MultiChain Developer Q&A - Recent questions tagged getblock

Height Of A Block

Sun, 24 Jun 2018 09:04:18 +0000

My understanding is this, that, MultiChain, internally, manages collection of blocks, in the form of "Merkle Tree".

In my chain, "getblockchaininfo" command depicts, "blocks: 81"....i.e. my chain is having "Total Block Count = 81".

Initially, I thought, 81th-block, shall be the leaf in my "Merkle Tree".

but, I was wrong, as, from the output of commands "getblockhash & getblock".....I had seen that 81th-block is actually the root of the Merkle Tree.

How I reached to that conclusion ?

Well, because total confirmations in the output of "getblock" ...was ONLY ONE.

So, the analogy I have build from aforesaid observations is as follows:

Any "New Block", in the MultiChain, shall increase the "Height" of existing blocks, BY ONE.

Am I building correct analogy ?

Following was the output of getblockhash & getblock for the reference:

uselesschain1: getblockhash 81
{"method":"getblockhash","params":[81],"id":1,"chain_name":"uselesschain1"}

0038578b101797832a59e84d2a7847015e04810834904d2f777548669b3ea57f

uselesschain1: getblock 0038578b101797832a59e84d2a7847015e04810834904d2f777548669b3ea57f
{"method":"getblock","params":["0038578b101797832a59e84d2a7847015e04810834904d2f777548669b3ea57f"],"id":1,"chain_name":"uselesschain1"}

{
"hash" : "0038578b101797832a59e84d2a7847015e04810834904d2f777548669b3ea57f",
"miner" : "1JZzMjVbs1cgb4fDKRSRAHXwj8dVERPJFQjJu6",
"confirmations" : 1,
"size" : 266,
"height" : 81,
"version" : 3,
"merkleroot" : "8eeeda5a3fc176fa795041ee820fef2ca173fc8e50d1dd7d6a17022603a44241",
"tx" : [
"8eeeda5a3fc176fa795041ee820fef2ca173fc8e50d1dd7d6a17022603a44241"
],
"time" : 1529827770,
"nonce" : 57,
"bits" : "2000ffff",
"difficulty" : 0.00000006,
"chainwork" : "0000000000000000000000000000000000000000000000000000000000005200",
"previousblockhash" : "00091aa81e8e8e106ca2a83b58b86534c1e9c219d986f10f8652a702810c8b7d"
}

Behaviour of getblock

Fri, 30 Mar 2018 10:47:43 +0000

Hi, I was doing a bit of testing with getblock and noticed some unexpected behaviour

When I give the request a blockId way beyond the current block height of the chain I'll get an error - Block height out of range - All good

But when I give the request some random strings, for example ''a", "ab", "fab" all return the first block 0 in the chain.

Passing "1234fab" returns block 1234 - I can see what's it's doing there,

and passing a transaction Hash returns "Block not found".

I was testing this to understand what error handling to do on our end, and feel the behaviour for passing an incorrect block-id is a bit inconsistent. It would be much cleaner to just return a block not found response in all these error conditions.

What are your thoughts?

Cheers

Marty

Setup a mining pool for a blockchain created using MultiChain

Wed, 29 Nov 2017 07:53:46 +0000

Hello,
I am working on my college project and multichian is perfect for my project. I need to implement a mining pool for my chain which i created using multichian . I came upon some problems which are referenced in this question : https://www.multichain.com/qa/6583/how-does-install-mining-pool-in-multichain?show=6583#q6583
As you are aware that multichain doesn't provide the "getblockteplate" json-rpc so i searched on the web and multichian website and found that multichain's "getblock" is almost similar to "getblocktemplate".
I am using NOMP ( https://github.com/zone117x/node-open-mining-portal ) to setup the pool for testing. I changed the RPC call inside the code of NOMP to make it work with "getblock". It calls the "getblock" but returns this error : error: { code: -1, message: 'value is type obj, expected str' }. In the developers section on the website, it is written to report any code -1 errors to the devs.

This is my RPC call : _this.daemon.cmd('getblock', [ { "params" : [blockNumber, "4"] } ], function(results){ console.log(results); });

Also there is no "coinbaseaux" in the "getblock" rpc and pools require that too.
If you can help me out, I'll be really thankful :)
Thanks

getblock info for calculating balances

Mon, 23 Oct 2017 10:45:08 +0000

Looking at the data for getblock, we can store that data in our database and update balances. eg:

For asset transfers

vout n=0 : amount 30 of an asset with type transfer, we can add that to an address
vout n=1 (or next number with different address) : amount of 30 (from above n=0) deduct from the address listed there

For native currency transfers, not quite sure how best to calculate it, as the tx fee varies.

