Fabric blockchain Python
a total of 22 weeks, divided into five stages,
the first stage is 4 weeks, go language foundation and network concurrency, learning the introctory go language,
the second stage is 4 weeks, go language practical web development, crawler development, cryptography, consensus algorithm, realizing lightweight public chain, learning the website and crawler that can develop golang, Achieve lightweight blockchain
stage 3, 4-week Ethereum source code analysis and smart contract DAPP development, master Ethereum core and smart contract development, as well as blockchain,
stage 4, 4-week super ledger, bitcoin EOS, source code analysis and smart contract practice, master super ledger development, cat bitcoin, bifurcated EOS after learning, As well as DAPP development of smart contract
phase 5, 6-week project practice, five enterprise level projects, and one year of blockchain project experience after learning
from the characteristics of the language itself, go is a very efficient language, which highly supports concurrency. Go language itself pays more attention to distributed system, and concurrency processing is relatively good, such as advertising and search, That kind of high concurrency server
go language advantages:
excellent performance, can be directly compiled into machine code, does not rely on other libraries, go is extremely fast. Its performance is similar to Java or C + +
concurrency is supported at the language level, which is the biggest feature of go. It is born to support concurrency, and go is the concurrency supported in gene, which can make full use of multi-core and make it easy to use concurrency
the built-in runtime supports garbage collection, which is one of the features of dynamic language. Although GC is not perfect at present, it is enough to cope with most of the situations we can encounter, especially GC after go1.1
it's easy to learn. The authors of go language all have the gene of C, so go naturally has the gene of C. There are 25 go keywords, but the expressive ability is very strong. It almost supports most of the features you've seen in other languages: inheritance, overloading, object, etc
rich standard libraries, go has built a large number of libraries, especially the network library, which is also my favorite part< As like as two peas, br / > built-in powerful tools, Go language is built with many tools chain, the best should be gofmt tools, automatic formatting code, make team review become so simple, code format is exactly the same, it is very difficult to think differently.
cross platform compilation and fast compilation. Compared with the sluggish compilation speed of Java and C + +, the fast compilation time of go is a major efficiency advantage
disadvantages of go language:
package management: package management of go language is absolutely not perfect. By default, it has no way to make a specific version of the dependency library, nor can it create replicable builds. In contrast, python, node and Ruby all have better package management systems. However, with the right tools, the package management of go language can also perform well
lack of development framework: go language does not have a major framework, such as Ruby's rails framework, Python's Django framework or PHP's laravel. This is a heated discussion in the go language community, because many people think that we should not start with using frameworks. This is true in many cases, but if you just want to build a simple crud API, it's much easier to use Django / djrf, rails laravel, or Phoenix
exception handling: go language can help developers deal with compilation errors by simply returning errors (or call stack) through functions and expected calling codes. Although this method is effective, it is easy to lose the scope of the error, so it is difficult to provide meaningful error information to users. Error package can solve this problem by allowing us to add context and stack trace to return error
another problem is that we may forget to handle errors. Static analysis tools such as errcheck and megacheck can avoid these errors. Although these solutions are very effective, they may not be the right way.
however, as Ethereum and hyperledger fabric have the best support for go language, go language must be learned
next, I'll give you the answer to another question, hoping to help you
Background: I started to study blockchain technology in 2015, so I have a certain understanding of blockchain
statement: it is estimated that everyone who sees this question wants to get started with blockchain, so this answer is mainly an introction at the entry level. It's just an introction at the entry level, which is not suitable for blockchain practitioners to improve their learning.
the hypervessel platform developed by IBM China Research Institute provides a blockchain development and testing environment for blockchain enthusiasts and developers. Through this platform, users can create a multi node blockchain based on hyperledger fabric free of charge and quickly, and play smart contracts on their own chains
of course, decent, a foreign decentralized content sharing platform, can also be created.
