web3-service-worker-cache

A web3 service worker reducing your costly calls to Ethereum full nodes.

Why use Service Workers?

Access to Ethereum full nodes is starting to cost money [1, 2, 3]. As Ethereum developers wanting to build decentralized and autonomous applications, continuously paying fiat to service providers isn't according to our principles, however. Also, assuming a constant and stable connection for your users may end up ruining their experience when using our app. Indeed, building for offline-first usage, isn't a new concept.

Web2 has many concepts for improving user experiences by reducing reliance on stable connections. One of these concepts is called Service Workers.

Service workers is a set of JavaScript that can run as a proxy between your application and a service it's using. "They're intended to to enable the creation of effective offline experiences" and to take appropriate actions for when the network is flaky.

What can web3-service-worker-cache do for you?

Service workers are capable of intercepting network calls. web3 is known for excessively calling full nodes to stay in sync and make sure that a user signs transactions based on up-to-date data. But lots of data that is delivered from the full node via web3 to an application is indeed immutable and, hence, nicely cachable.

Luckily, service workers are now a widely-implemented web standard available in most browsers [4]. They should, hence, allow us to automatically cache lots of web3 transactions without ever having to talk to a full node again. Looking at OpenEthereum's JSON RPC call documentation, we can savely assume that the following calls have potential for caching without revalidation as their responses are immutable:

• eth_getBlockByHash
• eth_getBlockByNumber
• eth_getBlockTransactionCountByHash
• eth_getBlockTransactionCountByNumber
• eth_getTransactionByBlockHashAndIndex
• eth_getTransactionByBlockNumberAndIndex
• eth_getTransactionByHash
• eth_getTransactionReceipt

Additionally, there's calls have a potential for being cached for a specific amount of time or assuming the future existence of an invalidation event (as e.g. the existence of a new transaction or block):

• eth_estimateGas
• eth_getStorageAt

Debugging

Mozilla Firefox

To see the messages a service worker is logging, in Firefox got to this page, find your worker and click "Inspect".

Google Chrome

Tutorial on how to use service workers in Google Chrome with self-signed certificates.

Note on Completeness

• This project is a work in progress

License

See License.

References

• 1: https://infura.io/pricing
• 2: https://www.alchemyapi.io/pricing
• 3: https://www.quiknode.io/pricing
• 4: https://caniuse.com/serviceworkers