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Posting Transactions

There are several ways to post transactions to Arweave. Each has its own unique affordances and constraints. The diagram below illustrates the four main approaches to posting transactions.

Direct to Peer,Direct to Gateway, Bundled, and Dispatched.

Guaranteed Transactions

When posting a large quantity of transactions or when fast settlement time is desireable consider using a bundling service. Bundlers settle large volumes of transactions immediately and make the transaction data available within milliseconds. The bundling service holds onto posted transactions until they are confirmed on-chain. If the transactions are not included in the most recent block the bundling service re-posts them with each new block until they are recorded on chain with a sufficient number of confirmations.

Direct Transactions

Transactions posted directly to Arweave come in two varieties wallet-to-wallet transactions and data transactions. The first transfers AR tokens between wallet addresses. The second posts data to Arweave and pays the associated storage costs.

Interestingly, data transactions may also transfer AR tokens to a wallet address while paying storage costs at the same time.

All transactions allow the user to specify up to 2KB worth of metadata in the form of custom tags.

Direct to Peer

Transactions may be posted directly to an Arweave peer (mining node). This is perhaps the most decentralized means of posting a transaction as clients can choose what peer they wish to post to.

This approach is not without drawbacks. Peers may come and go making it difficult to reliably post transactions from an app. While it's possible to query a list of active peers and choose one before posting it adds overhead and friction to the process. Additionally, transactions posted to peers are only queryable at the gateway after being mined in a block. This introduces a 1-2 minute delay between posting the transaction to a peer and it being available to read in a browser from a gateway.

For the above reasons, developers tend to configure arweave-js to point to a gateway when posting direct transactions as the optimistic cache at the gateway makes the transaction available almost immediately.

Direct to Gateway

Gateways sit between clients and Arweave's network of peers. One of the primary functions of the gateway is to index transactions and optimistically cache the data posted to the network while waiting for it to be included in a block. This makes the transaction queryable in a "Pending" state almost instantly which allows applications built on top of a gateway to be more responsive. There is still a risk of transactions dropping out of the optimistic cache if they are not mined in a block by the peers.

An example of how to post a direct transaction using arweave-js can be found in this guide.

Bundled Transactions

Services built on top of Arweave that provide additional utility for Permaweb builders are sometimes called Permaweb Services. A bundler is one such service. Bundlers take multiple individual transactions and bundle them together into a single transaction that is posted directly to Arweave. In this way a single transaction at the protocol level can contain tens of thousands of bundled transactions. There is one restriction, however, only data transactions can be included in a bundle. Wallet-to-wallet transactions (that transfer AR tokens between wallet addresses) must be done as individual transactions posted directly to Arweave.

Another difference when using a bundling service like irys.xyzopen in new window is that you must make a small deposit on the bundler node you intend to use prior to posting transactions. This enables the bundler service to charge for many small (or large) uploads without the overhead of settling AR tokens transfers directly on Arweave each time.

irys.xyzopen in new window allows clients to make deposits in a number of supported crypto currenciesopen in new window.

When transactions are posted to they are also appear in the optimistic cache of connected gateways so they are available to query in a matter of milliseconds.

An example of how to post bundled transactions using can be found in this guide.

Dispatched Transactions

Another way to post bundled transactions is from the browser. While browsers enforce some constraints around the size of data that can be uploaded, browser based wallets are able to post transactions to bundlers. Arweave browser wallets implement a dispatch() API method. If you are posting small transactions (100KB or less) you can use the wallets dispatch() method to take advantage of bundled transactions even if isn't packaged with your application.

An example of how to post a 100KB or less bundled transaction with an Arweave wallets dispatch() method can be found in this guide.