Apache Karaf Cellar 4.x - Documentation

• 语言: 英语
• 格式: .pdf
• 来源: downloads.apache.org

摘要

Apache Karaf Cellar 4.x 是一个用于在多个 Karaf 实例之间同步状态和资源的工具。它支持两种拓扑结构：Cross Topology（默认）和 Star Topology。文档详细介绍了如何安装、部署和管理 Cellar，包括注册特征、启动集群以及配置节点组件。Cellar 提供了分布式 OSGi 运行时环境，支持同步配置、功能和 OSGi 事件，并通过 Hazelcast 实现集群通信和资源管理。

AI总结

### Apache Karaf Cellar 4.x Documentation Summary

#### 1. **Introduction**
- **Purpose**: Karaf Cellar synchronizes the status of multiple Karaf instances (nodes) and provides a distributed OSGi runtime.
- **Features**:
- Synchronizes bundles, configurations, and features.
- Supports distributed OSGi services and advanced clustering (e.g., load balancing, session replication, log centralization).
- Broadcasts local resource changes as cluster events (disabled by default due to potential side effects).
- **Topologies**:
- **Cross Topology**: Default topology where all nodes perform actions and broadcast events.
- **Star Topology**: Actions are performed only on a designated "manager" node, with other nodes acting as consumers.

#### 2. **Installation**
- **Requirements**:
- Java SE Development Kit 1.7.x or higher.
- Apache Maven 3.0.3 or higher.
- **Building**:
- From sources: Extract and build using Maven.
- Platform-specific instructions for Windows and Unix systems.
- **Deployment**:
- Register Cellar features using Karaf's feature repository.
- Start Cellar by installing the feature.

#### 3. **Core Runtime and Hazelcast**
- **Hazelcast**:
- Used for cluster identification and distributed data storage.
- Default configuration uses multicast for node discovery (multicast disabled in later versions).
- **Networking**:
- Configurable for different communication protocols.

#### 4. **Cellar Nodes**
- **Node Identification**:
- Nodes are identified by host and port.
- Use `cluster:node-list` to view nodes and `cluster:node-ping` to test connectivity.
- **Node Components**:
- Components include listeners, producers, handlers, consumers, and synchronizers.
- Synchronizers enforce policies for event propagation.
- **Events**:
- Supported events: Configuration changes, features repository updates, and OSGi EventAdmin (optional).
- Events can be filtered using whitelists and blacklists.

#### 5. **Clustered Resources and Groups**
- **Clustered Resources**:
- Synchronize bundles, configurations, features, and OBR resources.
- **Groups**:
- Groups define distributed memory and event exchange between nodes.
- Configure groups to enable or disable specific events.

#### 6. **Architecture Overview**
- **Key Concepts**:
- Nodes belong to one or more groups.
- Each group has a configuration to control which events are broadcasted.
- Events are propagated via distributed topics provided by the group.
- **Event Types**:
- Configuration changes.
- Features repository additions/removals.
- Features installations/uninstallations.
- Optional support for EventAdmin and OBR events.

#### 7. **Design and Functionality**
- **Distributed Runtime**:
- Enables remote OSGi service calls.
- Provides advanced clustering features like HTTP load balancing and log centralization.
- **Broadcasting**:
- Local changes are broadcasted to the cluster based on group configurations.

#### 8. **Key Commands**
- Node Management:
- `cluster:node-list`: List known nodes.
- `cluster:node-ping`: Test node connectivity.
- Event Blocking:
- Commands like `cluster:feature-block`, `cluster:bundle-block`, and `cluster:config-block` control inbound/outbound events.

#### 9. **OBR Support**
- **Enabling OBR**:
- Install the `cellar-obr` feature to enable OBR synchronization across nodes.

#### 10. **Summary**
- **Karaf Cellar** provides a robust framework for managing distributed Karaf instances, enabling synchronization of resources and distributed OSGi services.
- Key functionalities include cluster node management, event propagation, and advanced clustering features.
- Architecture is based on groups and distributed topics, ensuring efficient event handling and data synchronization.