In this article we will show practical implication of emercoin blockchain app DPO. You could find theory and technology description in our previous article.
Before we begin, be sure to check our BTC Miamy meetup group. Will be glad to see your participation by any means.
EMC DPO Deployment on Your Server
In this section, we shall learn how to deploy and configure EMC DPO on your server, powered by the OS Ubuntu 16.04 LTS (amd64). It is also compatible with the following other operating systems: Ubuntu 14.04 LTS (amd64), Debian 8 (amd64, armhf), RHEL/CentOS 7 (x86_64).
1. Installing the Emercoind service
Let’s use the standard apps to install Emercoind:
apt-key adv — keyserver keyserver.ubuntu.com — recv B58C58F4 add-apt-repository ‘deb http://download.emercoin.com/ubuntu xenial emercoin’ apt update && apt -y install emercoin
Make sure that emercoind is installed, working, and starting to download the blockchain:
emc getinfo { “version”: 60000, “protocolversion”: 70002, “walletversion”: 60000, “balance”: 1.090000, “newmint”: 0.000000, “stake”: 0.000000, “blocks”: 216541, “moneysupply”: 39554119.651462, “timeoffset”: 0, “connections”: 8, “proxy”: “”, “ip”: “0.0.0.0”, “difficulty”: 206196413.012576, “testnet”: false, “keypoololdest”: 1487850355, “keypoolsize”: 501, “mintonly”: false, “unlocked_until”: 0, “paytxfee”: 0.010000, “relayfee”: 0.000100, }
Wait until the blockchain is downloaded. Then send some coins to the wallet (at the rate of 0.12 EMC approx. for one blockchain data creation/refreshment operation).
A new wallet address can be created by running the following command:
emc getnewaddress
2. Creating NVS entries
It is necessary to create entries in the blockchain’s NVS for the manufacturer (vendor) and for the products themselves (separate entry for each product unit).
2.1. Creating the main entry of the Vendor
Let’s define the input data.
- The manufacturer (vendor) be referred as “Your Company”
- For the vendor logo, click this link: emercoin.com/images/main-logo.png
- We would also like to create an additional field called ‘Description’, and enter the following data there: ‘The description of Your Company’
- The entry will be active for 730 days
After that, such an entry can be created by running the following command:
emc name_new “dpo:Your Company” “Name=Your Company Description=The description of your Company Logo=http://emercoin.com/images/main-logo.png" 730
Once this command is executed, we get a Transaction ID code, if everything has gone successfully.
Wait until this entry has made it into the blockchain. To do this, run the command:
emc name_show “dpo:Your Company”
Once the entry is in the blockchain, we should see something like this:
{ “name”: “dpo:Your Company”, “value”: “Name=Your Company\nDescription=The description of your Company\nLogo=emercoin.com/images/main-logo.png", “txid”: “b11384b162e2d3d2900d10e942c6ae3aa8bca94801dc119677685d68d35c9712”, “address”: “ERGPQNKpmJNaXeaq6ZDYwgghQDMBQGVema”, “expires_in”: 127749, “expires_at”: 343616, “time”: 1487856529 }
Remember the ‘address’ field data — this is the main address from which all subsequent product entries will be derived.
We also have to devise a ‘salt’, that is, add an arbitrary set of symbols to user passwords to make it harder for phishers to bust passwords. As an example, we might form the following password: johNah2koosie3iG.
2.2. Creating Product Entries
Define the input data.
