Compressing files. Working with online documents means that local files frequently need to be uploaded for sharing, or downloaded to be used for local processing. Files may be extremely large, which can cause problems with transmission (delivery) in terms of speed and network usage. To reduce this problem, files have to be compressed (i.e. reduced in size) before transmission and then expanded after transmission. A common method of doing this is to convert them to zip files (.zip format). Zip files are basically stores of data files which may have been compressed. There are many different algorithms for doing the compression – with most compression software supporting several of these. The last item in a zip file is an index, which shows the placement of each of the data files and allows other files to be added. Quite often the zip file will also contain some program code (a sequence of instructions) to allow the files within the zip file to be unzipped (known as self-extracting files). There is a wide range of software available for zipping files, with one of the most popular being WinZip.
Slide 2
Key terms
Uploaded: When you upload a file you move it from one systemto another system. For example,you can upload files from yourcomputer to a web page.Download: This is when youmove files from a system to yourpersonal computer.Algorithms: A mathematicalstep-by-step sequence used towork out calculations or carry outinstructions.
Slide 3
Controls over online documents
Version control Version control is important when users are sharing documents online, as all users need to be working from the most up-to-date version of the same document. One of the simplest ways of implementing version control is to allow just one user to open a document, or part of the document, for update at any one time. When one user has the document open and someone else tries to access it, the document will be locked . It is only unlocked when the original user has completed updating the file and has closed it again. The method of ‘locking data’ has many uses within online documents and with database systems. It is commonly used on legal, engineering and medical documents which must be complete and up to date.
Did you know?Other methods of version control include the software allocating the latest version number showing the time and identity of the person making the changes. If, for any reason, a document does become corrupt (damaged) or is missing important updates, it is possible to roll back to a commonly agreed version number.
Levels of access and file permissions The system administrator within an organisation can control the levels of access users have to a particular document. They can allocate access to individuals or particular groups of documents by using file permissions . Some users may only be able to read documents but not edit them. Other users may be allowed to read and edit documents some may be allowed to add new documents and some will be allowed to delete documents. File permissions can be used to restrict access to certain documents and to restrict what can be done to them. An example within an accountancy business is shown in Figure 1.3 on page 10.
Slide 4
The biggest advantage of using online document software is that you can allow many people to share a version of a document and work on it at the same time as other people (known as collaborative working). You can also access content:
• anywhere there is an available internet connection
• via different devices (e.g. PC, smartphone, tablet)
• on different operating devices (e.g. Windows ® and Mac).Online documents can also have automatic backup. Backing up files means that you save a copy of the fi le at a known point in time. This means that you can always go back to that version if you lose or corrupt the present version.
Some software programs will automatically make a copy of the file you have open and are working on at set time intervals. In Microsoft Word ® you can set how often you would like the file to automatically backup (every 30 minutes, every 60 minutes, etc). Automatic backup of online documents is just an extension of this concept.
The advantages of using online software
Slide 5
• Read-only access. This allows a user to look at and read a document but not to change it. A university lecturer could use a Word document to create a test for their class, if the document was set as ‘read-only’ then the class would not be able to make any changes to the wording.
• Read/Write access. This allows a user to look at and read a document, but also to make changes to it.
• Full control. This allows users to retrieve a document, read it, edit it, add a new document or delete or archive an existing document. Full control is usually given to people who administer the system. They may be senior people within the organisation or senior administrators who report directly to senior management.
