57 skills found · Page 1 of 2
damusnet / React Swipe ViewsA React Component for binded Tabs and Swipeable Views
ignoreintuition / V Chart PluginEasily bind a chart to the data stored in your Vue.js components.
cassiozen / React AutobindUtility function to Automatically bind methods defined within a component's Class to the current object's lexical `this` instance.
svapreddy / ClearxClearX is an alternative way to Redux and MobX to maintain the application state and provides a simple interface to bind it to UI components.
mushan0x0 / Rc Form HooksUse hooks to bind form components to actions such as uniform validation and get values.
Laralabs / ToasterEasily generate and bind message data to the view for use in frontend JS components
application-stacks / Runtime Component OperatorA generic Operator capable of deploying any runtime component image with enterprise QoS and bind it to other services. Documentation: https://ibm.biz/rco-docs-v1
theluk / React FormularThis libraray is an experimental approach to bind forms and its inputs and editors together using the new React Context API. It aims to be fully customizable and composable. It´s only a set of Higher-Order-Components. Because of the decoupled nature, Middlewares makes it easy to build custom Validations, Security Guards and other data interceptors.
mmun / Ember Component AttributesEasily bind attributes to your ember components
Mdshobu / Liberty House Club Whitepaper# Liberty House Club **A Parallel Binance Chain to Enable Smart Contracts** _NOTE: This document is under development. Please check regularly for updates!_ ## Table of Contents - [Motivation](#motivation) - [Design Principles](#design-principles) - [Consensus and Validator Quorum](#consensus-and-validator-quorum) * [Proof of Staked Authority](#proof-of-staked-authority) * [Validator Quorum](#validator-quorum) * [Security and Finality](#security-and-finality) * [Reward](#reward) - [Token Economy](#token-economy) * [Native Token](#native-token) * [Other Tokens](#other-tokens) - [Cross-Chain Transfer and Communication](#cross-chain-transfer-and-communication) * [Cross-Chain Transfer](#cross-chain-transfer) * [BC to BSC Architecture](#bc-to-bsc-architecture) * [BSC to BC Architecture](#bsc-to-bc-architecture) * [Timeout and Error Handling](#timeout-and-error-handling) * [Cross-Chain User Experience](#cross-chain-user-experience) * [Cross-Chain Contract Event](#cross-chain-contract-event) - [Staking and Governance](#staking-and-governance) * [Staking on BC](#staking-on-bc) * [Rewarding](#rewarding) * [Slashing](#slashing) - [Relayers](#relayers) * [BSC Relayers](#bsc-relayers) * [Oracle Relayers](#oracle-relayers) - [Outlook](#outlook) # Motivation After its mainnet community [launch](https://www.binance.com/en/blog/327334696200323072/Binance-DEX-Launches-on-Binance-Chain-Invites-Further-Community-Development) in April 2019, [Binance Chain](https://www.binance.org) has exhibited its high speed and large throughput design. Binance Chain’s primary focus, its native [decentralized application](https://en.wikipedia.org/wiki/Decentralized_application) (“dApp”) [Binance DEX](https://www.binance.org/trade), has demonstrated its low-latency matching with large capacity headroom by handling millions of trading volume in a short time. Flexibility and usability are often in an inverse relationship with performance. The concentration on providing a convenient digital asset issuing and trading venue also brings limitations. Binance Chain's most requested feature is the programmable extendibility, or simply the [Smart Contract](https://en.wikipedia.org/wiki/Smart_contract) and Virtual Machine functions. Digital asset issuers and owners struggle to add new decentralized features for their assets or introduce any sort of community governance and activities. Despite this high demand for adding the Smart Contract feature onto Binance Chain, it is a hard decision to make. The execution of a Smart Contract may slow down the exchange function and add non-deterministic factors to trading. If that compromise could be tolerated, it might be a straightforward idea to introduce a new Virtual Machine specification based on [Tendermint](https://tendermint.com/core/), based on the current underlying consensus protocol and major [RPC](https://docs.binance.org/api-reference/node-rpc.html) implementation of Binance Chain. But all these will increase the learning requirements for all existing dApp communities, and will not be very welcomed. We propose a parallel blockchain of the current Binance Chain to retain the high performance of the native DEX blockchain and to support a friendly Smart Contract function at the same time. # Design Principles After the creation of the parallel blockchain into the Binance Chain ecosystem, two blockchains will run side by side to provide different services. The new parallel chain will be called “**Binance Smart Chain**” (short as “**BSC**” for the below sections), while the existing mainnet remains named “**Binance Chain**” (short as “**BC**” for the below sections). Here are the design principles of **BSC**: 1. **Standalone Blockchain**: technically, BSC is a standalone blockchain, instead of a layer-2 solution. Most BSC fundamental technical and business functions should be self-contained so that it can run well even if the BC stopped for a short period. 2. **Ethereum Compatibility**: The first practical and widely-used Smart Contract platform is Ethereum. To take advantage of the relatively mature applications and community, BSC chooses to be compatible with the existing Ethereum mainnet. This means most of the **dApps**, ecosystem components, and toolings will work with BSC and require zero or minimum changes; BSC node will require similar (or a bit higher) hardware specification and skills to run and operate. The implementation should leave room for BSC to catch up with further Ethereum upgrades. 3. **Staking Involved Consensus and Governance**: Staking-based consensus is more environmentally friendly and leaves more flexible option to the community governance. Expectedly, this consensus should enable better network performance over [proof-of-work](https://en.wikipedia.org/wiki/Proof_of_work) blockchain system, i.e., faster blocking time and higher transaction capacity. 4. **Native Cross-Chain Communication**: both BC and BSC will be implemented with native support for cross-chain communication among the two blockchains. The communication protocol should be bi-directional, decentralized, and trustless. It will concentrate on moving digital assets between BC and BSC, i.e., [BEP2](https://github.com/binance-chain/BEPs/blob/master/BEP2.md) tokens, and eventually, other BEP tokens introduced later. The protocol should care for the minimum of other items stored in the state of the blockchains, with only a few exceptions. # Consensus and Validator Quorum Based on the above design principles, the consensus protocol of BSC is to fulfill the following goals: 1. Blocking time should be shorter than Ethereum network, e.g. 5 seconds or even shorter. 2. It requires limited time to confirm the finality of transactions, e.g. around 1-min level or shorter. 3. There is no inflation of native token: BNB, the block reward is collected from transaction fees, and it will be paid in BNB. 4. It is compatible with Ethereum system as much as possible. 5. It allows modern [proof-of-stake](https://en.wikipedia.org/wiki/Proof_of_stake) blockchain network governance. ## Proof of Staked Authority Although Proof-of-Work (PoW) has been recognized as a practical mechanism to implement a decentralized network, it is not friendly to the environment and also requires a large size of participants to maintain the security. Ethereum and some other blockchain networks, such as [MATIC Bor](https://github.com/maticnetwork/bor), [TOMOChain](https://tomochain.com/), [GoChain](https://gochain.io/), [xDAI](https://xdai.io/), do use [Proof-of-Authority(PoA)](https://en.wikipedia.org/wiki/Proof_of_authority) or its variants in different scenarios, including both testnet and mainnet. PoA provides some defense to 51% attack, with improved efficiency and tolerance to certain levels of Byzantine players (malicious or hacked). It serves as an easy choice to pick as the fundamentals. Meanwhile, the PoA protocol is most criticized for being not as decentralized as PoW, as the validators, i.e. the nodes that take turns to produce blocks, have all the authorities and are prone to corruption and security attacks. Other blockchains, such as EOS and Lisk both, introduce different types of [Delegated Proof of Stake (DPoS)](https://en.bitcoinwiki.org/wiki/DPoS) to allow the token holders to vote and elect the validator set. It increases the decentralization and favors community governance. BSC here proposes to combine DPoS and PoA for consensus, so that: 1. Blocks are produced by a limited set of validators 2. Validators take turns to produce blocks in a PoA manner, similar to [Ethereum’s Clique](https://eips.ethereum.org/EIPS/eip-225) consensus design 3. Validator set are elected in and out based on a staking based governance ## Validator Quorum In the genesis stage, a few trusted nodes will run as the initial Validator Set. After the blocking starts, anyone can compete to join as candidates to elect as a validator. The staking status decides the top 21 most staked nodes to be the next validator set, and such an election will repeat every 24 hours. **BNB** is the token used to stake for BSC. In order to remain as compatible as Ethereum and upgradeable to future consensus protocols to be developed, BSC chooses to rely on the **BC** for staking management (Please refer to the below “[Staking and Governance](#staking-and-governance)” section). There is a **dedicated staking module for BSC on BC**. It will accept BSC staking from BNB holders and calculate the highest staked node set. Upon every UTC midnight, BC will issue a verifiable `ValidatorSetUpdate` cross-chain message to notify BSC to update its validator set. While producing further blocks, the existing BSC validators check whether there is a `ValidatorSetUpdate` message relayed onto BSC periodically. If there is, they will update the validator set after an **epoch period**, i.e. a predefined number of blocking time. For example, if BSC produces a block every 5 seconds, and the epoch period is 240 blocks, then the current validator set will check and update the validator set for the next epoch in 1200 seconds (20 minutes). ## Security and Finality Given there are more than ½\*N+1 validators are honest, PoA based networks usually work securely and properly. However, there are still cases where certain amount Byzantine validators may still manage to attack the network, e.g. through the “[Clone Attack](https://arxiv.org/pdf/1902.10244.pdf)”. To secure as much as BC, BSC users are encouraged to wait until receiving blocks sealed by more than ⅔\*N+1 different validators. In that way, the BSC can be trusted at a similar security level to BC and can tolerate less than ⅓\*N Byzantine validators. With 21 validators, if the block time is 5 seconds, the ⅔\*N+1 different validator seals will need a time period of (⅔\*21+1)*5 = 75 seconds. Any critical applications for BSC may have to wait for ⅔\*N+1 to ensure a relatively secure finality. However, besides such arrangement, BSC does introduce **Slashing** logic to penalize Byzantine validators for **double signing** or **inavailability**, which will be covered in the “Staking and Governance” section later. This Slashing logic will expose the malicious validators in a very short time and make the “Clone Attack” very hard or extremely non-beneficial to execute. With this enhancement, ½\*N+1 or even fewer blocks are enough as confirmation for most transactions. ## Reward All the BSC validators in the current validator set will be rewarded with transaction **fees in BNB**. As BNB is not an inflationary token, there will be no mining rewards as what Bitcoin and Ethereum network generate, and the gas fee is the major reward for validators. As BNB is also utility tokens with other use cases, delegators and validators will still enjoy other benefits of holding BNB. The reward for validators is the fees collected from transactions in each block. Validators can decide how much to give back to the delegators who stake their BNB to them, in order to attract more staking. Every validator will take turns to produce the blocks in the same probability (if they stick to 100% liveness), thus, in the long run, all the stable validators may get a similar size of the reward. Meanwhile, the stakes on each validator may be different, so this brings a counter-intuitive situation that more users trust and delegate to one validator, they potentially get less reward. So rational delegators will tend to delegate to the one with fewer stakes as long as the validator is still trustful (insecure validator may bring slashable risk). In the end, the stakes on all the validators will have less variation. This will actually prevent the stake concentration and “winner wins forever” problem seen on some other networks. Some parts of the gas fee will also be rewarded to relayers for Cross-Chain communication. Please refer to the “[Relayers](#relayers)” section below. # Token Economy BC and BSC share the same token universe for BNB and BEP2 tokens. This defines: 1. The same token can circulate on both networks, and flow between them bi-directionally via a cross-chain communication mechanism. 