# HG changeset patch # User David Scott # Date 1271414672 -3600 # Node ID ad754527bddd1c97d28fbffb1c30f56e49178252 # Parent 36c5ecfdb70f3973b99d5d52ed89a828e16cd5a3 Add a basic skeleton of a deprecation policy for the XenAPI. There's lots of missing detail; feedback is essential! Signed-off-by: David Scott diff -r 36c5ecfdb70f -r ad754527bddd docs/evolution/Makefile --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/docs/evolution/Makefile Fri Apr 16 11:44:32 2010 +0100 @@ -0,0 +1,4 @@ +default: + pdflatex main.tex + pdflatex main.tex + diff -r 36c5ecfdb70f -r ad754527bddd docs/evolution/coversheet.tex --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/docs/evolution/coversheet.tex Fri Apr 16 11:44:32 2010 +0100 @@ -0,0 +1,42 @@ +% +% Copyright (c) 2009 Citrix Systems Inc. +% This file is covered by the version 1.2 of the GNU Free Documentation License (see fdl.tex) +% + +\pagestyle{empty} + +\doctitle{} \hfill \revstring{} + +\vspace{1cm} + +\begin{center} +%\resizebox{8cm}{!}{\includegraphics{\coversheetlogo}} + +\vspace{2cm} + +\begin{Huge} + \doctitle{} +\end{Huge} + +\vspace{1cm} +\begin{Large} +Version: \revstring{}\\ +Date: \datestring{} +\\ +\releasestatement{} + +\vspace{1cm} +\begin{tabular}{rl} +\docauthors{} +\end{tabular} +\end{Large} +\end{center} +\vspace{.5cm} + +\vfill + +\noindent +\legalnotice{} + +\newpage +\pagestyle{fancy} diff -r 36c5ecfdb70f -r ad754527bddd docs/evolution/fdl.tex --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/docs/evolution/fdl.tex Fri Apr 16 11:44:32 2010 +0100 @@ -0,0 +1,488 @@ +\chapter{GNU Free Documentation License} +%\label{label_fdl} + + \begin{center} + + Version 1.2, November 2002 + + + Copyright \copyright 2000,2001,2002 Free Software Foundation, Inc. + + \bigskip + + 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA + + \bigskip + + Everyone is permitted to copy and distribute verbatim copies + of this license document, but changing it is not allowed. +\end{center} + + +\begin{center} +{\bf\large Preamble} +\end{center} + +The purpose of this License is to make a manual, textbook, or other +functional and useful document "free" in the sense of freedom: to +assure everyone the effective freedom to copy and redistribute it, +with or without modifying it, either commercially or noncommercially. +Secondarily, this License preserves for the author and publisher a way +to get credit for their work, while not being considered responsible +for modifications made by others. + +This License is a kind of "copyleft", which means that derivative +works of the document must themselves be free in the same sense. It +complements the GNU General Public License, which is a copyleft +license designed for free software. + +We have designed this License in order to use it for manuals for free +software, because free software needs free documentation: a free +program should come with manuals providing the same freedoms that the +software does. But this License is not limited to software manuals; +it can be used for any textual work, regardless of subject matter or +whether it is published as a printed book. We recommend this License +principally for works whose purpose is instruction or reference. + + +\begin{center} +{\Large\bf 1. APPLICABILITY AND DEFINITIONS} +\addcontentsline{toc}{section}{1. APPLICABILITY AND DEFINITIONS} +\end{center} + +This License applies to any manual or other work, in any medium, that +contains a notice placed by the copyright holder saying it can be +distributed under the terms of this License. Such a notice grants a +world-wide, royalty-free license, unlimited in duration, to use that +work under the conditions stated herein. The \textbf{"Document"}, below, +refers to any such manual or work. Any member of the public is a +licensee, and is addressed as \textbf{"you"}. You accept the license if you +copy, modify or distribute the work in a way requiring permission +under copyright law. + +A \textbf{"Modified Version"} of the Document means any work containing the +Document or a portion of it, either copied verbatim, or with +modifications and/or translated into another language. + +A \textbf{"Secondary Section"} is a named appendix or a front-matter section of +the Document that deals exclusively with the relationship of the +publishers or authors of the Document to the Document's overall subject +(or to related matters) and contains nothing that could fall directly +within that overall subject. (Thus, if the Document is in part a +textbook of mathematics, a Secondary Section may not explain any +mathematics.) The relationship could be a matter of historical +connection with the subject or