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diff --git a/doc/info/mds.texinfo b/doc/info/mds.texinfo index 92f5192..2abf079 100644 --- a/doc/info/mds.texinfo +++ b/doc/info/mds.texinfo @@ -10117,6 +10117,8 @@ output servers, and even windowing servers. @node Server Architecture @section Server Architecture +@cpindex Server architecture +@cpindex Architecture, servers This chapter aims to enumerate advantages and disadvantages with micro-display servers, traditional monolithic display servers and @@ -10138,6 +10140,9 @@ any insight. @node The Microserver Architecture @subsection The Microserver Architecture +@cpindex Microserver architecture +@cpindex Architecture, microserver +@cpindex Microdisplay servers Description: The display server is implement with multiple binaries that speak with each other using a well defined protocol. @@ -10150,17 +10155,22 @@ Advantages: @itemize @bullet{} @item +@cpindex Code quality +@cpindex Quality of code Knowing the names of the servers you use and their purpose makes it very easy to find where you want to do patching in the source code. @item +@cpindex Code quality +@cpindex Quality of code Spaghetti code to a larger extent is virtually impossible; the microserver architecture guarantees a certain quality of the code architecture for the display server. @item +@cpindex Flexibility If the message passing used in the display server allows for message modification and retrieval ordering, extending, modifying and using the display @@ -10169,6 +10179,7 @@ and will often not require any modifications to the existing servers. @item +@cpindex Flexibility Replacing the display server is easier for a micro-display server than it is for a monolithic display server, because the servers could be @@ -10177,6 +10188,8 @@ under two distinct protocol during the transitional period. @item +@cpindex Code quality +@cpindex Quality of code Not as many subprotocols needs to be defined. For example, recording the output of the display does not require a special protocol, one only @@ -10184,10 +10197,12 @@ needs to write a server that listens on messages passed between servers. @item +@cpindex Stability If a server crashes it does not crash the entire session. Crashes can most often be repaired. @item +@cpindex Flexibility Because servers can easily be omitted and replaced when starting the display server, it becomes much easier to mount the display server on top of an @@ -10200,6 +10215,7 @@ written to running on top of Wayland; of course with some functionallity of @code{mds} missing. @item +@cpindex Security It is trivial to only have setuid on for the part of the display server where it is required. @end itemize @@ -10209,15 +10225,30 @@ part of the display server where it is required. @node The Monolithic Server Architecture @subsection The Monolithic Server Architecture +@cpindex Monolithic server architecture +@cpindex Architecture, monolithic server +@cpindex Monolithic display servers Description: The display server is implemented as one binary. @noindent -Implementations: X11, Mir, Wayland@footnote{Wayland -is not actually monolithic, it is just a protocol. -But Wayland is written with a monolithic mindset, -and it is preferred that the display server -implementation is monolithic.}, Surface Flinger, +@cpindex X11 +@cpindex X.org +@cpindex Mir +@cpindex Wayland +@cpindex Weston +@cpindex Surface Flinger +@cpindex Quartz Compositor +@cpindex Desktop Window Manager +@cpindex Mac OS X, Quartz Compositor +@cpindex OS X, Quartz Compositor +@cpindex Windows, Desktop Window Manager +Implementations: X11@footnote{X11 is a protocol, I beleave +all X11 servers are monolithic, atleast the major ones are}, +Mir, Wayland@footnote{Wayland is not actually monolithic, +it is just a protocol. But Wayland is written with a +monolithic mindset, and it is preferred that the display +server implementation is monolithic.}, Surface Flinger, Quartz Compositor, Desktop Window Manager. @noindent @@ -10225,6 +10256,10 @@ Advantages: @itemize @bullet{} @item +@cpindex Confidentiality +@cpindex Privacy +@cpindex Security +@cpindex Flexibility The monolithic architecture makes it trivial to isolate information for clients to achieve confidentiality. Prioritising confidentiality @@ -10232,11 +10267,13 @@ however leads to problems implementing features such as screenshooting and global hotkeys. @item +@cpindex Performance Monolithic server does not need to pass messages between modules, but can rather perform normal function calls and achieve greater performance. @item +@cpindex Size Monolithic display servers can have a smaller memory footprint than its full-fledged counterparts. @end itemize @@ -10246,6 +10283,15 @@ footprint than its full-fledged counterparts. @node The Hybrid Server Architecture @subsection The Hybrid Server Architecture +@cpindex Hybrid server architecture +@cpindex Architecture, hybrid server +@cpindex Hybrid display servers +@cpindex Milliserver architecture +@cpindex Architecture, milliserver +@cpindex Millidisplay servers +@cpindex Macroserver architecture +@cpindex Architecture, macroserver +@cpindex Macrodisplay servers Description: The display server is implmeneted with the microserver architecture except some components are built into the master server for @@ -10275,6 +10321,10 @@ Can achieve most of the microserver architecture's advantages, but not always to the same extent. @item +@cpindex Confidentiality +@cpindex Privacy +@cpindex Security +@cpindex Flexibility By