{"componentChunkName":"component---src-templates-blog-list-template-js","path":"/engineering/7","result":{"data":{"allMarkdownRemark":{"edges":[{"node":{"excerpt":"What is a Smart Contract? Smart Contracts 📝 are simple programs stored on a blockchain network. You can say it's like an agreement between…","fields":{"slug":"/engineering/guest-post/ethereum-smart-contract-tutorial/"},"html":"

What is a Smart Contract?

\n

Smart Contracts đź“ť are simple programs stored on a blockchain network.

\n

You can say it's like an agreement between two people in the form of computer code. The transactions in a smart contract are processed by the blockchain and stored as a 42 character hex address with the prefix \"0x\"). All of which means that they can be sent automatically without needing a third party.

\n

🤔 Remember: They're stored in a public database. And once a smart contract is deployed, it cannot be changed.

\n

What is Solidity?

\n

Solidity is one of the most popular languages used for building smart contracts on Ethereum Blockchain. It's also an object-oriented programming language.

\n

Build Your First Smart Contract

\n
    \n
  1. Open Remix IDE from here.
    2. \n
  2. Click on Sure and then Done.
    3. \n
  3. Under default_workshop, click on create new file.
    4. \n
  4. Rename it as Hostel.sol.
    5. \n
\n

Now you're ready to write your first Smart Contract. 🤩

\n

Contract Code

\n
    \n
  1. You have to provide the solidity version in the smart contract:
    2. \n
\n
pragma solidity ^0.5.16;
\n
    \n
  1. Now create the main contract named Hostel:
    2. \n
\n
contract Hostel{\n    ...\n}
\n
    \n
  1. Now, inside the contract Hostel{...} follow the steps below.
    2. \n
  2. Create some variables where the smart contract will store the payable address (42 char hex string with prefix : \"0x\") of the Landlord & the Tenant.
    3. \n
\n
    address payable tenant;\n    address payable landlord;
\n
    \n
  1. Create some public variables where the smart contract will store some integer values. For this, there's a data type called uint (256-bit unsigned integer)
    2. \n
\n
    uint public no_of_rooms = 0;\n    uint public no_of_agreement = 0;\n    uint public no_of_rent = 0;
\n
    \n
  1. Now, create a structure to store details of each Hostel room like Hostel no., Hostel name, Hostel address, No of total agreements, Monthly rent, One-time security deposit, Last agreement sign time, Vacancy, Landlord address, and Current Tenant Address.
    2. \n
\n
    struct Room{\n        uint roomid;\n        uint agreementid;\n        string roomname;\n        string roomaddress;\n        uint rent_per_month;\n        uint securityDeposit;\n        uint timestamp;\n        bool vacant;\n        address payable landlord;\n        address payable currentTenant;\n    }
\n
    \n
  1. map previous structure with a uint(named : roomid).
    2. \n
\n
mapping(uint => Room) public Room_by_No;
\n
    \n
  1. Similar to the above, create a structure for each Rental Agreement and map that with a uint(named: agreementid). This will store details like: Hostel no., Agreement No, Hostel name, Hostel address, Monthly rent, One-time security deposit,Lockin Period, Agreement sign time, Landlord address, and Tenant Address.
    2. \n
\n
    struct RoomAgreement{\n        uint roomid;\n        uint agreementid;\n        string Roomname;\n        string RoomAddresss;\n        uint rent_per_month;\n        uint securityDeposit;\n        uint lockInPeriod;\n        uint timestamp;\n        address payable tenantAddress;\n        address payable landlordAddress;\n    }
\n
mapping(uint => RoomAgreement) public RoomAgreement_by_No;
\n
    \n
  1. Now, create a structure for each Rent payment and map that with a uint. This will store details like: Rent No., Hostel no., Agreement No, Hostel name, Hostel address, Monthly rent, Rent payment time, Landlord address, and Tenant Address.
    2. \n
\n
    struct Rent{\n        uint rentno;\n        uint roomid;\n        uint agreementid;\n        string Roomname;\n        string RoomAddresss;\n        uint rent_per_month;\n        uint timestamp;\n        address payable tenantAddress;\n        address payable landlordAddress;\n    }
\n
   mapping(uint => Rent) public Rent_by_No;
\n
    \n
  1. \n

    Create some modifiers that will help you verify a few things before running a function.

    \n

    Here require(...); means that if the given condition is not satisfied, the function won't execute, and the given string will appear as an error code.

    \n
    2. \n
\n

The following will check if the message sender is the landlord.

\n
    modifier onlyLandlord(uint _index) {\n        require(msg.sender == Room_by_No[_index].landlord, "Only landlord can access this");\n        _;\n    }
\n

The following will check if the message sender is anyone except the landlord.

\n
    modifier notLandLord(uint _index) {\n        require(msg.sender != Room_by_No[_index].landlord, "Only Tenant can access this");\n        _;\n    }
\n

The following will check whether the room is vacant or not.

\n
    modifier OnlyWhileVacant(uint _index){\n        \n        require(Room_by_No[_index].vacant == true, "Room is currently Occupied.");\n        _;\n    }
\n

The following will check whether the tenant has enough Ether in his wallet to pay the rent.