- The product be called: “Name of your product”
- For the photo of the product, click this link: www.blockchainengine.org/wp-content/uploads/2016/04/Smart4.png
- We would also create an additional field called ‘Description’, and enter the following data there: ‘The description of your product’
- For starters, we would like to create 100 serial numbers of the product: from SN-55001 to SN-55100
- Each product entry will be active for 730 days
After that, such entries can be created by executing the following script (having first installed php-cli and pwgen):
Source: https://github.com/snvakula/svtools/blob/master/emcdpo-genbulk.sh
#!/bin/bash URL=”http://emcdpo.info/dpo" SALT=”johNah2koosie3iG” ADDRESS=”ERGPQNKpmJNaXeaq6ZDYwgghQDMBQGVema” VENDOR=”Your Company” ITEM=”Name of your product” PHOTO=”www.blockchainengine.org/wp-content/uploads/2016/04/Smart4.png" OTHERS=”Description=The description of your product” PREFIX=”SN-” FIRST=55001 LAST=55100 DAYS=730 while [ $FIRST -le $LAST ]; do echo “Creating serial $PREFIX$FIRST:” SECRET=$(pwgen 8 1) OTP=$(php -r “echo(hash(‘sha256’, md5(‘$SECRET’.’$SALT’)));”) echo “ * SECRET: $SECRET” echo “ * OTP: $OTP” echo “ * Public URL: $URL/key/$PREFIX$FIRST” echo “ * Private URL: $URL/key/$PREFIX$FIRST?otp=$SECRET” COUNT=0 while emc name_show “dpo:$VENDOR:$PREFIX$FIRST:$COUNT” >/dev/null 2>&1 do let COUNT=COUNT+1 done echo “ * NVS Record: dpo:$VENDOR:$PREFIX$FIRST:$COUNT” VALUE=”Item=$ITEM\nPhoto=$PHOTO\n$OTHERS\nOTP=$OTP” VALUE=$(echo -e “$VALUE”) echo -n “ * Transaction ID: “ emc name_new “dpo:$VENDOR:$PREFIX$FIRST:$COUNT” “$VALUE” $DAYS $ADDRESS echo let FIRST=FIRST+1 done
where URL is the web address of EMC DPO deployment.
Execution of this script results in the creation of NVS entries (if you have done it all correctly) and data output to the console will look like:
`Creating serial SN-55001:
- SECRET: maifeB32
- OTP: bb680a8bcae3e5be23f3c9ed4d3d0e97d42cebe561f53a5a7502e2d150a937fb
- Public URL: http://emcdpo.info/dpo/key/SN-55001
- Private URL: http://emcdpo.info/dpo/key/SN-55001?otp=maifeB32
- NVS Record: dpo:Your Company:SN-55001:0
- Transaction ID: 7e1c5a131887a08971225790047bf9e8asq3ca5f947beb9ba0ced6541931939f`
We then save the Public URL and Private URL for each separate serial number, make QR-codes out of them, and place them as follows: one on the outside of the box; the other, naturally, inside the box, under the protective film.
3. EMC DPO Web Application Deployment
First we install dependencies and activate the desired modules:
apt install curl git apache2 libapache2-mod-php php-xml a2enmod rewrite
Clone a git-repository into /var/www:
cd /var/www git clone https://github.com/Emercoin/emcdpo
Install composer and its components:
cd /var/www/emcdpo/engine curl -sS https://getcomposer.org/installer | php php composer.phar install — prefer-dist
Designate the www-data user (or any other, through which the web server will be executing the code) as the owner of the emcdpo folder:
chown -R www-data:www-data /var/www/emcdpo/engine
Record our parameters into the file /var/www/emcdpo/engine/src/settings.php:
// General Settings CONST DPO_VENDOR = ‘Your Company’; CONST SALT = ‘johNah2koosie3iG’; CONST NVS_DAYS = 730; CONST ALLOWED_UPDATES = 2; CONST SEARCH_DEPTH = 10; // Emercoin RPC Settings CONST RPC_TYPE = “https”; CONST RPC_USERNAME = “emccoinrpc”; CONST RPC_PASSWORD = “RahRoh6ca8chaf6naji9dfaazaeghaidiLooyePi4aeQuah9lai4Eij5gotoocha”; CONST RPC_HOST = “localhost”; CONST RPC_PORT = ‘6662’;
Emercoin RPC login details can be read in the file /etc/emercoin/emercoin.conf
Then configure the web-server. To do this, create an Apache configuration file /etc/apache2/sites-available/emcdpo.conf, with the following code an example of this:
Alias /dpo /var/www/emcdpo/engine/web <Directory /var/www/emcdpo/engine/web> Options -MultiViews RewriteEngine On RewriteBase /dpo RewriteCond %{RQUEST_FILENAME} !-d RewriteCond %{REQUEST_FILENAME} !-f RewriteRule ^ index.php [QSA,L] </Directory>
Activate the configuration and restart Apache:
a2ensite emcdpo systemctl restart apache2
Now EMC DPO will be available at the following address: http://YOURHOSTNAME/dpo, and it is now ready for use.
Then, based on received URL and codes, you can generate product labels. To do so, you can, for example, use this program
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