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@ -416,8 +416,8 @@ key "nethack:website"
. .
The games often took place in a textual world, leaving the task of picturing The games often took place in a textual world, leaving the task of picturing
the world up to the player. the world up to the player.
Multi-player games were not as common as they are today, whereas most games Multiplayer games were not as common as they are today, whereas most games
today are expected to have a multi-player mode, most early games did not. today are expected to have a multiplayer mode, most early games did not.
\end_layout \end_layout
\begin_layout Standard \begin_layout Standard
@ -453,8 +453,8 @@ key "esa:website,thenumbers:website"
\begin_layout Standard \begin_layout Standard
Due to the increasing importance of computer gaming, more focus should be Due to the increasing importance of computer gaming, more focus should be
spent on improving the quality of the gaming service. spent on improving the quality of the gaming service.
As more and more computer games are gaining multi-player capabilities, As more and more computer games are gaining multiplayer capabilities, the
the demands for multiplayer networking software rises. demands for multiplayer networking software rises.
This thesis is about techniques for improving the quality of this networking This thesis is about techniques for improving the quality of this networking
software. software.
\end_layout \end_layout
@ -738,7 +738,7 @@ the nine nines
\begin_inset Formula $99.999999999\%$ \begin_inset Formula $99.999999999\%$
\end_inset \end_inset
of availability, or rougly of availability, or roughly
\begin_inset Formula $15ms$ \begin_inset Formula $15ms$
\end_inset \end_inset
@ -757,11 +757,11 @@ Citation needed
industry would not have been accepted in the telecoms industry. industry would not have been accepted in the telecoms industry.
This level of instability should not be accepted in the game server industry This level of instability should not be accepted in the game server industry
either. either.
An unavailabvle phone system could potentially have life threatening consequenc An unavailable phone system could potentially have life threatening consequence
es, leaving the public unable to contant emergency services. s, leaving the public unable to contact emergency services.
The same can not be said about an unavailable game server. The same can not be said about an unavailable game server.
The statement that game servers are less important than phone systems is The statement that game servers are less important than phone systems is
not a reason not to draw wisdom from what the telecoms have already learnt. not a reason not to draw wisdom from what the telecoms have already learned.
\end_layout \end_layout
\begin_layout Standard \begin_layout Standard
@ -1271,9 +1271,8 @@ textbf{TCP}}{Transmission Control Protocol, a streaming network protocol}
\begin_layout Standard \begin_layout Standard
The UDP protocol is not supported for communication between client and server. The UDP protocol is not supported for communication between client and server.
The TCP protocol was chosen in favour of UDP, due to the fact that the The TCP protocol was chosen in favor of UDP, due to the fact that the implement
implementation process using TCP was faster than if UDP would have been ation process using TCP was faster than if UDP would have been used.
used.
UDP is generally considered to be faster than TCP for the transfer of game UDP is generally considered to be faster than TCP for the transfer of game
(and other) related data, this is discussed in more depth in (and other) related data, this is discussed in more depth in
\begin_inset CommandInset ref \begin_inset CommandInset ref
@ -1333,7 +1332,7 @@ key "Farber:2002:NGT:566500.566508"
\emph on \emph on
Counter Strike Counter Strike
\emph default \emph default
or massively multiplayer online role playing games (MMORPG:s), for example or massively multiplayer online role playing games (MMORPGs), for example
\emph on \emph on
World of Warcraft World of Warcraft
@ -1402,8 +1401,8 @@ The first prototype of the GGS consisted of simple modules, however, due
Once the basic structure of the GGS had been established, the first prototype Once the basic structure of the GGS had been established, the first prototype
was removed, remaining was the structure of the modules and the internal was removed, remaining was the structure of the modules and the internal
flow of the application. flow of the application.
This could be seen as an interative workflow, with the first prototype This could be seen as an iterative workflow, with the first prototype being
being the first iteration. the first iteration.
The second iteration later became the final result of the GGS. The second iteration later became the final result of the GGS.
\end_layout \end_layout
@ -1421,7 +1420,7 @@ The layout of the GGS is both layered and modular.
\begin_layout Standard \begin_layout Standard
An informal specification and list of requirements of the system was outlined An informal specification and list of requirements of the system was outlined
early on in the project. early on in the project.
Usaility goals for developers were set. Usability goals for developers were set.
During the project several demo applications were constructed, by constructing During the project several demo applications were constructed, by constructing
these applications, the usability goals were enforced. these applications, the usability goals were enforced.
