I’m doing some multiuser/player development using the Palabre Socket Server, a nice XML socket server for Flash written in Python.

The documentation is a bit spotty, as it’s primarily the work of a lone developer who choses to code more often than document, so I combed through the FAQ and the Forums and the News Posts and assembled this document, which I will try to update as I discover new things.

This doc is for reference only, and I’m not an expert on this software, so your best bet for questions is the Palabre Forums.

New: Flow Diagrams

I’ve started making a flow diagram of the Palabre systems to help get my head around what it’s doing. Here’s the work so far:

Starting the Server  |  Parsing Incoming Data  |  Client Triggered Actions (1)  |  Client Triggered Actions (2)

(These images are formated to be printed out on legal paper or viewed on a 1600×1200 display)

You can also download the original Visio document.

Which XML node can i send and receive ?

This is a list of simple nodes to connect to the server and send simple messages.
 

Connection with nickname and optionnaly password for root
SEND>  <connect nickname="KoolBoy" [ password="YYY" ] />

Answer from the server (nickname in use or non acceptable)
RECEIVE>  <connect isok="1" />

If you want to check the connection
SEND>  <ping />

The server should answer :
RECEIVE>  <pong />

Asking for room list
SEND>  <getrooms />

Rooms list (also supports sub-rooms, operator mode for some clients in rooms, params in rooms (title, locked, …)
RECEIVE> <rooms nb="2" ><room name="XXX" clients="5" /><room clients="20" name="YYY" /></rooms>

Asking to join Room XXX (if room does not exists it is created then)
SEND>  <join room="XXX" />

Room Joined
RECEIVE> <joined room="XXX" />

And the list of clients for this room
SEND>  <clients room="XXX" nb="5" > <client name="Toto" /> <client name="Titi" /> […] </clients>

Joined/Left Information

RECEIVE> <client name="Nickname" joined="Lobby" /> 
RECEIVE> <client name="Nickname" left="Lobby" />

Now when you change/add a room param the full list is not sent back, only the modified param.

And now, the room creator may set the room params as "open"  to everybody with :

<setparam name="openParams" value="True" />
<setparam name="openParams" value="False" />

If set to "true" (or "1"), anybody can use <setparam /> and <removeparam /> in this room

If set to false, only the room creator can do it.

 UPDATE: it seems the syntax has changed a bit:

<setparam room="roomname" name="color" value="blue" />

<removeparam room="roomname" name="color" />

Custom Nodes works exactly as MSG nodes

You can pass toroom/toclient/r/c params to tell Palabre who to send it too but the name of the node is up to you !
So it’s easier to send Messages/Position/Whatever information :

<msg toroom="X" >Hi everyone</msg>
<position toroom="X"><x>12</x><y>15</y></position>

Sub XML nodes allow you to encapsulate XML subnodes in <msg> or whatever nodes

<msg toroom="X" ><title>Hi everyone</title><content>Bla bla bla bla bla bla</content></msg>
<position toroom="X"><x>12</x><y>15</y></position> 

Sending a message "msg" or "m"

(Param "c" or "toclient" -> the message is only delivered to one client)
(Param "r" or "toroom" is delivered to entire room)
(Param "b" or "back" tells the server to send the same message back to the send)
(Param "broadcast" sends to everyone)

SEND> <m r="XXX" >Hello everyone i’m very happy to join you all!</m>
RECEIVE>  <m f="Toto" r="XXX">Hello KoolBoy glad to meet you!</m>
RECEIVE>  <m f="Titi" r="XXX">Hi how are you KoolBoy ?</m>
SEND>  <m r="XXX" >Have to go ! Bye !</m>
SEND>  <leave r="XXX" />

Setting Clients Params

 And everyone receives :

 Or when you join a new room you receives everyone’s params:

Database Connectivity

Database identification supports all the databases modules of AdoDB . If you need to know who is connecting to your server, and have for example, a Mysql database with logins and passwords,
you can enable database Support.

odbc    access    mssql    mysql    mxodbc    mxoracle   oci8   odbc    odbc_mssql    postgres    vfp    sqlite 

If you enable it you need to have AdoDb Python and the required DB module installed .
(view  : http://phplens.com/lens/adodb/adodb-py-docs.htm )

With compiled Win32 version, DB identification works with Mysql,PostgreSQL, and SqlLite because of modules Licences. If you want other Databases with Win32 you’ll have to use the Source version and install the correct module.

