Open Intents - Android Intents Mechanism and Dependency Management

www.openintents.org support@openintents.org FOSDEM, February 6, 2010

Open IntentsAndroid Intents Mechanism

Friedger Müffke

@fmdroid#openintents

Outline

● Android intents and intents filter

● OpenIntents

● Dependency and intents manager

Android Platform

No monoliths ..

but interconnectedcomponents

All apps are equal!

Modular Apps

● Activity UI for one focused endeavor

● Service no UI, used for long running processes

● Broadcast receiver receives announcements

● Content provider makes data available

Intents (1)

VIEW + www.google.com

Web browser Android

VIEW + www.google.com

VIEW + Contact

VIEW + Image

DIAL + 123

PICK + Image

EDIT + Contact

SEND + Note

.....

Intents:

Intents:

Intent = Action + Data (+ Extras + Categories + Flags)

Intents (2)

● Transition and messaging between componentswithin application and beyond

● Source component + target component + data● Expected behaviour, e.g. TAKE_PICTURE● Used throughout the system● Explicit vs. implict intents

Named targetor Tests against intent filters

Intent filters (1)

● Advertising functionality of compontent

● Registered at install / start up timepart of Manifest.xml

● Define tests for implicit intents ● Multiple filters of component are ORed

Intent filters (2)● Action test

e.g. TAKE_PICTUREOne must matchIntent without action always accepted

● Data / Mime-type teste.g. content://contacts/people/1 geo:0,0?q=Pizza

image/jpeg text/htmlfilters with wildcardsmatch everything specifiedcontent: and file: schema implicitly supported

Intent filters (3)

● Category teste.g. CATEGORY_DEFAULT, CATEGORY_BROWSABLE

All categories must matchIntents for activities always include

CATEGORY_DEFAULT

● User can choose if more than one target found ● Exception if no target found

Manifest.xml<?xml version="1.0" encoding="utf-8"?> <manifest . . . > <application . . . > <activity

android:name="org.openintents.shopping.ShoppingActivity" android:icon="@drawable/small_pic.png" android:label="@string/shopping" . . . >

<intent-filter> <action android:name="android.intent.action.VIEW" /> <action android:name="android.intent.action.INSERT" /> <category android:name="android.intent.category.DEFAULT" /> <data android:mimeType = "vnd.android.cursor.dir/vnd.openintents.shopping.item" /> </intent-filter> </activity> <service . . ./> . . . <uses-permisson . . . /> <uses-library . . . /></application> </manifest>

In Practice

e.g. in Activity

Intent i = new Intent(Intent.ACTION_VIEW);i.setData(„http://www.openintents.org“);

this.startActivity(i);this.startActivityForResult(i, RESCODE);this.startService(i);this.bindService(i, con, 0);this.sendBroadcast(i);

Benefits

● Focus on core functionality● Reuse● Exchange system components, e.g.

home screen, keyboard, address book, dialer

● Automatic handling

Tasks, plug-ins, menus, live foldersDon't forget performance and security!

OI Extensions

OI Shopping listOI Notepad

OI About

OI Delete all

OI Convert CSV

OI Voice notes

OI Safe OI File manager

OI applications work together

Create new intents

VIEW SHOW

DISPLAY

EXHIBIT

EXPOSE

REVEAL

The Tower of Babel by Pieter Brueghel the Elder (1563)

Every developer can create their own new intents:

OpenIntents.org

● Discussion group since 2007● All about open applications and interoperability● Open source● List of Android libraries● Intents registry

● Backed by OpenIntents UG (haftungsbeschränkt)– Closed source apps– Organizer of droidcon

Intent registrywww.openintents.org

Browse and findintents, actions, applications, URIs, extras

Promote your ownintents and applications

As of January 2010: >50 registered intents

Reuse components! Don't reinvent the wheel!

Dependency Manager (1)● Intents create dependencies

between components● Standard implementation:

– run-time dependency checklate binding

– nearly constantly connected– Programs handles missing components

e.g. direct user to app store or explain missing feature

Dependency Manager (2)

● Components that rely on dependent components– A la distro package managers– Light-weight, late binding still possible– Helper library– Declaration in Manifest.xml uses-intent

● Resolution helper with UI– Interface to various sources, e.g. app stores,

personal listings, etc.

droidcon 2010Brussels, Berlin

Barcelona, London

All information at droidcon.be and droidcon.deFree barcampConference

Participate as speaker, sponsor or attendeeGet in touch with Android community

and decision makersPresent and discuss ideas and results

More info

Web site: www.openintents.org

Developer group: http://groups.google.com/group/openintentsCode repository: http://openintents.googlecode.comTwitter: http://twitter.com/openintents