Visoto

Visoto is a Go web application for browsing and visualizing RDF linked data resources via SPARQL endpoints. It renders resource pages using type-specific templates, supports full-text search, and exposes an MCP server for AI assistant integration.

Visoto is still in development and not all features work properly.

Features

• Resource browser — fetch any RDF resource by IRI; templates are resolved automatically from the resource's rdf:type
• Full-text search — search across linked data resources with class and property filters
• Multi-endpoint support — switch between named SPARQL endpoints (e.g. LINDAS prod/int/test) via a sidebar menu
• Graph Explorer — interactive RDF graph visualization powered by Graph Explorer (Ontodia fork)
• AI chat — ask questions about linked data resources, powered by Google Gemini
• Endpoint monitoring — track SPARQL endpoint availability and response times over time
• MCP server — built-in Model Context Protocol server at /mcp for AI tool integration
• Dark mode — toggle between light and dark themes
• Responsive UI — built with Tabler (Bootstrap 5) and Tabulator for data tables

Prerequisites

• Go 1.21+
• A SPARQL endpoint (default: LINDAS)
• Optional: Google Gemini API key (for the chat feature)

Setup

1. Clone the repo and install dependencies:

   go mod download

2. Create your config file:

   cp visoto.config.example visoto.config

   Edit visoto.config to set your SPARQL endpoint, port, and optional Gemini API key.

3. Run the server:

   go run ./cmd/visoto/

4. Open the app:

   • Web UI: http://localhost:8060
   • Health check: http://localhost:8060/ping
   • MCP server: http://localhost:8060/mcp

Alternative: run with Docker:

docker build -t visoto .
docker run -e GIN_MODE=release -p 8060:8060 \
  -v ./visoto.config:/app/visoto.config:ro \
  visoto

See docs/deployment.md for full production Docker + Caddy setup.

Configuration

Configuration is loaded from visoto.config (TOML format). See visoto.config.example for all options.

Key settings:

Setting	Description	Default
application.port	HTTP port (code default is 8080; example config uses 8060 — set explicitly)	8080
application.sparqlEndpoint	Default SPARQL endpoint URL	—
application.sparqlEndpoints	Named endpoints for the switcher menu	—
application.timeout	SPARQL query timeout (seconds)	30
application.gemini_api_key	Google Gemini API key for chat	—
rdf.prefixes	RDF prefix declarations (SPARQL or Turtle notation)	—
rdf.type_priority	Priority order for template resolution when a resource has multiple types	—
logging.level	Log level: DEBUG, INFO, WARN, ERROR	INFO
mcp.port	MCP port (unused when embedded in main server)	8070
GIN_MODE (env var)	Gin framework mode: debug, release, test	debug

Documentation

Document	Audience
Getting Started	Run locally for the first time
Architecture Overview	Understand how the system fits together
Configuration Reference	All visoto.config fields explained
Template Authoring Guide	Create custom templates for your RDF types
Deployment Guide	Docker + Caddy production setup

Project Structure

cmd/visoto/        — main entry point
internal/
  chat/            — Gemini AI chat handler
  config/          — TOML config loading
  logger/          — structured slog logger
  mcp/             — MCP server (AI tool integration)
  monitor/         — simple SPARQL endpoint health monitoring
  parser/          — SPARQL preprocessor (template → query → result)
  resource/        — RDF resource resolution and template matching
  search/          — full-text search over SPARQL endpoints
  sparql/          — SPARQL query execution
  templates/       — Go template loader
templates/
  layout/          — shared layout templates (base, sidebar, header, footer)
  pages/           — static page templates (home, search, monitoring, …)
  classes/         — class-level RDF templates
  instances/       — instance-level RDF templates
static/            — CSS, JS, images

Routes

Method	Path	Description
GET	/	Home page
GET	/search	Full-text search
GET	/resource/*path	Resource page (IRI-based)
GET	/monitoring	Endpoint monitoring dashboard
GET	/api/monitoring/status	Monitoring status (JSON)
POST	api/monitoring/toggle	Enable/disable monitoring
GET	/api/monitoring/data	Historical monitoring data (JSON)
GET	/api/metric/:id	Lazy-load metric counts (HTMX)
POST	/api/chat	Gemini AI chat
ANY	/mcp	MCP server endpoint
GET	/ping	Health check

Screenshots