\end_layout \end_layout
@ -2037,7 +2036,7 @@ INDSTATE
\end_inset \end_inset
alert the coordinator, de-registering the players alert the coordinator, unregistering the players
\end_layout \end_layout
\begin_layout Plain Layout \begin_layout Plain Layout
@ -2112,7 +2111,7 @@ In a first person shooter game, the speed of delivery of messages is essential.
Failure to deliver messages in time results in choppy gameplay for the Failure to deliver messages in time results in choppy gameplay for the
players. players.
In strategy games, the reliability of delivery may be more important than In strategy games, the reliability of delivery may be more important than
the speed, since the game is not perceieved as choppy even if the messages the speed, since the game is not perceived as choppy even if the messages
are delayed. are delayed.
\end_layout \end_layout
@ -2142,7 +2141,7 @@ status open
Tue apr 26, 9:15. Tue apr 26, 9:15.
Continue from here on. Continue from here on.
Discuss which results we may expect in a fully fledged GGS system. Discuss which results we may expect in a fully fledged GGS system.
What impedes the speeds, what raises the CPU load (and therefore the temperetur What impedes the speeds, what raises the CPU load (and therefore the temperatur
es & power consumption). es & power consumption).
What factors are there in the network saturation problem? What factors are there in the network saturation problem?
\end_layout \end_layout
@ -2387,8 +2386,7 @@ name "sec:Generic"
\begin_layout Standard \begin_layout Standard
The GGS is a game server. The GGS is a game server.
It was made with a desire to be suitable for any kind of game. It was made with a desire to be suitable for any kind of game.
Any game with a client-server behaviour should be perfectly suited for Any game with a client-server behavior should be perfectly suited for GGS.
GGS.
A game should not only be able to vary in terms of genre, graphics, gameplay A game should not only be able to vary in terms of genre, graphics, gameplay
etc, but also in the way the game is implemented. etc, but also in the way the game is implemented.
Such as different programming languages. Such as different programming languages.
@ -2459,7 +2457,7 @@ In order to make the GGS prototype fault tolerant the programming language
\begin_layout Standard \begin_layout Standard
The need for fault tolerance in game servers is not as obvious as it may The need for fault tolerance in game servers is not as obvious as it may
be for other typ of servers. be for other type of servers.
In general all servers strive to be fault tolerant as fault tolerance means In general all servers strive to be fault tolerant as fault tolerance means
more uptime and a safer system. more uptime and a safer system.
This applies to game servers as well, in brief good fault tolerance is This applies to game servers as well, in brief good fault tolerance is
@ -3110,7 +3108,7 @@ end{centering}
status open status open
\begin_layout Plain Layout \begin_layout Plain Layout
Add clients on each side, and replace the cloud with phole-landlines being Add clients on each side, and replace the cloud with pole-landlines being
cut by a pair of scissors cut by a pair of scissors
\end_layout \end_layout
@ -3196,11 +3194,11 @@ name "sec:Game-Development-Language"
There is only a very limited number of game developers who would like to There is only a very limited number of game developers who would like to
write their games in Erlang, therefore we had to come up with something write their games in Erlang, therefore we had to come up with something
to resolve this problem. to resolve this problem.
The main idea was to offer a replacable module which would introduce a The main idea was to offer a replaceable module which would introduce a
interface to different virtual machines which would run the game code. interface to different virtual machines which would run the game code.
This way a game developer can write the game in his favourite language This way a game developer can write the game in his favorite language while
while the server part still is written in Erlang and can benefit from all the server part still is written in Erlang and can benefit from all of
of its advantages. its advantages.
\end_layout \end_layout
\begin_layout Subsection \begin_layout Subsection
@ -3423,7 +3421,7 @@ The real time game chosen for testing the GGS is
Pong Pong
\emph default \emph default
, a game in which two players play a game involving a all and two paddles. , a game in which two players play a game involving a all and two paddles.
The goal for each player is to shoot eside the othre player's paddle while The goal for each player is to shoot beside the other players paddle while
not allowing the ball to pass by her own paddle. not allowing the ball to pass by her own paddle.
The game requires real time updates and is quite demanding when played The game requires real time updates and is quite demanding when played
in several instances concurrently. in several instances concurrently.
@ -3516,7 +3514,7 @@ Overview of the prototype
\begin_layout Standard \begin_layout Standard
The prototype of the GGS was developed using the Erlang language. The prototype of the GGS was developed using the Erlang language.
The functional and concurrent style of Erlang facilitates devlopment of The functional and concurrent style of Erlang facilitates development of
software based on a real-world model software based on a real-world model
\begin_inset CommandInset citation \begin_inset CommandInset citation
LatexCommand citep LatexCommand citep
@ -3543,7 +3541,7 @@ Light Weight Processes; LWP
much like the threads in an operating system. much like the threads in an operating system.