\n
    modifier enoughRent(uint _index) {\n        require(msg.value >= uint(Room_by_No[_index].rent_per_month), "Not enough Ether in your wallet");\n        _;\n    }
\n

The following will check whether the tenant has enough Ether in his wallet to pay a one-time security deposit and one month's rent in advance.

\n
    modifier enoughAgreementfee(uint _index) {\n        require(msg.value >= uint(uint(Room_by_No[_index].rent_per_month) + uint(Room_by_No[_index].securityDeposit)), "Not enough Ether in your wallet");\n        _;\n    }
\n

The following will check whether the tenant's address is the same as who has signed the previous rental agreement.

\n
    modifier sameTenant(uint _index) {\n        require(msg.sender == Room_by_No[_index].currentTenant, "No previous agreement found with you & landlord");\n        _;\n    }
\n

The following will check whether any time is left for the agreement to end.

\n
    modifier AgreementTimesLeft(uint _index) {\n        uint _AgreementNo = Room_by_No[_index].agreementid;\n        uint time = RoomAgreement_by_No[_AgreementNo].timestamp + RoomAgreement_by_No[_AgreementNo].lockInPeriod;\n        require(now < time, "Agreement already Ended");\n        _;\n    }
\n

The following will check whether 365 days have passed after the last agreement has been created.

\n
    modifier AgreementTimesUp(uint _index) {\n        uint _AgreementNo = Room_by_No[_index].agreementid;\n        uint time = RoomAgreement_by_No[_AgreementNo].timestamp + RoomAgreement_by_No[_AgreementNo].lockInPeriod;\n        require(now > time, "Time is left for contract to end");\n        _;\n    }
\n

The following will check whether 30 days have passed after the last rent payment.

\n
    modifier RentTimesUp(uint _index) {\n        uint time = Room_by_No[_index].timestamp + 30 days;\n        require(now >= time, "Time left to pay Rent");\n        _;\n    }
\n
    \n
  1. Now, create some functions
    2. \n
\n

The following function will be used to add Rooms.

\n
    function addRoom(string memory _roomname, string memory _roomaddress, uint _rentcost, uint  _securitydeposit) public {\n        require(msg.sender != address(0));\n        no_of_rooms ++;\n        bool _vacancy = true;\n        Room_by_No[no_of_rooms] = Room(no_of_rooms,0,_roomname,_roomaddress, _rentcost,_securitydeposit,0,_vacancy, msg.sender, address(0)); \n        \n    }
\n

Now, create a function to sign the rental agreement for a hostel room between the landlord and a tenant.

\n

Before creating the signAgreement function, remember the following:

\n\n

Let's use those modifiers here, so that:

\n\n

Remember those modifiers in point no.10? Use those modifiers here to execute the following function.

\n
    function signAgreement(uint _index) public payable notLandLord(_index) enoughAgreementfee(_index) OnlyWhileVacant(_index) {\n        require(msg.sender != address(0));\n        address payable _landlord = Room_by_No[_index].landlord;\n        uint totalfee = Room_by_No[_index].rent_per_month + Room_by_No[_index].securityDeposit;\n        _landlord.transfer(totalfee);\n        no_of_agreement++;\n        Room_by_No[_index].currentTenant = msg.sender;\n        Room_by_No[_index].vacant = false;\n        Room_by_No[_index].timestamp = block.timestamp;\n        Room_by_No[_index].agreementid = no_of_agreement;\n        RoomAgreement_by_No[no_of_agreement]=RoomAgreement(_index,no_of_agreement,Room_by_No[_index].roomname,Room_by_No[_index].roomaddress,Room_by_No[_index].rent_per_month,Room_by_No[_index].securityDeposit,365 days,block.timestamp,msg.sender,_landlord);\n        no_of_rent++;\n        Rent_by_No[no_of_rent] = Rent(no_of_rent,_index,no_of_agreement,Room_by_No[_index].roomname,Room_by_No[_index].roomaddress,Room_by_No[_index].rent_per_month,now,msg.sender,_landlord);\n    }
\n

Now, create a function that the tenant will use to pay the monthly rent to the landlord.

\n

Before creating the payRent function, remember the following:

\n\n
    function payRent(uint _index) public payable sameTenant(_index) RentTimesUp(_index) enoughRent(_index){\n        require(msg.sender != address(0));\n        address payable _landlord = Room_by_No[_index].landlord;\n        uint _rent = Room_by_No[_index].rent_per_month;\n        _landlord.transfer(_rent);\n        Room_by_No[_index].currentTenant = msg.sender;\n        Room_by_No[_index].vacant = false;\n        no_of_rent++;\n        Rent_by_No[no_of_rent] = Rent(no_of_rent,_index,Room_by_No[_index].agreementid,Room_by_No[_index].roomname,Room_by_No[_index].roomaddress,_rent,now,msg.sender,Room_by_No[_index].landlord);\n    }
\n

Let's create a function that the landlord will use to mark an agreement complete.

