Example for using DAG-PB for storing multiple chunks (#85)

* Example for using DAG-PB for storing multiple chunks (TODO: needs polish)

* Fixed DAG file type?

* Some progress with DAG stuff (almost working)

* Stored chunked file and retrieve

* Removed

* DAG example

* Final version

* Store verify proof for DAG rootCID

Author: bkontur

examples/README.md

@@ -57,8 +57,7 @@ docker pull ipfs/kubo:latest
 docker run -d --name ipfs-node   -v ipfs-data:/data/ipfs   -p 4001:4001   -p 8080:8080   -p 5001:5001   ipfs/kubo:latest
 docker logs -f ipfs-node
 # Connect nodes
-docker exec -it ipfs-node ipfs swarm connect /ip4/172.17.0.1/tcp/10001/ws/p2p/12D3KooWQCkBm1BYtkHpocxCwMgR8yjitEeHGx8spzcDLGt2gkBm
-docker exec -it ipfs-node ipfs swarm connect /ip4/172.17.0.1/tcp/12347/ws/p2p/12D3KooWRkZhiRhsqmrQ28rt73K7V3aCBpqKrLGSXmZ99PTcTZby
+docker exec -it ipfs-node ipfs swarm connect /ip4/172.17.0.1/tcp/10001/ws/p2p/12D3KooWQCkBm1BYtkHpocxCwMgR8yjitEeHGx8spzcDLGt2gkBm && docker exec -it ipfs-node ipfs swarm connect /ip4/172.17.0.1/tcp/12347/ws/p2p/12D3KooWRkZhiRhsqmrQ28rt73K7V3aCBpqKrLGSXmZ99PTcTZby
 
 # specific version
 # docker pull ipfs  /kubo:v0.35.0
@@ -73,6 +72,24 @@ docker exec -it ipfs-node ipfs swarm connect /ip4/172.17.0.1/tcp/12347/ws/p2p/12
 ```
 # cd polkadot-bulletin-chain - make sure we are here
 cd examples
-npm install @polkadot/api @polkadot/keyring @polkadot/util-crypto @polkadot/util multiformats ipfs-http-client
+npm install @polkadot/api @polkadot/keyring @polkadot/util-crypto @polkadot/util multiformats ipfs-http-client ipfs-unixfs
+```
+
+### Example for simple authorizing and store
+```
 node authorize_and_store.js
 ```
+
+### Example for multipart / chunked content / big files
+The code stores one file, splits into chunks and then uploads those chunks to the Bulletin.
+It collects all the partial CIDs for each chunk and saves them as a custom metadata JSON file in the Bulletin.
+
+Now we have two examples:
+1. **Manual reconstruction** — return the metadata and chunk CIDs, then reconstruct the original file manually.
+2. **IPFS DAG feature** —
+    * converts the metadata into a DAG-PB descriptor,
+    * stores it directly in IPFS,
+    * and allows fetching the entire file using a single root CID from an IPFS HTTP gateway (for example: `http://localhost:8080/ipfs/QmW2WQi7j6c7UgJTarActp7tDNikE4B2qXtFCfLPdsgaTQ`).
+```
+node store_chunked_data.js
+```

examples/authorize_and_store.js

@@ -36,25 +36,12 @@ async function store(api, pair, data) {
     return cid
 }
 
-// Connect to a local IPFS node or Infura/IPFS gateway
+// Connect to a local IPFS gateway (e.g. Kubo)
 const ipfs = create({
     url: 'http://127.0.0.1:5001', // Local IPFS API
 });
 
-// async function test() {
-//     try {
-//         const id = await ipfs.id();
-//         console.log('✅ Connected to IPFS node:');
-//         console.log('Peer ID:', id.id);
-//         console.log('Addresses:', id.addresses);
-//     } catch (err) {
-//         console.error('❌ Failed to connect to IPFS:', err.message);
-//     }
-// }
-
 async function read_from_ipfs(cid) {
-    // await test();
-
     // Fetch the block (downloads via Bitswap if not local)
     console.log('Trying to get cid: ', cid);
     const block = await ipfs.block.get(cid);