Framework agnostic meta framework
####Framework agnostic meta framework
When you build webapps, you often run into the problem of having to initialize lots of modules you want to use, e.g. httpserver, databases or storage engines. They often depend on each other and have to be initalized in specific order. This often leads to a giant ball of init code in your main app.js. It's also difficult to test such code.
With gleeman we tried to build a simple, unopiniated but powerfull module loader, which solves all these problems.
See the example directory.
Or have a look at the skeleton project.
gleeman uses the asyc.auto feature to resolve the dependencies. This leads to a number of advantages:
- The dependencies are easily managable in the definition.
- Dependencies can be added and removed easily without any pain.
- gleeman and async.auto care about the loading order.
- You can test your module without having to worry about any initialization of the depenedencies, you can set their state as you want - this is called dependency injection
- By defining a namespace property in your app, it is easy distributable as a package to be used in other projects, it can also be deployed to npm so that others are able to plug it into their gleeman based projects.
Your project starts with a simple js file
var join = require'path'join;var config =appsPath: join__dirname 'apps'apps:core:myapp: '';var run = require'gleeman'configrunconsole.logautoConfig;;
As you can see, gleeman-Function takes a configuration object as parameter and returns a runner to start the process. This can have an optional callback function. This function is called at the end of the initialisation process.
The configuration contains a property
appsPath. This is required, if you
want to use apps. The
apps-property itself contains the app you want to use
in your project. Every app belongs to a namespace where it lives in. The
namespace and the app name have to match with the directory structure of the
project. For the upper example the file structure is as follows:
examples/minimal-project├── index.js└── apps└── core├── myapp.js└── myapp.test.js
An app is a basic functionality of your project. It can be for example a basic express server, a css preprocessor, a database connection manager and so on. An app can add functionality to your project or just provide data.
The app itself consists of several functions. These functions are called in
the defined order by adding dependencies. All these functions get a
callback as first argument. This should be called, when the function has all
data it wants to return. The first parameter should be a potential error that
occured during process, the second is the result of the function. It is stored in the
result object with the namespace of the func as key. The functions that depend
on this function can then access the result of it, because the result is given
as the second, third, ..., n-th parameter of the function. In addition the
result-object itself is always given as the last parameter.
moduleexports =// do something complicated here// of cause even async stuff is possiblevar result = 'func_one_result';// call the callback, first parameter is the error, second the result of// this functionfunc_oneDonenull result;// this function depends on the upper on, so we have to mark thisfunc_two: 'core:myapp:func_one'// now we can use the result from abovefunc_twoReadynull resultFromOne + ' with 2';;
Here we can see two functions defined in a app called
myapp under the
func_one has no dependencies so there is no need to get
the app argument. It adds on property to the
app-object, the key is derived
from the namespace, app name and function name. In this case it will be
func_two depends on
func_one so we have to add it
as dependency. Because we do this, it will run after
func_ones result is
present in the
app-object. That's why we can access it afterwards.
The upper dependency can also be defined the other way around:
moduleexports =func_one:var result = 'func_one_result';func_oneDonenull result;'core:myapp:func_two'var resultFromOne = results'core:myapp:func_one';func_twoReadynull resultFromOne + ' with 2';;
As you might spot,
func_one has now an array-definition. But because the
func_two-namespace is now after the function definition, the dependencies
are resolved as in the prior example.
In this case, this makes no sense and is also errorprone, because in
func_two we rely on data of
func_one without explicitly knowing about it.
A typical use case can be to provide a function to add files to a list (e. g.
stylus files to render to css). You might want to start the rendering of the
stylus files just after all other apps have added their files to the list.
So you define the rendering function as a follow up function to all functions
that add a file to the list.
Besides apps in namespaces, it's also possible to add packages to your project.
They are standard npm modules. They have pretty much the same api as normal
apps. They should export an object with the functions and dependencies they
want to provide. In addition, they have to provide a property
This contains a string to access the packages' results or depend on one of
it's functions. This is the express server package we build:
var express = require'express';// Create servervar expressServer = express;// Basic configuationexpressServerconfigureexpressServeruseexpressbodyParser;expressServeruseexpressmethodOverride;expressServeruseexpressServerrouter;;// ... some other initialisationsmoduleexports =_namespace: 'gleeman:express'cbnull expressServer;;
As you can see it provides one function which returns the express server. If
your function depends on that express server, you can add it as dependency by
gleeman:express:server. The name is generated by the namespace
property and the name of the function.
We pre-built some frequently required modules
- gleeman-express Basic express server
- gleeman-express-http Basic http server which hooks in the express server
- gleeman-config Simple config module to provide configuration for your app
You may also find them useful to learn how to use
(The MIT License)
Copyright (c) 2012 Stephan Hoyer email@example.com
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
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