Skip to main content

Android programming - architecture video

I have been getting interested in Android programming, so I went over to their website and found some introductory videos.

Here's the first one with a little index of what is discussed and my take away from the video.



Video Index:
00:0 Introduction
00:40 Linux Kernel
01:09 Native Libraries
03:09 Android runtime
04:13 Core libraries
04:31 Application framework
07:00 Applications
07:25 Application building blocks
09:37 Example of re-using components in Android
12:18 Conclusion and resources
12:48 End

My Takeaway:

Architecture wise the Android platform has several layers:
  1. Linux Kernel
  2. Native Libraries
  3. Android Runtime
  4. Core Libraries
  5. Application Framework
The applications that we make are build on top of the "application framework" layer.

The Linux Kernel was chosen because of it's stability, services, security, and presence of several device drivers.

Native Libraries consist of various components for rendering graphics and fonts (Surface Manager, OpenGL, SGL, Freetype), a lightweight database engine (SQLLite), a browser engine (WebKit), and others.

The Android Runtime consists of Dalvik the Java Virtual Machine created by Google, which is optimized for running on embedded devices which have low resources. Dalvik runs *.dex files which are created by converting *.jar and *.class files. On top of Dalvik are the core Java libraries consisting of things like the Collections, IO API, etc.

Then the Core libraries layer consists of components such as Activity Manager, Resource Manager, Package Manager, Content Provider, Telephony Manager, XMPP, etc.

Android applications typically have 4 building blocks, which applications mayor may not use. These are:
  1. Activities
  2. Intent Receivers
  3. Services
  4. Content Providers
The video ends with an example of how various applications can re-use a photo picker component. So, we may have multiple applications like email, Blooger, etc which may need to select a photo. These applications do not have to write their own photo picker. They just show an "Intent" to pick a photo, and the component which fulfills that intent will be chosen. This binding is done pretty late, so we can actually change the component that fulfills the intent, and then henceforth that component will be used for that intent.

In the next few blog posts I will be embedding more Android videos along with my learnings.
Labels:

Comments

Loretta Doherty said…
Great, A lovely introduction. Well done!
1:48 AM
Post a Comment

Popular posts from this blog

My HSQLDB schema inspection story

This is a simple story of my need to inspect the schema of an HSQLDB database for a participar FOREIGN KEY, and the interesting things I had to do to actually inspect it. I am using an HSQLDB 1.8 database in one of my web applications. The application has been developed using the Play framework , which by default uses JPA and Hibernate . A few days back, I wanted to inspect the schema which Hibernate had created for one of my model objects. I started the HSQLDB database on my local machine, and then started the database manager with the following command java -cp ./hsqldb-1.8.0.7.jar org.hsqldb.util.DatabaseManagerSwing When I tried the view the schema of my table, it showed me the columns and column types on that table, but it did not show me columns were FOREIGN KEYs. Image 1: Table schema as shown by HSQLDB's database manager I decided to search on StackOverflow and find out how I could view the full schema of the table in question. I got a few hints, and they all pointed to
Post a Comment
Read more

Fuctional Programming Principles in Scala - Getting Started

Sometime back I registered for the Functional Programming Principles in Scala , on Coursera. I have been meaning to learn Scala from a while, but have been putting it on the back burner because of other commitments. But  when I saw this course being offered by Martin Odersky, on Coursera , I just had to enroll in it. This course is a 7 week course. I will blog my learning experience and notes here for the next seven weeks (well actually six, since the course started on Sept 18th). The first step was to install the required tools: JDK - Since this is my work machine, I already have a couple of JDK's installed SBT - SBT is the Scala Build Tool. Even though I have not looked into it in detail, it seems like a replacement for Maven. I am sure we will use it for several things, however upto now I only know about two uses for it - to submit assignments (which must be a feature added by the course team), and to start the Scala console. Installed sbt from here , and added the path
1 comment
Read more

Inheritance vs. composition depending on how much is same and how much differs

I am reading the excellent Django book right now. In the 4th chapter on Django templates , there is an example of includes and inheritance in Django templates. Without going into details about Django templates, the include is very similar to composition where we can include the text of another template for evaluation. Inheritance in Django templates works in a way similar to object inheritance. Django templates can specify certain blocks which can be redefined in subtemplates. The subtemplates use the rest of the parent template as is. Now we have all learned that inheritance is used when we have a is-a relationship between classes, and composition is used when we have a contains-a relationship. This is absolutely right, but while reading about Django templates, I just realized another pattern in these relationships. This is really simple and perhaps many of you may have already have had this insight... We use inheritance when we want to allow reuse of the bulk of one object in other
3 comments
Read more