Update README and config schema

CLAUDE.md

@@ -100,11 +100,15 @@ The backend follows a layered architecture with clear separation of concerns:
   - Pluggable backends: cc-metric-store, Prometheus, InfluxDB
   - Each cluster can have a different metric data backend
 - **internal/archiver**: Job archiving to file-based archive
+- **internal/api/nats.go**: NATS-based API for job and node operations
+  - Subscribes to NATS subjects for job events (start/stop)
+  - Handles node state updates via NATS
+  - Uses InfluxDB line protocol message format
 - **pkg/archive**: Job archive backend implementations
   - File system backend (default)
   - S3 backend
   - SQLite backend (experimental)
-- **pkg/nats**: NATS integration for metric ingestion
+- **pkg/nats**: NATS client and message decoding utilities
 
 ### Frontend Structure
 
@@ -146,6 +150,14 @@ applied automatically on startup. Version tracking in `version` table.
 ## Configuration
 
 - **config.json**: Main configuration (clusters, metric repositories, archive settings)
+  - `main.apiSubjects`: NATS subject configuration (optional)
+    - `subjectJobEvent`: Subject for job start/stop events (e.g., "cc.job.event")
+    - `subjectNodeState`: Subject for node state updates (e.g., "cc.node.state")
+  - `nats`: NATS client connection configuration (optional)
+    - `address`: NATS server address (e.g., "nats://localhost:4222")
+    - `username`: Authentication username (optional)
+    - `password`: Authentication password (optional)
+    - `creds-file-path`: Path to NATS credentials file (optional)
 - **.env**: Environment variables (secrets like JWT keys)
   - Copy from `configs/env-template.txt`
   - NEVER commit this file
@@ -207,9 +219,87 @@ applied automatically on startup. Version tracking in `version` table.
 2. Increment `repository.Version`
 3. Test with fresh database and existing database
 
+## NATS API
+
+The backend supports a NATS-based API as an alternative to the REST API for job and node operations.
+
+### Setup
+
+1. Configure NATS client connection in `config.json`:
+   ```json
+   {
+     "nats": {
+       "address": "nats://localhost:4222",
+       "username": "user",
+       "password": "pass"
+     }
+   }
+   ```
+
+2. Configure API subjects in `config.json` under `main`:
+   ```json
+   {
+     "main": {
+       "apiSubjects": {
+         "subjectJobEvent": "cc.job.event",
+         "subjectNodeState": "cc.node.state"
+       }
+     }
+   }
+   ```
+
+### Message Format
+
+Messages use **InfluxDB line protocol** format with the following structure:
+
+#### Job Events
+
+**Start Job:**
+```
+job,function=start_job event="{\"jobId\":123,\"user\":\"alice\",\"cluster\":\"test\", ...}" 1234567890000000000
+```
+
+**Stop Job:**
+```
+job,function=stop_job event="{\"jobId\":123,\"cluster\":\"test\",\"startTime\":1234567890,\"stopTime\":1234571490,\"jobState\":\"completed\"}" 1234571490000000000
+```
+
+**Tags:**
+- `function`: Either `start_job` or `stop_job`
+
+**Fields:**
+- `event`: JSON payload containing job data (see REST API documentation for schema)
+
+#### Node State Updates
+
+```json
+{
+  "cluster": "testcluster",
+  "nodes": [
+    {
+      "hostname": "node001",
+      "states": ["allocated"],
+      "cpusAllocated": 8,
+      "memoryAllocated": 16384,
+      "gpusAllocated": 0,
+      "jobsRunning": 1
+    }
+  ]
+}
+```
+
+### Implementation Notes
+
+- NATS API mirrors REST API functionality but uses messaging
+- Job start/stop events are processed asynchronously
+- Duplicate job detection is handled (same as REST API)
+- All validation rules from REST API apply
+- Messages are logged; no responses are sent back to publishers
+- If NATS client is unavailable, API subscriptions are skipped (logged as warning)
+
 ## Dependencies
 
 - Go 1.24.0+ (check go.mod for exact version)
 - Node.js (for frontend builds)
 - SQLite 3 (only supported database)
-- Optional: NATS server for metric ingestion
+- Optional: NATS server for NATS API integration

README.md

@@ -22,11 +22,12 @@ switching from PHP Symfony to a Golang based solution are explained
 ## Overview
 
