Factom C# API Implementation

##Now on NuGet!

What It can do:

• Create new Chains on the Factom Blockchain
• Add Entries to existing Chains
• Retrieve data from the Factom Blockchain

How to use:

I reccommend reading up on how Factom works before using this API, but it is not required. There are 2 classes that are currently built; Entry and Chain.

Retrieving Data From Factom

If you have the chain ID of a chain, you can get all the entries like so.

string chainIDString = "CHAIN-ID-HERE";
// First Convert the chain id string into a byte[]. The API has a build in converter.
byte[] chainIDBytes = Strings.DecodeHexIntoBytes(chainIdString);
// Now we can get all the entries in the chain, a List of EntryData will be returned.
var entries = Chain.GetAllChainEntries(chainIDBytes);
//Each index in entries contains the Entry hash and timestamp. To get it's content, use:
index = 0; // Index of entry you want to get
byte[] content = Entry.GetEntryData(entries[index].Entryhash);

Uploading Data To Factom

Find the Cost First

In the next two sections the creation of an entry is required. To get the cost of the entry, simply pass the created entry like so:

int cost = Entry.EntryCost(entry);

For commiting a chain add '10' to the cost.

cost += 10;

To Commit a Chain

First we need to make a new Entry, as a first entry is required to make a chain.

/// The call to make a new entry is Entry.NewEntry(byte[] content, byte[][] extIds, byte[] chainId)
/// content: The data you wish the entry to store
/// extIds: Used to generate a UNIQUE chainID. These will take up space in the Entry, and make these unique
///         for each new chain you create.
/// chainId: Leave null for the first entry, as it is computed by the extIds

byte[] content = Encoding.UTF8.GetBytes("This is my entry content");
// One idea is to use a hash of your content, or use a random number. You can use any number of extIds,
// here I use 2.
byte[][] extIDs = new[] {
            Encoding.UTF8.GetBytes("random-string-of-things"),
            Encoding.UTF8.GetBytes("this-will-hopefully-be-unique")
            }
var firstEntry = Entry.NewEntry(content, extIds, null);
// Now we can make our chain to commit.
var chain = Chain.NewChain(firstEntry);

// Factom is not free, you need a entry credit wallet. Put the name of your wallet here:
string walletName = "What you named your wallet";
byte[] chainID = Chain.CommitChain(chain, walletName);

Thread.Sleep(10000); // Must wait 10 seconds

Chain.RevealChain(chain); // Must reveal the entry
// If all went well your entry is now on Factom!
// DO NOT LOSE 'chainID'. This is how you find your chain after it is made, so make it a form of output
// and hang onto it

Some notes:

• Each entry can be a max of 10kb in size. (See "Entry" section of here to predict the size of your entry)
• The chain commit cost 10 entry credits + 1 entry credit per kb of data. Max chain initial commit = 20 entry credits
• There is no "are you sure?" once you commit, the entry credits are spent, so be careful when testing.

To Commit an Entry

So now you want to add more to an existing chain? Easy!

// We have to make another Entry like before, but now we do not need the extIds.
byte[] content = Encoding.UTF8.GetBytes("Some more content to add!");
// Convert the chainID string into byte[] if it's not already. I use a function I made, you can too.
// You can also use the chainID returned from the commit earlier.
byte[] chainId = Strings.DecodeHexIntoBytes("HEX-STRING-HERE"); //Should be in hex, case does not matter
var entry = Entry.NewEntry(content, null, chainId);

// Factom is not free, you need a entry credit wallet. Put the name of your wallet here:
string walletName = "What you named your wallet";
Entry.CommitEntry(entry, factomWalletName);

Thread.Sleep(10000); // Must wait 10 seconds

Entry.RevealEntry(factomEntry);
// Your entry is now on the chain if there are no exceptions.

Some notes:

• You can not "reserve a chain" as in anyone can add entries to your chains
• This means you need to verify your entries
• Entries cost 1 entry credit per kb

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Factom Resources

The Factom API rest calls can be found here: Factom Rest

The GoLang full implementation can be found here: Factom GoLang

Blog post using GoLang library: Blog Post

General Factom Docs: Factom Docs