\n

Before creating agreementCompleted function, remember the following:

\n\n

Let's create a function that the landlord will use to terminate an agreement.

\n

Before creating agreementTerminated function, remember the following:

\n\n
    function agreementTerminated(uint _index) public onlyLandlord(_index) AgreementTimesLeft(_index){\n        require(msg.sender != address(0));\n        Room_by_No[_index].vacant = true;\n    }
\n

Compile

\n

Now, click on the Solidity Compile option in the left sidebar.

\n
    \n
  1. Select compiler version 0.5.16+
    2. \n
  2. Then click on Compile Hostel.sol
    3. \n
\n

Similar to as follows:

\n\"Compiler\"\n

Deploy

\n

Click on the Deploy & Run Transactions option in the left sidebar.

\n
    \n
  1. Choose Environment > JavaScript VM (London)
    2. \n
  2. Now click on Deploy
    3. \n
\n\"Deploy\"\n

🎉 Congratulations, your smart contract has been deployed. 🎉

\n

Sample Transactions

\n

Remember that whenever a transaction is getting executed, it stores all the details in a unique hash key.

\n

Now, under Deployed Contract click on > HOSTEL AT ..... (MEMORY)

\n
    \n
  1. Click on the V icon (dropdown menu) of addRoom function.
    2. \n
  2. Fill up the details.
    3. \n
\n

Similar to as follows:

\n\"AddRoom\"\n
\n

Note: You're entering your details in wei not in ether (1 ether = 1000000000000000000 wei)

\n
\n
    \n
  1. \n

    Then click on transact

    \n

    🎉 Congratulations, you've successfully added your 1st room in the contract. 🎉

    \n

    (You can find the same in the terminal also.)

    \n

    Now the landlord of the room is your 1st Ether Address. (The one with 99.99 test ether in wallet.)

    \n
    2. \n
  2. Change the Account Address from the dropdown menu. (Choose anyone except the one with 99.99 ether)
    3. \n
\n\"Change\n
    \n
  1. Add the total amount you have previously chosen as (rent cost + security deposit)
    2. \n
  2. And then from the dropdown wei, choose ether
    3. \n
\n\"Change\n
    \n
  1. \n

    Scroll down and click on signAgreement, enter 1, and press signAgreement

    \n

    You can check the same by entering RoomAgreementNo : 1

    \n
    2. \n
\n\"Agreement\n

🎉 Congratulations, you've successfully signed your 1st agreement. 🎉

\n

All your transactions are shown in the terminal.

\n\"Terminal\"\n

Now, you can cross verify this by checking your ether account address.

\n

Advantages of Smart Contracts

\n

Now you may ask, \"what's the use of smart contracts when there are several centralized methods?\"

\n

Let me explain some advantages of smart contracts over centralized systems:

\n
    \n
  1. Here data cannot be changed or tampered with. So, it is almost impossible for malicious actors to manipulate data.
    2. \n
  2. It's completely decentralized.
    3. \n
  3. Unlike any centralized payment wallet, you don't have to pay any commission percentages to a middle man to transact.
    4. \n
\n

Storage & Others

\n

You may also ask \"how are all the transactions recorded?\"

\n

You have to remember that smart contracts store data in a block of the blockchain, and all transactions are stored with a unique hash key.

\n

In Remix IDE, you can download the complete transactions history as a JSON file. For that, follow these steps:

\n
    \n
  1. Click Deploy & Run Transaction
    2. \n
  2. Then, expand the Transactions Recorded (..) V dropdown menu.
    3. \n
  3. Then Click on the Save icon.
    4. \n
  4. Press ok.
    5. \n
\n

Gas Fee

\n

You may have noticed that whenever a transaction is executed, a few wei is getting deducted from your ether wallet.

\n

It's called gas fee, which is the payment made by users to compensate for the computing energy required to process and validate transactions.

\n

As more Ethereum miners come up in near future, the gas fee will decrease in an inverse relation.

\n

Future Possibilities

\n

After this, if you want to build a fullstack website using React, you can use this smart contract as a backend.

\n

For that you need to install/download:

\n

Frontend:

\n
    \n
  1. Node.js
    2. \n
\n

Backend:

\n
    \n
  1. web3.js
    2. \n
  2. Truffle
    3. \n
\n

Testing:

\n
    \n
  1. Ganache
    2. \n
  2. Metamask
    3. \n
\n

Just follow the official documentation of Web3.js to connect your smart contract with your React app.

\n

Conclusion

\n

You've successfully understood what Solidity is and how smart contracts work. And you've successfully built and deployed a perfectly working smart contract (where a tenant can pay rent in ether (ETH) directly to the landlord's wallet without paying a single wei to a middle man).

\n

To download the complete code used in this tutorial, click here.

\n

Want to quickly add user login and signup functionality to your React apps? Use LoginRadius for free.

