Case Study 3

In a multiprogramming and time-sharing environment, several users share the system simultaneously. This situation can result in various security problems. Name at least two of these problems. Can we ensure the same degree of security in a time-share machine as we have in a dedicated machine? Explain your answer.

Technology has become the fastest growing environment here on earth. One concrete example of that technology is the computer. Computers or human-like machines have actually contributed to the development of the world. As technology arises, more and more machines are being developed. From a single user gear into a multi-user and multiprogramming processes. These things help us do multiple tasks in work, studies, and interests.

But then problems would never fade away. They would always arise. And as these things are continually growing, more and more problems are still increasing.

Things like this happen also in a multiprogramming and time-sharing environments. Some situations like having different users at the same time may result to various security problems

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But first, let us discuss what is multiprogramming and time-sharing?

In using computers, multitasking is a method by which we perform multiple tasks also known as processes at the same period of time and share common processing resources such as a CPU. In the case of a computer with a single CPU, only one task is said to be running at any point in time, meaning that the CPU is actively executing instructions for that task. Multitasking solves the problem by scheduling which task may be the one running at any given time, and when another waiting task gets a turn.

In order to achieve the tasks performed by a single CPU, there are different scheduling strategies so that the jobs will be performed.

In multiprogramming systems, the running task keeps running until it performs an operation that requires waiting for an external event (e.g. reading from a tape) or until the computer's scheduler forcibly swaps the running task out of the CPU. Multiprogramming systems are designed to maximize CPU usage.

In time sharing systems, the running task is required to relinquish the CPU, either voluntarily or by an external event such as a hardware interrupt. Time sharing systems are designed to allow several programs to execute apparently simultaneously. The expression 'time sharing' was usually used to designate computers shared by interactive users at terminals.

One of the security problems that would happen is when he would copy some of your files, delete or change it.

 An example is when the other user may overwrite your files. This would occur at some point when you already finished the first job and you are now working with your second job, but the other user had already finished the job that you are currently doing and is starting to work with your first job, this thing may lead to mixing of programs and result to error. This may also corrupt your files and would let you start your job all over again. This kind of state may lead to a failing work, unfinished jobs and damaged files and lesser memory.

The other user of your system may copy some of the files or programs and/or memory space you have. If he found a folder in your system that he might use in some other time, he would have a duplicate with it and make use of it in other instances.

The other user may also delete or accidentally delete the files you have most especially when he would think that he will never need it anymore.

The second problem is the sharing of your systems resources that may result to deficient memory.  As we all know multiprogramming is a technique that allows a single processor to process several programs residing simultaneously in main memory and interleaving their execution by overlapping I/O request with CPU request. It attempts to increase CPU utilization by always having something for the CPU to execute. The system switches among the programs for efficient processing and minimal idle time.    

When multiple programs are present in memory, an ill-behaved program may (inadvertently or deliberately) overwrite memory belonging to another program, or even to the operating system itself.

Can we ensure the same degree of security in a time-share machine as we have in a dedicated machine?

A time-share machine allows multiprogramming processes and multi-tasking at the same time. One example of this is the personal computer and laptops. They are skilled to do multiprogramming skills simultaneously.

In this kind of situation, users share the system simultaneously. One example is when the other person in your group has all the files in his laptop and in order to work with your programs faster, you remote your laptop with his. This will allow you to view his desktop and all the files within his system. You could also manage to change his files since you are also working with his system. This kind of situation may lead to various security problems most especially on your personal files and of the things that you are currently working upon.

While a dedicated machine is a computer that services one primary function or task. For example is a computing device that has a built-in computer that is solely dedicated to compute numbers. Dedicated and time-share machine differs with each other when it comes to capabilities same as it would never have the same degree of security.

Case Study 2

Would a newspaper reporter and a supermarket manager use a handheld computer in their work?

A hand held computer is a mobile device and is a pocket-sized computing device, typically having a display screen with touch input and/or a miniature keyboard. A portable computer that is small enough to be held in one's hand. Although extremely convenient to carry, handheld computers have not replaced notebook computers because of their small keyboards and screens.

The handheld computer greatly reduces data entry time by providing a way to record data quickly and easily. Data can then be transferred to a desktop or laptop computer database or spreadsheet application for manipulation and storage. Their small size and long battery life allow them to be used in situations where laptop computers are inconvenient.

Handheld devices have become ruggedized for use in mobile field management situations to record information in the field. They are used to achieve a variety of tasks for increasing efficiency that include digitizing notes, sending and receiving invoices, asset management , recording signatures, managing parts and scanning barcodes. Handheld computers used at work have molded over time into a variety of form factors, including smart phones on the low end, handheld PDAs, Ultra-Mobile PCs and Tablet PCs. Laptops do not come under handheld computers as they are not small enough to hold in one's hand.

Now, what does a newspaper reporter do?

A newspaper reporter investigates a subject, performs research and conducts interviews to gather information, then writes a newspaper article on what he or she discovered. Sometimes used synonymously with the word journalist, a newspaper reporter is usually someone who actually performs research and investigation into a subject or story and reports it.

As a newspaper reporter, you must be accurate, quick and provides proper data for the reader. In gathering information, you must interview someone for that information. Sometimes if the person you’ve interviewed speaks faster, you must have a proper gadget for that. The handheld computer greatly reduces data entry time by providing a way to record data quickly and easily. The data you then gathered would be transferred to a laptop or PC for encoding it and make it as an article.

One example of handheld computer is the new iPhone 4 that has all the features any journalist (CJ or PJ) needs to never again be in a newsroom.

Of these features include FaceTime, the ability for video calling (right now just WiFi capable) is a feat that will put an end to mobile video cameras such as the FlipCam, which could not even transmit data remotely.

