Blockchain is a fancy word, and not many people understand it. If you want to explain this to your GF/partner, what would be the most simple way?
Right, blocks are chained in one way, as time goes on, in particular for STEEM blockchain, every 3 seconds, we append a new block to the end of the current chain.
We need a way to tell if the current block can be attached (we can’t just produce a random block and force appending it). For each block, we will have a unique block ID, and we will have a previous field that match the previous Block ID. The first block on steem blockchain has previous set to 0000000000000000000000000000000000000000. We might also notice that there are fewer transactions/data stored in the first few blocks.
Run this in SteemJS
1 2 3 4 | const blockNum = 1; steem.api.getBlock(blockNum, function(err, result) { log(result); }); |
const blockNum = 1; steem.api.getBlock(blockNum, function(err, result) { log(result); });
You will see the block_id and previous value of the first block.
1 | {"previous":"0000000000000000000000000000000000000000","timestamp":"2016-03-24T16:05:00","witness":"initminer","transaction_merkle_root":"0000000000000000000000000000000000000000","extensions":[],"witness_signature":"204f8ad56a8f5cf722a02b035a61b500aa59b9519b2c33c77a80c0a714680a5a5a7a340d909d19996613c5e4ae92146b9add8a7a663eef37d837ef881477313043","transactions":[],"block_id":"0000000109833ce528d5bbfb3f6225b39ee10086","signing_key":"STM8GC13uCZbP44HzMLV6zPZGwVQ8Nt4Kji8PapsPiNq1BK153XTX","transaction_ids":[]} |
{"previous":"0000000000000000000000000000000000000000","timestamp":"2016-03-24T16:05:00","witness":"initminer","transaction_merkle_root":"0000000000000000000000000000000000000000","extensions":[],"witness_signature":"204f8ad56a8f5cf722a02b035a61b500aa59b9519b2c33c77a80c0a714680a5a5a7a340d909d19996613c5e4ae92146b9add8a7a663eef37d837ef881477313043","transactions":[],"block_id":"0000000109833ce528d5bbfb3f6225b39ee10086","signing_key":"STM8GC13uCZbP44HzMLV6zPZGwVQ8Nt4Kji8PapsPiNq1BK153XTX","transaction_ids":[]}
And the second block gives:
1 | {"previous":"0000000109833ce528d5bbfb3f6225b39ee10086","timestamp":"2016-03-24T16:05:36","witness":"initminer","transaction_merkle_root":"0000000000000000000000000000000000000000","extensions":[],"witness_signature":"1f3e85ab301a600f391f11e859240f090a9404f8ebf0bf98df58eb17f455156e2d16e1dcfc621acb3a7acbedc86b6d2560fdd87ce5709e80fa333a2bbb92966df3","transactions":[],"block_id":"00000002ed04e3c3def0238f693931ee7eebbdf1","signing_key":"STM8GC13uCZbP44HzMLV6zPZGwVQ8Nt4Kji8PapsPiNq1BK153XTX","transaction_ids":[]} |
{"previous":"0000000109833ce528d5bbfb3f6225b39ee10086","timestamp":"2016-03-24T16:05:36","witness":"initminer","transaction_merkle_root":"0000000000000000000000000000000000000000","extensions":[],"witness_signature":"1f3e85ab301a600f391f11e859240f090a9404f8ebf0bf98df58eb17f455156e2d16e1dcfc621acb3a7acbedc86b6d2560fdd87ce5709e80fa333a2bbb92966df3","transactions":[],"block_id":"00000002ed04e3c3def0238f693931ee7eebbdf1","signing_key":"STM8GC13uCZbP44HzMLV6zPZGwVQ8Nt4Kji8PapsPiNq1BK153XTX","transaction_ids":[]}
As you can see, the previous value is the same as the block_id for the Block 1. This goes on and on. Let’s print the first 10 blocks’ previous and block_id:
Run the Code in SteemJS
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 | function getBlock(blockNum) { return new Promise((resolve, reject) => { steem.api.getBlock(blockNum, function(err, result) { if (err) reject(err); resolve({ block: blockNum, previous: result.previous, block_id: result.block_id, }); }); }); } (async function() { for (let i = 1; i <= 10; ++ i) { log(await getBlock(i)); } })(); |
function getBlock(blockNum) { return new Promise((resolve, reject) => { steem.api.getBlock(blockNum, function(err, result) { if (err) reject(err); resolve({ block: blockNum, previous: result.previous, block_id: result.block_id, }); }); }); } (async function() { for (let i = 1; i <= 10; ++ i) { log(await getBlock(i)); } })();
And you will see the rule applies. In fact, this is the fundamental rule of the blockchain – the rule to chain the blocks.
