Capabilities of Software Object Linking Embedding OLE n

Capabilities of Software

Object Linking & Embedding (OLE) n OLE allows information to be shared between different programs n n n For example, a spreadsheet created in Excel can be included in a Word document either by embedding it in the document, or by creating a link from the document. An embedded object has no connection with its original source file. A linked object ensures that the information displayed in the document will always be displayed – via the link – directly from the

Object Linking & Embedding (OLE) n Linked object n n n original information remains in the source file destination file displays a representation of the linked information but stores only the location of the original data linked information is updated automatically if you change the original data in the source file Use if file size is a consideration Embedded object n n becomes part of destination file. because an embedded object has no links to the source file, the object is not updated if you change the original data

Portability of Data n n n Portability is the ability to run the same program on different types of computer. It can also refer to the ability to transfer a file from one computer to another. For all sorts of reasons, it’s important to be able to transfer data between applications and between computers of the same or different types, perhaps using different operating systems. Files (binary, text or graphical) can be downloaded from the Internet using ftp (File Transfer Protocol) – software that can copy files between different types of computer

Examples of Portability n n You’re writing a report in Word and want to be able to insert an Excel spreadsheet in the report You’re using a desktop publishing system and you want to be able to import some graphics from a drawing package You’re doing a research assignment and want to download articles from the Internet on ‘Computers and Dolphins’ You want to e-mail your friend on a Unix machine in Hull from your PC in Southampton, and send her a scanned

Problems with portability n A document created using one word processing package (e. g. Word) commonly cannot be read by a another (e. g. Word Perfect) running on the same computer Formatting codes vary in different packages. n n A document created on one computer using a particular word processor appears differently on the screen of another computer running the same word processing package. n n For this reason, most word processing packages allow documents to be stored in ‘Text only’ format. Some word processors (e. g. Word Perfect) lay out a document based on the printer that is being used. Another possible problem is that fonts used with the original application may not exist, or be installed, on the

Upgradability n Software manufacturers commonly bring out upgrades about every two years. This causes some or all of the following problems: n Documents or applications produced by the upgraded software not ‘downwardly compatible’ (or ‘backwards compatible’). n n The new version is likely to contain new features nonexistent in earlier versions so that data or formatting may be lost if it is converted to the earlier version for another user. n The upgraded software frequently needs more memory, more disk space and a faster processor to work efficiently meaning that hardware has to be upgraded. On the other hand, of course, a new version often brings n n In other words, a document written in Version 6 can usually be read in Version 7, but not vice versa. Usually, the newer version allows the user to save the file as a ‘Version 6 file’ so that it can be read by the earlier version.

Criteria for selecting a software package n n n n n Compatibility with existing hardware. Will the software run on existing equipment? Compatibility with existing software. Can files from other packages be imported/exported? Quality of documentation Ease of learning. How good is the on-line help? Are tutorials available? Ease of use. Easy to use? Shortcuts for advanced users? Technical support. Is this available, and at what cost? Upgrade policy. Will future upgrades be available at a discount? Can files created in older versions be used? Speed. How long does it take to perform complex but frequent operations such as database queries? Cost. May involve cost of an individual package or a site licence

Evaluating software n Before selecting a particular package you could: n n n Read reviews of it in a computer magazine. Magazines commonly compare similar software packages on dozens of different criteria; Consult other users who have experience of the type of software you are thinking of purchasing; Perform benchmark tests (performance tests) to see how fast various packages perform a number of different tasks. Computer magazines often publish the results of benchmark tests.

Software Reliability n Batch systems are relatively easy to test. n n n More controlled environment, where data is entered as batch, processed and then output. Expected results easily compared with actual results Problems can be fixed and tests run again.

Software Reliability n More complex on-line systems with GUI interfaces are much more difficult to test: n n n No single, well-defined flow of events at user interface. It is often nearly impossible to restore a database to the condition it was in before a bug was detected. Continuous development techniques mean that new versions appear to quickly for the testing to keep pace. User find ways to use the new software in ways which were not anticipated by the designers. Performance tests are very difficult to set up for massive, on-line, multi-user systems.