I'm using Node.js to build an event based game server (to a flash client). But, I'm having trouble finding examples of how I should architect this message passing.
To simplify things, I was thinking in using a json:
{signature: 'event_name', { /* event data /*} }
So I can easily write to socket using any serialization library. Is it a good idea? Please point me to articles, tutorials or books if you think I don't know what I'm doing at all (which I think is the case)
I would use AMF. There is a pure javascript version of it: http://www.jamesward.com/2010/07/07/amf-js-a-pure-javascript-amf-implementation/
BSON is what you are looking for, it has similar properties to JSON, but it a lot smaller and faster to parse. The MongoDB driver for node has a BSON library in it, I don't know about any Flash librarys though.
Related
I have a nodejs application that will take a JSON configuration file.
The JSON file will have some ${} and #{} tags that will be used to build up a dynamic context by loading a template configuration and populating the tags. HOCON may also end up being used eventually but that's not in there yet.
I came across Typesafe Config in the past and it looks amazing for this kind of thing. I did a bit of searching around npm and didn't spot anything similar in the node world but perhaps I am too unfamiliar with what terms to search for.
Does anyone know of a similar library in nodejs or a sensible strategy I may employ to do this in nodejs?
I know it wouldn't be much effort to implement something myself with string replace on the JSON or some such although I can't help but think that this has been done before in node applications and probably in a much better way than I would do it for this single use case. On that basis it seems to make sense to ask here before I continue.
A bit late, but it seems there is still no dedicated npm module to convert hocon to js. However there is a library which could be easily converted to a npm module : https://github.com/scottburch/webpack-hocon-loader
I need to transfer data (objects) between client and server, and Twisted seems a good way to accomplish this. I've been doing a lot searching but still haven't found any example to understand the basic principle. So any simple code would help.
Thanks!
EDIT
Both client and server are written in python
The data may be large, so I need a fast, reliable transmission ( I've taken a look at producers, is that good?)
Flask is great, but I am using another framework, so the whole networking thing relies on Twisted.
It's hard to tell if your question is more about json, python or twisted, but here's an overview, more can follow once the specifics are known. Perhaps you could add some more info to your question so we can offer more assistance :-)
re Json: Json is just a string with a defined structure. If you are working in python and have an object to send as json, then you need to convert the object to a json string by use of
import json
json.dumps(objectName)
If your client is javascript then instead of json.dumps you might use JSON.stringify(objectname).
If you intend to use javascript for clients then some of the frameworks like jQuery make it very easy.
Pythons json.dumps has a lot of optional arguments, most of which you won't need. You can see the options at https://docs.python.org/2/library/json.html
Python is python, I assume you know how to create and populate objects. Will your client be python or javascript or something else? From a javascript client to a python server you would most likely use Ajax to send requests and get responses.
Twisted allows you to easily create a server that will listen on a given port and, when data arrives, an event will occur that supplies the data received. You can then do whatever you need to with the data. Just be careful about doing blocking things like database inserts since the server may miss some data or otherwise misbehave if you interrupt it's event loop. Twisted can be difficult to learn initially, but it is a very powerful and reliable system that is well proven. One alternative to consider, particularly if your clients are not python, is node.js. In my opinion, node is a little bit easier to grasp initially and there are thousands of add-on modules that let you do almost anything you'd want. I use both twisted and node for different things.
Neither node.js nor twisted are software that you can use to just quickly spin up a server or client without some study and experimentation. To use Twisted or Node.js properly confidently, using all their features and goodness, requires a bit of research and work on your part.
There are excellent frameworks like Flask that can be used to build a server that can react to a number of different Ajax calls from a client - you can have a single server be able to respond to several different kinds of requests instead of having a server for each Ajax type.
This is a small library that serializes an object with all its children to JSON and also parses it back to a fully working object:
https://github.com/Toubs/PyJSONSerialization/
Some of my friends are designing a game, and I am helping them out by implementing the game's backend server. The game is written in Flash, and I plan to develop the server in node.js because (a) it would be a cool project for learning node.js, and (b) it's fast, which is important for games.
The server's architecture is based on messages sent between the server and client (sort of like Minecraft's server protocol). The message format I have so far is a byte (the packet type), two bytes (the message length) and that many bytes (the message data, which is a mapping of key-value pairs). Problem is, I really don't want to develop my own serialization format (because while I probably could, implementing it would be a pain compared to using an existing solution).
Unfortunately, I am having problems finding a good candidate for the message data serialization format.
ActionScript's own remoting format might work, but I don't like it much.
JSON has support in node.js (obviously) and in ActionScript, but it's also textual and I would prefer binary for enhanced speed.
