Duda I/O: Web Services Framework

Duda is an event-driven web services framework which exposes a friendly C API.

It mainly purpose is to interface over Monkey HTTP server to implement fast services through asynchronous callbacks, where is possible to map specific URL routes against local functions.

Duda do not requires extra dependencies besides libc, but depending of the service needs, it can load on runtime packages to import specific objects with third party features. Some packages available are:

WebSocket
JSON
SQLite
SHA1
SHA256
Base64
Redis
In-Memory Key/Value store
much more!

Being implemented on top of Monkey stack, its fully compatible for projects targetting Embedded Linux, as well it's natively made for ARM, x86 and x86_64.

For mode technical details or API documentation please refer to the official project site:

http://duda.io

Quick Start with Duda Client Manager (aka DudaC)

DudaC is a separate program that takes care of setup a development environment for Duda web services. For more details about it please refer to the following guide:

http://duda.io/documentation/dudac

In order to get some services examples refer to this repository:

https://github.com/monkey/duda-examples

Then you can play with DudaC and duda-examples/NNN.

Duda Internals and Workflow

Before to describe how Duda works we need to describe the internals of Monkey HTTP server.

Monkey is an event-driven web server for Linux. It's completely optimized to obtain high performance at a low cost of system resources. It depends of specific Linux system calls and it's architecture allow the integration of third party components through the plugin API interface.

As described earlier, Duda is written on top of Monkey, this means that Duda is a Monkey plugin who wraps the Monkey plugin API and expose a friendly C API, it also take care of to hide the internal complexity of the web server in terms of threading and asynchronous events.

Supposing that Monkey is running and have Duda plugin loaded on it, every time that a HTTP request arrives, Monkey will trigger the Duda callbacks to determinate if exist a handler for it. Duda on it's own side, will verify if a web service have been registered, and if the service registered have requested some mapped URL that matches, Duda will give control to the web service, and this web service will use Duda API to send responses based on what it was made for.

                     +--------------------+
                     | Monkey HTTP Server |
                     +--------------------+
                               |
                     +-------------------+
                     | Monkey Plugin API |
                     +-------------------+
                               |
                         +----------+
                         | Duda I/O |
                         +----------+
                               |
          +--------------------+-------------------+
          |                    |                   |
  +---------------+    +--------------+   +--------+--------+
  | WebService #1 |    | WebSerive #2 |   |  WebService #N  |
  +---------------+    +--------------+   +-----------------+

Many web services can be registered with Duda, internally talking about the web service, this web services can be mapped to different virtual hosts, this provides a huge flexibility in terms of what is required to do.

Manually setup of a web service

Enable the duda plugin in conf/plugins.load.
Edit conf/plugins/duda/duda.conf configuration file and set the key ServicesRoot with the absolute path where the services files are located, e.g:

[DUDA] ServicesRoot /home/foo/monkey/services/ PackagesRoot /home/foo/monkey/plugins/duda/packages/

Edit the virtual host configuration file where the service will work, as an example edit conf/sites/default and add the following entry:

[WEB_SERVICE] Name hello Enabled on Root off <- optional DocumentRoot /home/foo/monkey/services/hello/html/ <- optional ConfDir /home/foo/monkey/services/hello/conf/ <- optional LogDir /home/foo/monkey/services/hello/logs/ <- optional DataDir /home/foo/monkey/services/hello/data/ <- optional

we have instructed to load service "hello", so Duda will try to locate the service file 'hello.duda' under ServicesRoot directory and load it.

Links

Project site: http://duda.io Bug Tracker : http://bugs.duda.io Mailing list: http://lists.monkey-project.com/listinfo/duda IRC : irc.freenode.net #monkey

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