Currently under Windows, Postgresql support is buggy.
Under other systems (non compiled palabre versions) you need to have the python Adodb module installed
and the correct database module installed (ex: for mysql : MysqlDB, for Posgresql : PsycoPg, …)

For full list and informations, please see :
http://phplens.com/lens/adodb/adodb-py-docs.htm#databases

To enable this support, open palabre.conf and in the section [database] change :

to

Then fill the lines bellow according to your database informations

And specify the request to be used to connect

[LOGIN] and [PASSWORD] will automaticaly be replaced with the "nickname" and "password" attributes of the connect node

So you can now use :

to connect.

How to Connect from Flash

Simple Actionscript code to connect to the server.

Modules

How to write a module?

1. in the "modules" subdirectory create a file "yourModule.py"
2. In that file create a class yourModule

3. Then specify when your module should be called.
Two options are available : self.server.registerAction() and seld.server.registerNode()

If you want your plugin to be called every time Palabre executes a specific action (example when server startup, when a client connects, when a client Leaves, when a client sends a password for connection, …)

Example : Do something when server starts :

Then add in your __init__ method :

And Create a method called : ‘onStartup’

If you want to add an action when clients sends a specific node, add in __init__ :

And create a method called ‘doNode’

4. In palabre.conf edit the [modules] section and add your module name to the list :

Restart Palabre … and You’re done !

Accessing Server Variable from a Module

You can access all the methods and properties of the server via :

Example: to find out if a particular nickname exists, you would look at the sever variable that holds the list of all nicknames:

so your test might look like :

You can also access to a client object via :

And to a room object via :

And then access to all the methods and properties of each object, for example :

or

Included Modules

helloworld.py

[view source]

It adds two nodes "hello" and "quote"
If you send "<hello/>" it will reply "<world>Hello World</world>" …
If you send "<quote>" it will reply with a random quote "<quote>Balblablabla</quote>"
Very simple plugin but shows you how to add actions and nodes easyly with Palabre

dbQueries.py

[view source]

WARNING ! Don’t use this one on production environments !
IF database access is configured in palabre.conf, it allows you to send ANY sql query in a <db/> node !
example : <db>SELECT * FROM my_table</db>
(WARNING, request could be DROP DATABASE ….)
And it will reply :

You can send "SHOW TABLES" or "SHOW COLUMNS my_table" and it will work too …

simpleLogin.py

[view source]

Just a plugin to explain how to write your own login module
This one is pretty easy .. just don’t send "hacker" as password and you’re in.

Cross Domain Support

Crossdomain support, will really help clarify the way you authorize SWF files to connect the server.

In palabre.conf, in the [crossdomain] section, on the line :

just specify the domains were people will access your SWFs from

Example:

If you have an swf on http://www.domain.com/test.swf
that can also be accessed through http://www.domain.net/test.swf ,
or http://192.168.0.1/test.swf

specify :

And in your test.fla(swf), execute before the connection to www.domain.com on port 2468 :

And even if the SWF is hosted on www.domain.net/test.swf the connection will work.