2. The total circulation of the same token should be managed across the two networks, i.e. the total effective supply of a token should be the sum of the token’s total effective supply on both BSC and BC. 3. The tokens can be initially created on BSC in a similar format as ERC20 token standard, or on BC as a BEP2, then created on the other. There are native ways on both networks to link the two and secure the total supply of the token. ## Native Token BNB will run on BSC in the same way as ETH runs on Ethereum so that it remains as “native token” for both BSC and BC. This means, in addition to BNB is used to pay most of the fees on Binance Chain and Binance DEX, BNB will be also used to: 1. pay “fees“ to deploy smart contracts on BSC 2. stake on selected BSC validators, and get corresponding rewards 3. perform cross-chain operations, such as transfer token assets across BC and BSC ### Seed Fund Certain amounts of BNB will be burnt on BC and minted on BSC during its genesis stage. This amount is called “Seed Fund” to circulate on BSC after the first block, which will be dispatched to the initial BC-to-BSC Relayer(described in later sections) and initial validator set introduced at genesis. These BNBs are used to pay transaction fees in the early stage to transfer more BNB from BC onto BSC via the cross-chain mechanism. The BNB cross-chain transfer is discussed in a later section, but for BC to BSC transfer, it is generally to lock BNB on BC from the source address of the transfer to a system-controlled address and unlock the corresponding amount from special contract to the target address of the transfer on BSC, or reversely, when transferring from BSC to BC, it is to lock BNB from the source address on BSC into a special contract and release locked amount on BC from the system address to the target address. The logic is related to native code on BC and a series of smart contracts on BSC. ## Other Tokens BC supports BEP2 tokens and upcoming [BEP8 tokens](https://github.com/binance-chain/BEPs/pull/69), which are native assets transferrable and tradable (if listed) via fast transactions and sub-second finality. Meanwhile, as BSC is Ethereum compatible, it is natural to support ERC20 tokens on BSC, which here is called “**BEP2E**” (with the real name to be introduced by the future BEPs,it potentially covers BEP8 as well). BEP2E may be “Enhanced” by adding a few more methods to expose more information, such as token denomination, decimal precision definition and the owner address who can decide the Token Binding across the chains. BSC and BC work together to ensure that one token can circulate in both formats with confirmed total supply and be used in different use cases. ### Token Binding BEP2 tokens will be extended to host a new attribute to associate the token with a BSC BEP2E token contract, called “**Binder**”, and this process of association is called “**Token Binding**”. Token Binding can happen at any time after BEP2 and BEP2E are ready. The token owners of either BEP2 or BEP2E don’t need to bother about the Binding, until before they really want to use the tokens on different scenarios. Issuers can either create BEP2 first or BEP2E first, and they can be bound at a later time. Of course, it is encouraged for all the issuers of BEP2 and BEP2E to set the Binding up early after the issuance. A typical procedure to bind the BEP2 and BEP2E will be like the below: 1. Ensure both the BEP2 token and the BEP2E token both exist on each blockchain, with the same total supply. BEP2E should have 3 more methods than typical ERC20 token standard: * symbol(): get token symbol * decimals(): get the number of the token decimal digits * owner(): get **BEP2E contract owner’s address.** This value should be initialized in the BEP2E contract constructor so that the further binding action can verify whether the action is from the BEP2E owner. 2. Decide the initial circulation on both blockchains. Suppose the total supply is *S*, and the expected initial circulating supply on BC is *K*, then the owner should lock S-K tokens to a system controlled address on BC. 3. Equivalently, *K* tokens is locked in the special contract on BSC, which handles major binding functions and is named as **TokenHub**. The issuer of the BEP2E token should lock the *K* amount of that token into TokenHub, resulting in *S-K* tokens to circulate on BSC. Thus the total circulation across 2 blockchains remains as *S*. 4. The issuer of BEP2 token sends the bind transaction on BC. Once the transaction is executed successfully after proper verification: * It transfers *S-K* tokens to a system-controlled address on BC. * A cross-chain bind request package will be created, waiting for Relayers to relay. 5. BSC Relayers will relay the cross-chain bind request package into **TokenHub** on BSC, and the corresponding request and information will be stored into the contract. 6. The contract owner and only the owner can run a special method of TokenHub contract, `ApproveBind`, to verify the binding request to mark it as a success. It will confirm: * the token has not been bound; * the binding is for the proper symbol, with proper total supply and decimal information; * the proper lock are done on both networks; 10. Once the `ApproveBind` method has succeeded, TokenHub will mark the two tokens are bounded and share the same circulation on BSC, and the status will be propagated back to BC. After this final confirmation, the BEP2E contract address and decimals will be written onto the BEP2 token as a new attribute on BC, and the tokens can be transferred across the two blockchains bidirectionally. If the ApproveBind fails, the failure event will also be propagated back to BC to release the locked tokens, and the above steps can be re-tried later. # Cross-Chain Transfer and Communication Cross-chain communication is the key foundation to allow the community to take advantage of the dual chain structure: * users are free to create any tokenization, financial products, and digital assets on BSC or BC as they wish * the items on BSC can be manually and programmingly traded and circulated in a stable, high throughput, lighting fast and friendly environment of BC * users can operate these in one UI and tooling ecosystem. ## Cross-Chain Transfer The cross-chain transfer is the key communication between the two blockchains. Essentially the logic is: 1. the `transfer-out` blockchain will lock the amount from source owner addresses into a system controlled address/contracts; 2. the `transfer-in` blockchain will unlock the amount from the system controlled address/contracts and send it to target addresses. The cross-chain transfer package message should allow the BSC Relayers and BC **Oracle Relayers** to verify: 1. Enough amount of token assets are removed from the source address and locked into a system controlled addresses/contracts on the source blockchain. And this can be confirmed on the target blockchain. 2. Proper amounts of token assets are released from a system controlled addresses/contracts and allocated into target addresses on the target blockchain. If this fails, it can be confirmed on source blockchain, so that the locked token can be released back (may deduct fees). 3. The sum of the total circulation of the token assets across the 2 blockchains are not changed after this transfer action completes, no matter if the transfer succeeds or not.  The architecture of cross-chain communication is as in the above diagram. To accommodate the 2 heteroid systems, communication handling is different in each direction. ## BC to BSC Architecture BC is a Tendermint-based, instant finality blockchain. Validators with at least ⅔\*N+1 of the total voting power will co-sign each block on the chain. So that it is practical to verify the block transactions and even the state value via **Block Header** and **Merkle Proof** verification. This has been researched and implemented as “**Light-Client Protocol**”, which are intensively discussed in [the Ethereum](https://github.com/ethereum/wiki/wiki/Light-client-protocol) community, studied and implemented for [Cosmos inter-chain communication](https://github.com/cosmos/ics/blob/a4173c91560567bdb7cc9abee8e61256fc3725e9/spec/ics-007-tendermint-client/README.md). BC-to-BSC communication will be verified in an “**on-chain light client**” implemented via BSC **Smart Contracts** (some of them may be **“pre-compiled”**). After some transactions and state change happen on BC, if a transaction is defined to trigger cross-chain communication,the Cross-chain “**package**” message will be created and **BSC Relayers** will pass and submit them onto BSC as data into the "build-in system contracts". The build-in system contracts will verify the package and execute the transactions if it passes the verification. The verification will be guaranteed with the below design: 1. BC blocking status will be synced to the light client contracts on BSC from time to time, via block header and pre-commits, for the below information: * block and app hash of BC that are signed by validators * current validatorset, and validator set update 2. the key-value from the blockchain state will be verified based on the Merkle Proof and information from above #1. After confirming the key-value is accurate and trustful, the build-in system contracts will execute the actions corresponding to the cross-chain packages. Some examples of such packages that can be created for BC-to-BSC are: 1. Bind: bind the BEP2 tokens and BEP2E 2. Transfer: transfer tokens after binding, this means the circulation will decrease (be locked) from BC and appear in the target address balance on BSC 3. Error Handling: to handle any timeout/failure event for BSC-to-BC communication 4. Validatorset update of BSC To ensure no duplication, proper message sequence and timely timeout, there is a “Channel” concept introduced on BC to manage any types of the communication. For relayers, please also refer to the below “Relayers” section. ## BSC to BC Architecture BSC uses Proof of Staked Authority consensus protocol, which has a chance to fork and requires confirmation of more blocks. One block only has the signature of one validator, so that it is not easy to rely on one block to verify data from BSC. To take full advantage of validator quorum of BC, an idea similar to many [Bridge ](https://github.com/poanetwork/poa-bridge)or Oracle blockchains is adopted: 1. The cross-chain communication requests from BSC will be submitted and executed onto BSC as transactions. The execution of the transanction wil emit `Events`, and such events can be observed and packaged in certain “**Oracle**” onto BC. Instead of Block Headers, Hash and Merkle Proof, this type of “Oracle” package directly contains the cross-chain information for actions, such as sender, receiver and amount for transfer. 2. To ensure the security of the Oracle, the validators of BC will form anothe quorum of “**Oracle Relayers**”. Each validator of the BC should run a **dedicated process** as the Oracle Relayer. These Oracle Relayers will submit and vote for the cross-chain communication package, like Oracle, onto BC, using the same validator keys. Any package signed by more than ⅔\*N+1 Oracle Relayers’ voting power is as secure as any block signed by ⅔\*N+1 of the same quorum of validators’ voting power. By using the same validator quorum, it saves the light client code on BC and continuous block updates onto BC. Such Oracles also have Oracle IDs and types, to ensure sequencing and proper error handling. ## Timeout and Error Handling There are scenarios that the cross-chain communication fails. For example, the relayed package cannot be executed on BSC due to some coding bug in the contracts. **Timeout and error handling logics are** used in such scenarios. For the recognizable user and system errors or any expected exceptions, the two networks should heal themselves. For example, when BC to BSC transfer fails, BSC will issue a failure event and Oracle Relayers will execute a refund on BC; when BSC to BC transfer fails, BC will issue a refund package for Relayer to relay in order to unlock the fund. However, unexpected error or exception may still happen on any step of the cross-chain communication. In such a case, the Relayers and Oracle Relayers will discover that the corresponding cross-chain channel is stuck in a particular sequence. After a Timeout period, the Relayers and Oracle Relayers can request a “SkipSequence” transaction, the stuck sequence will be marked as “Unexecutable”. A corresponding alerts will be raised, and the community has to discuss how to handle this scenario, e.g. payback via the sponsor of the validators, or event clear the fund during next network upgrade. ## Cross-Chain User Experience Ideally, users expect to use two parallel chains in the same way as they use one single chain. It requires more aggregated transaction types to be added onto the cross-chain communication to enable this, which will add great complexity, tight coupling, and maintenance burden. Here BC and BSC only implement the basic operations to enable the value flow in the initial launch and leave most of the user experience work to client side UI, such as wallets. E.g. a great wallet may allow users to sell a token directly from BSC onto BC’s DEX order book, in a secure way. ## Cross-Chain Contract Event Cross-Chain Contract Event (CCCE) is designed to allow a smart contract to trigger cross-chain transactions, directly through the contract code. This becomes possible based on: 1. Standard system contracts can be provided to serve operations callable by general smart contracts; 2. Standard events can be emitted by the standard contracts; 3. Oracle Relayers can capture the standard events, and trigger the corresponding cross-chain operations; 4. Dedicated, code-managed address (account) can be created on BC and accessed by the contracts on the BSC, here it is named as **“Contract Address on BC” (CAoB)**. Several standard operations are implemented: 1. BSC to BC transfer: this is implemented in the same way as normal BSC to BC transfer, by only triggered via standard contract. The fund can be transferred to any addresses on BC, including the corresponding CAoB of the transfer originating contract. 