OSGi in Depth

OSGi in Depth......Page 1
brief contents......Page 6
contents......Page 8
foreword......Page 14
preface......Page 16
acknowledgments......Page 17
about this book......Page 19
Roadmap......Page 20
Author Online......Page 21
about the cover illustration......Page 22
1 OSGi as a new platform for application development......Page 24
1.1 What are development platforms and application frameworks?......Page 25
1.1.2 Enterprise platforms......Page 26
1.2.1 The problem domain......Page 27
1.2.2 The solution: a dynamic module system for Java......Page 29
1.2.3 The Enterprise OSGi......Page 31
1.3.1 OSGi manages the complexity of large systems......Page 32
1.3.2 OSGi provides extensibility without eroding the system......Page 34
1.3.4 OSGi allows for portability......Page 35
1.4 Building blocks: the essence of OSGi......Page 36
1.5 Players......Page 37
1.6 Are we starting from scratch?......Page 38
1.7 Summary......Page 39
2 An OSGi framework primer......Page 40
2.1 Modules and information hiding......Page 41
2.1.1 Establishing a formal import/export contract......Page 42
2.1.2 Activating a bundle......Page 44
2.2.1 Apache Felix, the open source OSGi framework......Page 45
2.2.2 Building OSGi bundles......Page 46
2.2.3 Installing bundles into Felix......Page 48
2.2.4 Starting the bundles in Felix......Page 49
2.2.5 Can we cheat using reflection?......Page 50
2.3.1 Changing a bundle’s interface......Page 52
2.3.2 Versioning bundles......Page 53
2.3.3 Changing a module’s implementation......Page 60
2.4 Services and loose coupling......Page 62
2.4.1 The Printer service......Page 63
2.4.2 Registering a service in the OSGi service registry......Page 64
2.4.3 Looking up a service from the OSGi service registry......Page 67
2.4.4 Running OSGi service-oriented applications......Page 70
2.5 The OSGi layered architecture......Page 75
2.6 Summary......Page 76
3 The auction application: an OSGi case study......Page 77
3.1 Establishing the requirements for an auction system......Page 78
3.2 Modularization and extensibility as application requirements......Page 79
3.3 Defining the interfaces......Page 80
3.3.1 Using service properties......Page 82
3.3.2 Implementing the seller module......Page 84
3.3.3 Avoiding temporal cohesion between bundles......Page 87
3.3.4 The registry design pattern......Page 90
3.4 Defining the extension points......Page 91
3.4.1 Developing our first auction extension......Page 93
3.4.2 Whiteboard design pattern......Page 96
3.4.3 Keeping service properties immutable......Page 98
3.4.4 Developing the auditor extension......Page 99
3.5 Putting it all together......Page 101
3.5.1 Semantic versioning......Page 106
3.6 The OSGi HTTP service......Page 107
3.6.1 Developing an HTTP buyer......Page 108
3.6.2 Testing the auction application......Page 111
3.8 Summary......Page 114
4 In-depth look at bundles and services......Page 116
4.1.2 Excluding classes from an exported package......Page 117
4.1.3 Avoiding split packages......Page 119
4.2 Expanding a bundle’s export contract......Page 120
4.2.2 Optional packages......Page 122
4.2.3 Fragment bundles......Page 124
4.3 Packages as requirements and capabilities......Page 126
4.4.1 Don’t forget to import the package!......Page 128
4.4.2 Keeping class space consistency......Page 129
4.5 Understanding OSGi’s class loading......Page 135
4.6 Decoupling bundles using services......Page 137
4.6.1 Advanced service filtering......Page 138
4.6.2 Prioritizing services......Page 140
4.6.3 Uniquely identifying services......Page 143
4.6.4 Service factories......Page 145
4.7.1 Unit tests......Page 149
4.7.2 Integration tests......Page 151
4.8 Summary......Page 153
5 Configuring OSGi applications......Page 154
5.1.1 The Notification Broker service......Page 155
5.1.2 Configuring the port of the notification broker......Page 156
5.2.1 The target service......Page 158
5.2.2 The configuring bundle......Page 161
5.2.4 Finding the Configuration service using bundle repositories......Page 163
5.3 Configuring using complex data types......Page 165
5.4 Deleting configuration......Page 166
5.5.1 Configuring bundle for configuration factories......Page 168
5.5.2 Managed service factories......Page 169
5.6 When configuration update fails......Page 172
5.6.1 Log listener......Page 173
5.7 Management agents......Page 174
5.7.2 The metadata provider......Page 175
5.7.3 The metadata consumer......Page 179
5.7.5 Achieving atomicity across configuration updates......Page 181