Threads in a Linux system, for example, are treated much like operating Threads in a Linux system, for example, are treated much like operating
system processes in different systems. system processes in different systems.
Due to the size of datastructures related to each process, swapping one Due to the size of data structures related to each process, swapping one
process for another (known as process for another (known as
\emph on \emph on
context switching context switching
@ -3607,7 +3605,7 @@ Erlang allows the GGS to create several process for each player connecting,
these processes can handle a multitude of different tasks, parsing data these processes can handle a multitude of different tasks, parsing data
for example. for example.
Since each task is handled by a different process, the tasks are clearly Since each task is handled by a different process, the tasks are clearly
separated and the failiure of one is easily recovered without affecting separated and the failure of one is easily recovered without affecting
the others. the others.
\end_layout \end_layout
@ -3721,9 +3719,9 @@ reference "fig:The-layout-of"
the entire GGS system is represented graphically. the entire GGS system is represented graphically.
The circles marked with 'C' topmost in the picture represent game clients. The circles marked with 'C' topmost in the picture represent game clients.
These circles represent processes running on gamers' computers, and not These circles represent processes running on gamers computers, and not
on the GGS machine. on the GGS machine.
If a game of chess is to be played on the server, the clients on the gamers' If a game of chess is to be played on the server, the clients on the gamers
machines will be chess game clients. machines will be chess game clients.
Clients connect through a network, pictured as a cloud, to the dispatcher Clients connect through a network, pictured as a cloud, to the dispatcher
process in the GGS. process in the GGS.
@ -3753,7 +3751,7 @@ name "sec:The-usage-of-erlang"
\begin_layout Standard \begin_layout Standard
Erlang was designed by Ericsson, beginning in 1986, for the purpose of creating Erlang was designed by Ericsson, beginning in 1986, for the purpose of creating
concurrent applications and improving telecom software. concurrent applications and improving telecom software.
Features essential for the telecom instustry to achieve high availability Features essential for the telecom industry to achieve high availability
in telecom switches were added to the language. in telecom switches were added to the language.
\begin_inset ERT \begin_inset ERT
status open status open
@ -3774,7 +3772,7 @@ textbf{Mutex}}{A construct for achieving mutial exclusion, used to avoid
\end_layout \end_layout
\begin_layout Standard \begin_layout Standard
Erlang uses message passing in favour of shared memory, mutextes and locks, Erlang uses message passing in favor of shared memory, mutexes and locks,
something which at the time was controversial among fellow developers something which at the time was controversial among fellow developers
\begin_inset CommandInset citation \begin_inset CommandInset citation
LatexCommand citet LatexCommand citet
@ -3790,7 +3788,7 @@ key "Armstrong:2010:ERL:1810891.1810910"
\end_layout \end_layout
\begin_layout Standard \begin_layout Standard
In using message passing in favour of the methods commonly used at the time, In using message passing in favor of the methods commonly used at the time,
the issues commonly associated with shared memory and locking were avoided. the issues commonly associated with shared memory and locking were avoided.
In Erlang, everything is a process, and everything operates in its own In Erlang, everything is a process, and everything operates in its own
memory space. memory space.
@ -3824,8 +3822,8 @@ key "Armstrong03"
\end_layout \end_layout
\begin_layout Standard \begin_layout Standard
The strong isolation of Erlang processes make them ideal for multicore and The strong isolation of Erlang processes make them ideal for multi-core
distributed systems. and distributed systems.
Distribution of software is included as a fundamental part in the Erlang Distribution of software is included as a fundamental part in the Erlang
language. language.
The 'physical' location of a process, e.g. The 'physical' location of a process, e.g.
@ -3840,7 +3838,7 @@ The distributed nature of Erlang is something the GGS makes use of when
scaling across several computers in order to achieve higher performance. scaling across several computers in order to achieve higher performance.
The distribution is also important in creating redundancy. The distribution is also important in creating redundancy.
Erlang promotes a non-defensive programming style in which processes are Erlang promotes a non-defensive programming style in which processes are
allowed to crash and be restarted in favour of having the processes recover allowed to crash and be restarted in favor of having the processes recover
from errors. from errors.
The distributed nature of Erlang means supervisor processes (discussed The distributed nature of Erlang means supervisor processes (discussed
in section in section
@ -3948,16 +3946,16 @@ OTP
The OTP (Open Telecom Platform) is a set of standard libraries and design The OTP (Open Telecom Platform) is a set of standard libraries and design
patterns, called patterns, called
\emph on \emph on
behaviours behaviors
\emph default \emph default
, which are used when developing Erlang systems. , which are used when developing Erlang systems.
