Should a web application have a notices/about page that details the components/libraries that we are using and there relevant licences?
Some Licences such as LGPL (Used by SevenZipSharp) have a combined works clause:
lgpl V3
- Combined Works. You may convey a Combined Work under terms of your choice that, taken together, effectively do not restrict modification
of the portions of the Library contained in the Combined Work and
reverse engineering for debugging such modifications, if you also do
each of the following:a) Give prominent notice with each copy of the Combined Work that the
Library is used in it and that the Library and its use are covered by
this License. b) Accompany the Combined Work with a copy of the GNU
GPL and this license document. c) For a Combined Work that displays
copyright notices during execution, include the copyright notice for
the Library among these notices, as well as a reference directing the
user to the copies of the GNU GPL and this license document. d) Do one
of the following: 0) Convey the Minimal Corresponding Source under the
terms of this License, and the Corresponding Application Code in a
form suitable for, and under terms that permit, the user to recombine
or relink the Application with a modified version of the Linked
Version to produce a modified Combined Work, in the manner specified
by section 6 of the GNU GPL for conveying Corresponding Source. 1) Use
a suitable shared library mechanism for linking with the Library. A
suitable mechanism is one that (a) uses at run time a copy of the
Library already present on the user’s computer system, and (b) will
operate properly with a modified version of the Library that is
interface-compatible with the Linked Version. e) Provide Installation
Information, but only if you would otherwise be required to provide
such information under section 6 of the GNU GPL, and only to the
extent that such information is necessary to install and execute a
modified version of the Combined Work produced by recombining or
relinking the Application with a modified version of the Linked
Version. (If you use option 4d0, the Installation Information must
accompany the Minimal Corresponding Source and Corresponding
Application Code. If you use option 4d1, you must provide the
Installation Information in the manner specified by section 6 of the
GNU GPL for conveying Corresponding Source.)
lgpl V2.1
You must give prominent notice with each copy of the work that the
Library is used in it and that the Library and its use are covered by
this License. You must supply a copy of this License. If the work
during execution displays copyright notices, you must include the
copyright notice for the Library among them, as well as a reference
directing the user to the copy of this License. Also, you must do one
of these things:a) Accompany the work with the complete corresponding machine-readable
source code for the Library including whatever changes were used in
the work (which must be distributed under Sections 1 and 2 above);
and, if the work is an executable linked with the Library, with the
complete machine-readable “work that uses the Library”, as object code
and/or source code, so that the user can modify the Library and then
relink to produce a modified executable containing the modified
Library. (It is understood that the user who changes the contents of
definitions files in the Library will not necessarily be able to
recompile the application to use the modified definitions.) b) Use a
suitable shared library mechanism for linking with the Library. A
suitable mechanism is one that (1) uses at run time a copy of the
library already present on the user’s computer system, rather than
copying library functions into the executable, and (2) will operate
properly with a modified version of the library, if the user installs
one, as long as the modified version is interface-compatible with the
version that the work was made with. c) Accompany the work with a
written offer, valid for at least three years, to give the same user
the materials specified in Subsection 6a, above, for a charge no more
than the cost of performing this distribution. d) If distribution of
the work is made by offering access to copy from a designated place,
offer equivalent access to copy the above specified materials from the
same place. e) Verify that the user has already received a copy of
these materials or that you have already sent this user a copy.
A number of other licences have similar clauses about displaying a notice in your application or combined works.
Does this mean that web applications need an about page detailing components used? I cant find any examples of websites doing this, although lots of sites will often be using OpenSource Libraries?
I guess the get out clause that websites/applications currently use is who would know if an OpenSource component was being used in a combined work/web application on the server side but that isn’t an excuse especially if the web app was ever audited.
Just because other does it wrong, doesn’t give you the right to do it wrong.
If the license for a library says that your application should include a page with the appropriate credits, then that is what you should do.
Edit:
(This is my interpretation of the license agreement, I may be wrong).
I believe there’s a (quite big) difference between a library and a web application. The license agreement posted above seems to be for other libraries, not for end-user webapplications. I believe that if you make your own library, from the SevenZipSharp library, the quote from the license agreement above applies – and forces you to distribute your library under LGPL as well. But if you use the SevenZipSharp library in an application that’s meant for the user and not for developers, the above quote from the license does not apply.