2. Transfer on BC: this is implemented as a special cross-chain transfer, while the real transfer is from **CAoB** to any other address (even another CAoB). 3. BC to BSC transfer: this is implemented as two-pass cross-chain communication. The first is triggered by the BSC contract and propagated onto BC, and then in the second pass, BC will start a normal BC to BSC cross-chain transfer, from **CAoB** to contract address on BSC. A special note should be paid on that the BSC contract only increases balance upon any transfer coming in on the second pass, and the error handling in the second pass is the same as the normal BC to BSC transfer. 4. IOC (Immediate-Or-Cancel) Trade Out: the primary goal of transferring assets to BC is to trade. This event will instruct to trade a certain amount of an asset in CAoB into another asset as much as possible and transfer out all the results, i.e. the left the source and the traded target tokens of the trade, back to BSC. BC will handle such relayed events by sending an “Immediate-Or-Cancel”, i.e. IOC order onto the trading pairs, once the next matching finishes, the result will be relayed back to BSC, which can be in either one or two assets. 5. Auction Trade Out: Such event will instruct BC to send an auction order to trade a certain amount of an asset in **CAoB** into another asset as much as possible and transfer out all the results back to BSC at the end of the auction. Auction function is upcoming on BC. There are some details for the Trade Out: 1. both can have a limit price (absolute or relative) for the trade; 2. the end result will be written as cross-chain packages to relay back to BSC; 3. cross-chain communication fees may be charged from the asset transferred back to BSC; 4. BSC contract maintains a mirror of the balance and outstanding orders on CAoB. No matter what error happens during the Trade Out, the final status will be propagated back to the originating contract and clear its internal state. With the above features, it simply adds the cross-chain transfer and exchange functions with high liquidity onto all the smart contracts on BSC. It will greatly add the application scenarios on Smart Contract and dApps, and make 1 chain +1 chain > 2 chains. # Staking and Governance Proof of Staked Authority brings in decentralization and community involvement. Its core logic can be summarized as the below. You may see similar ideas from other networks, especially Cosmos and EOS. 1. Token holders, including the validators, can put their tokens “**bonded**” into the stake. Token holders can **delegate** their tokens onto any validator or validator candidate, to expect it can become an actual validator, and later they can choose a different validator or candidate to **re-delegate** their tokens<sup>1</sup>. 2. All validator candidates will be ranked by the number of bonded tokens on them, and the top ones will become the real validators. 3. Validators can share (part of) their blocking reward with their delegators. 4. Validators can suffer from “**Slashing**”, a punishment for their bad behaviors, such as double sign and/or instability. 5. There is an “**unbonding period**” for validators and delegators so that the system makes sure the tokens remain bonded when bad behaviors are caught, the responsible will get slashed during this period. ## Staking on BC Ideally, such staking and reward logic should be built into the blockchain, and automatically executed as the blocking happens. Cosmos Hub, who shares the same Tendermint consensus and libraries with Binance Chain, works in this way. BC has been preparing to enable staking logic since the design days. On the other side, as BSC wants to remain compatible with Ethereum as much as possible, it is a great challenge and efforts to implement such logic on it. This is especially true when Ethereum itself may move into a different Proof of Stake consensus protocol in a short (or longer) time. In order to keep the compatibility and reuse the good foundation of BC, the staking logic of BSC is implemented on BC: 1. The staking token is BNB, as it is a native token on both blockchains anyway 2. The staking, i.e. token bond and delegation actions and records for BSC, happens on BC. 3. The BSC validator set is determined by its staking and delegation logic, via a staking module built on BC for BSC, and propagated every day UTC 00:00 from BC to BSC via Cross-Chain communication. 4. The reward distribution happens on BC around every day UTC 00:00. ## Rewarding Both the validator update and reward distribution happen every day around UTC 00:00. This is to save the cost of frequent staking updates and block reward distribution. This cost can be significant, as the blocking reward is collected on BSC and distributed on BC to BSC validators and delegators. (Please note BC blocking fees will remain rewarding to BC validators only.) A deliberate delay is introduced here to make sure the distribution is fair: 1. The blocking reward will not be sent to validator right away, instead, they will be distributed and accumulated on a contract; 2. Upon receiving the validator set update into BSC, it will trigger a few cross-chain transfers to transfer the reward to custody addresses on the corresponding validators. The custody addresses are owned by the system so that the reward cannot be spent until the promised distribution to delegators happens. 3. In order to make the synchronization simpler and allocate time to accommodate slashing, the reward for N day will be only distributed in N+2 days. After the delegators get the reward, the left will be transferred to validators’ own reward addresses. ## Slashing Slashing is part of the on-chain governance, to ensure the malicious or negative behaviors are punished. BSC slash can be submitted by anyone. The transaction submission requires **slash evidence** and cost fees but also brings a larger reward when it is successful. So far there are two slashable cases. ### Double Sign It is quite a serious error and very likely deliberate offense when a validator signs more than one block with the same height and parent block. The reference protocol implementation should already have logic to prevent this, so only the malicious code can trigger this. When Double Sign happens, the validator should be removed from the Validator **Set** right away. Anyone can submit a slash request on BC with the evidence of Double Sign of BSC, which should contain the 2 block headers with the same height and parent block, sealed by the offending validator. Upon receiving the evidence, if the BC verifies it to be valid: 1. The validator will be removed from validator set by an instance BSC validator set update Cross-Chain update; 2. A predefined amount of BNB would be slashed from the **self-delegated** BNB of the validator; Both validator and its delegators will not receive the staking rewards. 3. Part of the slashed BNB will allocate to the submitter’s address, which is a reward and larger than the cost of submitting slash request transaction 4. The rest of the slashed BNB will allocate to the other validators’ custody addresses, and distributed to all delegators in the same way as blocking reward. ### Inavailability The liveness of BSC relies on everyone in the Proof of Staked Authority validator set can produce blocks timely when it is their turn. Validators can miss their turn due to any reason, especially problems in their hardware, software, configuration or network. This instability of the operation will hurt the performance and introduce more indeterministic into the system. There can be an internal smart contract responsible for recording the missed blocking metrics of each validator. Once the metrics are above the predefined threshold, the blocking reward for validator will not be relayed to BC for distribution but shared with other better validators. In such a way, the poorly-operating validator should be gradually voted out of the validator set as their delegators will receive less or none reward. If the metrics remain above another higher level of threshold, the validator will be dropped from the rotation, and this will be propagated back to BC, then a predefined amount of BNB would be slashed from the **self-delegated** BNB of the validator. Both validators and delegators will not receive their staking rewards. ### Governance Parameters There are many system parameters to control the behavior of the BSC, e.g. slash amount, cross-chain transfer fees. All these parameters will be determined by BSC Validator Set together through a proposal-vote process based on their staking. Such the process will be carried on BC, and the new parameter values will be picked up by corresponding system contracts via a cross-chain communication. # Relayers Relayers are responsible to submit Cross-Chain Communication Packages between the two blockchains. Due to the heterogeneous parallel chain structure, two different types of Relayers are created. ## BSC Relayers Relayers for BC to BSC communication referred to as “**BSC Relayers**”, or just simply “Relayers”. Relayer is a standalone process that can be run by anyone, and anywhere, except that Relayers must register themselves onto BSC and deposit a certain refundable amount of BNB. Only relaying requests from the registered Relayers will be accepted by BSC. The package they relay will be verified by the on-chain light client on BSC. The successful relay needs to pass enough verification and costs gas fees on BSC, and thus there should be incentive reward to encourage the community to run Relayers. ### Incentives There are two major communication types: 1. Users triggered Operations, such as `token bind` or `cross chain transfer`. Users must pay additional fee to as relayer reward. The reward will be shared with the relayers who sync the referenced blockchain headers. Besides, the reward won't be paid the relayers' accounts directly. A reward distribution mechanism will be brought in to avoid monopolization. 2. System Synchronization, such as delivering `refund package`(caused by failures of most oracle relayers), special blockchain header synchronization(header contains BC validatorset update), BSC staking package. System reward contract will pay reward to relayers' accounts directly. If some Relayers have faster networks and better hardware, they can monopolize all the package relaying and leave no reward to others. Thus fewer participants will join for relaying, which encourages centralization and harms the efficiency and security of the network. Ideally, due to the decentralization and dynamic re-election of BSC validators, one Relayer can hardly be always the first to relay every message. But in order to avoid the monopolization further, the rewarding economy is also specially designed to minimize such chance: 1. The reward for Relayers will be only distributed in batches, and one batch will cover a number of successful relayed packages. 2. The reward a Relayer can get from a batch distribution is not linearly in proportion to their number of successful relayed packages. Instead, except the first a few relays, the more a Relayer relays during a batch period, the less reward it will collect. ## Oracle Relayers Relayers for BSC to BC communication are using the “Oracle” model, and so-called “**Oracle Relayers**”. Each of the validators must, and only the ones of the validator set, run Oracle Relayers. Each Oracle Relayer watches the blockchain state change. Once it catches Cross-Chain Communication Packages, it will submit to vote for the requests. After Oracle Relayers from ⅔ of the voting power of BC validators vote for the changes, the cross-chain actions will be performed. Oracle Replayers should wait for enough blocks to confirm the finality on BSC before submitting and voting for the cross-chain communication packages onto BC. The cross-chain fees will be distributed to BC validators together with the normal BC blocking rewards. Such oracle type relaying depends on all the validators to support. As all the votes for the cross-chain communication packages are recorded on the blockchain, it is not hard to have a metric system to assess the performance of the Oracle Relayers. The poorest performer may have their rewards clawed back via another Slashing logic introduced in the future. # Outlook It is hard to conclude for Binance Chain, as it has never stopped evolving. The dual-chain strategy is to open the gate for users to take advantage of the fast transferring and trading on one side, and flexible and extendable programming on the other side, but it will be one stop along the development of Binance Chain. Here below are the topics to look into so as to facilitate the community better for more usability and extensibility: 1. Add different digital asset model for different business use cases 2. Enable more data feed, especially DEX market data, to be communicated from Binance DEX to BSC 3. Provide interface and compatibility to integrate with Ethereum, including its further upgrade, and other blockchain 4. Improve client side experience to manage wallets and use blockchain more conveniently ------ [1]: BNB business practitioners may provide other benefits for BNB delegators, as they do now for long term BNB holders.
