Rewrite BlazeGraph connection guide with practical instructions

docs/guides/connecting-to-blazegraph.md

@@ -2,5 +2,96 @@
 
 # Connecting to BlazeGraph
 
-- Build and run the Docker container as normal and connect Graph Explorer to BlazeGraph through the proxy server.
-- If using Docker, ensure that the container running Graph Explorer can properly access the container running BlazeGraph. You can find documentation on how to connect containers via [Docker networks](https://docs.docker.com/network/).
+[BlazeGraph](https://blazegraph.com/) is an open-source RDF graph database that supports the SPARQL query language. Graph Explorer connects to BlazeGraph through its SPARQL endpoint.
+
+> [!NOTE]
+>
+> BlazeGraph 2.1.5 is the final release. The project is no longer actively maintained.
+
+## Running BlazeGraph with Docker
+
+Pull and run the BlazeGraph Docker image:
+
+```
+docker run -d -p 9999:9999 --name blazegraph lyrasis/blazegraph:2.1.5
+```
+
+You can verify BlazeGraph is running by visiting `http://localhost:9999/blazegraph/` in your browser.
+
+## Connecting Graph Explorer
+
+Open Graph Explorer and add a new connection with the following settings:
+
+- Name: `BlazeGraph`
+- Query Language: `SPARQL`
+- Public or Proxy Endpoint: `https://localhost`
+- Using Proxy Server: `true`
+- Graph Connection URL: `http://localhost:9999/blazegraph/namespace/kb/sparql`
+
+| Setting                      | Description                                                                       |
+| ---------------------------- | --------------------------------------------------------------------------------- |
+| **Public or Proxy Endpoint** | The URL where Graph Explorer is accessible in your browser.                       |
+| **Using Proxy Server**       | Enables the Graph Explorer proxy server, which forwards requests to the database. |
+| **Graph Connection URL**     | The full URL to the BlazeGraph SPARQL endpoint, including the namespace path.     |
+
+> [!NOTE]
+>
+> The default namespace in BlazeGraph is `kb`. If you created a custom namespace, replace `kb` with your namespace name in the Graph Connection URL.
+
+## Running Graph Explorer with Docker
+
+If Graph Explorer is also running as a Docker container, it needs to be on the same network as BlazeGraph:
+
+```
+docker network create graph-net
+docker run -d -p 9999:9999 --name blazegraph --network graph-net lyrasis/blazegraph:2.1.5
+docker run -p 80:80 -p 443:443 \
+  --name graph-explorer \
+  --network graph-net \
+  --restart unless-stopped \
+  --env HOST=localhost \
+  public.ecr.aws/neptune/graph-explorer
+```
+
+| Option                     | Description                                                                                       |
+| -------------------------- | ------------------------------------------------------------------------------------------------- |
+| `-p 80:80 -p 443:443`      | Maps HTTP and HTTPS ports from the container to the host.                                         |
+| `--network graph-net`      | Connects the container to the shared Docker network so it can reach BlazeGraph by container name. |
+| `--restart unless-stopped` | Automatically restarts the container on failure or host reboot, unless explicitly stopped.        |
+| `--env HOST=localhost`     | Sets the hostname used in the self-signed TLS certificate generated by Graph Explorer.            |
+
+When both containers are on the same network, update the **Graph Connection URL** to use the container name: `http://blazegraph:9999/blazegraph/namespace/kb/sparql`
+
+For more details on container networking, see the [Docker networks documentation](https://docs.docker.com/network/).
+
+## Troubleshooting
+
+### Schema sync fails or queries return errors
+
+Verify that the SPARQL endpoint is reachable by testing it directly:
+
+```
+curl -X POST http://localhost:9999/blazegraph/namespace/kb/sparql \
+  -H "Content-Type: application/x-www-form-urlencoded" \
+  -d "query=SELECT * WHERE { ?s ?p ?o } LIMIT 1"
+```
+
+If this returns SPARQL results, BlazeGraph is working correctly. If it returns a 404, check that the namespace in the URL matches your BlazeGraph configuration.
+
+### Connection refused between containers
+
+If Graph Explorer cannot reach BlazeGraph, verify all containers are on the same Docker network:
+
+```
+docker network inspect graph-net
+```
+
+The default `localhost` address does not work between Docker containers. Use container names (e.g., `blazegraph`) as hostnames instead.
+
+### BlazeGraph UI not accessible
+
+If you cannot reach `http://localhost:9999/blazegraph/` in your browser, check that the container is running:
+
+```
+docker ps --filter name=blazegraph
+```