Using oracles while developing smart contracts on blockchain

V diplomskem delu se bomo seznanili s tehnologijo veriženja blokov, pametnimi pogodbami, oraklji ter platformo za razvoj pametnih pogodb. Pametne pogodbe same po sebi ne morejo dostopati do podatkov, ki so zunaj njihovega omrežja. Orakelj je način, s katerim lahko pametna pogodba komunicira z zunanjim svetom. Deluje po principu, da poskuša biti zaupanja vredna identiteta in da v našem imenu izvede transakcijo na pametno pogodbo, s katero v to prenese želene podatke. Namen diplomskega dela je analiza ponudnikov orakeljskih storitev. Prav tako je cilj storitve orakljev ob implementaciji testirati pametne pogodbe na platformi Ethereum ter jih med seboj primerjati glede na format podatkov, katere podpirajo, glede na dostopnost dokumentacije, hitrost izvajanja ter preprostost uporabe.In this thesis, we will become accustomed to blockchain technology, smart contracts, oracles, and platforms for developing smart contracts. Smart contracts cannot access data outside their network by themselves. Oracle is the way for smart contracts to communicate with the outside world. It works by being a trusted intermediary to bring external data into smart contracts via a transaction. The purpose of this thesis is to analyze different oracle service providers, implement, and test them on the Ethereum smart contract and compare what type of data source they provide, how well their documentation is written, and what are the execution time and usability