integrating some servers into the master server, the hybrid architecture can isolate information for clients to achieve confidentiality. Prioritising @@ -10282,6 +10332,7 @@ confidentiality however leads to problems implementing features such as screenshooting and global hotkeys. @item +@cpindex Performance Large and high frequency messages does not need to be passed around to other servers if they are integrated into the master server. This lets hybrid display server @@ -10299,6 +10350,12 @@ and an implementation thereof. @node The Megalithic Server Architecture @subsection The Megalithic Server Architecture +@cpindex Megalithic server architecture +@cpindex Architecture, megalithic server +@cpindex Megalithic display servers +@cpindex Megaserver architecture +@cpindex Architecture, megaserver +@cpindex Megadisplay servers Description: A monolithic display server where applications are loaded or compiled into the display server itself. @@ -10314,6 +10371,7 @@ Advantages: @itemize @bullet{} @item +@cpindex Performance No interprocess communication is required, apart from letting the display server know to load modules if it does not compile in its programs. This lets megalithic @@ -10326,25 +10384,34 @@ Disadvantages: @itemize @bullet{} @item +@cpindex Code quality +@cpindex Quality of code Imposes restrictions on which languages applications can use. @item +@cpindex Flexibility Imposes restrictions on how applications can behave. @item +@cpindex Flexibility +@cpindex Code quality +@cpindex Quality of code Cannot be networked without exposing an alternative display server protocol. @item +@cpindex Stability The display becomes more crash prune; if an application crashes it is likely to crash the entire display. @item +@cpindex Security Applications will run with the same privileges as the display server, which is root on most operating systems. @end itemize @noindent +@cpindex Gaming Megalithic display servers could be interesting for high performing gaming consoles. @@ -10353,6 +10420,9 @@ performing gaming consoles. @node The Modular Server Architecture @subsection The Modular Server Architecture +@cpindex Modular server architecture +@cpindex Architecture, modular server +@cpindex Modular display servers Description: A monolithic display server where server-like programs can be loaded as modules into the display server but applicates are connected with interprocess communication. @@ -10367,6 +10437,7 @@ Advantages: @itemize @bullet{} @item +@cpindex Flexibility Can achieve that flexibility of micro-display servers, but not when networked, with the same memory footprint as monolithic display servers. @@ -10375,6 +10446,7 @@ as monolithic display servers. Has the same advantages as monolithic kernels. @item +@cpindex Performance Applications that require absolute performance can be loaded as modules and achieve the same performance as megalithic kernels, however with the same caveats. @@ -10391,6 +10463,9 @@ server display. @node The Modular Microserver Architecture @subsection The Modular Microserver Architecture +@cpindex Modular microserver architecture +@cpindex Architecture, modular microserver +@cpindex Modular microdisplay servers Description: A modular display server with a module that enables clients to act as modules that communicates via interprocess communication rather than being loaded @@ -10425,6 +10500,9 @@ transformed version. @node The Exoserver Architecture @subsection The Exoserver Architecture +@cpindex Exoserver architecture +@cpindex Architecture, exoserver +@cpindex Exodisplay servers Description: An exo-display server is a tiny display server that attempts to let applications access the underlaying system directly and implements basic @@ -10439,10 +10517,12 @@ Advantages: @itemize @bullet{} @item +@cpindex Performance Can achieve the same performance as megalithic display servers. @item +@cpindex Stability Can achieve the same robustness as micro-display servers. @end itemize @@ -10452,6 +10532,9 @@ Disadvantages: @itemize @bullet{} @item +@cpindex Flexibility +@cpindex Code quality +@cpindex Quality of code Cannot be networked without exposing an alternative display server protocol. @end itemize @@ -10467,7 +10550,7 @@ performing gaming consoles. X.org is been critiqued for several shortcoming, some of which have caused people to start on new display -servers replace X.org. This chapter will list some +servers to replace X.org. This chapter will list some issues and discuss how they can be avoided in mds. @menu @@ -10587,6 +10670,7 @@ in the server. @node Why Not Wayland @section Why Not Wayland +@cpindex Wayland Development of @command{mds} started out of concern that Wayland would not meet our needs, and the knowledge that X does not. We are now @@ -10595,6 +10679,7 @@ less than X.@footnote{Not even counting that the documentation for Wayland is way more lacking that X's documentation.} +@cpindex Flexibility Wayland only has protocols for drawing onto a buffer and input devices, and some very limited output protocols. Wayland is inherently inflexible. @@ -10628,11 +10713,13 @@ communicate with it. @node Why Not Mir @section Why Not Mir +@cpindex Mir The major problem with Mir, and why we need @command{mds} instead, is that contributions to Mir are subject Canonical's contributions-limiting agreement (CLA). +@cpindex Flexibility Mir, like Wayland, is very limited. Mir is however easier to extend. Ignoring the CLA, Mir is better Wayland, but for similar reasons it is still not |