MessagePack looked like a good candidate, but I can't find an ActionScript implementation. (There's one called as3-msgpack on Google Code, but I get weird errors and can't access it.)
BSON has an ActionScript implementation, but no node.js support besides their MongoDB library (and I'm planning on using Redis).
So, can anyone offer any other serialization formats that I might have missed? Or should I just stick with one of these (or roll my own)?
Isn't that why HTTP supports gzipped content? Just use JSON and gzip the content when you send it. The time spent gzipping is more than recovered by the reduced latency of the transmission.
Check this article for more on gzip with Actionscript. On node.js I think that gzip-compress is fairly popular.
Actually, if I were in your shoes I would implement two methods and time them. Use JSON because it is common and easy to do. But then implement AMQP instead and compare them. If you want to massively scale this then you might find that AMQP makes it easier. Also. message queuing is just such a nice fit into the node.js world view.
AMQP on Actionscript, and someone doing similar on node.js.
Leverage JSAMF in Node.js for AMF communications with Flash.
http://www.jamesward.com/2010/07/07/amf-js-a-pure-javascript-amf-implementation/
If you wanted to, you could create your entire API in client side JavaScript, and use JSON as the data exchange format, then call ExternalInterface by AS to communicate with the client JavaScript API, which would make for an elegant server side solution.
It is worth noting that Flash Player has built in support for decompressing gzip compressed data. It may be worth compressing some of your JSON objects, things like localised string tables, game configuration data, etc which can grow to be a few hundred kb but are only loaded once on game load.
I'm working on a version of MessagePack for AS3.
At the current version it does the basic (encoding/decoding). Planning streams for the future.
Check the project page: https://github.com/loteixeira/as3-msgpack
I'm writing a RIM BlackBerry client app. BlackBerry uses a simplified version of Java (no generics, no annotations, limited collections support, etc.; roughly a Java 1.3 dialect). My client will be speaking JSON to a server. We have a bunch of JAXB-generated POJOs, but they're heavily annotated, and they use various classes that aren't available on this platform (ArrayList, BigDecimal, XMLGregorianCalendar). We also have the XSD used by the JAXB-XJC compiler to generate those source files.
Being the lazy programmer that I am, I'd really rather not manually translate the existing source files to Java 1.3-compatible JSON-marshalling classes. I already tried JAXB 1.0.6 xjc. Unfortunately, it doesn't understand the XSD file well enough to emit proper classes.
Do you know of a tool that will take JAXB 2.0 XSD files and emit Java 1.3 classes? And do you know of a JSON marshalling library that works with old Java?
I think I am doomed because JSON arrived around 2006, and Java 5 was released in late 2004, meaning that people probably wouldn't be writing JSON-parsing code for old versions of Java.
However, it seems that there must be good JSON libraries for J2ME, which is why I'm holding out hope.
For the first part good luck but I really don't think you're going to find a better solution than to modify the code yourself. However, there is a good J2ME JSON library you can find a link to the mirror here.
I ended up using apt (annotation processing tool) to run over the 1.5 sources and emit new 1.3-friendly source. Actually turned out to be a pretty nice solution!
I still haven't figured out an elegant way to do the actual JSON marshalling, but the apt tool can probably help write the rote code that interfaces with a JSON library like the one Jonathan pointed out.
I'd like to know what is the most efficient way of handling properties in Scala. I'm tired of having gazillion property files, xml files and other type of configuration files in Java and wonder if there's "best practice" to handle those someway more efficient in Scala?
Why would you have a gazillion property files?
I'm still using the Apache commons Digester, which works perfectly well in Scala. It's basically a very easy way of making a user-defined XML document map to method calls on a user-defined configurator class. I find it extremely useful when I want to parse some configuration data (as opposed to application properties).
For application properties, you might either use a dependency injection framework (like Spring) or just plain old property files. I'd also be interested to see if Scala offers anything on top of this, though.
EDIT: Typesafe config gives you a simple and powerful solution for configuration - https://github.com/typesafehub/config
ORIGINAL (possibly not very useful):
Quoting from "Programming in Scala":
"In Scala, you can configure via Scala code itself."
Scala's runtime linking allows for classes to be swapped at runtime and the general philosophy of these languages tends to favour convention over configuration. If you don't want to deal with gazillion property files, just don't have them.
Check out Configgy which looks like a neat little library. It includes nesting and change-notification. It also include a logging library.
Unfortunately, it didn't compile for me on the Mac instances I tried. Let us know if you have better luck and what you think...
Update: solved Mac compilation problems. See this post.