Category Archives: Tutoriale Linux

From 0 To 6000: Celebrating One Year Of Proton, Valve’s Brilliant Linux Gaming Solution

Linux Gaming

This week, Valve’s Proton turns one year old, and it has unarguably propelled the notion of gaming on Linux further than I would have thought possible. It has led to noticeably more mainstream press and YouTube coverage of desktop Linux, including this gem from Linus Tech Tips titled “Linux Gaming Finally Doesn’t Suck.” (Forbes)

Google Open-Sources Gesture Tracking AI For Mobile Devices

Google previewed the new technique at the 2019 Conference on Computer Vision and Pattern Recognition in June and recently implemented it in MediaPipe, a cross-platform framework for building multimodal applied machine learning pipelines to process perceptual data of different modalities (such as video and audio). Both the source code and an end-to-end usage scenario are available on GitHub. (Source: VentureBeat)

Essential Developer Guide for Building Blockchain Applications Using Hyperledger Sawtooth |

Hyperledger Sawtooth is an enterprise blockchain platform for building distributed ledger applications and networks. The design philosophy targets keeping ledgers distributed and making smart contracts safe, particularly for enterprise use.

Sawtooth simplifies blockchain application development by separating the core system from the application domain. Application developers can specify the business rules appropriate for their application, using the language of their choice, without needing to know the underlying design of the core system.

Sawtooth is also highly modular. This modularity enables enterprises and consortia to make policy decisions that they are best equipped to make. Sawtooth’s core design allows applications to choose the transaction rules, permissioning, and consensus algorithms that support their unique business needs.

For those who are not familiar with Hyperledger project Intro to Hyperledger Family and Hyperledger Blockchain Ecosystem and Hyperledger Design Philosophy and Framework Architecture articles are strongly recommended.

The features offered by Hyperledger Sawtooth are the following:

  • A truly distributed DLT: The Hyperledger Sawtooth blockchain network is made up of validator nodes. The ledger is shared between all validator nodes and each node has the same information. They participate in a consensus to manage the network.
  • Proof of Elapsed Time (PoET) consensus and support for large-scale networks: Hyperledger Sawtooth includes a novel consensus algorithm, PoET. PoET is a Byzantine Fault-tolerance (BFT) consensus algorithm that supports large-scale networks with minimal computing and much more efficient resource consumption compared to proof of work algorithms. PoET was invented by Intel and utilizes the special CPU instruction set called Software Guard Extensions (SGX), to achieve the scaling benefits of the Nakamoto-style consensus algorithms. Each node waits for a random period of time and the first node to finish is the leader and commits the next block.
  • Fast transaction performance: Hyperledger Sawtooth keeps the latest version of assets in the global state and transactions in the block chain on each network node. This means that you can look up the state quickly to carry out CRUD actions, which provides fast transaction processing. Sawtooth requires transactions to be processed in batches and supports parallel scheduling of transactions. Parallel transaction execution not only accelerates the execution of transactions but also correctly handles the double spending problem known as Unspent Transaction Output (UTXO).
  • Support for a broad variety of languages: Sawtooth supports the implementation of transaction families (safe and smart contracts) in a wide variety of programming languages, including Python, Go, Rust, Java, and JavaScript.
  • The ability to configure private, public, and consortium blockchain networks:

Sawtooth can be configured with different permissions to build private, consortium, or public networks by specifying which nodes are allowed to join the validator network and participate in the consensus, and which clients are allowed to submit batches and transactions.

In this article, I give step-by-step guide for building blockchain applications using Hyperledger Sawtooth. Good knowledge of blockchain concepts, JavaScript and Python as well as basic skills in Linux OS is required in order to complete tutorials listed on this article.

In short, we follow below steps:

  1. Install Hyperledger Sawtooth on a cloud service like AWS
  2. Configure Sawtooth validators and REST API
  3. Design a namespace and address for a transaction family
  4.  Implement a transaction family
  5. Build a transaction processor
  6.  Grant permission on the Sawtooth network
  7. Develop client applications with the Sawtooth REST API and SDK

To help blockchain developers to find their feet in Hyperledger Sawtooth development, I’ve written a series of hands-on tutorials to cover each topic in depth as follows.

Install Hyperledger Sawtooth

Follow Install and Work with Hyperledger Sawtooth recipe.

Configure Sawtooth Validators and REST API

Follow Configuring Hyperledger Sawtooth Validator and REST API on AWS recipe.

Design a Namespace and Address for Transaction Family and Implement Transaction Family

Follow Designing Namespace and Address for Hyperledger Sawtooth Transaction Family recipe

Build a Transaction Processor and Grant Permission on the Sawtooth Network

Follow Building Transaction Handler and Processor for Hyperledger Sawtooth with Python SDK recipe

Develop Client Applications with the Sawtooth REST API and SDK

Follow Transaction Processor and Python Egg For Hyperledger Sawtooth recipe.


About Authors

This article is written by Matt Zand (Founder of High School Technology Services) in collaboration with Brian Wu who is a senior blockchain developer at DC Web Makers.

Running Blockchain Applications in Hyperledger Explorer |

Hyperledger Explorer is a powerful utility that allows users to create user-friendly web-based applications. It is a blockchain dashboard and provides the ability to view, invoke, deploy, and query raw blockchain data and network information, including block details, chain codes, and transactions stored in the ledger.

For those who are not familiar with Hyperledger project Intro to Hyperledger Family and Hyperledger Blockchain Ecosystem and Hyperledger Design Philosophy and Framework Architecture articles are strongly recommended.

