• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month
  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
  6. 6
  7. 7
  8. 8
  9. 9
  10. 10
  11. 11
  12. 12
  13. 13
  14. 14
  15. 15

File transfer protocols

Extracts from this document...


File transfer protocols File transfer is the process of transmitting complete files from one computer to another. To achieve a successful transfer, both sending and receiving devices must establish the protocol (set of rules) by which they will communicate. Various protocols are commonly recognised but they vary in their performance and suitability for particular tasks. Some examples are described below. FTP File Transfer Protocol (FTP) allows large amounts of information to be transferred between computers very conveniently. FTP originated with the UNIX operating system and was to transfer files of all types between remote computer systems. A popular application of is for the uploading and downloading of Web site pages. ASCII This is only appropriate for text files, which contain no control characters. Thus it cannot be used to transfer files produced with a word processor, spreadsheet or graphics package. Neither can it transfer command (COM) or executable (EXE) files, or files in compressed (ZIP, for ex) form. Apart from this, the protocol is not good at controlling errors. Xmodem A file-transfer protocol used for asynchronous communications. It is commonly used in communications packages. The Xmodem protocol transfers data in blocks of 128 bytes, giving each transmitted frame a sequential block number; this number is used to identify the location of errors. A checksum (see Block Check Characters) is attached to each block to check transmission errors. Its ability to find and correct errors makes it suitable for the transfer of files, which must retain their integrity, such as program files. Zmodem Is one of the most advanced protocols, being much faster than Xmodem. Its error correction controls are absolutely reliable. CCITT V42bis This protocol includes a data compression (through encoding, data is reduced in volume) technique and error detection and correction. Both the sending and receiving modem must possess the error correction facility. Implementation Top Down implementation is one way to achieve implementation of software. ...read more.


The types of tests which should be considered for a system are as follows Inputs- form design (ease of use) - data transmission - input validation and correction Files- empty files - addition/deletion/update - access - controls/security Outputs- output documents/screens - recipient understanding ComputerProcedures- program linkages - operating procedures - recovery and security - timings Clerical Procedures- effects on other systems - user understanding - error correction - timings User Education and Training The success of a new system is very much dependent on the attitudes of the people who use it. Education aims to convince users of the benefits of the system to themselves, their department and the company. Management policy regarding re-deployment ,redundancy etc should be clearly stated. while casualties may result from the introduction of new systems, there are also many positive aspects such as ? reducing very boring clerical activities ? upgrading of skills ? ? improving job satisfaction ? d? Education, therefore, complements and is a pre-requisite to training. e? Training enables users to understand their role in the new system, and prepares them for their own specific tasks. The users and people affected by the new system must be trained, and arrangements for release from normal duties must be made. Many different methods of training are available including f? formal lectures a? ? discussions/seminars ? computer-assisted training (tutorial packages,help facilities etc) ? user manuals/quick reference guides ? Usually a combination of methods will be chosen with an emphasis on 'hands on' experience. Timing and pacing of training is also important, too early and users may forget aspects or become disinterested, too late and users will become flustered. Training does not cease with implementation, but must meet needs of new staff and system changes. changeover Implementation may involve change from a manual system to a computer system or from one computer system to an other. In both cases the system data and procedures require to be changed. ...read more.


If you create a validation rule for a field Microsoft Access doesn't normally allow a Null value to be stored in the field. If you want to allow a Null value add Is Null to the validation rule as in "<>8 Or Is Null". Query criteria in MS Access Field Data Field data finds an exact match for a field Smith will find smith - Access is not case sensitive wildcards Two wildcards can be used to replace field characters. any single character 0 any character B* will find values beginning with B */*/91 will find all dates in 1991 Range Operations ? Sm?th will find Smith and Smyth > greater than < less than >= greater than or equal to >=l0000 finds values greater than or equal to �10000 <= less than or equal to <=#01/12/92# finds values greater than or equal to 01/12/92 Compound Criteria The user can specify more than one example and criteria at any one time, Multiple examples fall into two categories; AND - OR situations AND All conditions specified must be satisfied before access displays data OR At least one of the conditions specified before data is shown Special Operators Date () will extract records with today's date Like Will extract records similar to eg, 'Like Peters*' will extract surnames similar to Peters NOT finds records not matching the condition, eg Not Smith will exclude records NULL extracts records with a blank field Summary Fields in MS Access Operator Function SUM calculates total value in field AVG calculates the' average value COUNT counts the number of records MIN finds the lowest value MAX finds the highest value H. T. Harvey 24 Dec 2000 H. T. Harvey 24 Dec 2000 H. T. Harvey 24 Dec 2000 H. T. Harvey 24 Dec 2000 H. T. Harvey 24 Dec 2000 H. T. Harvey 24 Dec 2000 H. T. Harvey 24 Dec 2000 H. T. Harvey 24 Dec 2000 H. T. Harvey 24 Dec 2000 H. T. Harvey 24 Dec 2000 ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our AS and A Level Computer Science section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related AS and A Level Computer Science essays

  1. Marked by a teacher

    The systems development life cycle (SDLC) is a conceptual model used in project management ...

    3 star(s)

    One of the problems that had been identified with other software development practices was that clients often didn't really know what they wanted or didn't want until they saw a practical implementation. It was through the process of customers commenting on an evolving application that new requirements were teased out.

  2. Peer reviewed

    information systems assignment 2

    4 star(s)

    The software can be very expensive or not expensive at all, the cheapest versions only give limited features and function, whereas the most expensive software is very highly functional which provides high performance giving the best results. Drawbacks A downfall to management information systems are it can be difficult to use as it needs training and experience to use.

  1. Computing Project

    Login Form procedure TFMLogin.BtnLoginClick(Sender: TObject); This procedure is used by the user to login to the system and gain access to the main menu Main MenuForm procedure TFmMenu.BtnRegAMemClick(Sender: TObject); This procedure diplays the Regester A Member Form procedure TFmMenu.BtnAddDVDClick(Sender: TObject); This procedure displays the Add DVD Form procedure TFmMenu.BtnRntDVDClick(Sender: TObject);

  2. ICT Sample Work India Red

    Tom is involved with calculation of prices of major bookings of restaurant, but he has other people calculating orders. IDENTIFICATION OF THE USER(S) The users of this solution will be the Tom Wilkinsons (the client), as well as Sachin Patel, Ahmed Patel and John Thompson.

  1. Unit 6 - Advanced Spreadsheet Skills

    Different Worksheets These worksheets will have the different types of data and functions within them, there are sets requirements to which all worksheets must abide by. 7.1 Main Menu: The Main Menu must contain links to all pages and these must be clearly seen, these will be created through the use of macros.

  2. Computing Project

    put the data type as numbers then it will not let me add a 0 at the front. USER MANUAL BRIEF INTRODUCTION The instructor database is a simple system to handle bookings given to the instructor. The system allows the instructor to control appointments already made and allows him to make new appointments.

  1. LAN &amp;amp; WAN Protocols

    Layer 5 (Session) - Only responsible for three things. For managing, starting and ending sessions for an end user application process. NFS - Originally designed and created by Microsystems same company who came up with JAVA programming. NFS (Network File System)

  2. AQA Computing CPT3 June 08 Peter's Petrol Pumps

    The Pump is set Ready for Use. As expected (SS9) Correct working of console display Number of litres: 1.7 Price per litre: 89.9 The number of litres should go up in 0.1 of a litre. The amount to pay is the number of litres multiplied by the price per litre.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work