\end_layout \end_layout
\begin_layout Standard \begin_layout Standard
The GGS makes heavy use of the behaviours supplied in the OTP. The GGS makes heavy use of the behaviors supplied in the OTP.
The behaviours impose a programming style suitable for distributed and The behaviors impose a programming style suitable for distributed and concurren
concurrent applications, perfectly suitable for the GGS. t applications, perfectly suitable for the GGS.
In particular, the GGS uses the following behaviours: In particular, the GGS uses the following behaviors:
\end_layout \end_layout
\begin_layout Itemize \begin_layout Itemize
@ -3965,7 +3963,7 @@ The
\emph on \emph on
supervisor supervisor
\emph default \emph default
behaviour, which is used when creating a supervisor. behavior, which is used when creating a supervisor.
Supervisors are used when monitoring processes in the Erlang system. Supervisors are used when monitoring processes in the Erlang system.
When a process exits wrongfully, the supervisor monitoring the process When a process exits wrongfully, the supervisor monitoring the process
in question decides which action to take. in question decides which action to take.
@ -3985,8 +3983,8 @@ The
\emph on \emph on
gen_tcp gen_tcp
\emph default \emph default
behaviour, which is used to work with TCP sockets for network communication. behavior, which is used to work with TCP sockets for network communication.
Using the gen_tcp behaviour, network messages are converted to internal Using the gen_tcp behavior, network messages are converted to internal
Erlang messages and passed to a protocol parser, where the messages are Erlang messages and passed to a protocol parser, where the messages are
processed further. processed further.
\end_layout \end_layout
@ -3996,14 +3994,14 @@ The
\emph on \emph on
gen_server gen_server
\emph default \emph default
behaviour, which is used when constructing OTP servers in Erlang. behavior, which is used when constructing OTP servers in Erlang.
Using this behaviour, a state can easily be kept in a server process, greatly Using this behavior, a state can easily be kept in a server process, greatly
increasing the usefulness of the server process. increasing the usefulness of the server process.
There are many gen_servers in the GGS, it is the most widely used behaviour There are many gen_servers in the GGS, it is the most widely used behavior
in the project. in the project.
In addition to intruducing a state to the server, the gen_server behaviour In addition to introducing a state to the server, the gen_server behavior
also imposes patterns for synchronous and asynchronous communication between also imposes patterns for synchronous and asynchronous communication between
other gen_servers and other OTP behaviours. other gen_servers and other OTP behaviors.
\end_layout \end_layout
\begin_layout Itemize \begin_layout Itemize
@ -4011,14 +4009,14 @@ The
\emph on \emph on
gen_fsm gen_fsm
\emph default \emph default
behaviour is used in the protocol parser module in the GGS. behavior is used in the protocol parser module in the GGS.
Using the gen_fsm behaviour, finite state machines are easily developed. Using the gen_fsm behavior, finite state machines are easily developed.
Protocol parsers are an ideal example of where to use finite state machines, Protocol parsers are an ideal example of where to use finite state machines,
which are widely used for parsing strings of text. which are widely used for parsing strings of text.
\end_layout \end_layout
\begin_layout Standard \begin_layout Standard
In addition to supplying behaviours, the OTP also has a style for packaging In addition to supplying behaviors, the OTP also has a style for packaging
and running Erlang applications. and running Erlang applications.
By packaging the GGS as an By packaging the GGS as an
\emph on \emph on
@ -4214,7 +4212,7 @@ tt [1,2,3]}
\series bold \series bold
Strings Strings
\series default \series default
doubly qouted lists of characters, for example doubly quoted lists of characters, for example
\begin_inset ERT \begin_inset ERT
status open status open
@ -4236,7 +4234,7 @@ tt "Hello world"}
Records Records
\series default \series default
are erlang tuples coupled with a tag for each tuple element. are erlang tuples coupled with a tag for each tuple element.
This allows refering to elements by name instead of by position. This allows referring to elements by name instead of by position.
An example of a record looks like this: An example of a record looks like this:
\begin_inset ERT \begin_inset ERT
status open status open
@ -4298,8 +4296,8 @@ localstorage
by a call for the world object. by a call for the world object.
Interaction with the players is done the same way using the player object Interaction with the players is done the same way using the player object
instead. instead.
The localstorage is a convenient way to store globals and other data seperated The localstorage is a convenient way to store global data and other data
from the game state. separated from the game state.
In section In section
\begin_inset CommandInset ref \begin_inset CommandInset ref
LatexCommand ref LatexCommand ref
@ -4307,7 +4305,7 @@ reference "sub:Exposing-Erlang-functionality"
\end_inset \end_inset
a concrete example of the implementation of the localStorage and world a concrete example of the implementation of the localstorage and world
objects is given. objects is given.
