| Most of the functionality of Geode is implemented in the subproject gemfire-core. |
| There, under com/gemstone/gemfire you will find an array of packages that |
| hold the public API and also the implementation of those APIs. |
| |
| Here are the main architectural components: |
| |
| - storage (in memory and on disk) |
| - distribution engine (peer to peer messaging) |
| - replication messages and algorithms |
| - clustering service |
| - query engine |
| - transaction service |
| - distributed lock service |
| - function execution service |
| - client/server communication and subscriptions |
| |
| Here are some good starting areas for each component: |
| |
| * **Storage: Region implementation**: `internal/cache` |
| |
| Notable classes are `GemFireCacheImpl`, `LocalRegion`, `DistributedRegion`, |
| `AbstractRegionMap`, and `AbstractRegionEntry`. |
| |
| For partitioned regions start with `PartitionRegion`, `BucketRegion`, |
| `PartitionedRegionDataStore` and `PartitionedRegionHelper`. |
| |
| * **Storage: Persistence**: `internal/cache` and `internal/cache/persistence` |
| |
| Start with `DiskStoreImpl` and `Oplog`. |
| |
| * **Replication Messages**: `internal/cache` |
| |
| Replication is primarly implemented in messaging classes in this |
| package. There are lots of messaging classes here, such as |
| `DistributedCacheOperation` & subclasses, |
| `RemoteOperationMessage` & subclasses, `PartitionMessage` & subclasses, |
| `SearchLoadAndWriteProcessor`, `GetInitialImageOperation` |
| and `StateFlushOperation`. |
| |
| Also look in `CacheDistributionAdvisor` and `RegionAdvisor`. These hold |
| profiles of peers and are used to determine who should receive replication |
| messages. |
| |
| * **Clustering Service**: `distributed/internal` |
| |
| Notable classes in these packages for message distribution are |
| `InternalDistributedSystem`, `DistribuitonManager`, `DistributionMessage`, |
| `ReplyProcessor21`, `JGroupMembershipManager`. All peer-to-peer messages |
| are implemented as subclasses of `DistributionMessage`. |
| |
| * **Query Engine**: `cache/internal/query` |
| |
| Start with `DefaultQueryService`. |
| |
| * **Transaction Service**: `internal/cache` |
| |
| The primary classes are `TXState` and `TXCommitMessage`. |
| |
| * **Distributed Lock Service**: `distributed/internal/locks` |
| |
| `DLockService` and `DLockGrantor` are good classes to begin with. |
| |
| * **Function Execution Engine**: `cache/execute/internal` |
| |
| Start with `FunctionServiceManager` and the subclasses of `AbstractExecution`. |
| |
| * **Client/Server**: `cache/client/internal` and `internal/cache/tier/sockets` |
| |
| `cache/client/internal` contains the client-side code. Look at `ServerRegionProxy`, |
| which hooks into `LocalRegion` (in the `internal/cache` package) to turn it |
| into a client-side `Region`. Classes ending with `Op` perform the actual |
| messaging interaction with servers using the class `OpExecutorImpl`. |
| |
| Subscription feeds are received and handled by `CacheClientUpdater`. |
| |
| On the server side the classes in `internal/cache/tier/sockets` come into |
| play. `AcceptorImpl` accepts connections from clients and `ServerConnection` |
| threads handle individual requests. `CacheClientProxy` sends subscription |
| messages to clients. `CacheClientNotifier` receives events from the `Cache` |
| and hands them to the appropriate proxies. |
| |
| |
| |
| |
