Arianne

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{{Navigation for Marauroa Top|Internals}}
{{Navigation for Marauroa Developers}}
 
 
This is possibly the most complex part of all the middleware that makes up Arianne.<br>
Role Playing Design is the determining factor on how ''easy'' is to create a new game for Arianne. We had to choose easing the creation of turn time limited based games. Arianne will work better with this kind of games (also known as realtime games).
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The whole Marauroa system is managed by two main entities, RPAction and RPObject. There are also several helper classes like Attributes, RPSlot and RPClass
 
==AtributtesAttributes==
Attributes is a collection of pairs of values in the form name-value.
We can store almost any basic type in a Attribute object:
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For example an avatar can have:
-* left hand
-* right hand
-* backpack
-* left pocket
-* right pocket
 
and we can store objects in each of these slots.
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There are optional and mandatory attributes. If a mandatory attribute is not found, the message is skipped by the RPServerManager.
 
Mandatory ActionsAction Attributes are action_id and type.
 
The action_id is used to identify the action when a resulting response comes in a perception
 
=Perceptions=
The basic structure for sending world updates to clientclients is called perceptions.
 
There are two types of perception:
* Sync perceptions,: thatthese are used to synchronize clients with the server world representation,. thatThis is the only valid sourceway forof knowningknowing world's status.
* Delta perception,: thatthis is used to send only the changes to the world since the last perception.
 
Our actual Perception system is called Delta<sup>2</sup>. It is heavily attached to the Marauroa core, so I recommend you to use it :) ▼
As we are using UDP transport, it is prone that we lose from time to time a package related to perceptions, and so we aren't going to be able to recover the world status, because each perception requiere the previous one to be able to work correctly. In this case we will send an Out of Sync Message to Server, so that server sends us a new Sync perception.
 
▲Our actual Perception system is Delta<sup>2</sup>. It is heavily attached to the Marauroa core, so I recommend you to use it :)
 
== How Perceptions and Actions work ==
Actions are sent from the client to the server in order to make theirthe character to doperform an action. In order for the client to know the result of the action the Server needneeds to send ita reply to the client. How will this be done?
 
OnIn a first tryattempt, we used to send clientclients back an action that was the result of their action. However, butthis makemade the code really hard because we had to update totwo different things, perceptions and actions,. soInstead the ideasolution appearedappears intuitively: Why not join action reply and perceptions.
 
So the action reply is stored inside each object (that executed the action ) with a set of attributes that determine the action return status and the attributes. This way of workingdoing makereplies makes it a bit harder toon RPManager but it simplify a lotsimplifies the creation of new clients a lot.
 
See Actions reply in the Objects documentdocumentation to know exactly what is returned. However, but keep in mind that itthe return result depends of each particular game.
 
==Delta<sup>2</sup> perception Algorithm==
The main idea behind the DPA is not to sendavoid sending ALL the objects to a client each time, but only those that hashave been modified.
 
Imagine that we have 1000 objects, and only O1 and O505 are active objects that are modified each turn. Ok?
 
The Traditional method:
<pre>
- Get objects that our player should see ( 1000 objects )
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</pre>
 
I hope you see the problem..., we are sending again objects that neverhaven't changed each turn.
 
The delta perception algorithm:
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</pre>
 
The next step onof the delta perception algorithm is pretty clear: delta<sup>2</sup> The idea is to send only what changes of the objects that changed. ThatThis whyway youwe save even more bandwidth, making perceptions around 20% of the original delta perception size.
 
The delta<sup>2</sup> algorithm is based on four containers:
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* List of deleted objects
 
An area reallyvery related to DPA is RPZone (see lower in this doc)
 
Well, asAs you should know, an MPEG video adds a full frame each X number of frames, so it can be used as synchronization in case the file getgets corrupted. The idea is that if you fail to continue decompressing data, you can always omit things until the next full frame and then when you get synced. The idea here is similar, if we fail to synchronize with server we send himit aan Out of Sync Message so that server will send a sync perception so that the clients can synchronize,. asRemember, UDP is not a secure transport.
 
To make perception works it is important to call the modify method on RPZone so this way objects modified are stored in the modified list.▼
 
▲To make perceptionperceptions workswork, it is important to call the modify method onin RPZone, so this way objects modified are stored in the modified list.
 
=Zones and Worlds=
Worlds in Marauroa can be so big, so huge, that we need to split itthem in to several pieces.
Each of these pieces are what we call an RPZone.
 
So our world is made of several RPZones that are '''independent''' of each other.
To move from one RPZone to another RPZone you have to code thatthe correct behaviour onin RPRuleProcessor. Just look at any of theour coded examples.
 
==RPWorld==
As we have already said, itRPWorld stores several RPZones that are independent of each other.<br>
RPWorld provides onInit and onFinish methods that are called on server initinitialisation and server finalization to define what to do with the world on these events. There is no default behaviour and you need to extend this class to redefine the behaviour.
 
Also it provides methods for adding and getting new RPZones:
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* changeZone that moves one object from the old zone to the new zone and adds a proper valid id.
 
At last, RPWorld also contains a method called nextTurn that is called by RPManager to move from one turn to the next turn. It mainly resetresets the delta<sup>2</sup> data.
 
==RPZone==
Objects must be stored somewhere, and we use Zones now to store them. A zone is just a container of Objects which has a name.
 
Each RPZone '''must''' have ana unique name.
 
In order to improve the modifiability of the Marauroa platform we have made RPZone to be an interface so that if you want you can implement it as you think it is more efficientrequire.
 
But onin the usualmost casecases, if you think the Delta<sup>2</sup> system is fine and matchmatches your gamegames style, you can use MarauroaRPZone that is our reference implementation of Delta<sup>2</sup> algorithm.
 
The actual Marauroa RPZone consists of several data structures:
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* a Perception
 
The idea is to have already computed, in the Zone, the perception sohence saving LOTS of time that would normally be needed to generate it. All the data structures contain the same objects, but the hashmap is used to do a fast search of objects using itsthe RPObject.ID,. thisThis is the most usualcommon way for locating thean object with a known ID. List is used to improve the time required to build a total perception. AndPerception well, weis used perception to pre-calculate the delta perception (i.e. to find the changes between the current state of the zone and the previous state send to the client last turn)
 
Actually theThe perception is the same for all the players onin the Zone.▼
 
In order to make perceptions work, you have to manually call the modify method so that you notify the zone about changes in a character or object.▼
▲Actually the perception is the same for all the players on the Zone.
 
[[Category:Marauroa]]
▲In order to make perceptions work, you have to manually call modify method so that you notify the zone about changes in a character.
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