Another is the overall video capabilities of the phone itself. No more is there a need for a film crew or bulky cameras for on-the-spot news. Point, shoot, edit, send. This is possible and will be the future. High school and college students will use this technology to enhance their newspapers’ websites as schools cut back on their budgets. Professional journalists and bloggers will do the same.

How about a delivery person for a courier service?

A courier is a person or company who delivers messages, packages and mail. Couriers are distinguished from ordinary mail services by features such as speed, security, tracking, signature, specialization and individualization of services, and committed delivery times, which are optional for most everyday mail services.

It has being proven and tested that some companies nowadays are using the latest technology for that faster and easier processing of their job. On of which is the DX group, a courier firm which handles a million items of mail daily, is rolling out handheld devices to its 850 couriers to ensure accurate delivery and create real-time parcel tracking. The system plans a route and delivery order for couriers, taking into account the time of day, likely amount of traffic, and number of deliveries in the area. It also monitors couriers’ locations, and warns customers and couriers of deliveries that are likely to be late.

Types of systems and their specific OS

1.     Batch Systems

Ø  A batch system is one in which jobs are bundled together with the instructions necessary to allow them to be processed without intervention.

ØA batch process is one that runs without user interaction, such as the execution of a script. Often, batch processes are run automatically by some kind of scheduler, or in response to submission into a queue.

Example OS for batch processing:      

OS/360

OS/360, officially known as IBM System/360 Operating System, was a batch processing operating system developed by IBM for their then-new System/360 mainframe computer announced in 1964; it was heavily influenced by the earlier IBSYS/IBJOB and Input/Output Control System (IOCS) packages. It was among the earliest operating systems to make direct access storage devices a prerequisite for their operation.

2.     Interactive Systems

Ø  An operating system that allows users to run interactive programs. All operating systems that are on PCs are interactive OS's.

Ø  Requires time-sharing software, which allows each user to interact directly with the computer.

Example OS for batch operating system:

Dartmouth Time Sharing System

The Dartmouth Time-Sharing System, or DTSS for short, was the first large-scale time sharing system to be implemented successfully. Its implementation began at Dartmouth College in 1963 by a student team under the direction of John Kemeny and Thomas Kurtz with the aim of providing easy access to computing facilities for all members of the college. By 1964 the system was in use where it remained so until the end of 1999. DTSS was originally implemented to run on a GE-200 series computer with a GE Datanet 30 as a terminal processor that also managed the 235. Later, DTSS was re-implemented on the GE 635, still using the Datanet 30 for terminal control. The 635 version provided interactive time-sharing to up to nearly 300 simultaneous users in the 1970s, a very large number at the time.

Interactive system would be usable if there is an interaction with the user. Therefore, this kind of operating system will not work out or do the task if command of the user is lacking.  

2.     Real-time Systems

Ø  A real-time operating system (RTOS) is an operating system that is intended to serve real time application requests.

Ø  Often used as a control device in a dedicated application such as controlling scientific experiments, medical imaging systems, industrial control systems, and some display systems.

Example of Interactive System OS:

RTLinux

RTLinux or RTCore is a hard realtime RTOS microkernel that runs the entire Linux operating system as a fully pre-emtive process.

It was developed by Victor Yodaiken (Yodaiken 1999), Michael Barabanov (Barabanov 1996), Cort Dougan and others at the New Mexico Institute of Mining and Technology and then as a commercial product at FSMLabs. Wind River Systems acquired FSMLabs embedded technology in February 2007 and now makes a version available as Wind River Real-Time Core for Wind River Linux.

RTLinux was based on a lightweight virtual machine where the Linux "guest" was given a virtualized interrupt controller and timer - and all other hardware access was direct. From the point of view of the real-time "host", the Linux kernel is a thread. Interrupts needed for deterministic processing are processed by the real-time core, while other interrupts are forwarded to Linux, which runs at a lower priority than real time threads. Linux drivers handle almost all I/O. First-In-First-Out pipes (FIFOs) or shared memory can be used to share data between the operating system and RTCore.

 

2.     Hybrid Systems

Ø The hybrid operating system approach which is to combine a general-purpose operating system with a real-time operating system is a promising approach to satisfy the real-time property, which is a usually required or embedded system.

Example of Hybrid System OS:

Windows NT

Windows NT is a family of operating systems produced by Microsoft, the first version of which was released in July 1993. It was a powerful high-level-language-based, processor-independent, multiprocessing, multiuser operating system with features comparable to Unix. It was intended to complement consumer versions of Windows that were based on MS-DOS.  NT was the first fully 32-bit version of Windows, whereas its consumer-oriented counterparts, Windows 3.1x and Windows 9x, were 16-bit/32-bit hybrids. Windows 2000, Windows Xp, Windows Server 2003, Windows Vista, Windows Home Server, Windows Server 2008 and Windows 7are based on Windows NT, although they are not branded as Windows NT.

2.     Embedded System

Ø  Computers placed inside other products

Ø Designed to perform one or a few dedicated functions often with real time computing constraints. It is embedded as part of a complete device often including hardware and mechanical parts. Embedded systems control many devices in common use today.

Sample OS for embedded systems:

Windows CE (also known officially as Windows Embedded Compact or Windows Embedded CE post version 6.0 , and sometimes abbreviated WinCE)

-is an operating system developed by Microsoft for minimalistic computers and embedded systems.  Windows CE is a distinct operating system and kernel, rather than a trimmed-down version of desktop Windows. It is not to be confused with Windows Xp embedded which is NT-based. Microsoft licenses Windows CE to OEMs and device makers. The OEMs and device makers can modify and create their own user interfaces and experiences, while Windows CE provides the technical foundation to do so. Windows CE is supported on Intel x86 and compatibles,MIPS, ARM and Hitachi SuperH  processors.