 This is a Golang web backend for the ClusterCockpit job-specific performance
-monitoring framework. It provides a REST API for integrating ClusterCockpit with
+monitoring framework. It provides a REST API and an optional NATS-based messaging
-an HPC cluster batch system and external analysis scripts. Data exchange between
+API for integrating ClusterCockpit with an HPC cluster batch system and external
-the web front-end and the back-end is based on a GraphQL API. The web frontend
+analysis scripts. Data exchange between the web front-end and the back-end is
-is also served by the backend using [Svelte](https://svelte.dev/) components.
+based on a GraphQL API. The web frontend is also served by the backend using
-Layout and styling are based on [Bootstrap 5](https://getbootstrap.com/) using
+[Svelte](https://svelte.dev/) components. Layout and styling are based on
+[Bootstrap 5](https://getbootstrap.com/) using
 [Bootstrap Icons](https://icons.getbootstrap.com/).
 
 The backend uses [SQLite 3](https://sqlite.org/) as the relational SQL database.
@@ -35,6 +36,10 @@ databases, the only tested and supported setup is to use cc-metric-store as the
 metric data backend. Documentation on how to integrate ClusterCockpit with other
 time series databases will be added in the future.
 
+For real-time integration with HPC systems, the backend can subscribe to
+[NATS](https://nats.io/) subjects to receive job start/stop events and node
+state updates, providing an alternative to REST API polling.
+
 Completed batch jobs are stored in a file-based job archive according to
 [this specification](https://github.com/ClusterCockpit/cc-specifications/tree/master/job-archive).
 The backend supports authentication via local accounts, an external LDAP
@@ -130,27 +135,60 @@ ln -s <your-existing-job-archive> ./var/job-archive
 
