Lesson 15

Implementing Network Applications

This lesson focuses on applications only possible with networks.

E-Mail

E-Mail has several advantages over the use of a telephone:

If the person being called is not at their desk, the message is stored until they return

It is easy to keep a record of all correspondence.

Internet E-Mail

Within HCT

Each college has a local e-mail system operating on their LAN.

Each college has a system-wide e-mail system operating through modem links between colleges.

Every instructor has an Internet e-mail account allowing them to swap e-mail with millions of people worldwide.

E-Mail Standards

Worldwide standards are very important to e-mail. Without them it would be impossible for a user of a Unix mini-computer in Finland to swap mail with an Apple Macintosh user in India.

Several standards are in common use:

X.400

This standard includes user interfaces, encoding information, protocols, etc.

Simple Mail Transfer Protocol - SMTP

This is the e-mail system used by the Internet. It is part of the TCP/IP protocol stack.

Message Handling System

This standard is built into Novell Netware.

Translating Between Standards

Many e-mail systems can work with multiple standards. cc:Mail, for example, normally uses its own proprietary protocol, but can also understand X.400 or SMTP. Translation between standards is normally performed on a dedicated PC called a gateway.

Scheduling

Scheduling means planning your time - your day, your week or your month.

The biggest advantage of network based scheduling programs comes when everyone in an organization uses the same system and meetings need to be arranged. If you give me permission, I can check your schedule and see when you are free. I can then add a meeting time to both of our schedules. When the meeting comes around, the scheduling software will remind us that it is time to meet.

Groupware

Groupware is software designed to allow groups of people to work cooperatively across a network.

At the simplest level an electronic Bulletin Board System is a groupware - enabling a group of people to communicate and share ideas and documents.

Sometimes groupware is like a mixture of e-mail and a multi-user database. For example if a report is to be produced by a group of people, a groupware system will enable them to work on it in an orderly way. First one person checks it out, works on it then returns it. Next a second person does the same. The groupware software keeps a record of who had it and on what dates. Some groupware system let several people work on a document at the same time, each one seeing - as they happen - the changes made by the others.

The most well known groupware system is called Lotus Notes.

Running Ordinary Applications From a Network Server

Consider our college - there are two ways we can install MS Office:

1. Individually on each workstation:

Advantages:

Reduces network traffic.

Application may run faster.

Disadvantages:

Must buy many individual copies - expensive.

Must install on every machine - a big job.

Must maintain configurations on every machine - a very big job.

Difficult to impose common settings and ensure common versions.

2. Just once, on the server:

Advantages:

A 200 user license is cheaper than 200 individual copies.

Only one copy to install - much less work.

Only one copy to maintain.

Disadvantages:

Loads the network.

To share a program on the network, the administrator must give all users read but not write permissions to the application’s directory on the server.

Note:

In a server based setup, the programs are stored on the server, but they do not run on the server. They are copied from the server’s disk, across the network, and into the RAM of the workstation. They run on the workstation’s processor.

Note:

It is possible for a workstation to cause a program to run on a server - but this is unusual. An example of this is a client / server database, where queries are processed on the server and only the results are transferred to the station.

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