5.8 Summary......Page 182
6 A world of events......Page 184
6.1 The publish-subscribe model......Page 185
6.2 The Event Admin......Page 187
6.2.1 Topics......Page 188
6.2.2 Event object......Page 190
6.3.1 Blocking dispatch and event-delivery guarantees......Page 192
6.3.2 Hierarchical topic names......Page 196
6.3.3 Event filtering......Page 197
6.3.4 Predefined event properties......Page 198
6.4.1 Losing events......Page 199
6.4.2 Feeble filtering......Page 200
6.5 Decoupling using events......Page 201
6.6 OSGi framework events......Page 203
6.6.1 Accessing a bundle’s content......Page 206
6.6.2 The extender pattern......Page 207
6.6.3 Subscribing to OSGi events using the Event Admin......Page 210
6.7 Summary......Page 211
7 The persistence bundle......Page 212
7.1 Bundle’s storage area......Page 213
7.2.1 Bootstrapping JDBC drivers......Page 215
7.2.3 Consuming OSGi-aware JDBC drivers......Page 216
7.3 Object-relation mapping through JPA......Page 218
7.3.1 JPA annotations......Page 222
7.3.2 Distilling JPA......Page 224
7.4 Summary......Page 226
8 Transactions and containers......Page 228
8.1 Undoing work......Page 229
8.2 Transactions......Page 231
8.2.1 Global transactions......Page 232
8.2.2 Transaction providers......Page 234
8.3 Containers......Page 235
8.3.1 Error handling......Page 241
8.3.2 User transactions......Page 242
8.4 Summary......Page 244
9 Blending OSGi and Java EE using JNDI......Page 245
9.2 Understanding Java’s yellow pages......Page 246
9.2.1 Looking up objects......Page 247
9.2.2 Binding objects......Page 249
9.2.3 Naming federations......Page 250
9.3 Establishing the initial context......Page 252
9.3.1 Initial contexts in OSGi......Page 254
9.4 Handling object conversions......Page 257
9.4.1 Converting JNDI objects to be OSGi aware......Page 259
9.5 Exposing OSGi services in JNDI......Page 263
9.5.1 Registering URL context factories......Page 265
9.5.2 Registering URL context factories in OSGi......Page 266
9.6 Embedding OSGi......Page 267
9.6.1 Bridging JNDI......Page 268
9.7 Summary......Page 270
10 Remote services and the cloud......Page 272
10.1.1 Exporting a remote service......Page 273
10.1.2 Consuming a remote service......Page 274
10.2 Distribution providers......Page 275
10.2.1 Selecting the proper endpoint......Page 277
10.2.2 Negotiating policies......Page 278
10.3 Dealing with the semantics of distributed systems......Page 281
10.4 Elasticity at the cloud......Page 283
10.4.1 Designing for the cloud......Page 284
10.4.2 Cloud computing......Page 287
10.4.3 OSGi as the cloud platform......Page 288
10.5 Summary......Page 291
11 Launching OSGi using start levels......Page 293
11.1 Managing disorderly bundles......Page 294
11.2.1 Bootstrapping the OSGi framework......Page 296
11.2.2 The Start-Level service......Page 297
11.2.3 Safe-mode boot......Page 301
11.2.5 A transient start of a bundle......Page 302
11.2.6 A lazy start of a bundle......Page 303
11.3 Deploying applications......Page 305
11.3.1 Updating features......Page 306
11.3.2 Updating extensions......Page 310
11.3.3 Deploying file install using OBR......Page 312
11.3.4 The File Install service......Page 314
11.4 Simplifying launching of the framework......Page 315
11.5 Summary......Page 318
12 Managing with JMX......Page 320
12.1 Java’s management API......Page 321
12.2 Managing bundles......Page 323
12.3 Managing services......Page 326
12.4 Managing import and export packages......Page 327
12.5 Managing an OSGi framework instance......Page 328
12.6 Management notifications......Page 330
12.7 Managing bundle configuration......Page 334
12.8 OSGi JMX patterns......Page 336
12.9 Summary......Page 337
13 Putting it all together by extending Blueprint......Page 339
13.1 Application bundles and their containers......Page 340
13.1.2 Implementing the SAB container......Page 341
13.2 Declarative assembly using Blueprint......Page 345
13.3 Extending Blueprint......Page 348
13.3.1 Extending Blueprint with namespaces......Page 350
13.3.2 Intercepting Blueprint......Page 359
13.4.1 Using the Event Admin service......Page 364
13.4.2 Using JPA......Page 369
13.4.3 Using the Configuration Admin service and Blueprint......Page 372
13.6 Epilogue......Page 377
OSGi manifest headers......Page 379
A......Page 383
C......Page 384
D......Page 385
F......Page 386
J......Page 387
M......Page 388
O......Page 389
R......Page 390
S......Page 391
T......Page 392
Z......Page 393
OSGi-back......Page 394