coryrylan / Ngx Json Ld:pencil: A small component to easily bind JSON-LD schema to Angular templates.
rattrayalex / FluxboneBind your Backbone Models & Collections to React Components
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tangcr / Redis Redis是什么 Redis是一个NOSQL，NOSQL有许多种，它们分为： 列存储，如：Hbase、Cassandra这种 文档存储，如：MongoDB（首推） key-value存储，如：Berkeley DB、MemcacheDB、Redis，其中Redis最强 图存储，这块基本不用，有：Neo4j、Versant XML存储，如：Berkeley DB Xml还有XBASE，ORACLE很早已经支持这种存储方式了 光知道这些NOSQL的名词是没有用的，关键在于要知道在哪种场景下选用哪种NOSQL才是我们真正要去掌握的。 我们这边说Redis就拿Redis说事吧，它能干什么呢？ Redis基础应用场景 web间session共享，即多个war工程共享一个session 分布式缓存，因为redis为键值对，而且它提供了丰富的adapter可以支持到C、.net、java客户端，因此对于异质平台间进行数据交换起到了作用，因此它可以用作大型系统的分布式缓存，并且其setnx的锁常被用于”秒杀“，”抢红包“这种电商活动场景中。 安装Redis 我本来想在这儿写”Redis上的‘坑‘“，最后我还是觉得把它放到后面章节中去写吧，因为中国人的思维是先有感性再有理性的一种逆向思维，其实这点很像美国人，因此中国人在世界上是最聪明的民族之一，所以我们还是先从动手搭一个Redis的环境来说起吧，老规矩，红色加粗很重要。 一定要使用Linux来布署Redis，请不要偷懒使用Redis 2.8.1 for windows那个版本，如果你使用了这个版本你将无法跟上这一系列教程的步伐。因为Redis为GCC+这样的东西开发出来的，它天生就是运行在LINUX/Unix环境下的，而那个windows版的Redis是一个”烟“割版，而且是一个unofficial的版本，非官方授权的哈。 先从Docker开始 如果已经有Linux/Unix环境的同协们可以直接跳过这一章。 我们这边要开始变态了，因为我们要真正开始踏上SOA、PAAS、互联网的脚步了。 如果对于没有Linux/Unix环境的用户来说，我在这边推荐使用docker，即boot2docker windows版来安装，它下载后是一个这样的文件 安装前把你的网络连接中的IPV6协议前的勾去掉 双击它，在安装时记得选择Virtual-Box选项，因为docker本为linux/unix下之物，因此为了在windows下使用docker，boot2docker内嵌了一个virtualbox来虚拟docker的环境。 装完后它会在你的桌面上生成一个蓝色的图标，双击它，它会打开一个绿色的字，黑色的背景像matrix电影里的那种命令行窗口，这就是Docker。 装完后运行： [plain] view plain copy 在CODE上查看代码片派生到我的代码片 docker@boot2docker:~$ docker run hello-world 看到下面这些提示 [plain] view plain copy 在CODE上查看代码片派生到我的代码片 Hello from Docker. This message shows that your installation appears to be working correctly. To generate this message, Docker took the following steps: 1. The Docker client contacted the Docker daemon. 2. The Docker daemon pulled the “hello-world” image from the Docker Hub. (Assuming it was not already locally available.) 3. The Docker daemon created a new container from that image which runs the executable that produces the output you are currently reading. 4. The Docker daemon streamed that output to the Docker client, which sent it to your terminal. To try something more ambitious, you can run an Ubuntu container with: $ docker run -it ubuntu bash For more examples and ideas, visit: http://docs.docker.com/userguide/ 说明你的Docker安装成功了。 在Docker中安装unix环境 有了Docker我们就用Docker虚拟一个Ubuntu（UNIX）环境吧，在这边我们使用的是Ubuntu14。 ubuntu14请下载这个包：戳: 下载Ubuntu14包 下载后直接在docker下运行下面这条命令： [plain] view plain copy 在CODE上查看代码片派生到我的代码片 cat ubuntu-14.04-x86_64.tar.gz |docker import - ubuntu:ubuntu14 这个过程会很快，完成后查看自己的image： 成功导入了ubuntu，这样我们就可以在Docker中运行出一个自己的ubuntu了。 [plain] view plain copy 在CODE上查看代码片派生到我的代码片 docker run -i -t ubuntu:ubuntu14 /bin/bash 以上运行后，进入了该ubuntu的bash环境。 注：如果上述命令出错，可以使用下面这条命令： [plain] view plain copy 在CODE上查看代码片派生到我的代码片 docker run -i -t ubuntu:ubuntu14 //bin/bash 两个 “/” 哈 如果你能看到类似于root@ubuntu14_这样的命令行界面说明你的ubuntu14也已经安装成功了，下面我们就要在这个docker->ubuntu14中安装和布署我们的Redis了，这个过程和在Linux下一样。 在ubuntu14下先安装SSHD，以便于我们使用WINSCP这样的SFTP工具来管理我们的ubuntu14中的文件系统 在ubuntu14中安装SSHD 第一步： [plain] view plain copy 在CODE上查看代码片派生到我的代码片 docker run -t -i ubuntu/mk:v1 /bin/bash 进入我们的ubuntu环境，这边的ubuntu/mk就是我本机的docker中ubuntu14 container（容器）的名字，如果按照上面的延续此处可以替换成ubuntu:ubuntu14这个名字吧。 第二步： 升级一下你的apt-get，它就是一个命令行IE下载工具，如果你不update，那么你apt-get的源、内核都为旧的，因此为了升级apt-get请键入下面的命令 [plain] view plain copy 在CODE上查看代码片派生到我的代码片 apt-get update 这个过程很快（依赖于你的网络环境） 第三步： 下载和安装openssh组件 [plain] view plain copy 在CODE上查看代码片派生到我的代码片 apt-get install openssh-server openssh-client 第四步： 修改你的root密码 [plain] view plain copy 在CODE上查看代码片派生到我的代码片 passwd 键入两次你的root密码，我这边都为6个小写的a 第五步： 退出容器，并保存以上修改，如果docker在退出后你接着退出docker环境或者是关机那么刚才的4步全部不生效，你一定要commit它才能生效，为此： 你先要知道你刚才用docker run命令运行的ubuntu14的容器的ID，你可以使用 [plain] view plain copy 在CODE上查看代码片派生到我的代码片 docker ps -a 来查到你latest的一次容器的ID，它是一组16进制一样的编码如：1edfb9aabde8890，有了这个container id我们就可以commit我们刚才装的openssh的环境了 commit刚才在容器中所做的修改 [plain] view plain copy 在CODE上查看代码片派生到我的代码片 docker commit 1edfb9aabde8890 ubuntu:ssh 第六步： 运行带有openssh的ubuntu14以便于我们使用winscp这样的SFTP工具连入我们的ubuntu14中去，依次输入下面的命令： [plain] view plain copy 在CODE上查看代码片派生到我的代码片 docker kill $(docker ps -q) 杀掉正在运行的所有的container的进程 [plain] view plain copy 在CODE上查看代码片派生到我的代码片 docker rm $(docker ps -a -q) 删除所有在进程中的容器，以上2步又被称为docker大扫除 Docker是这样的机制的，它可以开启多个容器，每个容器带着一堆的image（镜像），要删一个镜像必须先停止这个镜像所在的容器，再把这个镜像删除，因此我们使用上面这两条命令对于Docker来一个大扫除。 接着我们先查一下我们目前手头有的镜像 [plain] view plain copy 在CODE上查看代码片派生到我的代码片 docker images 你会看到一个images列表，里面有我们的ubuntu:14，有我们的ubuntu:ssh也有一个hello-world，我们把ubuntu:14这个镜像删了吧（为了保持干净哈） 每个image也它自己的id，即image id，因此你用docker images命令查到该镜像的id后可以使用： [plain] view plain copy 在CODE上查看代码片派生到我的代码片 docker rmi imageid 这条命令把一个不用的镜像给删了。 接下去我们要启动我们的ubuntu14:ssh了，可以使用下面这条命令： [plain] view plain copy 在CODE上查看代码片派生到我的代码片 docker -d -p 122:22 ubuntu:ssh //usr/sbin/sshd -D 这条命令的意思为： -d即把我们的image启动在后台进程，它将会是一个daemon进程，而不会像刚才我们使用-t一样，一旦exit后该image进程也自动退出了 -p为端口映射，什么意思呢，这边要说一下docker的端口映射问题。我们知道docker安装后它会利用virtualbox中的vhost only的nat机制来建立一个虚拟的IP 可以打开我们的virtualbox中在菜单”全局->设定->网络”中进行查找 所以我们可以知道一旦boot2docker环境运行后它的地址为192.168.56.*这个段，一般为192.168.56.101这个地址，你可以在boot2docker启动后直接使用winscp边入这个docker环境。 地址：192.168.56.101 端口：22 用户名：docker 密码：tcuser 以上为默认值，具体地址按照你的virtualbox中在boot2docker安装时自动给出的设置来做参考。 而， 我们在这个docker中安装了一个ubuntu14:ssh的image，然后用后台进程的方式打开了这个ubuntu14:ssh，因此它自己也有一个IP（可能是172也可能是169段），具体不得而知，一般来说它是每次启动镜像后自己变换的（可以使用动态网络域名绑定docker中镜像的ip来达到域名不变的目的-集群环境下有用）。 我们都知道ssh是以端口22来进行TCP连接的，因此我们把ubuntu14的IP上的22端口映射到了我们的docker主机192.168.56.101上的122端口。 参数//usr/sbin/sshd -D代表该镜像启动会的entrypoint即启动后再启动一个什么命令，在最后的-D（大写的D）告诉docker这是一个启动文件 于是，一旦该命令发出后，显示image启动的提示后（启动后你会得到一个image id）你就可以直接打开你的winscp使用： 地址：192.168.56.101 端口：122 （此处是122，不是22，因为我们把image的22端口映射到了192.168.56.101-docker主机上的122端口了） 用户名：root 密码：aaaaaa 即可以连入我们的ubuntu14环境了，如果此时你安装了putty还可以使用putty+winscp直接进入ubuntu14的命令行环境中去，于是你就有ubuntu14的试验环境了。 在ubuntu14下安装redis 网上很多在ubuntu14下安装redis的教程都不对的，大家看了要上当的，原因在于如下，请各位看完： 网上的redis环境搭建直接使用的是apt-get update完后用wget https://github.com/ijonas/dotfiles/raw/master/etc/init.d/redis-server 这样的方式来安装的，这样装固然方便，可是也因为方便所以取到的redis不是最新的redis版本，一般为2.8.x版或者是redis3.0.rc，这依赖于你的unit/linux所连接的wget库 redis为c写成，它的2.4-2.8版都为不稳定版或者是缺少功能或者是有bug，而这些bug在你如果真正使用redis作为网站生产环境时将会因为这些bug而无法面对峰涌而来的巨大并发，因此当有这样的redis运行了一段时间后你的生产环境会面临着巨大的压力 还是redis不够新不够稳定的原因，由于在redis3前redis还不支持集群、主备高可用方案的功能，因此不得不依靠于繁杂的打补丁式的如：linux/unix-keepalive或者是haproxy这种系统级层面然后写一堆的复杂脚本去维护你的redis集群，还要用外部手段（Linux/Unix Shell脚本）去维护多个redis节点间的缓存数据同步。。。这这这。。。不复合我们的网站扩容、增量、运维和面对巨大用户（万级并发-最高支持百万用户如：新浪微博、微信）的场景 因此，我在这边推荐大家使用下面我将要使用的“下载源码包结合你本机的Linux/Unix内核进行实时编译”的安装过程。 第一步：下载redis目前最稳定版本也是功能最完善，集群支持最好并加入了sentinel（哨兵-高可用）功能的redis3.0.7版即redis-stable版，为此我们需要获取redis-stable版 redis官方下载连接 就是用的这个redis-stable.tar.gz包，这是我在写博客时目前最新最稳定版本，修复了大量的BUG和完善了功能。 第二步： 下载后我们把该包上传到我们的docker中的ubuntu14中，我们把它放在/opt目录下 然后我们使用tar -zxvf redis-stable.tar.gz对它进行解压 解压后它就会生成一个redis-stable目录，进入该目录 cd redis-stable 别急，我们先一会编译和安装它 第三步：编译安装redis 我们先输入gcc -v 这个命令来查看我们的gcc版本，如果它低于4.2以下那么你在编译redis3.0.7时一定会碰到大量的出错信息，如前面所述，redis为gcc写成，最新的redis需要gcc4.2-5这个版本才能进行编译，而一般去年或者之前装的linux/unix 的 gcc都为4.0以下或者甚至是3.x版。 升级GCC先 [plain] view plain copy 在CODE上查看代码片派生到我的代码片 apt-get install build-essential 因此apt-get update显得很重要，要不然你获取的gcc也将不是最新的版本，目前我的gcc为5.3.1为这周刚做的升级。 升级后我们开始编译redis3.0.7了，为此我们需要在redis-stable目录下 键入如下命令： [plain] view plain copy 在CODE上查看代码片派生到我的代码片 make PREFIX=/usr/local/redis1 install 我们告知我们的GCC把redis-stable编译并同时安装在/usr/local/redis1目录下 这个过程很快，可能只有10秒钟时间（依据你的机器来说，建议使用>=8gb, 4核CPU的PC机），然后我们就可以看到everything ok了。我们进入/usr/local/redis1就可以看到我们刚才安装的redis3.0.7稳定版了。 我们进入我们的redis目录 cd /usr/local/redis1/bin 在此目录下我们即可以运行我们的redis server了，不过请别急，在启动前我们需要对redis进行一些配置。 我的博客面对的是“全栈式”工程师的，架构师只是成为全栈式工程师中的一个起点，如果你不会搭环境那么你就不能接触到最新的技术，因此这就是许多程序员工作了近5年，7年结果发觉也只会一个SSH的主要原因。 Redis3配置要领 使用winscp通过122连入docker下的ubuntu14，进行redis的配置。 我们需要编辑的文件为/usr/local/redis1/bin/redis.conf这个文件 [plain] view plain copy 在CODE上查看代码片派生到我的代码片 daemonize yes # When running daemonized, Redis writes a pid file in /var/run/redis.pid by # default. You can specify a custom pid file location here. pidfile "/var/run/redis/redis1.pid" # Accept connections on the specified port, default is 6379. # If port 0 is specified Redis will not listen on a TCP socket. port 7001 我们把: daemonize设为yes，使得redis以后台进程的方式来运行，你可以认为为“server”模式，如果redis以server模式运行的话它会生成一个pid文件 ，因此我们把它的路径放在/var/run/redis目录中，并命名它为redis1.pid文件 ，为此你需要在/var/run目录下建立redis这个目录 端口号我们把它设为7001，这样好辩识，因为将来我们会进一步做redis集群，所以我们的redis都为redis1, redis2, redis3那么我们的端口号也为7001, 7002, 7003。。。