Akka Scala 学习高清原版pdf

Akka Scala Documentation

Release 2.3.4

Typesafe Inc

June 30, 2014

CONTENTS

1 Introduction 1

1.1 What is Akka? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2 Why Akka? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

1.3 Getting Started . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2.3 What is an Actor? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

2.4 Supervision and Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

2.5 Actor References, Paths and Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

2.6 Location Transparency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

2.7 Akka and the Java Memory Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

2.8 Message Delivery Reliability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

2.9 Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

3 Actors 69

3.1 Actors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

3.2 Typed Actors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

3.9 Testing Actor Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149

3.10 Actor DSL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165

4 Futures and Agents 167

4.1 Futures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167

4.2 Agents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 173

5 Networking 177

5.1 Cluster Specification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 177

5.2 Cluster Usage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185

5.3 Remoting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204

5.4 Serialization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213

6 Utilities 245

6.1 Event Bus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245

6.2 Logging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250

6.3 Scheduler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257

6.4 Duration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 260

6.5 Circuit Breaker . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 261

6.6 Akka Extensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265

6.7 Microkernel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 267

7 HowTo: Common Patterns 269

7.1 Throttling Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 269

7.8 Case Study: An Auto-Updating Cache Using Actors . . . . . . . . . . . . . . . . . . . . . . . . 270

7.9 Discovering message flows in actor systems with the Spider Pattern . . . . . . . . . . . . . . . . 271

7.10 Scheduling Periodic Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 271

7.11 Template Pattern . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 272

8 Experimental Modules 273

8.1 Persistence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 273

8.2 Multi Node Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288

8.3 Actors (Java with Lambda Support) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 293

8.4 FSM (Java with Lambda Support) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312

8.5 External Contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321

9.6 Team . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 360

10 Project Information 361

10.1 Migration Guides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 361

10.2 Issue Tracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 371

10.3 Licenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 372

10.4 Sponsors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 372

10.5 Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 372

11 Additional Information 375

11.1 Frequently Asked Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 375

11.2 Books . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 378

1.1 What is Akka?

Scalable real-time transaction processing

We believe that writing correct concurrent, fault-tolerant and scalable applications is too hard. Most of the time it’s

because we are using the wrong tools and the wrong level of abstraction. Akka is here to change that. Using the

Actor Model we raise the abstraction level and provide a better platform to build scalable, resilient and responsive

applications—see the Reactive Manifesto for more details. For fault-tolerance we adopt the “let it crash” model

which the telecom industry has used with great success to build applications that self-heal and systems that never

stop. Actors also provide the abstraction for transparent distribution and the basis for truly scalable and fault-

tolerant applications.

Akka is Open Source and available under the Apache 2 License.

See the chapter for Scala or Java.

Fault Tolerance

See Fault Tolerance (Scala) and Fault Tolerance (Java).

You can find more details in the respective chapter for Java or Scala.

Akka has both a Scala Documentation and a java-api.

See the Use-case and Deployment Scenarios for details.

Akka is available from Typesafe Inc. under a commercial license which includes development or production

support, read more here.

One thing to learn and admin, with high cohesion and coherent semantics.

Akka is a very scalable piece of software, not only in the context of performance but also in the size of applications

it is useful for. The core of Akka, akka-actor, is very small and easily dropped into an existing project where you

need asynchronicity and lockless concurrency without hassle.

You can choose to include only the parts of akka you need in your application and then there’s the whole package,

the Akka Microkernel, which is a standalone container to deploy your Akka application in. With CPUs growing

more and more cores every cycle, Akka is the alternative that provides outstanding performance even if you’re

only running it on one machine. Akka also supplies a wide array of concurrency-paradigms, allowing users to

choose the right tool for the job.