features:
blockchain is an immutable and orderly chain record composed of block records. The main features are as follows:
1: decentralization
e to the use of Distributed Accounting and storage, there is no centralized hardware or management organization, the rights and obligations of any node are equal, and the data blocks in the system are jointly maintained by the nodes with maintenance function in the whole system. Thanks to the decentralization of blockchain, bitcoin also has the characteristics of decentralization
2: openness
the system is open, in addition to the private information of the parties to the transaction is encrypted, the data of the blockchain is open to all, and anyone can query the blockchain data and develop related applications through the open interface, so the information of the whole system is highly transparent
3: autonomy
blockchain adopts consensus based specifications and Protocols (such as a set of open and transparent algorithms) to enable all nodes in the whole system to exchange data freely and safely in a de trusted environment, so that the trust in "people" is changed into the trust in machines, and any human intervention does not work
4: information cannot be tampered with
once the information is verified and added to the blockchain, it will be stored permanently. Unless more than 51% of the nodes in the system can be controlled at the same time, the modification of the database on a single node is invalid, so the data stability and reliability of the blockchain are extremely high
5: anonymity
since the exchange between nodes follows a fixed algorithm, their data interaction does not need to be trusted (the program rules in the blockchain will judge whether the activity is effective by themselves), so the counterparties do not need to make the other party trust themselves by disclosing their identities, which is very helpful for credit accumulation
compared with the traditional distributed database, there are two main differences:
1: the traditional distributed database supports adding, deleting, checking and modifying, while the blockchain only supports searching and inserting, and blocks cannot be deleted or modified
2: the traditional distributed database is generally a master-slave structure: master and slaves structure. In order to ensure high availability, it is realized by standby master, while the blockchain is a decentralized database. There is no master-slave structure
blockchain and bitcoin:
when it comes to blockchain, most people talk about bitcoin. However, blockchain is not equal to bitcoin. It is now the era of blockchain 3.0, and bitcoin is only the proct of blockchain 1.0
the evolution mode of blockchain is:
& ᦇ 9642; Blockchain 1.0 digital currency; Blockchain 2.0 digital assets and smart contracts; Blockchain 3.0 - Implementation of distributed applications in various instries
classification of blockchain:
public blockchains
public blockchain means that any indivial or group in the world can send transactions, and transactions can be effectively confirmed by the blockchain, and anyone can participate in its consensus process. Public blockchain is the earliest and the most widely used blockchain. The virtual digital currencies of bitcoin series are all based on public blockchain. There is only one blockchain corresponding to this currency in the world
consortium blockchains
instry blockchains: multiple preselected nodes are designated as bookkeepers within a certain group, and the generation of each block is jointly determined by all preselected nodes (preselected nodes participate in the consensus process). Other access nodes can participate in transactions, but not the bookkeeping process (essentially, trusteeship bookkeeping), It just becomes distributed accounting, the number of preselected nodes, and how to determine the bookkeeper of each block to become the main risk point of the blockchain). Anyone else can conct limited query through the open API of the blockchain
private blockchain: it only uses the general ledger technology of blockchain for bookkeeping. It can be a company or an indivial, enjoying the write permission of the blockchain. This blockchain is not very different from other distributed storage schemes Dec2015) conservative giants (traditional finance) want to experiment with private blockchain, while the application of public chain, such as bitcoin, has been instrialized, and the application procts of private chain are still groping.
Can be
blockchain to achieve a simple description of the principle of
blockchain technology as a digital accounting technology, its core is to save the transaction data block, in the form of encryption, according to the order of time chain record. Blockchain itself is a public database. The system stores the new business data in a container called block, and adds the block to the chain composed of existing blocks. It's a bit like a snake. The more you eat, the longer the snake's body; In the application scenario of bitcoin, the data is a set of transfer transaction records. In the application scenario of bike sharing, these data can be the transaction records of car borrowing and returning
The simple implementation code ofblockchain
in the above code, the data structure stored in the core of blockchain is list, which can be accessed through
new_ New blocks generated by block () are constantly added to the end of the blockchain. The hash value of each block contains all the data information of the block. In the process of calculating the hash
value, the hash
value of the previous block needs to be referenced, so tamper proof is realized. The biggest value of blockchain database is this highly tamper proof trusted computing. This has been successfully demonstrated in our simple blockchain implementation. In commercial level blockchain applications, the process of creating new blocks is called smart contract, and blockchain is growing through smart contract
the following is the running result of the code, which is different at different times
running results
< img / >
and Python is an object-oriented interpretive computer programming language
it's better to learn together without conflict. I think it's Python because it's a language that can do a lot of things.