这样来延续。那么很多同协这时要问了，“为什么我们不把它命名成master, slave1, slave2这样的名字呢？”，理由很简单，无论是现在的hadoop还是zookeeper它们的集群是跨机房的，多个master间也有MASTER-SLAVE模式互为备份，因为一些大型网站不仅仅只有一个IDC机房，它们一般都会有2个，3个IDC机房，或者是在同一个IDC机房中有“跨机柜”的布署来形成超大规模集群，就和ALI的TAOBAO网一样，它在北美都有机房，因此当你需要在LOCAL NATIVE建一个IDC机房，在北美再做一个机房，你不要想把一个MASTER设在中国，SLAVE设到美国去，而是多地甚至是多机柜都有MASTER，一旦一个MASTER宕机了，这种集群会通过一个叫“选举策略”选出一个节点把这个节点作为当前“群”的MASTER，因此我们的命名才会是redis1, redis2, redis3...这样来命名的。 此处把原来的： [plain] view plain copy 在CODE上查看代码片派生到我的代码片 save 900 1 save 300 10 save 60 10000 中的300 10 和60 10000注释掉。这边代表的是： redis以每900秒写一次、300秒写10次，60秒内写1万次这样的策略把缓存放入一个叫.rdb的磁盘文件中，这点和ehcache或者是memcache很像，以便于redis在重启时可以从本地持久化文件中找出关机前的数据记录。 如果按照默认的话，此三个策略会轮流起效，在大并发环境中，这样的写策略将会对我们的性能造成巨大的影响，因此我们这边只保留900秒写1次这条策略，这边有人会问，如果你这样会有数据丢失怎么办。。。别急，这个问题我们后面会解答，这涉及到redis的“正确”使用，如果它只是一个缓存，我相信5分钟内缓存的丢失此时程序直接访问数据库也不会有太大问题，又要保证数据完整性又要保证性能这本身是一个矛与盾的问题，除非你钱多了烧那我会给出你一个烧钱的配置策略，连新浪都不会这么烧钱，呵呵。 dbfilename，此处我们维持redis原有的缓存磁盘文件的原名 dir "/usr/local/redis1/data"为rdb文件所在的目录 这边大家要注意的是一个是只能写文件名，另一个地方只能写目录名。 为此我们需要在/usr/local/redis1下建立 data目录。 把此处的appendonly设为no，这样我们就关闭了Redis的AOF功能。 AOF 持久化记录服务器执行的所有写操作命令，并在服务器启动时，通过重新执行这些命令来还原数据集。AOF是redis在集群或者是高可用环境下的一个同步策略，它会不断的以APPEND的模式把redis的缓存中的数据从一个节点写给另一个节点，它对于数据的完整性保证是要高于rdb模式的。 RDB 是一个非常紧凑（compact）的文件，它保存了 Redis 在某个时间点上的数据集。 这种文件非常适合用于进行备份： 比如说，你可以在最近的 24 小时内，每小时备份一次 RDB 文件，并且在每个月的每一天，也备份一个 RDB 文件。 这样的话，即使遇上问题，也可以随时将数据集还原到不同的版本。RDB 非常适用于灾难恢复（disaster recovery）：它只有一个文件，并且内容都非常紧凑，可以（在加密后）将它传送到别的数据中心如阿里的mysql异地机房间使用FTP传binlog的做法。 按照官方的说法，启用AOF功能，可以在redis高可用环境中如果发生了故障客户的数据不会有高于2秒内的历史数据丢失，它换来的代价为高昂的I/O开销，有些开发者为了追求缓存中的数据100%的正确有时会碰到因为redis在AOF频繁刷新时整个环境如死机一的情况，并且你会看到恶梦一般的”Asynchronous AOF fsync is taking too long “警告信息，这是因为redis它是单线程的，它在进行I/O操作时会阻塞住所有的操作，包括登录。。。这个很可怕，不过这个BUG/ISSUE已经在最新redis中进行了优化，它启用了另一根进程来进行AOF刷新，包括优化了RDB持久化功能，这也是为什么我让大家一定一定要用最新最稳定版的redis的原因。 一般默认情况下redis内的rdb和AOF功能同为开启， 如果RDB的数据不实时，同时使用两者时服务器重启也只会找AOF文件。 因为RDB文件只用作后备用途，建议只在Slave上持久化RDB文件，而且只要15分钟备份一次就够了，所以我只保留save 900 1这条规则。 如果Enalbe AOF： 好处是在最恶劣情况下也只会丢失不超过两秒数据，启动脚本较简单只load自己的AOF文件就可以了。 代价一是带来了持续的IO，二是AOF rewrite的最后将rewrite过程中产生的新数据写到新文件造成的阻塞几乎是不可避免的。只要硬盘许可，应该尽量减少AOF rewrite的频率，AOF重写的基础大小默认值64M太小了，可以设到5G以上。默认超过原大小100%大小时重写，这边可以设定一个适当的数值。 如果不Enable AOF ，仅靠Master-Slave Replication 实现高可用性也可以。能省掉极大的IO也减少了rewrite时带来的系统波动。代价是如果Master/Slave同时倒掉（那你的网站基本也就歇了），会丢失十几分钟的数据，启动脚本也要比较两个Master/Slave中的RDB文件，载入较新的那个。新浪微博就选用了这种架构。 最后我们不要忘了设一个redis的log文件，在此我们把它设到了/var/log/redis目录，为此我们需要在/var/log目录下建立一个redis目录。 好了，保存后我们来启动我们的redis吧。 我们使用以下这条命令来启动我们的redis server。 然后我们在我们的windows机上装一个windows版的redis 2.8.1 for windows（只用它来作为redis的client端） 然后我们在windows环境下使用： redis-cli -p 7001 -h 192.168.56.101 咦，没反映，连不上，哈哈。。。。。。 那是肯定连不上的，因为： 我们刚才在用docker启动ubuntu14时使用docker -d -p 122:22 ubuntu:ssh //usr/sbin/sshd -D来启动的，这边我们并未把redis服务的7001端口映射到192.168.56.101这台docker主机上，怎么可以通过windows主机（可能windows的ip为169.188.xx.xx）来访问docker内的进程服务呢？对吧，为此我们：先把刚才做了这么多的更改docker commit成一个新的image如：redis:basic吧。 然后我们对docker进行一次大扫除，然后我们启动redis:basic这个image并使用以下命令： [plain] view plain copy 在CODE上查看代码片派生到我的代码片 docker -d -p 122:22 -p 7001:7001 redis:basic //usr/sbin/sshd -D 看，此处我们可以使用多个-p来作docker内容器的多端口映射策略（它其实使用的就是iptables命令）。 好了，用putty连入这个image的进程并启动redis服务，然后我们拿windows中的redis-cli命令来连。 如果在linux环境下还是没有连通（可能的哦），那是因为你没有禁用linux下的防火墙，我们可以使用iptables -F来禁用linux的防火墙或者使用： vi /etc/selinux/config 然后把 SELINUX=enforcing 这句用”#“注释掉 增加一句： SELINUX=disabled #增加 这样每次启动后linux都不会有iptables的困扰了（这是在本机环境下这么干哦，如果你是生产环境请自行加iptables策略以允许redis服务端口可以被访问）。 看到下面这个PONG即代表你的redis服务已经在网络环境中起效了。 下面我们要开始使用Java客户端来连我们的Redis Service了。 使用Spring Data + JEDIS来连接Redis Service Spring+Session+Redis pom.xml 在此我们需要使用spring data和jedis，下面给出相关的maven配置 [html] view plain copy 在CODE上查看代码片派生到我的代码片 <dependencies> <!-- poi start --> <dependency> <groupId>org.apache.poi</groupId> <artifactId>poi</artifactId> <version>${poi_version}</version> </dependency> <dependency> <groupId>org.apache.poi</groupId> <artifactId>poi-ooxml-schemas</artifactId> <version>${poi_version}</version> </dependency> <dependency> <groupId>org.apache.poi</groupId> <artifactId>poi-scratchpad</artifactId> <version>${poi_version}</version> </dependency> <dependency> <groupId>org.apache.poi</groupId> <artifactId>poi-ooxml</artifactId> <version>${poi_version}</version> </dependency> <!-- poi end --> <!-- active mq start --> <dependency> <groupId>org.apache.activemq</groupId> <artifactId>activemq-all</artifactId> <version>5.8.0</version> </dependency> <dependency> <groupId>org.apache.activemq</groupId> <artifactId>activemq-pool</artifactId> <version>${activemq_version}</version> </dependency> <dependency> <groupId>org.apache.xbean</groupId> <artifactId>xbean-spring</artifactId> <version>3.16</version> </dependency> <!-- active mq end --> <!-- servlet start --> <dependency> <groupId>javax.servlet</groupId> <artifactId>servlet-api</artifactId> <version>${javax.servlet-api.version}</version> <scope>provided</scope> </dependency> <dependency> <groupId>javax.servlet.jsp</groupId> <artifactId>jsp-api</artifactId> <version>2.1</version> <scope>provided</scope> </dependency> <dependency> <groupId>javax.servlet</groupId> <artifactId>jstl</artifactId> <version>1.2</version> </dependency> <!-- servlet end --> <!-- redis start --> <dependency> <groupId>redis.clients</groupId> <artifactId>jedis</artifactId> <version>2.7.2</version> </dependency> <dependency> <groupId>org.redisson</groupId> <artifactId>redisson</artifactId> <version>1.0.2</version> </dependency> <!-- redis end --> <dependency> <groupId>org.slf4j</groupId> <artifactId>jcl-over-slf4j</artifactId> <version>${slf4j.version}</version> </dependency> <dependency> <groupId>org.slf4j</groupId> <artifactId>slf4j-log4j12</artifactId> <version>${slf4j.version}</version> </dependency> <!-- spring conf start --> <dependency> <groupId>org.springframework.data</groupId> <artifactId>spring-data-redis</artifactId> <version>1.6.2.RELEASE</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-webmvc</artifactId> <version>${spring.version}</version> <exclusions> <exclusion> <groupId>commons-logging</groupId> <artifactId>commons-logging</artifactId> </exclusion> </exclusions> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-tx</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-aop</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-context-support</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework.data</groupId> <artifactId>spring-data-redis</artifactId> <version>1.6.2.RELEASE</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-orm</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-jms</artifactId> <version>${spring.version}</version> </dependency> <dependency> <groupId>org.springframework.session</groupId> <artifactId>spring-session</artifactId> <version>${spring.session.version}</version> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-core</artifactId> <version>${spring.version}</version> </dependency> <!-- spring conf end --> </dependencies> redis-config.xml [html] view plain copy 在CODE上查看代码片派生到我的代码片 <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p" xmlns:context="http://www.springframework.org/schema/context" xmlns:jee="http://www.springframework.org/schema/jee" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:aop="http://www.springframework.org/schema/aop" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> <context:property-placeholder location="classpath:/spring/redis.properties" /> <context:component-scan base-package="org.sky.redis"> </context:component-scan> <bean id="jedisConnectionFactory" class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory"> <property name="hostName" value="${redis.host.ip}" /> <property name="port" value="${redis.host.port}" /> <property name="poolConfig" ref="jedisPoolConfig" /> </bean> <bean id="jedisPoolConfig" class="redis.clients.jedis.JedisPoolConfig"> <property name="maxTotal" value="${redis.maxTotal}" /> <property name="maxIdle" value="${redis.maxIdle}" /> <property name="maxWaitMillis" value="${redis.maxWait}" /> <property name="testOnBorrow" value="${redis.testOnBorrow}" /> <property name="testOnReturn" value="${redis.testOnReturn}" /> </bean> <bean id="redisTemplate" class="org.springframework.data.redis.core.StringRedisTemplate"> <property name="connectionFactory" ref="jedisConnectionFactory" /> </bean> <!