© Santiago Palladino 2019
S. PalladinoEthereum for Web Developershttps://doi.org/10.1007/978-1-4842-5278-9_4

4. Querying the Network

Santiago Palladino1 
(1)
Ciudad Autónoma de Buenos Aires, Argentina
 

After a not-so-brief interlude on writing smart contracts, we will review the different ways to connect to the Ethereum network to retrieve data. We will cover different connection methods, as well as patterns for listening to changes, and put it all together in a sample application for monitoring transfers of an ERC20 token.

Connecting to the Network

The first step in retrieving data from the network is to actually connect to an Ethereum node. Since web applications do not connect directly to the network, they depend on a node to answer any queries on ...

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