\begin_inset Note Note \begin_inset Note Note
status open status open
@ -4351,7 +4349,7 @@ name "sub:Exposing-Erlang-functionality"
\end_layout \end_layout
\begin_layout Standard \begin_layout Standard
This section contains a concrete example of how the localStorage and world This section contains a concrete example of how the localstorage and world
objects are exposed to a GDL VM. objects are exposed to a GDL VM.
The example comes from the GGS prototype, which uses JavaScript powered The example comes from the GGS prototype, which uses JavaScript powered
by Google V8 as its GDL VM. by Google V8 as its GDL VM.
@ -4428,10 +4426,10 @@ age must be connected to the GGS object, this can be seen in line 5.
\end_layout \end_layout
\begin_layout Standard \begin_layout Standard
Both the GGS and localStorage objects are dummy objects, which provide no Both the GGS and localstorage objects are dummy objects, which provide no
functionality, these two objects are simply placed in the GDL for the purpose functionality, these two objects are simply placed in the GDL for the purpose
clearing up the code. clearing up the code.
In order to perform an action using the GGS and localStorage objects, the In order to perform an action using the GGS and localstorage objects, the
\begin_inset ERT \begin_inset ERT
status open status open
@ -4847,7 +4845,7 @@ TODO: Go in to more detail about how the world, player and localstorage
status open status open
\begin_layout Plain Layout \begin_layout Plain Layout
My idea here is that we describe the erlang-js (which failed, but nontheless), My idea here is that we describe the erlang-js (which failed, but nonetheless),
v8, UUID and other external communication. v8, UUID and other external communication.
We shouldn't describe sockets here though.. We shouldn't describe sockets here though..
or.. or..
@ -4863,7 +4861,7 @@ external
\begin_inset Quotes erd \begin_inset Quotes erd
\end_inset \end_inset
to thre GDL. to three GDL.
Discuss the GGS world object (there is a reference to this secxtion for Discuss the GGS world object (there is a reference to this secxtion for
that purpose) that purpose)
\end_layout \end_layout
@ -4911,7 +4909,7 @@ target "http://www.objectmentor.com/resources/articles/srp.pdf"
\begin_layout Standard \begin_layout Standard
The responsibility and concern of each module comes from the responsibility The responsibility and concern of each module comes from the responsibility
and concern of the real-world entity the model represents. and concern of the real-world entity the model represents.
The modelling of the GGS after a real world system was discussed in chapter The modeling of the GGS after a real world system was discussed in chapter
\begin_inset CommandInset ref \begin_inset CommandInset ref
LatexCommand vref LatexCommand vref
@ -4998,8 +4996,8 @@ Is this the proper way to day the dispatcher greets connecting players?
The dispatcher is the module which handles the interfacing to the operating The dispatcher is the module which handles the interfacing to the operating
system when working with sockets. system when working with sockets.
Operating system limits concering the number of open files, or number of Operating system limits concerning the number of open files, or number
open sockets are handled here. of open sockets are handled here.
The operating system limits can impose problems on the GGS, this is discussed The operating system limits can impose problems on the GGS, this is discussed
more in detail in chapter more in detail in chapter
\begin_inset CommandInset ref \begin_inset CommandInset ref
@ -5080,7 +5078,7 @@ reference "sub:The-protocol-parser"
\end_inset \end_inset
. .
Raw communication, witout passing the data through a protocol parser is Raw communication, without passing the data through a protocol parser is
in theory possible, but is not useful. in theory possible, but is not useful.
\end_layout \end_layout
@ -5118,7 +5116,7 @@ The coordinator spawns a new player process, with the same socket reference
\begin_layout Enumerate \begin_layout Enumerate
The player process resumes operation, immediately starting a new protocol The player process resumes operation, immediately starting a new protocol
parser process, and begind receiving and sending network messaged again. parser process, and begins to receive and send network messages again.
\end_layout \end_layout
\begin_layout Standard \begin_layout Standard
@ -5165,7 +5163,7 @@ name "sub:The-protocol-parser"
\end_layout \end_layout
\begin_layout Standard \begin_layout Standard
The protocol parser is an easily interchangable module in the GGS, handling The protocol parser is an easily interchangeable module in the GGS, handling
the client-to-server, and server-to-client protocol parsing. the client-to-server, and server-to-client protocol parsing.
In the GGS prototype, there is only one protocol supported, namely the In the GGS prototype, there is only one protocol supported, namely the
@ -5174,7 +5172,7 @@ GGS Protocol
\emph default \emph default
. .
