Powerful customisations with Sugar’s ACL

Today I want to explore a customisation possibility that is so powerful and still often neglected: customising Sugar’s ACL framework.

The Actions and field visibility part of the ACL in Sugar is normally applied through the use of Roles within the application’s UI, while the visibility of a record is applied through the visibility framework that either allows a user to see a module’s entry or not.

There are two important nuances about Roles in Sugar that I should mention:

  1. Most restrictive prevails, if a user happens to be assigned to more than one Role
  2. Roles do not apply to Sugar Admin type users

The power of the ACL framework is due to the fact that it applies both to the back-end of the system (eg: the API will not allow writes) and to the UI as well by driving buttons and visual screen elements that would allow the user to perform or not the actions.

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Arduino Temperature Driven Fan

Schema of Arduino controlled two speeds fan with LCD
Schema of Arduino controlled two speeds fan with LCD

This project is about driving a two speed fan with an Arduino, based on the environment’s temperature.

The project has been designed to help automating an existing fire-based heating system. The idea is that the environment will be warmed faster, by driving heated air into the room with a multi speed fan, while the fire is hot and the surrounding environment not yet.

I wanted to make it a little more interesting by adding a LCD display to show temperature, humidity and fan status, and four buttons to increase and decrease the two temperature values that drive the fan speeds.

Arduino Prototype of Temperature Driven Fan
Arduino Prototype of Temperature Driven Fan

When the temperature is below the lowest temperature threshold, the fan will be running at full speed. With temperatures between the lowest and the highest threshold the fan will be running at half speed and with temperatures above the highest threshold the fan will be off.

This project demonstrates the use of an Arduino (or compatible) micro controller with a temperature and humidity sensor to drive outputs, it demonstrates the usage of a LCD display, push buttons and EEPROM memory storage.

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SugarCRM – Team security query caching

Following up on my previous article about Sugar’s Team Security implementation, I thought it would be interesting and useful to discuss and mention a new setting to improve it.

Prerequisites

For this article I’ve used:

  • Sugar Enterprise v7.6.0.0
  • The infrastructure setup described on my previous article Setup a Debian Based Sugar development environment (or similar)
  • In-memory caching is enabled using memcache/memcached (my current preference) depending on the linux flavour used

Introduction

Some time ago, I was analysing the performance of the Team Security query. The slowest part of the query seems to be caused by the subquery with joins between the tables team_sets_teams and team_memberships within listview queries.

Then I thought: Sugar caches most of the semi-static data (vardefs, language files, etc) into whatever caching mechanism is used by the system, why don’t we run an IN() condition using the cached list of ids per user, instead of a subquery on every listview load?

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Sugar 7 – Setup a Development Environment

Build a Sugar development VM using Debian 7.8

This post is supposed to guide through the setup of a VirtualBox virtual machine for local development of Sugar 7.5.x. The OS of choice is Debian 7.8 as it is my personal preference for server setups and it currently fits all the software requirements of Sugar without much additional manual work.

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How to drive a small motor at different speeds using an Arduino

Control motor speed with Arduino
Control DC motor’s speed using Arduino

For one of my projects I needed to drive a small motor at different speeds, so I gave this a go by reading and learning more about what is required.

We can achieve that with an Arduino microcontroller by using PWM signals. For this project I am using an Arduino Mini clone, and decided to drive the motor with a N-Channel MOSFET (voltage controlled transistors), activated by a PWM signal.

PWM Duty Cycle
PWM Duty Cycle – Source Wikipedia

Keeping the frequency of the signal constant, and varying the width of the “on” time vs the width of the “off” time (changing the duty cycle), will make the motor spin at different speeds.

The signal values that Arduino expects for the duty cycle is from 0 to 255 and it can be set by using the function analogWrite(pin, value). By providing a different duty cycle value to our Arduino pin (in my case PWM pin number 5), the motor will spin at different speed.

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How does authentication work in Sugar 7?

Different application’s approach: Sugar 7 framework

For whoever is reading this article and is not familiar with Sugar on the most recent version 7.x of the product, it is important to note that the application’s core is now a RESTful based API.

The presentation layer is based on SugarCRM’s framework “Sidecar”, that uses quite a few Open Source libraries (including Bootstrap, jQuery, Handlebar and Backbone.js).

The framework’s MVC layer is cached/stored within the browser at the first application’s load and interacts with the REST API on every subsequent call, creating a more powerful experience as a Single Page Application.

The great concept around the newer application’s framework is that everything can now be achieved interacting with the application via API calls, if it can be done in the application by using the interface (except BWC functionality).

By doing so, the framework provides extreme flexibility and huge integration capabilities, and therefore it allows customers to build any business process around the application.

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