1 2 3 4 5 6 7 8 9 10 | {"block":1,"previous":"0000000000000000000000000000000000000000","block_id":"0000000109833ce528d5bbfb3f6225b39ee10086"} {"block":2,"previous":"0000000109833ce528d5bbfb3f6225b39ee10086","block_id":"00000002ed04e3c3def0238f693931ee7eebbdf1"} {"block":3,"previous":"00000002ed04e3c3def0238f693931ee7eebbdf1","block_id":"000000035b094a812646289c622dba0ba67d1ffe"} {"block":4,"previous":"000000035b094a812646289c622dba0ba67d1ffe","block_id":"00000004f9de0cfeb08c9d7d9d1fe536d902dc4a"} {"block":5,"previous":"00000004f9de0cfeb08c9d7d9d1fe536d902dc4a","block_id":"00000005014b5562a1133070d8bee536de615329"} {"block":6,"previous":"00000005014b5562a1133070d8bee536de615329","block_id":"00000006e323e35687e160b8aec86f1e56d4c902"} {"block":7,"previous":"00000006e323e35687e160b8aec86f1e56d4c902","block_id":"000000079ff02a2dea6c4d9a27f752233d4a66b4"} {"block":8,"previous":"000000079ff02a2dea6c4d9a27f752233d4a66b4","block_id":"000000084f957cc170a27c8330293a3343f82c23"} {"block":9,"previous":"000000084f957cc170a27c8330293a3343f82c23","block_id":"00000009f35198cfd8a866868538bed3482d61a4"} {"block":10,"previous":"00000009f35198cfd8a866868538bed3482d61a4","block_id":"0000000aae44a2f4d57170dab16fb1619f9e1d0e"} |
{"block":1,"previous":"0000000000000000000000000000000000000000","block_id":"0000000109833ce528d5bbfb3f6225b39ee10086"} {"block":2,"previous":"0000000109833ce528d5bbfb3f6225b39ee10086","block_id":"00000002ed04e3c3def0238f693931ee7eebbdf1"} {"block":3,"previous":"00000002ed04e3c3def0238f693931ee7eebbdf1","block_id":"000000035b094a812646289c622dba0ba67d1ffe"} {"block":4,"previous":"000000035b094a812646289c622dba0ba67d1ffe","block_id":"00000004f9de0cfeb08c9d7d9d1fe536d902dc4a"} {"block":5,"previous":"00000004f9de0cfeb08c9d7d9d1fe536d902dc4a","block_id":"00000005014b5562a1133070d8bee536de615329"} {"block":6,"previous":"00000005014b5562a1133070d8bee536de615329","block_id":"00000006e323e35687e160b8aec86f1e56d4c902"} {"block":7,"previous":"00000006e323e35687e160b8aec86f1e56d4c902","block_id":"000000079ff02a2dea6c4d9a27f752233d4a66b4"} {"block":8,"previous":"000000079ff02a2dea6c4d9a27f752233d4a66b4","block_id":"000000084f957cc170a27c8330293a3343f82c23"} {"block":9,"previous":"000000084f957cc170a27c8330293a3343f82c23","block_id":"00000009f35198cfd8a866868538bed3482d61a4"} {"block":10,"previous":"00000009f35198cfd8a866868538bed3482d61a4","block_id":"0000000aae44a2f4d57170dab16fb1619f9e1d0e"}
Steem Blockchain is a public database. Every 3 seconds, one witness helps to package operations (comment, vote, transfer etc) into a block, seal it with the signing key, and finally push to the chain for a small reward.
As the blockchain gets bigger and bigger, it takes enormous efforts to alter the chain, as you will need to modify every prior blocks.
–EOF (The Ultimate Computing & Technology Blog) —
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