Stream Class Usage

Library to work with RecordsKeeper streams.

You can publish, retrieve and verify stream data by using Stream class. You just have to pass the required parameters to invoke the pre-defined functions of the Stream class.

Libraries

Import these python libraries first to get started with the functionality.

import requests
import json
from requests.auth import HTTPBasicAuth
import yaml
import binascii
import sys

Creating Connection

Entry point for accessing Address class resources.

  • URL: Url to connect to the chain ([RPC Host]:[RPC Port])
  • Chain-name: chain name
with open("config.yaml", 'r') as ymlfile:
    cfg = yaml.load(ymlfile)

network = cfg['network']  #network variable to store the network that you want to access

url = network['url']
chain = network['chain']

Node Authentication

Importing values from config file.

  • User name: The rpc user is used to call the APIs.
  • Password: The rpc password is used to authenticate the APIs.
user = network['rkuser']
password = network['passwd']

Now we have node authentication credentials.

Stream Class

class Stream

Stream class to call stream related functions like publish, retrieve, retrieveWithAddress, retrieveWithKey and verify data functions which are used to publish data into the stream, retrieve data from the stream and verify data from the stream.

1. Publish

You have to pass these four parameters to the publish function call:

  • Data Hex of the data to be published
  • Address of the publihser
  • Stream to which you want your data to be published
  • key Value for the data to be published
publish(address, stream, key, data)

txid = publish(address, stream, key, data)

print txid    #prints the transaction id of the data published

It will return the transaction id of the published data.

2. Retrieve an existing item from a particular stream against a transaction id

You have to pass these two arguments to the retrieve function call:

  • Stream name: which you want to access
  • Transaction id: id of the data that you want to retrieve
retrieve(stream, txid)    #call retrieve function with stream and txid as the required parameters
result = retrieve(stream, txid)

print result  #prints data

It will return the data corresponding to the passed transaction id.

3. Retrieve an item against a particular publisher address

You have to pass these three arguments to the retrieveWithAddress function call:

  • Stream name: which you want to access
  • Publisher address: address of the data publisher you want to verify
  • Count: no of items you want to retrieve
retrieveWithAddress(stream, address, count)
result = retrieveWithAddress(stream, address, count)

print result['key']      #prints key value of the data
print result['txid']     #prints transaction id of the data
print result['data']     #prints raw data

It will return the key value, raw data and transaction id of the published item.

4. Retrieve an item against a particular key value

You have to pass these three arguments to the retrieveWithKey function call:

  • Stream name: which you want to access
  • Key: key value of the published data you want to verify
  • Count: no of items you want to retrieve
retrieveWithKey(stream, key, count)
result = retrieveWithKey(stream, key, count)

print result['publisher']    #prints publisher's address of the published data
print result['txid']         #prints transaction id of the data
print result['data']         #prints raw data

It will return the key value, raw data and transaction id of the published item.

5. Verify an data item on a particular stream of RecordsKeeper Blockchain

You have to pass these three arguments to the retrieveWithKey function call:

  • Stream name: which you want to access
  • Data: against which you want to make a query
  • Count: count of items which will be queried
verifyData(stream, data, count)
result = verifyData(stream, data, count)

print result    #prints if verification is successful or not

It will return the result if verification is successful or not.

6. Retrieve data items on a particular stream of RecordsKeeper Blockchain

You have to pass these two arguments to the verifyWithKey function call:

  • Stream name: which you want to access
  • Count: count of items which will be queried
retrieveItems(stream, count)
result = retrieveItems(stream, count)

print result['address']    #prints address of the publisher of the item
print result['key']        #prints key value of the stream itme
print result['data']       #prints raw data published
print result['txid']       #prints transaction id of the item published

It will return the address, key value, data and transaction id of the stream item published.