\n","frontmatter":{"date":"November 24, 2021","updated_date":null,"description":"Smart contracts are an exciting way to build decentralized applications (dapps) on a blockchain. This tutorial helps you learn and build your first smart contract using Solidity on Ethereum blockchain.","title":"Build Your First Smart Contract with Ethereum & Solidity","tags":["Blockchain","Ethereum","Solidity"],"pinned":null,"coverImage":{"childImageSharp":{"fluid":{"aspectRatio":1.5037593984962405,"src":"/static/228990fbfc76ea8c2e7af2b164f89999/58556/coverimage.webp","srcSet":"/static/228990fbfc76ea8c2e7af2b164f89999/61e93/coverimage.webp 200w,\n/static/228990fbfc76ea8c2e7af2b164f89999/1f5c5/coverimage.webp 400w,\n/static/228990fbfc76ea8c2e7af2b164f89999/58556/coverimage.webp 800w,\n/static/228990fbfc76ea8c2e7af2b164f89999/99238/coverimage.webp 1200w","sizes":"(max-width: 800px) 100vw, 800px"}}},"author":{"id":"Aritra Belel","github":"belelaritra","avatar":null}}}},{"node":{"excerpt":"JSON (JavaScript Object Notation) is a text-based, language-independent format that is easily understandable by humans and machines. JOSE…","fields":{"slug":"/engineering/guest-post/what-are-jwt-jws-jwe-jwk-jwa/"},"html":"

JSON (JavaScript Object Notation) is a text-based, language-independent format that is easily understandable by humans and machines.

\n

JOSE (Javascript Object Signing and Encryption) is a framework used to facilitate the secure transfer of claims between any two parties. Its specifications provide a general approach to encryption of any content, not necessarily in JSON. However, it is built on JSON for easy use in web applications. Let's explore some of these specifications.

\n

JWT — JSON Web Token

\n

JWT is a standard mechanism used for authentication. It is compact and URL-safe to represent the claims to be transferred between two parties. Claims are a set of key/value pairs that provide a target system with information about a client to apply an appropriate level of access control to its resources. Claim names could be Registered (IANA), Public, or Private. Some registered claim names are:

\n\n

Structure

\n

JWT is mainly composed of three parts: header, payload, and signature that are Base64 URL-encoded.

\n\n
[header].[payload].[signature]
\n

Here's a simple JWT example.

\n

JSON Web Token:

\n

eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6MTIzNDU2Nzg5LCJuYW1lIjoiSm9zZXBoIn0.OpOSSw7e485LOP5PrzScxHb7SR6sAOMRckfFwi4rp7o

\n
header:\n{\n  "alg" : "HS256",                      Header\n                            --------------------------------->  eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9\n  "typ" : "JWT"\n}\n\nPayload:\n{\n  "id" : 123456789,                     Payload\n                            --------------------------------->  eyJpZCI6MTIzNDU2Nzg5LCJuYW1lIjoiSm9zZXBoIn0\n  "name" : "Joseph"\n}\n                                                Signature\nOpOSSw7e485LOP5PrzScxHb7SR6sAOMRckfFwi4rp7o  ---------------->  OpOSSw7e485LOP5PrzScxHb7SR6sAOMRckfFwi4rp7o
\n

This shows the decoded JSON Web Token. In the deserialized form, JWT contains only the header and the payload as plain JSON objects.

\n

JWS — JSON Web Signature

\n

JWS is used to represent content secured with digital signatures or Hash-based Message Authentication Codes (HMACs) with the help of JSON data structures. It cryptographically secures a JWS Header and JWS Payload with a JWS Signature. The encoded strings of these three are concatenated using dots similar to JWT. The identifiers and algorithms used are specified in the JSON Web Algorithms specification.

\n

The JWS Header MUST contain an alg parameter, as it uses the algorithm to encode the JWS Header and the JWS Payload to produce the JWS Signature. Some of the commonly used algorithms to sign the JWS Header and Payload are:

\n\n

JWS example:

\n
eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9 ----------------> JWS Header\n\neyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ --------------> JWS Payload
\n

It has an Encoded JWS Header followed by an Encoded JWS Payload separated by a '.'. This is the JWS Signing input which, on signing with the HMAC SHA-256 algorithm and base64url encoding, gives the Encoded JWS Signature value:

\n
dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk
\n

On concatenation:

\n
eyJ0eXAiOiJKV1QiLA0KICJhbGciOiJIUzI1NiJ9.eyJpc3MiOiJqb2UiLA0KICJleHAiOjEzMDA4MTkzODAsDQogImh0dHA6Ly9leGFtcGxlLmNvbS9pc19yb290Ijp0cnVlfQ.dBjftJeZ4CVP-mB92K27uhbUJU1p1r_wW1gFWFOEjXk
\n

Learn more about JWS here

\n

JWE — JSON Web Encryption

\n

JSON Web Encryption enables encrypting a token so that only the intended recipient can read it. It standardizes the way to represent the encoded data in a JSON data structure. Representation of the encrypted payload may be by JWE compact serialization or JWE JSON serialization.

