Add documentation for Engine Connection Manager

.gitignore

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 # log folder
 *.log
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-nohup.out
+nohup.out
+
+# for claude
+.claude

docs/modules/README.md

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+# Apache Linkis Service Modules
+
+## Overview
+
+Apache Linkis is built using a microservices architecture and can be categorized into three service types:
+
+1. **Microservice Governance Services**: Infrastructure services including service discovery, API gateway, and service communication
+2. **Computation Governance Services**: Core services for computation task lifecycle management
+3. **Public Enhancement Services**: Shared services that provide common capabilities across the platform
+
+Each service type contains multiple actual deployable Java applications (sub-modules) that work together to provide the complete functionality.
+
+## Service Structure
+
+Based on the actual deployment structure, the services are organized as follows:
+
+### Microservice Governance Services
+These are the infrastructure services that provide the foundation for the microservices architecture:
+- [Eureka Service](./microservice-governance/eureka.md) - Service registry and discovery
+- [Gateway Service](./microservice-governance/gateway.md) - API gateway for request routing
+
+### Computation Governance Services
+These services handle the core computation task lifecycle:
+- [Entrance Service](./computation-governance/entrance.md) - Task submission and entrance point
+- [Manager Service](./computation-governance/manager.md) - Resource and application management
+- [ECM Service](./computation-governance/ecm.md) - Engine Connection Manager
+- [JobHistory Service](./computation-governance/jobhistory.md) - Task execution history tracking
+
+### Public Enhancement Services
+These services provide shared capabilities used across the platform:
+- [Public Service](./public-enhancements/publicservice.md) - Core public services
+- [Configuration Service](./public-enhancements/configuration.md) - Configuration management
+- [BML Service](./public-enhancements/bml.md) - Big Data Material Library
+- [DataSource Service](./public-enhancements/datasource.md) - Data source management
+- [Context Service](./public-enhancements/context.md) - Context and variable sharing
+- [Monitor Service](./microservice-governance/monitor.md) - System monitoring
+
+## RPC Development Example
+
+Linkis uses RPC (Remote Procedure Call) for inter-service communication. Here's a basic example of how to use RPC in Linkis:
+
+```java
+// Get sender for target service
+Sender sender = Sender.getSender("linkis-publicservice");
+
+// Create request protocol
+InsLabelAttachRequest request = new InsLabelAttachRequest();
+request.setServiceInstance(serviceInstance);
+request.setLabels(labels);
+
+// Send request via RPC
+sender.ask(request);
+```
+
+## Documentation Structure
+
+Each service module documentation includes:
+- API interfaces
+- Database table structures
+- RPC methods provided to other services