Hyperledger Explorer is a highly maintainable and open source browser that can be configured and built natively on macOS and Ubuntu. At the time of writing, Hyperledger Explorer has not yet gone live. The latest release, v0.3.8, supports Fabric v1.3.

It is common to encounter errors here and there, especially around issues related to versions and/or setting up environments. To save time while debugging, I have included notes, along with recommended fixes, for some of errors you might run into while walking through this recipe.

In our previous tutorials, we learned how to i- Work with Hyperledger Explorer and its Development Environment ii- Install Hyperledger Explorer and its PostgreSQL Database, iii- Configure Explorer to connect to a blockchain network like Fabric and iv- Build a Hyperledger Explorer application. This recipe as a next step will show you how to run the Hyperledger Explorer application.

Hyperledger Explorer Configuration

Before running Hyperledger Explorer, we should examine the configuration of Explorer, which is defined in the explorerconfig.json file.

Update the following information according to the individual needs of the project:

  • Where the synchronization will be running, which is either explorer (local) or from a different location standalone (host)
  • The type of blockchain network (Fabric)
  • How often the blockchain data will synchronize with explorer

Run Hyperledger Explorer Application

Execute the following steps to run your Hyperledger application:

1. Use the vi editor or your editor of choice to make the modifications as needed:

	cd blockchain-explorer/app

	vi explorerconfig.json

# Here we will run local with Explorer, update the "sync" property as needed to # as below:

"sync": {

"type": "local",

"platform": "fabric",

"blocksSyncTime": "3"



2. Now, start Explorer from another Terminal. When you are done using Explorer, you should stop Explorer and the node server:

	cd blockchain-explorer/

	sudo ./

# To stop Explorer, use this command:

	sudo ./

3. You can check for error statuses in the log file: [logs/console/console-yyyy-mm-dd.log]. If everything goes well, you will see the following:


(node:14817) DeprecationWarning: grpc.load: Use the @grpc/proto-

loader module with

grpc.loadPackageDefinition instead

Please open web browser to access: http://localhost:8080/

pid is 14817



4. The console log might show an Explorer error, such as the following:

postgres://hppoc:password@ <<<<<<<<<<<<<<<<<<<<<<<<<< Explorer Error >>>>>>>>>>>>>>>>>>>>>

{ Error: The gRPC binary module was not installed. This may be fixed by running "npm rebuild"

Original error: Cannot find module '/home/ubuntu/blockchain-explorer/node_modules/grpc/src/node/extension_binary/node-v57-linux-x64-glibc/grpc_node.node'

at Object.<anonymous> (/home/ubuntu/blockchain-explorer/node_modules/grpc/src/grpc_extension.js:43:17)

at Module._compile (module.js:653:30)

at Object.Module._extensions..js (module.js:664:10)

at Module.load (module.js:566:32)

at tryModuleLoad (module.js:506:12)

at Function.Module._load (module.js:498:3)

at Module.require (module.js:597:17)

at require (internal/module.js:11:18)

at Object.<anonymous> (/home/ubuntu/blockchain-explorer/node_modules/grpc/src /client_interceptors.js:145:12)

at Module._compile (module.js:653:30) code: 'MODULE_NOT_FOUND' } Received kill signal, shutting down gracefullyClosed out connections

5. This may be fixed by running npm rebuild and then starting Explorer again:

	cd ~/blockchain-explorer/

	npm rebuild

> grpc@1.14.2 install /home/ubuntu/blockchain-explorer/node_modules/grpc

> node-pre-gyp install --fallback-to-build --library=static_library


Note: There is an application log, [logs/app/app.log], that provides more information than the console log if there are any errors when running the Explorer application.

6. On the other hand, Explorer runs in the background. To observe the progression, you could use the tail command for the app.log file:

	tail -f logs/app/app.log

7. We can now launch Explorer from a browser: http://localhost:8080.

8. If you are running on AWS EC2, you will need to carry out a further two steps. Replace the localhost with your instance’s public IP address and add or modify a security group associate with the EC2 instance to allow inbound traffic from TCP port 8080. If everything is good, you should see the explorer DASHBOARD default page. From here, you can navigate to the application to check and monitor various blockchain data:

You have now successfully built the Hyperledger Explorer application, integrated it with the Hyperledger Fabric framework, and utilized Explorer to visualize the blockchain network data on the browser.

About Authors

This article is written by Matt Zand (Founder of High School Technology Services) in collaboration with Brian Wu who is a senior blockchain instructor at Coding Bootcamps.

Install Leafpad on Ubuntu 19.04

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Leafpad is an open source text editor for Linux, BSD, and Maemo. Created with the focus of being a lightweight text editor with minimal dependencies, it is designed to be simple and easy-to-compile. Leafpad is the default text editor for LXDE Desktop environment.

Leafpad Features

Leafpad’s features include a codeset option, auto codeset detection, an unlimited Undo/Redo feature and drag and drop capabilities.Leafpad has a small footprint compared to editors such as gedit or Kate.

Install Leafpad on Ubuntu 19.04

Leafpad is not avaialble as .deb package from ubuntu 19.04 so you have to install from the source

sudo apt-get install build-essential checkinstall intltool libgtk2.0-dev

mkdir -v $HOME/leafpad-build



tar xvf leafpad- && cd leafpad-

sudo ./configure

sudo make

sudo checkinstall -D –install=yes –fstrans=no –pakdir “$HOME/leafpad-build”
–pkgname leafpad –backup=no –deldoc=yes –deldesc=yes –delspec=yes
–default –pkgversion “”

sudo make distclean

Open the leafpad using the following command

sudo ldconfig

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