\n

Structure

\n

The JWE compact serialization form has five main components:

\n
    \n
  1. JOSE header
    2. \n
  2. JWE Encrypted Key
    3. \n
  3. JWE initialization vector
    4. \n
  4. JWE Ciphertext
    5. \n
  5. JWE Authentication Tag
    6. \n
\n

All these components are base64url-encoded and are concatenated using dots (.).

\n\n
 "header":\n{\n    "alg" : "RSA-OAEP",                --------------------> For content encryption key\n\n    "enc" : "A256GCM"                  --------------------> For content encryption algorithm\n},\n\n "encrypted_key" : "qtF60gW8O8cXKiYyDsBPX8OL0GQfhOxwGWUmYtHOds7FJWTNoSFnv5E6A_Bgn_2W"\n\n\n"iv" : "HRhA5nn8HLsvYf8F-BzQew",       --------------------> initialization vector\n\n"ciphertext" : "ai5j5Kk43skqPLwR0Cu1ZIyWOTUpLFKCN5cuZzxHdp0eXQjYLGpj8jYvU8yTu9rwZQeN9EY0_81hQHXEzMQgfCsRm0HXjcEwXInywYcVLUls8Yik",\n\n"tag" : "thh69dp0Pz73kycQ"             --------------------> Authentication tag\n}
\n

Learn more about JWE here

\n

JWK — JSON Web Key

\n

JWK is a JSON structure representing a set of public keys as a JSON object using the Elliptic Curve or RSA algorithms. Public key representations can help verify the signature with the corresponding private key.

\n

Structure

\n

JWK consists of a JWK Container Object and an array of JWK Key Objects.

\n\n
{\n"alg":"RSA",\n\n"mod": "0vx7agoebGcQSuuPiLJXZptN9nndrQmbXEps2aiAFbWhM78LhWx4cbbfAAtVT86zwu1RK7aPFFxuhDR1L6tSoc_BJECPebWKRXjBZCiFV4n3oknjhMs\ntn64tZ_2W-5JsGY4Hc5n9yBXArwl93lqt7_RN5w6Cf0h4QyQ5v-65YGjQR0_FDW2QvzqY368QQMicAtaSqzs8KJZgnYb9c7d0zgdAZHzu6qMQvRL5hajrn1n91CbOpbI\nSD08qNLyrdkt-bFTWhAI4vMQFh6WeZu0fM4lFd2NcRwr3XPksINHaQ-G_xBniIqbw0Ls1jF44-csFCur-kEgU8awapJzKnqDKgw",\n\n"exp":"AQAB",\n\n"kid":"2011-04-29"\n}
\n

It provides a Key ID for matching.

\n

JWA — JSON Web Algorithms

\n

The JWA specification focuses mainly on enumerating the algorithms necessary for JWS, JWK AND JWE. It also describes the operations that are specific to these algorithms and key types.

\n

Algorithms for JWS: These algorithms are used to sign the contents of the JWS Header and the JWS Payload

\n
\n \"JWS\n
Source: ietf-jose-json-web-algorithms
\n
\n

Algorithms for JWE These algorithms encrypt the Content Encryption Key (CEK) and produce the JWE Encrypted Key

\n
\n \"JWE\n
Source: ietf-jose-json-web-algorithms
\n
\n

Algorithms for JWK: JWA specifies a set of algorithm families to be used for the public keys represented by JWK

\n
\n \n
Source: ietf-jose-json-web-algorithms
\n
\n

Learn more about JWA here.

\n

Conclusion

\n

The IETF JSON Object Signing and Encryption (JOSE) working group was chartered to develop a secure object format based on JSON and simplify adding object-based security features to internet applications.

\n

The basic requirements for these object formats are confidentiality and integrity mechanisms encoded in JSON. JWT, JWS, JWE, JWK, and JWA are the JOSE working group items intended to describe these object formats.

\n

The JOSE specifications have many use cases and are sought out for integrity protection, encryption, security tokens, OAuth, web cryptography, etc. Check out this site to know more about JOSE use cases.

\n

Want to learn how to use JWT for authentication in your apps? Check out this informational JWT authentication guide.

\n

References:

\n\n","frontmatter":{"date":"November 24, 2021","updated_date":null,"description":"Learn about the JOSE framework and its specifications, including JSON Web Token (JWT), JSON Web Signature (JWS), JSON Web Encryption (JWE), JSON Web Key (JWK), and JSON Web Algorithms (JWA). For easier reference, bookmark this article.","title":"What are JWT, JWS, JWE, JWK, and JWA?","tags":["JSON","Encryption"],"pinned":null,"coverImage":{"childImageSharp":{"fluid":{"aspectRatio":1.5037593984962405,"src":"/static/7898fa94ca50b14a5edee22b6dd76018/58556/coverImage.webp","srcSet":"/static/7898fa94ca50b14a5edee22b6dd76018/61e93/coverImage.webp 200w,\n/static/7898fa94ca50b14a5edee22b6dd76018/1f5c5/coverImage.webp 400w,\n/static/7898fa94ca50b14a5edee22b6dd76018/58556/coverImage.webp 800w,\n/static/7898fa94ca50b14a5edee22b6dd76018/99238/coverImage.webp 1200w","sizes":"(max-width: 800px) 100vw, 800px"}}},"author":{"id":"Yashesvinee V","github":"Yashesvinee","avatar":null}}}},{"node":{"excerpt":"In this tutorial, you'll learn how to easily convert an OpenCV project into a web app that you can showcase. You'll use a library called…","fields":{"slug":"/engineering/guest-post/opencv-web-app-with-streamlit/"},"html":"

In this tutorial, you'll learn how to easily convert an OpenCV project into a web app that you can showcase. You'll use a library called Streamlit, which helps you easily build a web user interface in Python. Yes, you heard it right — no HTML, CSS, or JavaScript required. Just Python!