 ## Project file structure
 
+- [`.github/`](https://github.com/ClusterCockpit/cc-backend/tree/master/.github)
+  GitHub Actions workflows and dependabot configuration for CI/CD.
 - [`api/`](https://github.com/ClusterCockpit/cc-backend/tree/master/api)
   contains the API schema files for the REST and GraphQL APIs. The REST API is
   documented in the OpenAPI 3.0 format in
-  [./api/openapi.yaml](./api/openapi.yaml).
+  [./api/swagger.yaml](./api/swagger.yaml). The GraphQL schema is in
+  [./api/schema.graphqls](./api/schema.graphqls).
 - [`cmd/cc-backend`](https://github.com/ClusterCockpit/cc-backend/tree/master/cmd/cc-backend)
-  contains `main.go` for the main application.
+  contains the main application entry point and CLI implementation.
 - [`configs/`](https://github.com/ClusterCockpit/cc-backend/tree/master/configs)
   contains documentation about configuration and command line options and required
-  environment variables. A sample configuration file is provided.
+  environment variables. Sample configuration files are provided.
-- [`docs/`](https://github.com/ClusterCockpit/cc-backend/tree/master/docs)
-  contains more in-depth documentation.
 - [`init/`](https://github.com/ClusterCockpit/cc-backend/tree/master/init)
   contains an example of setting up systemd for production use.
 - [`internal/`](https://github.com/ClusterCockpit/cc-backend/tree/master/internal)
   contains library source code that is not intended for use by others.
+  - [`api`](https://github.com/ClusterCockpit/cc-backend/tree/master/internal/api)
+    REST API handlers and NATS integration
+  - [`archiver`](https://github.com/ClusterCockpit/cc-backend/tree/master/internal/archiver)
+    Job archiving functionality
+  - [`auth`](https://github.com/ClusterCockpit/cc-backend/tree/master/internal/auth)
+    Authentication (local, LDAP, OIDC) and JWT token handling
+  - [`config`](https://github.com/ClusterCockpit/cc-backend/tree/master/internal/config)
+    Configuration management and validation
+  - [`graph`](https://github.com/ClusterCockpit/cc-backend/tree/master/internal/graph)
+    GraphQL schema and resolvers
+  - [`importer`](https://github.com/ClusterCockpit/cc-backend/tree/master/internal/importer)
+    Job data import and database initialization
+  - [`memorystore`](https://github.com/ClusterCockpit/cc-backend/tree/master/internal/memorystore)
+    In-memory metric data store with checkpointing
+  - [`metricdata`](https://github.com/ClusterCockpit/cc-backend/tree/master/internal/metricdata)
+    Metric data repository implementations (cc-metric-store, Prometheus)
+  - [`metricDataDispatcher`](https://github.com/ClusterCockpit/cc-backend/tree/master/internal/metricDataDispatcher)
+    Dispatches metric data loading to appropriate backends
+  - [`repository`](https://github.com/ClusterCockpit/cc-backend/tree/master/internal/repository)
+    Database repository layer for jobs and metadata
+  - [`routerConfig`](https://github.com/ClusterCockpit/cc-backend/tree/master/internal/routerConfig)
+    HTTP router configuration and middleware
+  - [`tagger`](https://github.com/ClusterCockpit/cc-backend/tree/master/internal/tagger)
+    Job classification and application detection
+  - [`taskmanager`](https://github.com/ClusterCockpit/cc-backend/tree/master/internal/taskmanager)
+    Background task management and scheduled jobs
 - [`pkg/`](https://github.com/ClusterCockpit/cc-backend/tree/master/pkg)
   contains Go packages that can be used by other projects.
+  - [`archive`](https://github.com/ClusterCockpit/cc-backend/tree/master/pkg/archive)
+    Job archive backend implementations (filesystem, S3)
+  - [`nats`](https://github.com/ClusterCockpit/cc-backend/tree/master/pkg/nats)
+    NATS client and message handling
 - [`tools/`](https://github.com/ClusterCockpit/cc-backend/tree/master/tools)
   Additional command line helper tools.
   - [`archive-manager`](https://github.com/ClusterCockpit/cc-backend/tree/master/tools/archive-manager)
-    Commands for getting infos about and existing job archive.
+    Commands for getting infos about an existing job archive.
+  - [`archive-migration`](https://github.com/ClusterCockpit/cc-backend/tree/master/tools/archive-migration)
+    Tool for migrating job archives between formats.
   - [`convert-pem-pubkey`](https://github.com/ClusterCockpit/cc-backend/tree/master/tools/convert-pem-pubkey)
     Tool to convert external pubkey for use in `cc-backend`.
   - [`gen-keypair`](https://github.com/ClusterCockpit/cc-backend/tree/master/tools/gen-keypair)
@@ -162,7 +200,7 @@ ln -s <your-existing-job-archive> ./var/job-archive
   - [`frontend`](https://github.com/ClusterCockpit/cc-backend/tree/master/web/frontend)
     Svelte components and static assets for the frontend UI
   - [`templates`](https://github.com/ClusterCockpit/cc-backend/tree/master/web/templates)
-    Server-side Go templates
+    Server-side Go templates, including monitoring views
 - [`gqlgen.yml`](https://github.com/ClusterCockpit/cc-backend/blob/master/gqlgen.yml)
   Configures the behaviour and generation of
   [gqlgen](https://github.com/99designs/gqlgen).

configs/config-demo.json

@@ -5,14 +5,9 @@
     "resampling": {
       "minimumPoints": 600,
       "trigger": 180,
-      "resolutions": [
+      "resolutions": [240, 60]
-        240,
-        60
-      ]
     },
-    "apiAllowedIPs": [
+    "apiAllowedIPs": ["*"],
-      "*"
-    ],
     "emission-constant": 317
   },
   "cron": {
@@ -103,4 +98,5 @@
       }
     ]
   }
-}
+}
+

configs/config.json

@@ -15,6 +15,10 @@
         240,
         60
       ]
+    },
+    "apiSubjects": {
+      "subjectJobEvent": "cc.job.event",
+      "subjectNodeState": "cc.node.state"
     }
   },
   "cron": {

internal/config/schema.go

@@ -119,6 +119,21 @@ var configSchema = `
         }
       },
       "required": ["trigger", "resolutions"]
+    },
+    "apiSubjects": {
+      "description": "NATS subjects configuration for subscribing to job and node events.",
+      "type": "object",
+      "properties": {
+        "subjectJobEvent": {
+          "description": "NATS subject for job events (start_job, stop_job)",
+          "type": "string"
+        },
+        "subjectNodeState": {
+          "description": "NATS subject for node state updates",
+          "type": "string"
+        }
+      },
+      "required": ["subjectJobEvent", "subjectNodeState"]
     }
 	},
   "required": ["apiAllowedIPs"]