docs/modules/computation-governance/README.md

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+# Computation Governance Services
+
+The computation governance services handle the core computation task lifecycle management in Linkis.
+
+## Service Modules
+
+- [Entrance Service](./entrance.md) - Task submission and entrance point
+- [Manager Service](./manager.md) - Resource and application management
+- [ECM Service](./ecm.md) - Engine Connection Manager
+- [JobHistory Service](./jobhistory.md) - Task execution history tracking
+
+## Overview
+
+These services form the core of Linkis' computation governance capabilities, managing the complete lifecycle of computation tasks from submission to execution and monitoring.
+
+## Common Features
+
+### Task Lifecycle Management
+- Task submission and validation
+- Task scheduling and resource allocation
+- Task execution monitoring
+- Task result management
+- Task error handling and recovery
+
+### Engine Management
+- Dynamic engine connection creation
+- Engine lifecycle management
+- Engine resource monitoring
+- Engine scaling capabilities
+
+### Resource Governance
+- Multi-tenant resource isolation
+- Load balancing across engines
+- Resource usage tracking
+- Quota management
+
+## API Interface Summary
+
+### Entrance Service APIs
+- Task submission: `POST /api/entrance/submit`
+- Task status query: `GET /api/entrance/{id}/status`
+- Task progress: `GET /api/entrance/{id}/progress`
+- Task log retrieval: `GET /api/entrance/{id}/log`
+- Task cancellation: `GET /api/entrance/{id}/kill`
+
+### Manager Service APIs
+- Engine instance management
+- Resource allocation and monitoring
+- Node status querying
+- Engine creation requests
+
+### ECM Service APIs
+- Engine connection management
+- Engine lifecycle operations
+- Resource reporting
+- Engine metrics collection
+
+### JobHistory Service APIs
+- Job history querying
+- Job detail retrieval
+- Job statistics reporting
+
+## Database Schema Summary
+
+### Job History Group Table
+```sql
+CREATE TABLE `linkis_ps_job_history_group_history` (
+  `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT 'Primary Key, auto increment',
+  `job_req_id` varchar(64) DEFAULT NULL COMMENT 'job execId',
+  `submit_user` varchar(50) DEFAULT NULL COMMENT 'who submitted this Job',
+  `execute_user` varchar(50) DEFAULT NULL COMMENT 'who actually executed this Job',
+  `source` text DEFAULT NULL COMMENT 'job source',
+  `labels` text DEFAULT NULL COMMENT 'job labels',
+  `params` text DEFAULT NULL COMMENT 'job params',
+  `progress` varchar(32) DEFAULT NULL COMMENT 'Job execution progress',
+  `status` varchar(50) DEFAULT NULL COMMENT 'Script execution status, must be one of the following: Inited, WaitForRetry, Scheduled, Running, Succeed, Failed, Cancelled, Timeout',
+  `log_path` varchar(200) DEFAULT NULL COMMENT 'File path of the job log',
+  `error_code` int DEFAULT NULL COMMENT 'Error code. Generated when the execution of the script fails',
+  `error_desc` varchar(1000) DEFAULT NULL COMMENT 'Execution description. Generated when the execution of script fails',
+  `created_time` datetime(3) DEFAULT CURRENT_TIMESTAMP(3) COMMENT 'Creation time',
+  `updated_time` datetime(3) DEFAULT CURRENT_TIMESTAMP(3) COMMENT 'Update time',
+  `instances` varchar(250) DEFAULT NULL COMMENT 'Entrance instances',
+  `metrics` text DEFAULT NULL COMMENT 'Job Metrics',
+  `engine_type` varchar(32) DEFAULT NULL COMMENT 'Engine type',
+  `execution_code` text DEFAULT NULL COMMENT 'Job origin code or code path',
+  `result_location` varchar(500) DEFAULT NULL COMMENT 'File path of the resultsets',
+  `observe_info` varchar(500) DEFAULT NULL COMMENT 'The notification information configuration of this job',
+  PRIMARY KEY (`id`),
+  KEY `idx_created_time` (`created_time`),
+  KEY `idx_submit_user` (`submit_user`)
+);
+```
+
+### Job History Detail Table
+```sql
+CREATE TABLE `linkis_ps_job_history_detail` (
+  `id` bigint(20) NOT NULL AUTO_INCREMENT COMMENT 'Primary Key, auto increment',
+  `job_history_id` bigint(20) NOT NULL COMMENT 'ID of JobHistory',
+  `result_location` varchar(500) DEFAULT NULL COMMENT 'File path of the resultsets',
+  `execution_content` text DEFAULT NULL COMMENT 'The script code or other execution content executed by this Job',
+  `result_array_size` int(4) DEFAULT 0 COMMENT 'size of result array',
+  `job_group_info` text DEFAULT NULL COMMENT 'Job group info/path',
+  `created_time` datetime(3) DEFAULT CURRENT_TIMESTAMP(3) COMMENT 'Creation time',
+  `updated_time` datetime(3) DEFAULT CURRENT_TIMESTAMP(3) COMMENT 'Update time',
+  `status` varchar(32) DEFAULT NULL COMMENT 'status',
+  `priority` int(4) DEFAULT 0 COMMENT 'order of subjob',
+  PRIMARY KEY (`id`)
+);
+```
+
+### Common Lock Table
+```sql
+CREATE TABLE `linkis_ps_common_lock` (
+  `id` int(11) NOT NULL AUTO_INCREMENT,
+  `lock_object` varchar(255) COLLATE utf8_bin DEFAULT NULL,
+  `locker` VARCHAR(255) CHARSET utf8mb4 COLLATE utf8mb4_bin DEFAULT NULL COMMENT 'locker',
+  `time_out` longtext COLLATE utf8_bin,
+  `update_time` datetime DEFAULT CURRENT_TIMESTAMP,
+  `create_time` datetime DEFAULT CURRENT_TIMESTAMP,
+  PRIMARY KEY (`id`),
+  UNIQUE KEY `uniq_lock_object` (`lock_object`)
+);
+```
+
+## RPC Methods Summary
+
+### Entrance Service RPCs
+- `submitTask(TaskRequest request)`
+- `getTaskStatus(String taskId)`
+- `cancelTask(String taskId)`
+- `getTaskResult(String taskId)`
+
+### Manager Service RPCs
+- `requestEngine(EngineRequest request)`
+- `releaseEngine(String engineId)`
+- `getEngineStatus(String engineId)`
+- `getNodeMetrics(String nodeId)`
+
+### ECM Service RPCs
+- `createEngineConnection(EngineCreateRequest request)`
+- `terminateEngineConnection(String engineId)`
+- `reportEngineResourceUsage(String engineId, ResourceUsage usage)`
+- `getEngineMetrics(String engineId)`
+
+### JobHistory Service RPCs
+- `saveJobHistory(JobHistory history)`
+- `queryJobHistory(JobHistoryQuery query)`
+- `getJobDetails(Long jobId)`
+- `updateJobStatus(Long jobId, String status)`
+
+## Dependencies
+
+- linkis-commons - Shared utilities
+- linkis-protocol - Communication protocols
+- linkis-rpc - Remote procedure calls
+- Various engine connection plugins
+- Spring Cloud ecosystem