\n

Prerequisites

\n\n

Let's get started.

\n

Install Dependencies

\n

Install OpenCV and Streamlit using pip. You would also need Pillow — another image library.

\n
pip install opencv-python streamlit Pillow
\n
\n

If you use Python 2.7, note that OpenCV doesn't directly support Python 2.7 in their latest versions. Accordingly, you have to specify an older version like this pip install opencv-python==4.2.0.32

\n
\n

Create a Small OpenCV Project

\n
import cv2\n\ndef brighten_image(image, amount):\n    img_bright = cv2.convertScaleAbs(image, beta=amount)\n    return img_bright\n\ndef blur_image(image, amount):\n    img = cv2.cvtColor(image, 1)\n    blur_img = cv2.GaussianBlur(img, (11, 11), amount)\n    return blur_img\n\ndef enhance_details(img):\n    hdr = cv2.detailEnhance(img, sigma_s=12, sigma_r=0.15)\n    return hdr\n\nimg = cv2.imread(filename='tony_stark.webp')\n\n# do some cool image processing stuff\nimg = enhance_details(img)\nimg = brighten_image(img, amount=25)\nimg = blur_image(img, amount=0.2)\n\ncv2.imshow('Tony Stark', img)\ncv2.waitKey(0)\ncv2.destroyAllWindows()
\n

Here are three image processing functions that accept an image, do some processing, and return the processed image.

\n
    \n
  1. brighten_image — increases the brightness of the image.
    2. \n
  2. blur_image — applies a blur effect on the image.
    3. \n
  3. enhance_details — applies an effect to enhance the details of the image.
    4. \n
\n

These functions make use of the OpenCV functions to do the actual processing — for e.g.: cv2.GaussianBlur, etc. I'm not explaining in-depth about them and the various parameters they accept since this tutorial is more focused on integrating OpenCV with Streamlit. However, feel free to jump to the OpenCV documentation to know more details about them.

\n

This program reads the image from the filepath using cv2.imread(); then, it passes the image to these functions that do the processing. Finally, the image is displayed using cv2.imshow(). cv2.waitKey(0) is to wait till the user presses any key, after which the program is exited.

\n

Streamlit Basics

\n

Streamlit offers some common UI components out of the box that you can place on your webpage. This makes it super easy to code up something real quick. The way Streamlit works is that it reruns the Python script every time a user interacts with the components. They have some caching and optimizations, but this simple design makes it easy to build interactive webpages using Streamlit.

\n
\n

Someone said, “Talk is cheap. Show me the code.” So, let's see some code.

\n
\n

Open an editor and copy-paste this to demo-app.py

\n
import streamlit as st\n\nst.title("OpenCV Demo App")\nst.subheader("This app allows you to play with Image filters!")\nst.text("We use OpenCV and Streamlit for this demo")\nif st.checkbox("Main Checkbox"):\n    st.text("Check Box Active")\n\nslider_value = st.slider("Slider", min_value=0.5, max_value=3.5)\nst.text(f"Slider value is {slider_value}")\n\nst.sidebar.text("text on side panel")\nst.sidebar.checkbox("Side Panel Checkbox")
\n

To start a streamlit app, simply run the command streamlit run with the filename — for example:

\n
streamlit run demo-app.py
\n

You should get a similar output as follows.

\n
  You can now view your Streamlit app in your browser.\n\n  Local URL: http://localhost:8501\n  Network URL: http://192.168.1.8:8501
\n

Click on the links in the output to open the Streamlit app in your browser. You'll see something as follows.

\n

\"Streamlit

\n

If you see the code, it's very straightforward. It imports streamlit as st. The default is a simple linear layout where you can place components on the webpage in a sequential manner.

\n

For example, st.title() , st.checkbox(), st.slider() places the components on the main page in the order they're called..

\n

Streamlit also offers a side panel. In order to place components in the sidepanel, you can do as follows:

\n

st.sidebar.title() , st.sidebar.checkbox(), st.sidebar.slider()

\n

There are other components also apart from these. You can explore more in the docs.