with related matters, or of legal, +commercial, philosophical, ethical or political position regarding +them. + +The \textbf{"Invariant Sections"} are certain Secondary Sections whose titles +are designated, as being those of Invariant Sections, in the notice +that says that the Document is released under this License. If a +section does not fit the above definition of Secondary then it is not +allowed to be designated as Invariant. The Document may contain zero +Invariant Sections. If the Document does not identify any Invariant +Sections then there are none. + +The \textbf{"Cover Texts"} are certain short passages of text that are listed, +as Front-Cover Texts or Back-Cover Texts, in the notice that says that +the Document is released under this License. A Front-Cover Text may +be at most 5 words, and a Back-Cover Text may be at most 25 words. + +A \textbf{"Transparent"} copy of the Document means a machine-readable copy, +represented in a format whose specification is available to the +general public, that is suitable for revising the document +straightforwardly with generic text editors or (for images composed of +pixels) generic paint programs or (for drawings) some widely available +drawing editor, and that is suitable for input to text formatters or +for automatic translation to a variety of formats suitable for input +to text formatters. A copy made in an otherwise Transparent file +format whose markup, or absence of markup, has been arranged to thwart +or discourage subsequent modification by readers is not Transparent. +An image format is not Transparent if used for any substantial amount +of text. A copy that is not "Transparent" is called \textbf{"Opaque"}. + +Examples of suitable formats for Transparent copies include plain +ASCII without markup, Texinfo input format, LaTeX input format, SGML +or XML using a publicly available DTD, and standard-conforming simple +HTML, PostScript or PDF designed for human modification. Examples of +transparent image formats include PNG, XCF and JPG. Opaque formats +include proprietary formats that can be read and edited only by +proprietary word processors, SGML or XML for which the DTD and/or +processing tools are not generally available, and the +machine-generated HTML, PostScript or PDF produced by some word +processors for output purposes only. + +The \textbf{"Title Page"} means, for a printed book, the title page itself, +plus such following pages as are needed to hold, legibly, the material +this License requires to appear in the title page. For works in +formats which do not have any title page as such, "Title Page" means +the text near the most prominent appearance of the work's title, +preceding the beginning of the body of the text. + +A section \textbf{"Entitled XYZ"} means a named subunit of the Document whose +title either is precisely XYZ or contains XYZ in parentheses following +text that translates XYZ in another language. (Here XYZ stands for a +specific section name mentioned below, such as \textbf{"Acknowledgements"}, +\textbf{"Dedications"}, \textbf{"Endorsements"}, or \textbf{"History"}.) +To \textbf{"Preserve the Title"} +of such a section when you modify the Document means that it remains a +section "Entitled XYZ" according to this definition. + +The Document may include Warranty Disclaimers next to the notice which +states that this License applies to the Document. These Warranty +Disclaimers are considered to be included by reference in this +License, but only as regards disclaiming warranties: any other +implication that these Warranty Disclaimers may have is void and has +no effect on the meaning of this License. + + +\begin{center} +{\Large\bf 2. VERBATIM COPYING} +\addcontentsline{toc}{section}{2. VERBATIM COPYING} +\end{center} + +You may copy and distribute the Document in any medium, either +commercially or noncommercially, provided that this License, the +copyright notices, and the license notice saying this License applies +to the Document are reproduced in all copies, and that you add no other +conditions whatsoever to those of this License. You may not use +technical measures to obstruct or control the reading or further +copying of the copies you make or distribute. However, you may accept +compensation in exchange for copies. If you distribute a large enough +number of copies you must also follow the conditions in section 3. + +You may also lend copies, under the same conditions stated above, and +you may publicly display copies. + + +\begin{center} +{\Large\bf 3. COPYING IN QUANTITY} +\addcontentsline{toc}{section}{3. COPYING IN QUANTITY} +\end{center} + + +If you publish printed copies (or copies in media that commonly have +printed covers) of the Document, numbering more than 100, and the +Document's license notice requires Cover Texts, you must enclose the +copies in covers that carry, clearly and legibly, all these Cover +Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on +the back cover. Both covers must also clearly and legibly identify +you as the publisher of these copies. The front cover must present +the full title with all words of the title equally prominent and +visible. You may add other material on the covers in addition. +Copying with changes limited to the covers, as long as they preserve +the title of the Document and satisfy these conditions, can be treated +as verbatim copying in other respects. + +If the required texts for either cover are too voluminous to fit +legibly, you should put the first ones listed (as many as fit +reasonably) on the actual cover, and continue the rest onto adjacent +pages. + +If you publish or distribute Opaque copies of the Document numbering +more than 100, you must either include a machine-readable Transparent +copy along with each Opaque copy, or state in or with each Opaque copy +a computer-network location from which the general network-using +public has access to download using public-standard network protocols +a complete Transparent copy of the Document, free of added material. +If you use the latter option, you must take reasonably prudent steps, +when you begin distribution of Opaque copies in quantity, to ensure +that this Transparent copy will remain thus accessible at the stated +location until at least one year after the last time you distribute an +Opaque copy (directly or through your agents or retailers) of that +edition to the public. + +It is requested, but not required, that you contact the authors of the +Document well before redistributing any large number of copies, to give +them a chance to provide you with an updated version of the Document. + + +\begin{center} +{\Large\bf 4. MODIFICATIONS} +\addcontentsline{toc}{section}{4. MODIFICATIONS} +\end{center} + +You may copy and distribute a Modified Version of the Document under +the conditions of sections 2 and 3 above, provided that you release +the Modified Version under precisely this License, with the Modified +Version filling the role of the Document, thus licensing distribution +and modification of the Modified Version to whoever possesses a copy +of it. In addition, you must do these things in the Modified Version: + +\begin{itemize} +\item[A.] + Use in the Title Page (and on the covers, if any) a title distinct + from that of the Document, and from those of previous versions + (which should, if there were any, be listed in the History section + of the Document). You may use the same title as a previous version + if the original publisher of that version gives permission. + +\item[B.] + List on the Title Page, as authors, one or more persons or entities + responsible for authorship of the modifications in the Modified + Version, together with at least five of the principal authors of the + Document (all of its principal authors, if it has fewer than five), + unless they release you from this requirement. + +\item[C.] + State on the Title page the name of the publisher of the + Modified Version, as the publisher. + +\item[D.] + Preserve all the copyright notices of the Document. + +\item[E.] + Add an appropriate copyright notice for your modifications + adjacent to the other copyright notices. + +\item[F.] + Include, immediately after the copyright notices, a license notice + giving the public permission to use the Modified Version under the + terms of this License, in the form shown in the Addendum below. + +\item[G.] + Preserve in that license notice the full lists of Invariant Sections + and required Cover Texts given in the Document's license notice. + +\item[H.] + Include an unaltered copy of this License. + +\item[I.] + Preserve the section Entitled "History", Preserve its Title, and add + to it an item stating at least the title, year, new authors, and + publisher of the Modified Version as given on the Title Page. If + there is no section Entitled "History" in the Document, create one + stating the title, year, authors, and publisher of the Document as + given on its Title Page, then add an item describing the Modified + Version as stated in the previous sentence. + +\item[J.] + Preserve the network location, if any, given in the Document for + public access to a Transparent copy of the Document, and likewise + the network locations given in the Document for previous versions + it was based on. These may be placed in