Difference between revisions of "ACF how to write"

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===Step 6 - What Does It Do?===
===Step 6 - What Does It Do?===
This program only just displays a <textarea> box and a submit "update" button. The user can enter the which is saved into a file once he presses "update".
This program only just displays a <textarea> box and a submit "update" button. The user can enter text which is saved into a file once he presses "update".
====In Depth====
====In Depth====

Revision as of 09:46, 17 November 2007

How to Write an ACF Under Construction

For some examples please see svn

svn co svn://svn.alpinelinux.org/acf

  • shorewall
  • dhcp

From <nil> to a running ACF example application Under Construction

Step 1 - The Programming Language

  • ACF uses lua as programming language. Have a look at lua.org [1] before starting.

Step 2 - The Development Environment

Step 3 - Create A Development Directory

Once you entered the ACF Development Environment as described in step 2:

  • in your user home create a directory for your application (e.g. mkdir ~/myapp)
  • and cd into it (e.g. cd ~/myapp)

Step 4 - MVC, How Does It Affect My Coding?

ACF is an MVC based framework. What does this mean to you? Your application is separated into three layers: Model, View, Controller - each of which has one or more files.

  • Model: In Model the 'real work' is done (e.g. modifying config files, starting/stopping services etc.)
  • View: This is where you define what your application will look like. You can have one or more files, each presenting a dynamic html page which only as much code as neccessary to format the data you retrieve from Model.
  • Controller: The event dispatcher. In controller you place one function per event. If the user calls the respective 'event page' (web), acf will fire an action - the same-named function in controller will be called. This function then retrieves neccessary data from Model and passes it to View to be displayed to the user.

Step 5 - The Example Files To Start With

Now let us have a look at the files we need to place into our application directory:

  • Makefile
  • config.mk
  • myapp-model.lua
  • myapp-myview-html.lsp
  • myapp-controller.lua
  • myapp.menu


The Makefile once called does install our acf application so that we can look at it working.


APP_DIST=myapp-model.lua        \
         myapp-myview-html.lsp  \
         myapp-controller.lua   \

EXTRA_DIST=README Makefile config.mk




        rm -rf $(tarball) $(P)

dist: $(tarball)

        mkdir -p "$(install_dir)"
        cp -a $(APP_DIST) "$(install_dir)"

$(tarball):     $(DISTFILES)
        rm -rf $(P)
        mkdir -p $(P)
        cp $(DISTFILES) $(P)
        $(TAR) -jcf $@ $(P)
        rm -rf $(P)

# target that creates a tar package, unpacks is and install from package
dist-install: $(tarball)
        $(TAR) -jxf $(tarball)
        $(MAKE) -C $(P) install DESTDIR=$(DESTDIR)
        rm -rf $(P)

include config.mk

.PHONY: all clean dist install dist-install

Remark: Should you create additional view files for example, don't forget to place their names in Makefile under APP_DIST otherwise they will not be installed later on and your application will fail with an error message.

config.mk: For use with the Makefile. Just copy/paste it. We will look at it later.



-- acf model for myapp
-- Copyright(c) 2007 <Your name here> - Licensed under terms of GPL2
module (..., package.seeall)

cfgfile = "/tmp/myfile"

-- This function returns a cfe (table of values) containing the files'
-- value as string and an error code. If the file does not exist, we'll
-- simply return "" (an empty string, but NOT nil)
readfile = function()
   retval = ""
   error = 0
   fileptr = io.open( cfgfile, "r" )
   if fileptr ~= nil then
      retval = fileptr:read( "*a" )
      if retval == nil then
         retval = ""
   return error, cfe({ msg = retval })

-- This function will write new contents into our file
writefile = function( newcontents )
   fileptr = io.open( cfgfile, "w+" )
   if fileptr ~= nil then
      fileptr:write( newcontents )


   form = ...
   option = form.option
<h1>MyApp - MyView</h1>
<form action="" method="POST">
  <textarea name="textdata"><? io.write( form.value.msg ); ?></textarea>
  <input type="submit" name="cmd" value="update">


-- the myapp  controller
module (..., package.seeall) 

--- default code up here
--- do not change anything except: self.conf.action for redirect
local list_redir = function( self )
   self.conf.action = "myview"
   self.conf.type = "redir"
   error (self.conf)

local pvt = {}
mvc= {}
mvc.on_load = function( self, parent )
   if ( rawget(self.worker, self.conf.action) == nil ) then
   pvt.parent_on_exec = parent.worker.mvc.post_exec

-- This is where 'our' code starts

myview = function( self )
   -- self.clientdata contains the data from the html form
   -- in your myapp-myview-html.lsp
   local clidat = self.clientdata  

   -- user did submit the form (not just call the page)
   if clidat.cmd then
      if clidat.cmd == "update" then -- user pressed update button
         self.model.writefile( clidat.textdata )
   error, value = self.model.readfile()
   return cfe({ value = value })


# Cat   Group   Tab     Action
Test    MyApp   MyView  MyView

Step 6 - What Does It Do?

This program only just displays a <textarea> box and a submit "update" button. The user can enter text which is saved into a file once he presses "update".

In Depth

Now let us have a closer look at what the different files' contents:


In this file you define:

  • The Category in which a menu entry for your program will appear
  • The Group, resp. the subheading's name under Category
  • The Action with-in your controller that will be called once the user klicks on the menu entry defined by Category and Group.

The controller is an event dispatcher. So in here you define all the actions that the user can call or that are defined in the menu. Each action is a separate function that will receive self as the only parameter.

In our case the action is myview.

This function can call the model's functions to update and/or retrieve data (e.g. self.model.readfile()).

Anything that this function returns will be passed on to the view


The functions defined in here can be accessed by the controller to update/set/retrieve data, start/stop services, basically do any 'real work'.


This is our view. It receives the data to be displayed via controller. What ever is returned by a controller action (function) can be accessed by the view (see the first three lines .. <? .. ?>).

How to exchange data between model-view-controller?

The exchange data between model, view and controller ACF uses the so called Configuration Framework Entities (CFE).

Please see oink for further details on CFEs.