Anatomy of applications

• Applications execute code on microprocessors
• The execution is (often) "mediated" by an operating system
• The operating system is a software layer between applications and the hardware
• On desktop systems it also provides a GUI for user interaction

Microprocessor

Parts of an application

• Your code
• Their code

Their code

• Language standard libraries
  • e.g. printf() function from <stdio.h>
• Operating system APIs and libraries
  • Platform dependent and not portable
  • Low level access to hardware
  • Desktop services
• Additional libraries

Libraries

• A collection of functions
  • Often in compiled format, i.e. a binary library
  • With header files for the "public" API
  • You might find yourself building libraries from source

Dependencies

• Dependencies of an application are the libraries that are required for it to build and/or run
• Getting the dependencies are often the biggest source of frustration when trying to build a large application
  • You might need a specific version
  • The dependency itself might have additional dependencies (AKA Dependency hell)

Dependency/Package managers

• Resolve and download dependencies
  • fink, macports
  • newer: Homebrew
  • On Linux: apt or yum (there are others...)
  • On windows: OneGet and others (but I can't recommend any as I haven't used them)

Dynamic and static libraries

• Static libraries get bundled into the application
• Dynamic libraries are loaded by the application at run-time

Other types of applications

• GPU programming
• Microcontroller programming
• "Web apps"

GPU programming

• Have their own language or provide extensions to existing languages
• The code is executed in the GPU rather than the CPU
• GPU are great at parallel processing
• So if your problem is parallelizable then it is well suited to GPU computing

Microcontroller programming

• Direct access to a microcontroller's basic functions
  • or through libraries that implement common functionality
  • through custom OSs (e.g. RTOS)
  • through regular OS (Embedded Linux)
  • or through high level abstractions like Wiring/Arduino

Microcontroller boards

Microcontroller boards

Web Apps

• Part of the code runs on your equipment
• The other runs on a server
• The network is an intermediate layer
• There is an interconnection protocol to exchange commands and data