--将session放入redis --> <bean id="redisHttpSessionConfiguration" class="org.springframework.session.data.redis.config.annotation.web.http.RedisHttpSessionConfiguration"> <property name="maxInactiveIntervalInSeconds" value="1800" /> </bean> <bean id="customExceptionHandler" class="sample.MyHandlerExceptionResolver" /> </beans> redis.properties [plain] view plain copy 在CODE上查看代码片派生到我的代码片 redis.host.ip=192.168.0.101 redis.host.port=6379 redis.maxTotal=1000 redis.maxIdle=100 redis.maxWait=2000 redis.testOnBorrow=false redis.testOnReturn=true web.xml [html] view plain copy 在CODE上查看代码片派生到我的代码片 <?xml version="1.0" encoding="UTF-8"?> <web-app version="2.5" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"> <!-- - Location of the XML file that defines the root application context - Applied by ContextLoaderListener. --> <!-- tag::context-param[] --> <context-param> <param-name>contextConfigLocation</param-name> <param-value> classpath:/spring/redis-conf.xml </param-value> </context-param> <!-- end::context-param[] --> <!-- tag::springSessionRepositoryFilter[] --> <filter> <filter-name>springSessionRepositoryFilter</filter-name> <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class> </filter> <filter-mapping> <filter-name>springSessionRepositoryFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <session-config> <session-timeout>30</session-timeout> </session-config> <!-- end::springSessionRepositoryFilter[] --> <filter> <filter-name>encodingFilter</filter-name> <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class> <init-param> <param-name>encoding</param-name> <param-value>UTF-8</param-value> </init-param> <init-param> <param-name>forceEncoding</param-name> <param-value>true</param-value> </init-param> </filter> <filter-mapping> <filter-name>encodingFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <servlet> <servlet-name>dispatcher</servlet-name> <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class> <init-param> <param-name>contextConfigLocation</param-name> <param-value>classpath:/spring/spring-mvc.xml</param-value> </init-param> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>dispatcher</servlet-name> <url-pattern>/</url-pattern> </servlet-mapping> <!-- - Loads the root application context of this web app at startup. - The application context is then available via - WebApplicationContextUtils.getWebApplicationContext(servletContext). --> <!-- tag::listeners[] --> <listener> <listener-class>org.springframework.web.context.ContextLoaderListener</listener-class> </listener> <!-- end::listeners[] --> <servlet> <servlet-name>sessionServlet</servlet-name> <servlet-class>sample.SessionServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>sessionServlet</servlet-name> <url-pattern>/servlet/session</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app> 这边主要是一个： [html] view plain copy 在CODE上查看代码片派生到我的代码片 <filter> <filter-name>springSessionRepositoryFilter</filter-name> <filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class> </filter> <filter-mapping> <filter-name>springSessionRepositoryFilter</filter-name> <url-pattern>/*</url-pattern> </filter-mapping> <session-config> <session-timeout>30</session-timeout> </session-config> 这个filter一定要写在一切filter之前 SessionController [java] view plain copy 在CODE上查看代码片派生到我的代码片 package sample; import org.springframework.session.data.redis.config.annotation.web.http.EnableRedisHttpSession; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.RequestMapping; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpSession; /** * Created by mk on 15/1/7. */ @Controller @EnableRedisHttpSession public class SessionController { @RequestMapping("/mySession") public String index(final Model model, final HttpServletRequest request) { if (request.getSession().getAttribute("testSession") == null) { System.out.println("session is null"); request.getSession().setAttribute("testSession", "yeah"); } else { System.out.println("not null"); } return "showSession"; } } showSession.jsp文件 [html] view plain copy 在CODE上查看代码片派生到我的代码片 <%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%> <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> <title>showSession</title> </head> <body> <% String sessionValue=(String)session.getAttribute("testSession"); %> <h1>Session Value From Servlet is: <%=sessionValue%></h1> </body> </html> 测试 保证我们的redise-server是启动的，然后我们启动起这个web工程后使用： http://localhost:8080/webpoc/mySession访问一下这个controller 此时我们使用redis客户端工具连入查看spring session是否已经进入到了redis中去。 在redis客户端工具连入后我们可以在redis console中使用keys *来查看存入的key，LOOK，spring的session存入了redis中去了。 再来看我们的eclipse后台，由于我们是第一次访问这个controller，因此这个session为空，因此它显示如下： 我们在IE中再次访问该controller 由于之前的session已经存在于redis了，因此当用户在1800秒（30分钟）内再次访问controller，它会从session中获取该session的key testSession的值，因此eclipse后台打印为not null。 SpringRedisTemplate + Redis 讲过了spring session+redis我们来讲使用spring data框架提供的redisTemplate来访问redis service吧。说实话，spring这个东西真强，什么都可以集成，cassandra, jms, jdbc...jpa...bla...bla...bla...Spring集成Barack Hussein Obama? LOL :) pom.xml 不用列了，上面有了 redis-conf.xml 不用列了，上面有了 web.xml 也不用列了，上面也有了 SentinelController.java 我们就先用这个名字吧，后面我们会用它来做我们的redis sentinel（哨兵）的高可用（HA）集群测试 [java] view plain copy 在CODE上查看代码片派生到我的代码片 package sample; import java.util.HashMap; import java.util.Map; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import org.springframework.data.redis.core.BoundHashOperations; import org.springframework.data.redis.core.StringRedisTemplate; import org.springframework.stereotype.Controller; import org.springframework.ui.Model; import org.springframework.web.bind.annotation.ExceptionHandler; import org.springframework.web.bind.annotation.RequestMapping; import redis.clients.jedis.Jedis; import redis.clients.jedis.JedisSentinelPool; import util.CountCreater; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpSession; /** * Created by xin on 15/1/7. */ @Controller public class SentinelController { @Autowired private StringRedisTemplate redisTemplate; @RequestMapping("/sentinelTest") public String sentinelTest(final Model model, final HttpServletRequest request, final String action) { return "sentinelTest"; } @ExceptionHandler(value = { java.lang.Exception.class }) @RequestMapping("/setValueToRedis") public String setValueToRedis(final Model model, final HttpServletRequest request, final String action) throws Exception { CountCreater.setCount(); String key = String.valueOf(CountCreater.getCount()); Map mapValue = new HashMap(); for (int i = 0; i < 1000; i++) { mapValue.put(String.valueOf(i), String.valueOf(i)); } try { BoundHashOperations<String, String, String> boundHashOperations = redisTemplate .boundHashOps(key); boundHashOperations.putAll(mapValue); System.out.println("put key into redis"); } catch (Exception e) { e.printStackTrace(); throw new Exception(e); } return "sentinelTest"; } } 打开IE，输入：http://localhost:8080/webpoc/setValueToRedis 观察我们的后台 然后使用redis client连入后进行查看 看。。。这个值key=1的，就是我们通过spring的redisTemplate存入进去的值，即使用下面这段代码进行存入的值： [java] view plain copy 在CODE上查看代码片派生到我的代码片 for (int i = 0; i < 1000; i++) { mapValue.put(String.valueOf(i), String.valueOf(i)); } try { BoundHashOperations<String, String, String> boundHashOperations = redisTemplate.boundHashOps(key); boundHashOperations.putAll(mapValue); 如何你要存入一个简单的如key=test value=hello，你可以这样使用你的redisTemplate [java] view plain copy 在CODE上查看代码片派生到我的代码片 redisTemplate.execute(new RedisCallback<Object>() { @Override public Object doInRedis(RedisConnection connection) throws DataAccessException { connection.set( redisTemplate.getStringSerializer().serialize( "test"), redisTemplate .getStringSerializer() .serialize("hello")); return null; } }); 是不是很方便的哈？结束第一天的教程，明天开始搭建redis集群。