\n

Integrate Streamlit into Your OpenCV Project

\n

Let's integrate your OpenCV program into Streamlit. Here is the complete code:

\n
import cv2\nimport streamlit as st\nimport numpy as np\nfrom PIL import Image\n\n\ndef brighten_image(image, amount):\n    img_bright = cv2.convertScaleAbs(image, beta=amount)\n    return img_bright\n\n\ndef blur_image(image, amount):\n    blur_img = cv2.GaussianBlur(image, (11, 11), amount)\n    return blur_img\n\n\ndef enhance_details(img):\n    hdr = cv2.detailEnhance(img, sigma_s=12, sigma_r=0.15)\n    return hdr\n\n\ndef main_loop():\n    st.title("OpenCV Demo App")\n    st.subheader("This app allows you to play with Image filters!")\n    st.text("We use OpenCV and Streamlit for this demo")\n\n    blur_rate = st.sidebar.slider("Blurring", min_value=0.5, max_value=3.5)\n    brightness_amount = st.sidebar.slider("Brightness", min_value=-50, max_value=50, value=0)\n    apply_enhancement_filter = st.sidebar.checkbox('Enhance Details')\n\n    image_file = st.file_uploader("Upload Your Image", type=['jpg', 'png', 'jpeg'])\n    if not image_file:\n        return None\n\n    original_image = Image.open(image_file)\n    original_image = np.array(original_image)\n\n    processed_image = blur_image(original_image, blur_rate)\n    processed_image = brighten_image(processed_image, brightness_amount)\n\n    if apply_enhancement_filter:\n        processed_image = enhance_details(processed_image)\n\n    st.text("Original Image vs Processed Image")\n    st.image([original_image, processed_image])\n\n\nif __name__ == '__main__':\n    main_loop()
\n

Let's understand what's happening here.

\n

Apart from the image processing functions, you have a 'main_loop' function to add the logic for the webpage.

\n

Nothing fancy about st.title(), st.subheader(), st.text() — they just print some text in different sizes.

\n

Next, there are two sliders to get the amount by which you need to apply the blur and brightness filters.

\n

Note that st.sidebar places these components in the sidebar.

\n

slider() takes in some arguments: name of the slider, min value, max value, and the default value of the slider. This function returns the current value of the slider.

\n

Next, there's a checkbox component.

\n

checkbox() returns True if the checkbox is checked; else, it would return False.

\n

Next, there's a file_uploader component, through which users can upload files of different types specified by the type parameter. Here, it's restricted to the image file types needed for the demo usecase.

\n

When the program starts, there are no files selected by the user. At this time, this component returns None. When a file is uploaded from the UI, this component returns the path of the file.

\n

This is why there's an if-check on the return value of this component. If no files are selected, you can skip the rest of the program by returning from the main_loop() function.

\n

Remember that the entire program is rerun whenever there's user interaction on any components of the page. When a user uploads a file, the whole program is executed again — and the if-check fails so that the program executes the image processing logic.

\n

Pillow.Image() is used to open this file, then it's converted to a numpy array using np.array() so that OpenCV can process it.

\n

Now, it's passed to the different processing functions along with the amount parameter.

\n

Finally, the program displays the original and processed images using the st.image() component.

\n

The web app is ready!

\n

To start the app, simply run:

\n
streamlit run demo-app.py
\n

Now you can play with the filters. Of course, these are some basic filters, but you can extend it to more interesting filters — like cartoonify filters, etc. — using the rich features of OpenCV.

\n

\"Streamlit

\n

How to Publish Your App?

\n

To publish your app, you need to host this program somewhere. There are different hosting providers for complex projects. But for this hobby project, is there a simple and quick solution?

\n

Yes, there's one!

\n

You can host the Streamlit application in Streamlit Cloud for free. You can host up to 3 apps in an account for free with up to 1GB of memory.

\n

Check out this tutorial from the community to host your app in Streamlit Cloud.

\n

Conclusion

\n

You can find the source code for this tutorial here. The web app discussed above is hosted here if you want to try it out.

\n

Want to add user authentication and registration in your app quickly? Check out the LoginRadius Python integration.

\n","frontmatter":{"date":"November 10, 2021","updated_date":null,"description":"You can now easily publish your OpenCV apps to the web using Streamlit, a Python library. Follow this tutorial to learn the process step by step.","title":"How to Build an OpenCV Web App with Streamlit","tags":["OpenCV","Streamlit","Python"],"pinned":null,"coverImage":{"childImageSharp":{"fluid":{"aspectRatio":1.5037593984962405,"src":"/static/818e31111fb212b94c72ff9edb09bd3f/58556/coverimage.webp","srcSet":"/static/818e31111fb212b94c72ff9edb09bd3f/61e93/coverimage.webp 200w,\n/static/818e31111fb212b94c72ff9edb09bd3f/1f5c5/coverimage.webp 400w,\n/static/818e31111fb212b94c72ff9edb09bd3f/58556/coverimage.webp 800w,\n/static/818e31111fb212b94c72ff9edb09bd3f/99238/coverimage.webp 1200w","sizes":"(max-width: 800px) 100vw, 800px"}}},"author":{"id":"Dingu Sagar","github":"dingusagar","avatar":null}}}},{"node":{"excerpt":"Why Follow React Coding Best Practices? Writing code to create apps isn't just enough; the code should be as clean and maintainable as your…","fields":{"slug":"/engineering/guest-post/react-best-coding-practices/"},"html":"

Why Follow React Coding Best Practices?