Does anyone have advice on how to calculate from getblock and transaction data?

getblock verbose

Fri, 20 Oct 2017 19:09:34 +0000

I am using getblock (verbose=4), and i don't seem to be getting any extra information on the tx eg:

getblock "71",(verbose=4)
{"method":"getblock","params":["71,(verbose=4)"],"id":1,"chain_name":"php"}
{
"hash" : "00a31537cdba41ad687e9f14111313c56734d11f80458e2440f3410341251089",
"miner" : "16YU9NqCaugEEXfdB65o65wM6eZnerERVp",
"confirmations" : 1,
"size" : 551,
"height" : 71,
"version" : 3,
"merkleroot" : "d05b1f510319c9e764c84edf65743221b6bc8689d6a2ba971d4870afac9a40fb",
"tx" : [
"c7d95137bae38844529a211d35bd09071e18166f347d4077914ed639e6dbd73a",
"af31d8ae32fc6085e0c8ed1287160ec95268f8f596454dc23dec63c45ea4b1de"
],
"time" : 1508514758,
"nonce" : 169,
"bits" : "2000ffff",
"difficulty" : 0.00000006,
"chainwork" : "0000000000000000000000000000000000000000000000000000000000004800",
"previousblockhash" : "009eff6b475a45accdd570e052036eaae40b904b76a1bc5779660183e7c0e55d"
}

you can see this online at http://php.tagcash.com/Philippine%20Pesos%20(PHP)/tx/af31d8ae32fc6085e0c8ed1287160ec95268f8f596454dc23dec63c45ea4b1de

I can get the data I need by doing a getrawtransaction followed by a decoderawtransaction, but just wanted to make sure this was they best way to do it before moving on.

I thought I would be getting the data i need for the transaction there - do I have to take other steps to get to the data i need?

getblock expects bolean. please look at this error when I execute getblock with verbose = 4

Wed, 30 Aug 2017 14:37:30 +0000

getblock('0000010b36c727389e9ef920b7b4a6f327d95f7a33caf8d9c2091b762fef7d2a',4)

response i get:

status="500" and error="value is type int, expected bool"

and if i use TRUE or FALSE works fine.

so either documentation is misleading or this is a bug.

getblock

hash|height
(verbose=1)

Returns information about the block with hash (retrievable from getblockhash) or at the given height in the active chain. Set verbose to 0 or false for the block in raw hexadecimal form. Set to 1 or true for a block summary including the miner address and a list of txids. Set to 2 to 3 to include more information about each transaction and its raw hexadecimal. Set to 4 to include a full description of each transaction, formatted like the output of decoderawtransaction.

How does block/transaction confirmations work?

Fri, 04 Aug 2017 09:36:08 +0000

multichain-cli chain getblock {blocknumber} 4

{"method":"getblock","params":["{blocknumber}",4],"id":1,"chain_name":"chain"}

{
    "hash" : "{blockaddress}",
    "miner" : "{mineraddress}",
    "confirmations" : 1

}

Based on this example, how does block/transaction confirmations work? This block in question has only one transaction in it - the miner transaction.

I am getting for example a block with 20 transactions but each transaction is confirmed only twice or once and on others its 21 or 25 times confirmed.

Not quite clear on how this works or is being determined.

getblockhash returning 500 error : where is rpc request logs location?

Thu, 28 Apr 2016 10:36:54 +0000

Where can i find the rpc server logs.

I am writing a perl script to interact with a private blockchain and I am able to make few api calls but server is throwing "500 Internal Server Error" when I invoke getblockhash

Code snippet:
sub getBlockHash {
    $class=shift;
    my $height=shift;
    print "height inside fn: $height \n";    # I am getting the number correctly here.
    my $obj = {
       method => 'getblockhash',       # similar function with getinfo or getblockcount without
       params => [$height],                 # passing params works well.
    };                                                      # tried sendwithmetadata , it works with params

    my $res = $client->call( $uri, $obj );
     if ($res){
      print "Got res\n";
      if ($res->is_error) { print "Error : ", $res->error_message; return "ERROR"; }
      else {
            my $data = Dumper ($res->result);
            $bcount = substr ($data,length('$VAR1 = '),length($data));
            $bcount =~ s/\W//g;
            return $bcount;
           }
    } else {
      print "no res\n";
      print $client->status_line;
      return "ERROR";
    }
}
----------------- RESULT -----------------------
height inside fn: 15545
no res
500 Internal Server ErrorHash = ERROR

---------------------
Where can I find the logs to debug these kind of errors? is getblockhash not recognised?

I want to traverse the block starting from 0 to total number of blocks , using getblock api after I get the hash from getblockhash <height> call.
is there any other method to do this? I am interested to fetch transactions which has metadata attached to them.

any help much appreciated.
thanks