ipc: aidl is not a curse

IPC: AIDL is not a curse

Or how to eat it a binder and stay alive

Yonatan Levin

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What we going to do?

Having fun!

What we going to do?

● Good fellows with IPC

● Best friends with Binder

● Fall in love with AIDL

● Service with AIDL on separate process

example

Source Code

https://github.com/parahall/AIDLServiceExample.git

What is IPC

Inter-process communication (IPC) is a framework for the exchange of signals and data across multiple processes

Binder, IPC best friend

Binder, IPC best friend

Binder, IPC best friend

Bin

der

Why Binder?

PerformanceSecurityStabilityMemory managementSingle app with separate process

Why separate process?

- GC not affecting your app- Less chance to be killed:

- Process that serve others ranking at least as someone he serve

- Process with Service > Process with Background activities

- Crashing not affecting others- New Heap Space- We can! :)

Binder benefits

● Thread migration● Identifying senders to receivers● Unique object-mapping across process● AIDL!!!!● Bult-in support for marshalling● Local execution mode (no IPC) if same

process

We already using binder today!

LifeCycle callbacks (onResume, OnDestroy) invoked by ActivityManagerService

Intents

Content Provider

IPC with Intents and Content Provider

Example of Intent

So why not to use only intents

Not really OOPAsync onlyLoosely-definedNot so fastHigh Level Abstraction of Binder

Other alternatives

IPC with Messenger!!!

Messenger

● A reference to a Handler that can be sent to a remote process via an Intent

● Messages sent by the remote process via the messenger are delivered to the local handler

● Relatively fast

Messenger IPC

git checkout MessengerIPC

DarthVaderActivity

DarthVaderActivity - Cont’

EmpireService

EmpireService - Cont’

But what if?

We want sync calls?Very fast. Like really fast!Full OOPBusiness Transparent

AIDLbut … first let’s dive into Binder

Binder API

A long time ago in a galaxy far, far away....

A new hope - Builder

Steel the plans of binder

A manager that can save galaxy

And restore freedom to the galaxy....

Now you can breath easily

we have AIDL

AIDL

Our business operation on top of Binder object

Java-like interface

Defined in separate .aidl file

Aidl Generate code of real java interface

.AIDL interface and result

Directional FLAG● in means that the object is transferred from client to

service and only used for inputs. If any changes are made to the bar object in the service then they won’t reflect in the client.

● out indicates that the object has no relevant data and will be populated by the service and returned as a response.

● inout means that the data gets copied, i.e., if any changes are made to bar in the service then that’ll also reflect in the client’s bar object.

AIDL Data Types

All primitives and arrays of primitivesFileDescriptionSerializable/Parcelable****MapBundleListSparseArray

Ladies and Gentlemen - Full

Solution

git checkout ServiceViaAIDL

Sync Call - Death Star

IStarWarsImplementation

EmpireService

DarthVaderActivity

DarthVaderActivity

ASync Call - Find a luke

AIDL Interfaces

IStarWarsImplementation

DarthVaderActivity

So what we got?

Services running on separate processEasy expandable communicationFun :)

Special credits

Binder: Communication Mechanism of Android ProcessesDeep Dive into Android IPC/Binder Framework at AnDevCon IV by Aleksandar Gargentahttp://giphy.com/ for amazyng gifsAndroid API Guides

levinyon@gmail.com+972503456408

facebook.com/levin.yonatan