printer so that print jobs do not spool, but are instead delivered directly to the printer. If you do this, WBAR may have to wait for a print job to be completed before the program will allow you to continue. This is because the printer will wait for the print information to be delivered and printed before it returns control back to WBAR.