Using Palabre from Webpage SWF

• You have Palabre up and running on your computer (IP : x.x.x.x) on port 2468

• Port is open and anyone could do a telnet x.x.x.x 2468

• Your SWF is hosted on yourdomain.com/xyz.swf

• Your SWF is trying to connect to x.x.x.x on port 2468

• Your palabre.conf has the line

•  alloweddomains = yourdomain.com www.yourdomain.com

• Your SWF calls before connecting :

• System.security.loadPolicyFile("xmlsocket://x.x.x.x:2468");
  

The Game Design section was starting to look a little overrun by Flash and ActionScript tutorials, so I’ve added a whole new page for Flash and ActionScript. Check there for the latest experiments.

Speaking of which: Drawing Regular nGons in Flash.

That’s right. NGons, baby! Try to curb your enthusiasm.

I’m working on a project that requires the drawing (or at least calculating) of regular nGons (pentagons, hexagons, octagons, etc.), so I threw together a demo movie. As usual, source code is included.

I’ve collected together all of my various experiments with Flash on this page. Most of what you will find here are snippets of code and small movies that test certain features of Flash, or solve some small, specific problems. There are also a few game-like projects.

Each of the movies posted here also show the source code (or at least the important bits). The goal is to create a resource for other people who are learning Flash, especially ActionScript . All of the exercises below are created in Flash 8. Some of them will work in earlier versions, some will not.

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Regular nGons. We’ve all wanted to draw them at some time, right? Look no further, seeker of knowledge, I’ve got just what you’re looking for.

The method I’m using is pretty simple.

• Assume we are drawing our nGon with its center at 0,0
• Start with a point at
• x = 0
• y = nGon radius
• for an nGon with n sides
• rotate the point 360/n degrees
• do this n+1 times
• to close the polygon
• add 360/n degrees each time we iterate

So assume we want a 12 sided nGon. We rotate the first point 30 degrees, the next point 60 degrees, 90 degrees and so on.

For the rotation, I’m using:

And because Flash uses radians instead of degrees, we have to convert from degrees to radians when doing this calculation:

Add in an x and y offset to each point to place the polygon in the center of the screen.

Here the code that run the movie:

Since returning from GDC, I have been fired up to learn Flash as a tool for doing some simple gameplay prototyping. It has been rewarding, and at times fairly frustrating, as Flash has some interesting quirks of implementation. It has…personality.

So this is to be a dumping ground for bits and bobs of code and information that I’ve learned, and might help others over some rough spots. No particular order or theme. Just nuggets of Flashy goodness.

Loading Text as Unicode

Use the standard loadVars method:

The trick is to save the  text out as UTF-8 or UTF-16, with the *.utx file extension. I use JEdit for this, though there are a number of other free unicode text editors available.

Download the Flash File
^unicode.fla

Create and Format a Dynamic Text Field

This code creates a dynamic text field, creates a text formatting object, and applies the text format to the newly created text object.

Download the Flash File
^{dynamicText.fla}

Write-On Text in a Fixed Amount of Time

This code writes a text string into a dynamic text field, left-to-right, one or more characters at a time, in a fixed amount of time.

This was created for the Design-A-tron, to write-on a text string of arbitrary length, in the amount of time it took to play the gears running animation and sound. It is completely dependent on the framerate of your movie.

Download the Flash File
^{TextWriteOn.fla}

Here is a re-write of the base eRadiRace code, using the new Flash 8 Draw API to make the trails and do the simple collision.

Added a musical score. Now at v0.254

It still has a few bugs:

• Not all sounds seem to be playing when called (intermittent).
• [Fixed] A last minute change to add the Tutorial screen has made the avatars disappear after the first round.
• Collision could be tightened up just a bit.
• The frame where the player collides with the line is delayed in drawing by about a half a second, which makes it look like they shouldn’t have lost.

I’ll fix that avatar thing and post up the game loop code.

One of these days, I’ll start making games that fit in my pages.

Instructions

• Move the mouse left and right to control the paddle.
• Score by hitting the ball into the Green top and bottom goals.
• If the ball hits the Red left and right goals, that’s bad.

Because this is a flash game, you need to keep the mouse cursor within the active window to move the paddle. If the paddle stops moving, you’ve wandered out of the window.