IPFS 入门

Hello! Today, we're diving into the InterPlanetary File System (IPFS). It's a revolutionary way to store and access files, designed to make the internet more robust, decentralized, and efficient.

Think of it as a new foundation for how we share data online, moving beyond the traditional web.

Currently, when you visit a website or download a file, your request goes to a specific server. This is called location addressing, as you're asking for content at a particular address.

• If that server goes down, the content is unavailable.
• It creates a single point of failure.
• Content can be censored or removed by the server owner.

IPFS offers a decentralized alternative. Instead of relying on a few central servers, IPFS uses a peer-to-peer network. This means files are stored and shared across many computers (nodes) around the world.

It aims to create a permanent, decentralized web where content is always available.

One of IPFS's core innovations is content addressing. Instead of asking for a file at a specific location, you ask for a file based on what it is.

• Every piece of content gets a unique cryptographic fingerprint.
• This fingerprint is called a Content Identifier (CID).
• If even a single bit of the content changes, its CID changes too.

A CID is like a unique ID for your file, generated by hashing its content. It's a string of letters and numbers that serves as the file's address on the IPFS network.

For example, a CID might look like this: QmY7Yh4Uq....

This ensures that if you have a CID, you can verify that the content you receive is exactly what was intended.

When you add a file to IPFS, it's first broken down into smaller pieces. Each piece also gets its own CID.

These pieces are then distributed and stored across the IPFS network by various participating nodes. A node is simply any computer running the IPFS software.

To retrieve a file, you provide its CID. The IPFS network then uses a mechanism called a Distributed Hash Table (DHT) to ask all participating nodes: "Who has content with this CID?"

Any node that has the content can send it to you. This means you can get the file from multiple sources, making it more resilient and often faster.

Once a file is added to IPFS and receives a CID, that content is immutable. This means it cannot be changed.

• If you modify a file, even slightly, it generates a completely new CID.
• The old version of the file (and its CID) still exists on the network, allowing for easy version history.
• This immutability is crucial for data integrity and security in decentralized applications.

While IPFS is a separate protocol, IPFS gateways allow regular web browsers (which primarily understand HTTP) to access IPFS content.

A gateway is a server that fetches content from the IPFS network and then serves it over standard HTTP. For example, you might access an IPFS file via https://ipfs.io/ipfs/<your-CID>.

Let's quickly check your understanding of IPFS's core mechanism for identifying files.

In this lesson, we explored the fundamentals of the InterPlanetary File System (IPFS).

• IPFS is a decentralized, peer-to-peer file system, offering an alternative to the centralized web.
• It uses content addressing, where files are identified by their unique Content Identifiers (CIDs), not their location.
• Content on IPFS is immutable; any change creates a new CID.
• IPFS gateways provide a bridge for traditional web browsers to access IPFS content.

Next, we'll dive deeper into how to store DApp assets and other files using IPFS!