Free software concept
The peculiarity of software is that it is produced in one form – in the form of source code, but is distributed and used in another – in the form of a binary program, machine codes, by which it is impossible to unambiguously restore the original text. To modify a program, fix bugs, or even just find out exactly what a program does and how, you need to have its source code.
In a situation where software is an object of sale along with household items, it is automatically subject to the properties of material items that can be traded, exchanged, the right to own and use which should be protected by law. Gis courses Australia falls under the category of intellectual property: that is, the source code of the program is considered as a work, an object of copyright application.
The main criteria for free software are:
- The ability to use software for any purpose (“zero freedom”).
- An opportunity to study how the program works and adapt it for your own purposes (“first freedom”). The condition for this is the availability of the source code of the program.
- The ability to distribute copies of the program – to help a friend (“second freedom”).
- The ability to improve the software and publish your improved version in order to benefit the entire community (“third freedom”). The condition for this is the availability of the source code of the program.
Only a program that meets all the principles can be considered free, that is, guaranteed open and accessible. It should be emphasized that these principles only stipulate the availability of programs for general use, criticism and improvement, but do not in any way stipulate the monetary relations associated with the distribution of programs, and they do not imply free of charge either. In English-language texts, confusion often arises here, since the word “free” means not only “free”, but also “free” and is often used in relation to software that is distributed free of charge for use, but which at the same time is completely inaccessible for modification community, simply because its source code has not been published. Such free software is not free software at all. On the contrary, free software is quite possible to redistribute, while charging a fee, however, observing the criteria of freedom: each user is given the right to receive the source code of the programs, modify them and distribute them further. Any software whose users are not granted this right is proprietary.
Open access to the source code of programs is, in fact, a key feature of free software, therefore the term “open source software”, proposed a little later, seems to be even more apt to denote the phenomenon of free software than the term “free software” …
GNU Public License
Initially, free software was distributed without a license at all. However, the precedent that happened to one of the pioneers of free software, Richard Stallman, convinced him that documenting.
Richard Stallman developed the Emacs text editor based on the source code of James Gosling (who later became the author of the now famous Java product). Then Gosling freely distributed his source code to everyone interested. However, at some point, Gosling sold the rights to distribute Emacs to UniPress, and the company asked Stallman to stop distributing his version of Emacs, as they owned the rights. The incident prompted Stallman to rewrite the portions of the Emacs source that were now owned by UniPress, after which he developed his own software license.
The license formulated by Stallman was supposed to work in the same way as licenses for proprietary software: it is a standard agreement between the author of the program (copyright holder) and the user, in which the author stipulates the user’s rights in relation to the program. Unlike a commercial license, Stallman’s license stipulates the rights that a user obtains in relation to a free program: to receive source codes of programs, modify them, distribute modified and unmodified versions (see the above criteria for free software). In addition, this license stipulates a fundamental condition for Stallman to distribute free software: no user has the right, having made a modified version of free software, to distribute it without observing all the principles of free software. thereby limiting the rights of other users in relation to the program. In other words, you cannot make a modification of a free program nonfree.
The license containing this condition is called “copyleft”. Here is a play on words: in English copyright is called “copyright”, literally “copyright”, and “copyleft”, respectively, “copyright”. Indeed, the “copyleft” clause is directly opposite in meaning to copyright: copyright is intended to restrict the user from copying and distributing copies of a product, while “copyleft”, on the contrary, strictly prohibits restricting it. Subsequently, Stallman’s license was called the GNU Public License (GPL, GNU Public License).
History of open source GIS
The history of the development of open source GIS software begins in the late 70s, early 80s of the 20th century, and is associated with the creation in 1978 at the initiative of the US Fish and Wildlife Service of the open vector GIS MOSS (Map Overlay and Statistical System), the emergence which is one of the key events that determined the further direction of development of geographic information systems. MOSS was the first interactive mini-computer GIS that combined the ability to work with both raster and vector data. At one time, MOSS was used to solve various problems, both at the level of US ministries and in many state and local governments.
As well as open source software in general, albeit with some delay, open source GIS software is also undergoing a phase of intensive development, especially in the last 3-4 years. The FreeGIS.org list currently has 350 open source GIS software packages of various types, of which 56 have been updated over the past 2 years. Open GIS is created and maintained by various communities and organizations: commercial companies, enthusiastic groups, or research organizations.