1 import hashlib as hasher
2 import datetime as date
3
4 # Define what a Snakecoin block is
5 class Block:
6 def __init__(self, index, timestamp, data, previous_hash):
7 self.index = index
8 self.timestamp = timestamp
9 self.data = data
10 self.previous_hash = previous_hash
11 self.hash = self.hash_block()
12
13 def hash_block(self):
14 sha = hasher.sha256()
15 sha.update(str(self.index) + str(self.timestamp) + str(self.data) + str(self.previous_hash))
16 return sha.hexdigest()
17
18 # Generate genesis block
19 def create_genesis_block():
20 # Manually construct a block with
21 # index zero and arbitrary previous hash
22 return Block(0, date.datetime.now(), "Genesis Block", "0")
23
24 # Generate all later blocks in the blockchain
25 def next_block(last_block):
26 this_index = last_block.index + 1
27 this_timestamp = date.datetime.now()
28 this_data = "Hey! I'm block " + str(this_index)
29 this_hash = last_block.hash
30 return Block(this_index, this_timestamp, this_data, this_hash)
31
32 # Create the blockchain and add the genesis block
33 blockchain = [create_genesis_block()]
34 previous_block = blockchain[0]
35
36 # How many blocks should we add to the chain
37 # after the genesis block
38 num_of_blocks_to_add = 20
39
40 # Add blocks to the chain
41 for i in range(0, num_of_blocks_to_add):
42 block_to_add = next_block(previous_block)
43 blockchain.append(block_to_add)
44 previous_block = block_to_add
45 # Tell everyone about it!
46 print "Block #{} has been added to the blockchain!".format(block_to_add.index)
47 print "Hash: {}\n".format(block_to_add.hash)
******************************************************************************
* @file stm32_eth.c
* @author MCD Application Team
* @version V1.1.0
* @date 11/20/2009
* @brief This file provides all the ETH firmware functions.
******************************************************************************
* @
*
* THE PRESENT FIRMWARE WHICH IS FOR GUIDANCE ONLY AIMS AT PROVIDING CUSTOMERS
* WITH CODING INFORMATION REGARDING THEIR PRODUCTS IN ORDER FOR THEM TO SAVE
* TIME. AS A RESULT, STMICROELECTRONICS SHALL NOT BE HELD LIABLE FOR ANY
* DIRECT, INDIRECT OR CONSEQUENTIAL DAMAGES WITH RESPECT TO ANY CLAIMS ARISING
* FROM THE CONTENT OF SUCH FIRMWARE AND/OR THE USE MADE BY CUSTOMERS OF THE
* CODING INFORMATION CONTAINED HEREIN IN CONNECTION WITH THEIR PRODUCTS.
*
* <h2><center>© COPYRIGHT 2009 STMicroelectronics</center></h2>
*/
Puyin is a high-quality Tibetan tea asset, which is stored, identified, evaluated and authorized by three parties. It is a standard digital currency issued through encryption and digitization. Puyin implements it in strict accordance with the concept of "white paper on standard digital currency" as its operation guideline. It is also a digital currency based on blockchain technology.
1. Technical language
Python and go are two technical languages mentioned by many companies. Learning needs to be a priority. Moreover, these two languages have great application in the technical direction outside the blockchain. For example, go is used in the background construction of large concurrent systems, and Python is used in the construction of artificial intelligence systems. So learning these two languages is a priority
2. Technical framework
master one or more of bitcoin, Eth and hyperledger. Needless to say, BTC is written in C + +. A large number of currency projects, such as lightcoin, dash, Monroe, zcash, use bitcoin technology for secondary development
eth is the representative of blockchain 2.0, which can build a variety of application classes DAPP on eth network. Now a large number of application blockchain projects are developed using eth platform
hyperledger fabric is a blockchain development platform pushed by IBM, which is mainly used for the development of alliance chain, and is the most popular alliance chain development platform at present
3, algorithm
pow (proof of work), POS (proof of rights and interests algorithm), pbft (Byzantine fault-tolerant algorithm) are all important components of cryptography in blockchain. A full understanding of these algorithms will help you to have a better understanding of cryptography when you participate in the underlying development of blockchain projects
extended data:
blockchain technology is a kind of Distributed Accounting Technology, which is characterized by decentralization, openness and transparency, so that everyone can participate in the establishment of the database, and each established data can not be tampered with, and everyone participates, The problem of trust between strangers is solved
blockchain technology has emerged. It is an accounting technology with the participation of the whole people. The transaction information and data between AB and ab are published to the public and can not be tampered with. As we all know, there is no need for any authoritative Third Party C here. In other words, everyone in the system plays the role of C, which is also called decentralization