The role of the protocol parser is to translate the meaning of packets The role of the protocol parser is to translate the meaning of packets
sent using the prototocol in use to internal messages of the GGS system. sent using the protocol in use to internal messages of the GGS system.
The GGS protocol, discussed below is used as a sample protocol in order The GGS protocol, discussed below is used as a sample protocol in order
to explain how protocol parsers can be built for the GGS. to explain how protocol parsers can be built for the GGS.
\end_layout \end_layout
@ -5191,7 +5189,7 @@ name "sub:The-structure-of"
\end_layout \end_layout
\begin_layout Standard \begin_layout Standard
The GGS protocol is modelled after the HTTP protocol. The GGS protocol is modeled after the HTTP protocol.
The main reason for this is the familiarity many developers already have The main reason for this is the familiarity many developers already have
with HTTP due to its presence in internet software. with HTTP due to its presence in internet software.
Each GGS protocol packet contains a headers section. Each GGS protocol packet contains a headers section.
@ -5240,10 +5238,10 @@ Line 4 specifies the content length of the payload following immediately
\begin_layout Standard \begin_layout Standard
The parser of the GGS protocol implemented in the GGS prototype is designed The parser of the GGS protocol implemented in the GGS prototype is designed
as a finite state machine using the gen_fsm behaviour. as a finite state machine using the gen_fsm behavior.
When a full message has been parsed by the parser, the message is converted When a full message has been parsed by the parser, the message is converted
into the internal structure of the GGS messages, and sent in to the system into the internal structure of the GGS messages, and sent in to the system
from the protocol paser using message passing. from the protocol parser using message passing.
\end_layout \end_layout
\begin_layout Standard \begin_layout Standard
@ -5559,11 +5557,11 @@ The game VM contains the state of the VM and a table token associated with
\begin_layout Standard \begin_layout Standard
The VM itself makes it possible for the game developer to program in the The VM itself makes it possible for the game developer to program in the
prograimming language covered by the VM. programming language covered by the VM.
In future releases, more game VM:s will be added to support more programming In future releases, more game VM:s will be added to support more programming
languages. languages.
Because the game VM keeps track of the correct table, the game developer Because the game VM keeps track of the correct table, the game developer
doesn't need to take this into consideration when programming a game. does not need to take this into consideration when programming a game.
If a method within the game sends data to a player, it will be delivered If a method within the game sends data to a player, it will be delivered
to the player in the correct running game. to the player in the correct running game.
The same game token is used to store the game state in the database. The same game token is used to store the game state in the database.
@ -5635,7 +5633,7 @@ key "667766"
\begin_layout Standard \begin_layout Standard
The features of Mnesia originally intended for telecoms prove very useful The features of Mnesia originally intended for telecoms prove very useful
for the purposes of the GGS as well. for the purposes of the GGS as well.
The fault tolerance and speed of Mnesia are very valueable tools, the fast The fault tolerance and speed of Mnesia are very valuable tools, the fast
key/value lookups permit many lookups per second to the database. key/value lookups permit many lookups per second to the database.
\end_layout \end_layout
@ -5674,8 +5672,8 @@ Each game is uniquely identified by a table token and the data of each game
The World is used contain all game data related to the game state. The World is used contain all game data related to the game state.
This sort of game data may change during the runtime of the game. This sort of game data may change during the runtime of the game.
The Localstorage should contain data independent of the game state. The Localstorage should contain data independent of the game state.
Game resources, constants and globals are all examples of data that could Game resources, constants and global variables are all examples of data
reside within the Localstorage. that could reside within the Localstorage.
To store a value within the database, not only is the table token and the To store a value within the database, not only is the table token and the
name of the namespace required, but a unique key so that the value can name of the namespace required, but a unique key so that the value can
be successfully retrieved or modified later. be successfully retrieved or modified later.
@ -5686,7 +5684,7 @@ Each game is uniquely identified by a table token and the data of each game
\begin_layout Standard \begin_layout Standard
The interface of the database module is an implementation of the upcoming The interface of the database module is an implementation of the upcoming
W3C Web Storage specification. W3C Web Storage specification.
Web Storage is intended for use in web browsers, providing a persistant Web Storage is intended for use in web browsers, providing a persistent
storage on the local machine for web applications. storage on the local machine for web applications.