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NFGRICHARD / Curso WebSeja muito bem vindo ao Curso Desenvolvimento Web Moderno com JavaScript! COMPLETO 2020 + Projetos! Esse que talvez seja o maior e mais completo curso de tecnologia do mercado. São quase 600 aulas divididas em 33 capítulos com mais de 85 horas. Além dos fundamentos e vários exercícios, são vários projetos com as principais tecnologias da atualidade com aplicação na vida real, te ensinando a ser um desenvolvedor Web desde o básico até ao nível profissional avançado. Neste curso você vai aprender os 3 principais frameworks do mercado: Angular, React e VUE. Tudo que você precisa aprender para construir aplicações modernas para Web você aprenderá aqui e com aplicações reais. Desenvolvimento Web é hoje um dos assuntos mais relevantes do momento porque o mercado respira Web. E Se você deseja ser um profissional preparado para o mercado e não quer aprender apenas fórmulas, mas o porquês, esse curso é a escolha certa pra você. Neste curso iremos abordar o desenvolvimento Web de ponta a ponta, para que você seja capaz de construir uma aplicação com as principais tecnologias do mercado. São 14 cursos dentro de um só. Você irá aprender Javascript, que é hoje a linguagem da atualidade, várias empresas estão migrando suas bases de PHP, Python e outras para terem suas bases completamente feitas em javascript. Também irá aprender Node, os últimos recursos de HTML e CSS, Gulp, Webpack, jQuery, Bootstrap, React ( Tecnologia usada por umas das maiores empresas do mundo, o Facebook), Angular, Vue JS, ExpressJS, MySQL, MongoDB e Electron. O melhor de tudo é que durante a nossa jornada iremos agrupar essas tecnologias em desafios e projetos para consolidar o seu conhecimento. Você aprenderá a dominar tecnologias de frontend - que é a parte da aplicação executada no browser do usuário, e tecnologias de backend - que é o código executado no lado do servidor. O curso vai abranger essas duas partes, além de se preocupar muito com os fundamentos que são comuns à toda aplicação. Nesse curso você também irá aprender os paradigmas de programação usados na Web Moderna: Funcional, Orientação a Objeto e etc. Aplicações Web baseadas em Componentes. Conteúdo suficiente para você conseguir um emprego como desenvolvedor Web Fullstack e se tornar um desenvolvedor Web de sucesso. Um dos maiores diferenciais dos nossos cursos é que Nós não ensinamos apenas fórmulas, você vai terminar esse curso entendendo os porquês, a lógica de como a coisa acontece, o que vai te tornar um profissional muito mais qualificado e competitivo no mercado. E no projeto final do curso iremos desenvolver uma aplicação exclusiva que surgiu de uma necessidade real da Cod3r. Assista a essa aula sem custo e confira o que você vai poder desenvolver junto com a gente. Por isso o que temos aqui não é apenas um curso, e sim um agrupamento de 14 cursos e um investimento certo pra sua carreira. Assista as aulas abertas e confira a qualidade do nosso conteúdo, e veja também, os comentários dos nosso alunos sobre a nossa didática. Somos a escola de tecnologia com uma das melhores avaliações do mercado. Não tenho dúvida que você estará fazendo um excelente investimento se juntando à nossa comunidade de mais de 60 mil alunos. E sabe o que mais? Você vai receber um certificado de conclusão ao final do curso, e o seu acesso é vitalício, não expira. E se mesmo depois de tudo que apresentamos, mesmo assim você não gostou do curso, nós garantimos o seu dinheiro de volta em até 30 dias após a compra de forma simples. Desenvolvimento Web Moderno com JavaScript Completo é um curso voltado para todos os tipos de público: Iniciantes, intermediários e avançados. Um curso de desenvolvimento web zero to hero, onde você aprenderá dos conceitos básicos de programação, JavaScript, Node.js, Web, ESNext, HTML5, CSS3, Ajax, Gulp, Webpack, jQuery, Bootsrap, React, VueJS, Angular 9, banco de dados relacional, banco de dados não relacional, Express… Faremos vários projetos utilizando essas tecnologias, projetos que simulam aplicações reais, com backend e frontend para tornar-te um desenvolvedor fullstack, profissão com alta demanda no mercado de trabalho. Nosso curso também contará com uma aplicação que vai te ajudar nos estudos de inglês que é uma Aplicação Desktop com JavaScript, Electron JS e Vue JS - Neste curso iremos também desenvolver um projeto desktop com JavaScript! E que pode ajudar você nos seus estudos de inglês. Nessa aplicação usaremos: Electron JS, VueJS, Vuetify, Promises, Regex, Processamento de arquivos, Map, reduce, filter A aplicação que será desenvolvida irá processar várias legendas no formato SRT e procurar e agrupar quais são as palavras mais utilizadas nas legendas fornecidas. Essa aplicação pode ser útil para se descobrir quais são as palavras mais utilizadas em filmes e seriados, ou seja, além de aprender várias tecnologias, esse projeto pode te ajudar no aprendizado de inglês! Nosso curso termina com um projeto base de conhecimento que vai da primeira linha de código até a publicação da aplicação na AWS (Amazon Web Services). Dispomos de um suporte ágil e pronto para atendê-los em suas dúvidas, sejam conceituais, configuração de ambiente até codificação em si. Alguns conceitos sobre os tópicos que são abordados no curso: Lógica de programação: Lógica é a ferramenta mais importante do desenvolvedor. Nesse tópico abordaremos conceitos fortes para o desenvolvimento do programador tais quais algoritmo, estrutura de dados, conceito de lógica. JavaScript: JavaScript é, sem dúvidas, uma das linguagens mais utilizadas do mundo. Hoje em dia JavaScript é forte no frontend (Páginas da web) como no backend (Node.js). No módulo de Javascript abordaremos conceitos fundamentais como Var, Let, Const, Tipagem, Number, Math, String, Boolean… Abordaremos também conceitos importantes como: Array, Object, null, undefined, this, function, hoisting, estrutura de objetos. Operadores destructuring, atribuição, aritméticos, relacionais, unários, ternários. Falaremos sobre contexto de execução Browser x Node, tratamento de erros e mais. Abordaremos estruturas de controle tais como, if, if/else, if/else/if, switch, while, do/while, for, for/in e a utilização de break e continue para controle de fluxo do código. Nos aprofundaremos bastante no conceito mais importante de JavaScript: Funções! Em function veremos parâmetros, retorno com return, parâmetros variáveis com parâmetros Rest e Arguments, parâmetro padrão, variações do this, função bind, arrow functions ou funções arrow, funções anônimas, funções callbacks, funções construtoras, contexto léxico, closures, funções factory, IIFE (Immediately Invoked Function Expression ou funções auto invocadas. Call e Apply, etc. Outro conceito muito utilizado em JavaScript que é amplamente abordado no nosso curso é o de Objeto! Veremos uma introdução à orientação a objetos. Criação de objetos, objetos constantes, notação literal, getters e setters, funções do objeto, herança, comparação JSON x Objeto e classes. Também estudaremos sobre Arrays, forte ferramenta utilizada no JavaScript, veremos seus métodos importantes, Foreach, Map, Filter, Reduce, Concat, FlatMap que são fundamentais para desenvolvimento em JavaScript. Veremos também a diferença entreas abordagens Imperativa e Declarativa para desenvolvimento de código. Node.js: Estudaremos, Node.js, a utilização de JavaScript no backend. Abordaremos a definição de módulo, estudaremos o sistema de módulos, utilização de módulos de terceiros, require, exports, o famoso arquivo package.json, instância única x nova instância, objeto global do Node x objeto global browser, aprofundaremos nossos estudos sobre o conceito de this, como passar parâmetros entre módulos, instalar deps e scripts, ler arquivos, escrever arquivos, frameworks web, padrão middleware, utilizaremos a ferramenta postman, estudaremos express, entrada e saída padrão. ESNext: São os novos conceitos do JavaScript, o que acabou de chegar e o que está por vir na linguagem. Veremos o operador Rest/Spread, tagged template, Map, Set, For Of, Promises, uso de callbacks aninhadas, refatoração de callbacks para promises, Async/Await. Conceitos Web: JavaScript é uma linguagem fortemente ligada à web e é absoluto que devemos entender como funciona a programação web, então estudaremos os conceitos de protocolo HTTP, servidor web, client side x server side, conteúdo estático x dinâmico. HTML5, CSS3 , JavaScript. DNS, HTTPS, Web Service, computação em nuvem. HTML5: HTML5 (Hypertext Markup Language ou Linguagem de Marcação de Hipertexto) é o bloco de construção mais básico da web e possui fundamental importância para o seu funcionamento. Abordaremos extensivamente seus conceitos como: Anatomia de uma tag, de uma página, as tags propriamente ditas, texto, listas, links, tabelas, formulários, imagens, vídeos e tags não visuais. CSS3: CSS3 (Cascading Style Sheets) é o responsável pela estilização do HTML5, portanto das páginas web. Ferramenta importantíssima e largamente abordada no nosso curso de web moderno. Estudaremos: Anatomia do CSS3, criação de classes, seletores CSS3, especifidades do CSS3, herança, box model, margin collapse, propriedade display, altura e largura, inline-block, box sizing, overflow, float, unidades, texto, positon, media query, flex box, css grid. Integração HTML5, CSS3 e Javascript: Após estudá-los separadamente faremos a sua integração e veremos como eles funcionam bem em conjunto! Veremos a DOM, elementos, atributos, classes, modificar html, trabalharemos com eventos e finalizaremos o módulo com um projeto para a criação de um game Flappy Bird utilizando HTML5, CSS3 e JavaScript. Ajax: Ajax (Asynchronous JavaScript and XML) é um conjunto importantíssimo de técnicas de desenvolvimento para trabalharmos de forma assíncrona na web. Veremos XMLHttpRequest, Fetch, Axios, Ajax com jQuery e como carregar HTML via Ajax. Gulp: Gulp é uma ferramenta de automação de tarefas em JavaScript. Veremos os conceitos, a documentação, fundamentos, Babel, processando JavaScript e TypeScript com Gulp, processando SASS com Gulp. Webpack: Webpack é um empacotador de módulo JavaScript, HTML, CSS, imagens, etc. Veremos configuração e estruturação do projeto, pasta de saída, carregamento e externalização do arquivo .CSS, .SCSS (SASS). Desenvolvimento e produção, carregamento de arquivos de imagens. Adicionando WebServer. jQuery: jQuery é uma biblioteca de funções JavaScript que interage com HTML, desenvolvida para simplificar os scripts interpretados no navegador do cliente. Veremos como selecionar elementos, modificar HTML, manipular atributos, manipular CSS, eventos, animação, plugins. Bootstrap: Bootstrap é um framework para desenvolvimento de componentes de interface e frontend para sites e aplicações web usando HTML, CSS e JavaScript. Veremos como adicionar navegações, tipografia, espaços, título e bradcrumb, cores, flexbox, imagens, float, sistema de grid, botões, alertas, paginação, tooltip, slider, accordion, formulário. React: React é uma biblioteca JavaScript com foco em criar interfaces de usuário em páginas web. É mantida pelo Facebook, Instagram e outras empresas. Utilizada nos sites da Netflix, Walmart, entre outros. Estudaremos componentes, componentes com parâmetros, múltiplos componentes, componentes de classe, componentes pai e filho. Next: Nesta seção serão abordados os principais fundamentos e conceitos do NextJS. O Next.JS nada mais é do que um framework para React, a principal biblioteca para desenvolvimento web. As principais funcionalidades do Next são a renderização estática e pelo lado do servidor (SSR), possuir suporte para o TypeScript e um serviço próprio de tratamento de rotas. Nessa seção também será criada uma aplicação para Criação, Leitura, Edição e Remoção de dados, o famoso CRUD (Create, Read, Update, Delete) com NextJS. Utilizando o Firebase e Firestore como banco de dados, utilizando também o TailwindCSS para criar o visual do projeto e integrando com TypeScript. Tudo isso será mostrado e explicado durante a seção, desde a criação do projeto, a instalação das dependências, configuração e integração com o banco de dados e também a integração e uso tanto do Tailwind quanto do TypeScript. VueJS: VueJS é um framework JavaScript focado no desenvolvimento de interfaces para usuários e aplicativos de página única. Estudaremos os conceitos, binding, eventos, diretivas v-if, v-for e v-show. Aplicação de estilo CSS, templeta na Vue instance, componentes e diretivas personalizadas. Angular 9: Angular 9 é uma plataforma de aplicações web baseado em TypeScript liderado pela equipe Angular do Google. Faremos um backend com JSON server, conceituaremos a ferramenta, utilização do angular-cli, AppComponent, componente cabeçalho, rodapé, navegação, elementos do Angular, componente início, diretivas, bindings, *ngFor, mensagens de erro. Banco de Dados Relacional: Utilizaremos o MySQL para estudarmos modelo E/R, chave primária, relacionamentos, SQL, schema, modelo, tabelas, inserir, consultar, atualizar, excluir, id, consultas, consultas com agregação, inner join, outer join, left join, right join. Banco de Dados Banco de Dados Não Relacional: Utilizaremos o MongoDB para estudarmos NoSQL, as diferenças entre bancos relacionais e não relacionais, comandos básicos, inserção de dados, consultas, consultas agregadas, update, remove, consultas com lookup. Express: Express é um framework com uma miríade de métodos utilitários HTTP e middleware para criação de API’s. Estudaremos as configurações e launcher, tipos de respostas, Middleware, leitura de dados da requisição, body parser, comunicação entre módulos. Finalmente, nosso curso é bastante voltado para a prática com várias partes importantes de projetos reais e projetos complexos de vários graus de dificuldade. Conosco é teoria na cabeça e mão na massa! Sejam bem vindos ao melhor curso de web moderno da internet. Invista em desenvolvimento web, invista na sua carreira, venha pra Cod3r. Grande abraço e bons estudos! O que você aprenderá Tudo que vc precisa saber para construir aplicações modernas para Web Criar aplicações REAIS usando as mais modernas tecnologias do mercado Últimos recursos de HTML, CSS, Javascript e vários frameworks Aprender HTML 5 e os últimos recursos da linguagem Aprender CSS 3 e como aplicar estilo usando as últimas tecnologias: CSS Grid, Flexbox e muito mais Domine Javascript de verdade, não apenas aprendendo a sintaxe, mas como pensar em Javascript Os últimos recursos do Javascript: ECMAScript 6, 7, 8. Também conhecido como ES2015, ES2016, ES2017, ES2018 ... Os principais frameworks (e bibliotecas): React, Vue, Bootstrap 4, jQuery Entendenda os paradigmas de programação usados na Web Moderna: Funcional, Orientação a Objeto etc Boas práticas de programação e padrões de projeto Aplicações Web baseadas em Componentes Projeto de aplicações reais Seja um desenvolvedor Fullstack dominando o frontend e o backend Conteúdo suficiente para você conseguir um emprego como desenvolvedor Web Fullstack Aprendenda banco de dados relacional e não relacional NoSQL Use MySQL, Postgres e MongoDB Desenvolva um sistema com autenticação de usuário Use Node JS e desenvolva usando Javascript no backend Acesse os principais bancos de dados usando Javascript e Node Aprenda a construir builds profissionais com Gulp e Webpack Conquistar toda a base para se tornar um desenvolvedor web de sucesso Todo o conteúdo para se tornar um profissional capacitado para o mercado de trabalho Aprenda as principais tecnologias da web nas últimas versões Desenvolver uma Aplicação com Angular 9 Os principais conceitos do Angular 9: Componentes, Diretivas, Pipes, Services e muito mais Aprender Angular na Prática de forma muito objetiva Desenvolvimento Web Há algum requisito ou pré-requisito para o curso? Acesso à internet e computador Vontade de aprender pra se tornar um Desenvolvedor Web Não é necessário conhecimento prévio de desenvolvimento Web Para quem é este curso: Pessoas que desejam se tornar desenvolvedores Web Fullstack, dominando tanto backend e frontend Pessoas que desejam aprender banco de dados relacional, SQL e banco não relacional (NoSQL) Pessoas que desejam aprender a usar MySQL, Postgres e MongoDB Pessoas que desejam aprender Node JS e como desenvolver Javascript no backend Pessoas que desejam aprender as tecnologias da web nas últimas versões: HTML5, CSS3, Javascript (como os novos recursos do ES2015 em diante) Pessoas que desejam aprender as principais frameworks e bibliotecas do mercado: React, Vue JS, jQuery, Bootstrap 4 ... Pessoas que querem entrar no mercado de trabalho como desenvolvedor frontend, backend ou fullstack Pessoas que querem empreender e precisam desenvolver soluções para Web Pessoas que nunca desenvolveram aplicações REAIS e querem aprender a construir várias APP do ZERO Pessoa que querem aprender em apenas um curso tudo para precisa para se tornar um desenvolvedor Fullstack O necessário para se tornar um desenvolvedor web completo Pessoas que desejam entender o desenvolvimento web como um todo
cats-oss / KiteA Kotlin DSL to bind Android UI components to your app state.