the "History" section. + You may omit a network location for a work that was published at + least four years before the Document itself, or if the original + publisher of the version it refers to gives permission. + +\item[K.] + For any section Entitled "Acknowledgements" or "Dedications", + Preserve the Title of the section, and preserve in the section all + the substance and tone of each of the contributor acknowledgements + and/or dedications given therein. + +\item[L.] + Preserve all the Invariant Sections of the Document, + unaltered in their text and in their titles. Section numbers + or the equivalent are not considered part of the section titles. + +\item[M.] + Delete any section Entitled "Endorsements". Such a section + may not be included in the Modified Version. + +\item[N.] + Do not retitle any existing section to be Entitled "Endorsements" + or to conflict in title with any Invariant Section. + +\item[O.] + Preserve any Warranty Disclaimers. +\end{itemize} + +If the Modified Version includes new front-matter sections or +appendices that qualify as Secondary Sections and contain no material +copied from the Document, you may at your option designate some or all +of these sections as invariant. To do this, add their titles to the +list of Invariant Sections in the Modified Version's license notice. +These titles must be distinct from any other section titles. + +You may add a section Entitled "Endorsements", provided it contains +nothing but endorsements of your Modified Version by various +parties--for example, statements of peer review or that the text has +been approved by an organization as the authoritative definition of a +standard. + +You may add a passage of up to five words as a Front-Cover Text, and a +passage of up to 25 words as a Back-Cover Text, to the end of the list +of Cover Texts in the Modified Version. Only one passage of +Front-Cover Text and one of Back-Cover Text may be added by (or +through arrangements made by) any one entity. If the Document already +includes a cover text for the same cover, previously added by you or +by arrangement made by the same entity you are acting on behalf of, +you may not add another; but you may replace the old one, on explicit +permission from the previous publisher that added the old one. + +The author(s) and publisher(s) of the Document do not by this License +give permission to use their names for publicity for or to assert or +imply endorsement of any Modified Version. + + +\begin{center} +{\Large\bf 5. COMBINING DOCUMENTS} +\addcontentsline{toc}{section}{5. COMBINING DOCUMENTS} +\end{center} + + +You may combine the Document with other documents released under this +License, under the terms defined in section 4 above for modified +versions, provided that you include in the combination all of the +Invariant Sections of all of the original documents, unmodified, and +list them all as Invariant Sections of your combined work in its +license notice, and that you preserve all their Warranty Disclaimers. + +The combined work need only contain one copy of this License, and +multiple identical Invariant Sections may be replaced with a single +copy. If there are multiple Invariant Sections with the same name but +different contents, make the title of each such section unique by +adding at the end of it, in parentheses, the name of the original +author or publisher of that section if known, or else a unique number. +Make the same adjustment to the section titles in the list of +Invariant Sections in the license notice of the combined work. + +In the combination, you must combine any sections Entitled "History" +in the various original documents, forming one section Entitled +"History"; likewise combine any sections Entitled "Acknowledgements", +and any sections Entitled "Dedications". You must delete all sections +Entitled "Endorsements". + +\begin{center} +{\Large\bf 6. COLLECTIONS OF DOCUMENTS} +\addcontentsline{toc}{section}{6. COLLECTIONS OF DOCUMENTS} +\end{center} + +You may make a collection consisting of the Document and other documents +released under this License, and replace the individual copies of this +License in the various documents with a single copy that is included in +the collection, provided that you follow the rules of this License for +verbatim copying of each of the documents in all other respects. + +You may extract a single document from such a collection, and distribute +it individually under this License, provided you insert a copy of this +License into the extracted document, and follow this License in all +other respects regarding verbatim copying of that document. + + +\begin{center} +{\Large\bf 