The storage can be used to communicate in between browser windows (which The storage can be used to communicate in between browser windows (which
is difficult when using cookies), and to store larger chunks of data is difficult when using cookies), and to store larger chunks of data
@ -5743,7 +5741,7 @@ The player module, which is coupled to the TCP-module to react on incoming
\begin_layout Enumerate \begin_layout Enumerate
The protocol parser parses the message and brings it into the format of The protocol parser parses the message and brings it into the format of
the internal GGS presentation of such a message, which is just a specialized the internal GGS presentation of such a message, which is just a specialized
Erlang touple Erlang tuple
\end_layout \end_layout
\begin_layout Enumerate \begin_layout Enumerate
@ -5751,7 +5749,7 @@ The protocol parser sends this Erlang touple back to the player module
\end_layout \end_layout
\begin_layout Enumerate \begin_layout Enumerate
The player module checks if it is a Server-Command or a Game-Commane. The player module checks if it is a Server-Command or a Game-Command.
In our example it is a Game-Command and it sends the message to the table In our example it is a Game-Command and it sends the message to the table
module module
\end_layout \end_layout
@ -5806,7 +5804,7 @@ reference "sec:Example-of-a-GGS-server-application-in-JavaScript"
\end_inset \end_inset
) we see that the GGS-functios ) we see that the GGS-functions
\emph on \emph on
GGS.localStorage.setItem(key, value) GGS.localStorage.setItem(key, value)
\emph default \emph default
@ -5828,8 +5826,8 @@ In the example the
\emph on \emph on
GGS.sendCommandToAll() GGS.sendCommandToAll()
\emph default \emph default
is beeing called then which is a callback to a function of the table module is being called then which is a callback to a function of the table module
which iterates thrugh its player list and sends the command to every player which iterates through its player list and sends the command to every player
\end_layout \end_layout
\begin_layout Enumerate \begin_layout Enumerate
@ -5896,8 +5894,8 @@ GGS.sendCommand(player_id, command, args)
GGS. GGS.
\emph default \emph default
sendCommandToAll(command, args). sendCommandToAll(command, args).
The localStorage is a convenient way to store globals and other variables The localstorage is a convenient way to store global data and other variables
seperated from the game state. separated from the game state.
Unique id:s called gametokens are generated for hosted games so that they Unique id:s called gametokens are generated for hosted games so that they
are not mixed up. are not mixed up.
\begin_inset ERT \begin_inset ERT
@ -6454,7 +6452,7 @@ In Erlang, we have a simple version of supervisors.
\end_layout \end_layout
\begin_layout Standard \begin_layout Standard
When the linking of processes in order to monitor exit behaviour is coupled When the linking of processes in order to monitor exit behavior is coupled
with the transparent distribution of Erlang, a very powerful supervision with the transparent distribution of Erlang, a very powerful supervision
system is created. system is created.
For instance, we can restart a failing process on a different, new node, For instance, we can restart a failing process on a different, new node,
@ -6594,7 +6592,7 @@ To prevent any data loss, the good state of the worker processes is stored
\end_layout \end_layout
\begin_layout Subsection \begin_layout Subsection
Reduncancy Redundancy
\end_layout \end_layout
\begin_layout Standard \begin_layout Standard
@ -6675,7 +6673,7 @@ name "fig:redundancy"
\end_inset \end_inset
To the left normal execution is pictured; the server state is backed up. To the left normal execution is pictured; the server state is backed up.
To the right; the exceptional excution, where the state is retrieved from To the right; the exceptional execution, where the state is retrieved from
the backup to repopulate the server. the backup to repopulate the server.
\end_layout \end_layout
@ -6731,7 +6729,7 @@ playerCommand
\emph on \emph on
main() main()
\emph default \emph default
function of a C or Java programm function of a C or Java program
\emph on \emph on
. .
@ -6779,7 +6777,7 @@ nick
\begin_inset Quotes erd \begin_inset Quotes erd
\end_inset \end_inset
with the actuall new nickname as a argument. with the actual new nickname as a argument.
When a message arrives to the GGS which has the form corresponding to the When a message arrives to the GGS which has the form corresponding to the
nickname change, the nickname change, the
\emph on \emph on
@ -6820,7 +6818,7 @@ nick
\emph on \emph on
changeNick changeNick
\emph default \emph default
function uses a feature of the GGS called localStorage (see section function uses a feature of the GGS called localstorage (see section
\begin_inset CommandInset ref \begin_inset CommandInset ref
LatexCommand ref LatexCommand ref
reference "sec:Communication-with-the-GDL-VM" reference "sec:Communication-with-the-GDL-VM"
@ -7178,7 +7176,7 @@ There were two possible solutions to the problem of the JavaScript to Erlang
\begin_layout Standard \begin_layout Standard
Attempts at creating the communication path from JavaScript to Erlang were Attempts at creating the communication path from JavaScript to Erlang were
initially made, however the communiucation path never became stable enough initially made, however the communication path never became stable enough
for usage in the GGS and the erlang_js software was abandoned. for usage in the GGS and the erlang_js software was abandoned.
