第11章Webアプリケーション開発

Blockchains currently have a scaling problem. The average size of a block has increased over the years, and transaction fees are associated with each transaction. A common fee is the gas price, which is the cost of validating transactions and updating ledgers. Additionally, negative performance can occur on a blockchain with large amounts of transactions.

One approach to help with scaling is the use of sidechains. A sidechain is a secondary (i.e., level 2 or L2) blockchain that increases the blockchain network performance by aggregating transactions off-chain (i.e., off the mainnet/Ethereum network) and committing them to the mainnet at once. Polygon is a popular L2 scaling system for sidechaining. Other L2 scaling techniques include blockchain rollups, which are protocols designed to enable high throughput and lower costs. They address scaling by bundling transactions and reducing data sizes to increase transaction efficiency and limit storage costs. Examples of blockchain rollups include optimistic and zero-knowledge rollups. An optimistic rollup is a protocol that increases transaction output by bundling multiple transactions into batches, which are processed off-chain. In this case, transaction data is recorded on the mainnet via data compression techniques that lower cost and increase transaction speed. Optimistic rollups on Ethereum can improve scalability by a factor of 10 to 100. A zero-knowledge rollup (zk-rollup) is a protocol that bundles transactions into batches that are executed off the mainnet. For every batch, a zk-rollup operator submits a summary of required changes once the transactions in the batch have been executed. Operators have also produced validity proofs that demonstrate that the changes are accurate. These proofs are significantly smaller than transaction data so it is quicker and cheaper to verify them. Additionally, zk-rollups are used on Ethereum to reduce transaction data size via compression techniques, which ends up reducing user fees.

Figure 11.12 shows the addition of sidechains to the architecture to mitigate some of the challenges associated with Web 3.0 DApps. Notice how the user’s interaction with the Web 3.0 app has grown from mostly reading content in a Web 1.0 model to more fully participating in the content and functionality of the Web 3.0 app.

As you can see, the architecture has become rather complex to support DApps effectively. However, Web 3.0 is still in a nascent phase, and currently there are several solutions and tools being developed to make building and deploying Web 3.0 DApps even easier. Hardhat is a developer ecosystem for building and deploying smart contracts on a local network for testing.

This architecture focused on blockchains and used Ethereum as the principal implementation. However, there are other DLT solutions. Hashgraph is an approach where only selected nodes store the entire blockchain, and voting mechanisms are introduced to validate if the blocks are correct. Stacks is another DLT where only the smart contracts are decentralized, and the data is controlled by its owner. Owners can share or remove it—ensuring data privacy.

Web applications are used today to power commercial websites that are accessed by people to complete online transactions to buy goods of any kind. Mobile web applications and native versions of such are also available on smartphones and watches to help do the same. How does using web and native application frameworks help people in everyday life? Provide a couple of illustrative scenarios to explain your opinion. Your scenarios should not be limited to describing how the frameworks are used, but rather describe situations where these frameworks are applied in real life.

Due to the qualities and limitations of Web 2.0 and 3.0 architectures, it is likely that we’ll see solutions that are a combination of the two approaches and leverage their best attributes. One way to do this would be to have workflow processes that require a high rate of change implemented in a Web 2.0 architecture, while processes that would benefit from using a distributed ledger being executed in Web 3.0. For example, traditional commercial websites can keep using the Web 2.0 architecture, while payment solutions can be extended by accessing the Web 3.0 architecture to make payments using cryptocurrencies (e.g., Bitcoin).

Let’s consider an app for generating AI artwork. Many solutions exist today for doing this; however, we want our app to give “ownership” to the digital artwork a person generates. AI models are trained to recognize existing artwork (e.g., paintings available via the wikiart.org API) that may be copyrighted—so ownership is still being determined in the courts. Here, the term ownership is used to attribute AI image creation and nothing more. While AI models are very popular, some companies do not want to share data with AI model creators and prefer to have the AI models deployed in their own infrastructure to ensure full privacy. A non-fungible token (NFT) is a unique digital identifier on a blockchain that a user may want to create of their image and possibly sell (i.e., transfer ownership) on a marketplace. A common use case for this app might be:

1. A user logs in to the website and enters a prompt to generate an image.

2. After several rounds of adjusting their prompts, they end up with an image they want.

3. The user pays to have a non-fungible token created of the image, which is stored on a blockchain marketplace for sale.

As you can imagine, running an AI image generator on a blockchain might not perform well. Likewise, creating NFTs without blockchain technologies is counterintuitive. Therefore, the architecture for this solution needs to encompass both Web 2.0 and 3.0 approaches.

Figure 11.13 shows how the APIs will do the heavy lifting of working with the AI model to generate the artwork. Once the user is satisfied, they will interact with aspects of the UI that execute smart contracts to generate and add the NFT to the blockchain. Transactions will happen on the blockchain. APIs may interact directly with the blockchain, looking for similar works.

This model still has a centralized Web 2.0 server for artwork generation and account management; however, portions that deal with NFT ownership and selling of that ownership are managed within the Web 3.0 blockchain infrastructure. This approach serves the needs of many businesses that want to take advantage of Web 3.0 features while preserving their original Web 2.0 websites.