7. AGGREGATION WITH INDEPENDENT WORKS} +\addcontentsline{toc}{section}{7. AGGREGATION WITH INDEPENDENT WORKS} +\end{center} + + +A compilation of the Document or its derivatives with other separate +and independent documents or works, in or on a volume of a storage or +distribution medium, is called an "aggregate" if the copyright +resulting from the compilation is not used to limit the legal rights +of the compilation's users beyond what the individual works permit. +When the Document is included in an aggregate, this License does not +apply to the other works in the aggregate which are not themselves +derivative works of the Document. + +If the Cover Text requirement of section 3 is applicable to these +copies of the Document, then if the Document is less than one half of +the entire aggregate, the Document's Cover Texts may be placed on +covers that bracket the Document within the aggregate, or the +electronic equivalent of covers if the Document is in electronic form. +Otherwise they must appear on printed covers that bracket the whole +aggregate. + + +\begin{center} +{\Large\bf 8. TRANSLATION} +\addcontentsline{toc}{section}{8. TRANSLATION} +\end{center} + + +Translation is considered a kind of modification, so you may +distribute translations of the Document under the terms of section 4. +Replacing Invariant Sections with translations requires special +permission from their copyright holders, but you may include +translations of some or all Invariant Sections in addition to the +original versions of these Invariant Sections. You may include a +translation of this License, and all the license notices in the +Document, and any Warranty Disclaimers, provided that you also include +the original English version of this License and the original versions +of those notices and disclaimers. In case of a disagreement between +the translation and the original version of this License or a notice +or disclaimer, the original version will prevail. + +If a section in the Document is Entitled "Acknowledgements", +"Dedications", or "History", the requirement (section 4) to Preserve +its Title (section 1) will typically require changing the actual +title. + + +\begin{center} +{\Large\bf 9. TERMINATION} +\addcontentsline{toc}{section}{9. TERMINATION} +\end{center} + + +You may not copy, modify, sublicense, or distribute the Document except +as expressly provided for under this License. Any other attempt to +copy, modify, sublicense or distribute the Document is void, and will +automatically terminate your rights under this License. However, +parties who have received copies, or rights, from you under this +License will not have their licenses terminated so long as such +parties remain in full compliance. + + +\begin{center} +{\Large\bf 10. FUTURE REVISIONS OF THIS LICENSE} +\addcontentsline{toc}{section}{10. FUTURE REVISIONS OF THIS LICENSE} +\end{center} + + +The Free Software Foundation may publish new, revised versions +of the GNU Free Documentation License from time to time. Such new +versions will be similar in spirit to the present version, but may +differ in detail to address new problems or concerns. See +http://www.gnu.org/copyleft/. + +Each version of the License is given a distinguishing version number. +If the Document specifies that a particular numbered version of this +License "or any later version" applies to it, you have the option of +following the terms and conditions either of that specified version or +of any later version that has been published (not as a draft) by the +Free Software Foundation. If the Document does not specify a version +number of this License, you may choose any version ever published (not +as a draft) by the Free Software Foundation. + + +\begin{center} +{\Large\bf ADDENDUM: How to use this License for your documents} +\addcontentsline{toc}{section}{ADDENDUM: How to use this License for your documents} +\end{center} + +To use this License in a document you have written, include a copy of +the License in the document and put the following copyright and +license notices just after the title page: + +\bigskip +\begin{quote} + Copyright \copyright YEAR YOUR NAME. + Permission is granted to copy, distribute and/or modify this document + under the terms of the GNU Free Documentation License, Version 1.2 + or any later version published by the Free Software Foundation; + with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. + A copy of the license is included in the section entitled "GNU + Free Documentation License". +\end{quote} +\bigskip + +If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, +replace the "with...Texts." line