Pinning and Retrieving Files on IPFS

Welcome to Week 7! This module focuses on the practical aspects of using the InterPlanetary File System (IPFS) for decentralized storage, specifically how to pin and retrieve files. Understanding these operations is crucial for building robust decentralized applications (dApps) that leverage IPFS for data persistence.

What is Pinning?

In IPFS, 'pinning' is the process of ensuring that a specific piece of data remains available on the network. When you add a file to IPFS, it gets a unique Content Identifier (CID). However, IPFS is a distributed system, and nodes only store data they are interested in or that is actively pinned. If a node decides to garbage collect unpinned data, your file could disappear from the network.

Pinning guarantees data availability on IPFS.

Pinning tells your IPFS node to keep a copy of the data indefinitely, preventing it from being garbage collected. This is essential for making your dApp's data reliably accessible.

When you add a file to IPFS, it's assigned a CID. This CID is a hash of the file's content. Other nodes can retrieve the file using this CID if they have a copy. However, IPFS nodes are not obligated to store every piece of data they encounter. They have limited storage and will eventually garbage collect data that is not actively being used or pinned. Pinning is the mechanism by which you explicitly tell your IPFS node to retain a copy of the data. This ensures that the file remains accessible on the IPFS network as long as your node (or any other node that has pinned it) is online and running.

How to Pin Files

You can pin files to your IPFS node using the IPFS command-line interface (CLI) or through various web UIs and libraries. The fundamental command involves specifying the CID of the content you wish to pin.

What is the primary purpose of pinning in IPFS?

To ensure that a specific piece of data remains available on the IPFS network and is not garbage collected.

Using the IPFS CLI, the command is straightforward:

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For example, to pin a file with the CID

code

Qm...xyz

, you would typically run

code

ipfs pin add Qm...xyz

Retrieving Files from IPFS

Retrieving files from IPFS is as simple as requesting content by its CID. When you request a file, your IPFS node searches the network for peers that have a copy of that content. If found, the data is transferred to your node. If the content is pinned by your node, it's immediately available. If not, your node will fetch it from another peer.

Retrieval is content-addressable.

You can retrieve any file on IPFS by knowing its CID. Your IPFS node will find and download it from the network.

The core principle of IPFS is content addressing. Instead of locating files by their location (like a URL), you locate them by their content's unique identifier (the CID). When you want to retrieve a file, you provide its CID to your IPFS node. The node then broadcasts this request to the network, looking for peers that have the data associated with that CID. Once a peer with the data is found, the file is transferred. This process is inherently resilient, as the data can be retrieved from any node that has it, not just a single server.

Think of CIDs as permanent, unchangeable addresses for your data. If the data changes, the CID changes.

The command to retrieve and display a file's content using the IPFS CLI is:

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For instance,

code

ipfs cat Qm...xyz

will retrieve and display the content of the file associated with that CID.

Pinning Services

For dApps that require high availability and don't want to manage their own IPFS nodes, pinning services are invaluable. These services are dedicated IPFS nodes that you can pay to pin your content, ensuring it remains online and accessible even when your own node is offline. Popular pinning services include Pinata, Infura, and Web3.Storage.

Imagine IPFS as a vast, decentralized library. When you add a book (file), it gets a unique catalog number (CID). Pinning is like checking out that book and keeping it on your desk, ensuring you always have access. If you don't pin it, the librarian (IPFS node) might put it back on the general shelves, and you'd have to find it again. Pinning services are like having a personal assistant who always keeps your important books readily available.

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Text-based content

Library pages focus on text content

Key Takeaways

Mastering pinning and retrieval is fundamental to leveraging IPFS for persistent, decentralized data storage. By understanding how to pin your content, you ensure its availability, and by knowing how to retrieve it, you can build applications that reliably access this data.

Learning Resources

IPFS Docs: Pinning(documentation)

Official documentation explaining the concept and mechanics of pinning in IPFS.

IPFS Docs: Retrieving Content(documentation)

Learn how IPFS retrieves content using Content Identifiers (CIDs).

Pinata: What is Pinning?(documentation)

A clear explanation of pinning from a popular IPFS pinning service provider.

IPFS Companion Browser Extension(documentation)

A browser extension that helps you interact with IPFS, including pinning and retrieving files.

Awesome IPFS: Pinning Services(documentation)

A curated list of IPFS pinning services and related tools.

Video: How IPFS Pinning Works(video)

A conceptual overview of IPFS pinning and its importance in decentralized storage.

Tutorial: Pinning Files with IPFS CLI(tutorial)

A hands-on tutorial guiding you through pinning files using the IPFS command-line interface.

Web3.Storage Documentation(documentation)

Documentation for Web3.Storage, a service for storing and retrieving data on IPFS and Filecoin.

Infura IPFS Documentation(documentation)

Learn how to use Infura's IPFS API for pinning and retrieving files.

IPFS: The Permanent Web(wikipedia)

The official website for IPFS, providing an overview of its mission and technology.