\end_layout \end_layout
@ -7274,7 +7272,7 @@ n of TCP instead of UDP, thus losing some speed.
\end_layout \end_layout
\begin_layout Standard \begin_layout Standard
Furthermore, in a move to increase the speed of the GGS prototcol the binary Furthermore, in a move to increase the speed of the GGS protocol the binary
BSON protocol BSON protocol
\begin_inset CommandInset citation \begin_inset CommandInset citation
LatexCommand citet LatexCommand citet
@ -7283,7 +7281,7 @@ key "bson:website"
\end_inset \end_inset
was initially considered. was initially considered.
BSON is a protocol which can be used for vert fast traversal of data. BSON is a protocol which can be used for very fast traversal of data.
The BSON protocol is however rather difficult to read in its plain format, The BSON protocol is however rather difficult to read in its plain format,
and no implementation has been bade for the GGS. and no implementation has been bade for the GGS.
\end_layout \end_layout
@ -7305,7 +7303,7 @@ key "Slee2007"
\begin_layout Standard \begin_layout Standard
The use of Thrift, BSON, or other protocols can be supported quite easily The use of Thrift, BSON, or other protocols can be supported quite easily
by develpping protocol modules for each protocol. by developing protocol modules for each protocol.
No protocol modules for these protocols have however been developed during No protocol modules for these protocols have however been developed during
the writing of this thesis the writing of this thesis
\end_layout \end_layout
@ -7662,7 +7660,7 @@ Future improvements
\begin_layout Standard \begin_layout Standard
The specification of the GGS prototype is huge and like many other software The specification of the GGS prototype is huge and like many other software
projects relying on outside technologies, in time it would require a lot projects relying on outside technologies, in time it would require a lot
of maintanance. of maintenance.
Therefore there are a lot of areas in which the GGS could be improved such Therefore there are a lot of areas in which the GGS could be improved such
as performance, compatibility, ease of setup and usage. as performance, compatibility, ease of setup and usage.
\end_layout \end_layout
@ -7678,14 +7676,14 @@ Protocols
\begin_layout Standard \begin_layout Standard
Because of TCP being a connection oriented protocol, it is not suited for Because of TCP being a connection oriented protocol, it is not suited for
all types of game data transfers. all types of game data transfers.
Each transmission will consume more network bandwith than connectionless Each transmission will consume more network bandwidth than connectionless
protocols like UDP and cause uneccessary load on the processor. protocols like UDP and cause unnecessary load on the processor.
Therefore support for UDP would mean that more games could be run simultaneousl Therefore support for UDP would mean that more games could be run simultaneousl
y on the GGS. y on the GGS.
Another advantage of UDP is latency being reduced. Another advantage of UDP is latency being reduced.
Without having to setup a connection for each group packets of data being Without having to setup a connection for each group packets of data being
sent, they will be sent instantly and therefore arrive earlier. sent, they will be sent instantly and therefore arrive earlier.
Latency is of highest importance in realtime games as it improves realism Latency is of highest importance in real-time games as it improves realism
and fairness in gameplay and many game developers requires the freedom and fairness in gameplay and many game developers requires the freedom
to take care of safety issues as packet losses themselves. to take care of safety issues as packet losses themselves.
This concludes that UDP would be a benefit for the GGS, game developers This concludes that UDP would be a benefit for the GGS, game developers
@ -7735,7 +7733,7 @@ GGS relies on modern technologies.
Therefore it would be best for the GGS to have as many of these VM:s implemente Therefore it would be best for the GGS to have as many of these VM:s implemente
d as possible. d as possible.
The VM:s taken into consideration so far have been unstable or incomplete The VM:s taken into consideration so far have been unstable or incomplete
and it is possible to search for more VM:s, testing them and intergrate and it is possible to search for more VM:s, testing them and integrate
them into the GGS prototype. them into the GGS prototype.
\end_layout \end_layout
@ -7744,8 +7742,8 @@ Setup
\end_layout \end_layout
\begin_layout Standard \begin_layout Standard
The GGS prototype installation procedure requires different configuring The GGS prototype installation procedure requires different configuration
and building steps and thus it isn't in an acceptable release state. and building steps and thus it is not in an acceptable release state.
An executable installation file for each supported platform would be optimal. An executable installation file for each supported platform would be optimal.
\end_layout \end_layout
@ -7801,7 +7799,7 @@ addcontentsline{toc}{section}{Glossary}
\backslash \backslash
\printnomenclature
\end_layout \end_layout
\end_inset \end_inset