with this: + +\bigskip +\begin{quote} + with the Invariant Sections being LIST THEIR TITLES, with the + Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST. +\end{quote} +\bigskip + +If you have Invariant Sections without Cover Texts, or some other +combination of the three, merge those two alternatives to suit the +situation. + +If your document contains nontrivial examples of program code, we +recommend releasing these examples in parallel under your choice of +free software license, such as the GNU General Public License, +to permit their use in free software. diff -r 36c5ecfdb70f -r ad754527bddd docs/evolution/globals.tex --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/docs/evolution/globals.tex Fri Apr 16 11:44:32 2010 +0100 @@ -0,0 +1,26 @@ +% + +\newcommand{\xapi}{\textsc{XAPI}} +\newcommand{\xen}{\textsc{Xen}} +%% Document title +\newcommand{\doctitle}{Evolving the XenAPI} + +%% Document date +\newcommand{\datestring}{5th April 2010} + +\newcommand{\releasestatement}{Comments are welcome!} + +%% Document revision +\newcommand{\revstring}{Document Revision 0.1} + +%% Document authors +\newcommand{\docauthors}{ +David Scott: & {\tt dave.scott@xxxxxxxxxxxxx}} +\newcommand{\legalnotice}{Copyright \copyright{} 2010 Citrix, Inc.\\ \\ +Permission is granted to copy, distribute and/or modify this document under +the terms of the GNU Free Documentation License, Version 1.2 or any later +version published by the Free Software Foundation; with no Invariant Sections, +no Front-Cover Texts and no Back-Cover Texts. A copy of the license is +included in the section entitled "GNU Free Documentation License". +} + diff -r 36c5ecfdb70f -r ad754527bddd docs/evolution/main.tex --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/docs/evolution/main.tex Fri Apr 16 11:44:32 2010 +0100 @@ -0,0 +1,70 @@ +% + +\documentclass{article} + +\usepackage{a4wide} +\usepackage{graphics} +\usepackage{longtable} +\usepackage{fancyhdr} +\usepackage{url} + +\newcommand{\eqdef}{\stackrel{def}{=}} + +\setlength\topskip{0cm} +\setlength\topmargin{0cm} +\setlength\oddsidemargin{0cm} +\setlength\evensidemargin{0cm} +%\setlength\parindent{0pt} + +\input{globals} + +\begin{document} + +% The coversheet itself +\include{coversheet} + +% ... and off we go! + +\section{Introduction} +All APIs evolve as bugs are fixed, new features added and features are removed -- the XenAPI is no exception. This document lists policies describing how the XenAPI evolves over time. + +The goals of XenAPI evolution are: +\begin{itemize} +\item to allow bugs to be fixed efficiently\footnote{Some would consider even a bugfix to be a semantic change which breaks backwards compatability -- what if someone is relying on the buggy behaviour?}; +\item to allow new, innovative features to be added easily; +\item to keep old, unmodified clients working as much as possible; and +\item where backwards-incompatable changes are to be made, publish this information early to enable affected parties to give timely feedback. +\end{itemize} + +\section{Background} +In this document, the term ``XenAPI'' refers to the XMLRPC-derived wire protocol used by xapi. The XenAPI has ``objects'' which each have ``fields'' and ``messages''. The XenAPI is described in detail elsewhere. + +\section{Deprecation policy v1} +\begin{enumerate} + +\item XenAPI ``fields'' and ``messages'' may be marked as +\begin{verbatim} +deprecated_since +\end{verbatim} +where \texttt{release} identifies a major release of the software. + +\item Every release must be accomponied by a {\em deprecation statement} which lists all fields and messages marked as deprecated in the release. Next to each deprecated item should be an explanation of how to modify a client to avoid using the deprecated field or message. + +\item The deprecation statement shall be prominently displayed in the XenAPI html documentation. + +\item Fields and messages marked as deprecated will continue to exist for at least one more major software release. + +\item Eventually the deprecated fields and messages will be deleted. +\end{enumerate} + +\subsection{Shortcomings of this policy} +\begin{itemize} +\item The current policy deals only with syntax (presence/absence of fields and messages) but not semantics. We still need a way to communicate semantic changes. +\item Some changes are issued quickly between major software releases (e.g.\ security hotfixes). We need a way to publish this information quickly. + +\item Perhaps we should guarantee fields and messages should live for some period of wallclock time rather than talk about major releases? +\end{itemize} + +\include{fdl} + +\end{document}