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authorMattias Andrée <maandree@operamail.com>2015-07-13 07:50:43 +0200
committerMattias Andrée <maandree@operamail.com>2015-07-13 07:50:43 +0200
commit904c39340a67752aa771492a9cefa8aae50a0b80 (patch)
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parenttypo (diff)
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m + indices
Signed-off-by: Mattias Andrée <maandree@operamail.com>
Diffstat (limited to 'doc')
-rw-r--r--doc/info/mds.texinfo99
1 files changed, 93 insertions, 6 deletions
diff --git a/doc/info/mds.texinfo b/doc/info/mds.texinfo
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@@ -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