\n

Writing code to create apps isn't just enough; the code should be as clean and maintainable as your app. Before jumping into the good practices to follow, it's essential to realize the reasons behind the same. It becomes crucial for you to understand coding conventions because of the following reasons:

\n
    \n
  1. As a developer, you shall understand that writing code to build apps is not enough, but the code should also be Reliable, Scalable, and Maintainable. Generally, 40% - 80% of the total cost of software is spent on its maintenance.
    2. \n
  2. Readability is the priority. Any software is seldom fully supported by one single developer; There is a whole team or group of people working on it. Furthermore, new developers always join the project team. Thus, maintaining coding standards improves the product's readability that lets developers easily understand the codebase even faster.
    3. \n
  3. Like any product, the software must be well-packaged and clean. Following best coding practices helps you write clean code throughout the codebase by ensuring consistency.
    4. \n
\n

Starting with React Best Practices

\n

Code Structure

\n

There's basically no defined structure, but you should have a style to follow throughout the codebase. Thus, this section explains how you can structure your codebase for medium to large-sized apps.

\n
    \n
  1. \n

    Put all your imports in order at the very top of the code file. You shall ideally prioritize as follows:

    \n

    React imports <> Library imports <> import * as <> import ./<some file>

    \n

    Make sure all your imports statements are on new lines, as this will make your imports clean and easy to understand for all the components, third-party libraries, etc.

    \n
    2. \n
  2. Use index.js for each folder to export so that all the imports are referenced on the index.js file, and you don't have to write import statements again and again for every file.
    3. \n
  3. \n

    It's easy to get confused about whether to use double quotes (\" \") or single quotes (' ') while working with React. The simple answer is: maintain consistency whatever you're using.

    \n

    Also, consider that you use double quotes (\" \") for JSX attributes and single quotes (' ') for the JS code (Follow the standard way or maintain consistency).

    \n
    4. \n
  4. Most of the time, beginners merge two-three components inside a single file and play around with that. However, that's not a good practice to follow. Dividing the whole app into components and then working on it on a separate file is a good practice to maintain clean code.
    5. \n
  5. Do you sometimes use CSS styles with JSX? But it's a bad practice. Always make classNames for each element and put all the styling under respective CSS files only.
    6. \n
\n

Naming Conventions

\n
    \n
  1. Your filenames should always have consistent casing and extension. Either use .js or .jsx as explained in code structure for extensions. And PascalCase or camelCase for filenames.
    2. \n
  2. In React, name your file the same as the React component inside that file i.e. without a hyphen in the filename. For example: Registration-Form → ❌. RegistrationForm → ✔️.
    3. \n
  3. Not only filename but also make sure that your variables/functions/modules filenames are consistent with cases.
    4. \n
  4. Use well-descriptive names for variables/functions/modules/Actions, keeping in mind that it is application-specific so that even a third party or new developer can easily understand you code.
    5. \n
  5. It's bad to use the underscore prefix ( _ ) for a React component's internal methods because underscore prefixes seem to be used as a convention in other languages to denote private objects or variables. But everything in JavaScript is public. And there is no native support for privacy. So, even if you add underscore prefixes to your properties, It'll not make them private. _onClickSubmit() → ❌
    6. \n
  6. When making reducer functions, write Action types as domain/eventNames. For example: ADD_TODO and INCREMENT (in CAPITALS) as this matches the typical conventions in most programming languges for declaring the constant values.
    7. \n
  7. Talking about cases in a React component, use PascalCase for the same — and for their instances, use camelCase. For example:-
    8. \n
\n
const loginForm = <LoginForm />;\nimport LoginForm from './loginForm';
\n

Files and Folders

\n
    \n
  1. Your app's directory structure shall be as follows:
    2. \n
\n
└── /src\n  ├── /assets - Contains static assets such as  images, svgs, company logo etc.\n  ├── /components - reusable components like navigation bar, buttons, forms\n  ├── /services - JavaSript modules\n  ├── /store - redux store\n  ├── /utils - utilities, helpers, constants.\n  ├── /views/pages - majority of the app pages would be here\n  ├── index.js\n  └── App.js
\n
    \n
  1. Each component folder should have its respective files grouped under the same. It maintains the hierarchy throughout the codebase. The necessary files include:\nComponent.js, Component.css, Component.test.js
    2. \n
\n

Code

\n
    \n
  1. Play the game of HOOKS by following all its rules. You can read more about the rules here. Either manually follow these rules or use an ESLint plugin called eslint-plugin-react-hooks which enforces these rules. So, add these rules while working on any project
    2. \n
  2. Remove console. logs — unless you have strong motivation why you would like it.
    3. \n
  3. Avoid multiple if-else blocks. Instead, use ternary — best for clean code practice
    4. \n
  4. Remove all commented-out codes. The biggest motivation for writing comments is the bad code that you write. It would be good to spend more time writing descriptive functions, methods, and filenames that are self-explanatory.
    5. \n
  5. Write Tests for each component. It's a good practice to write test cases for each component developed as it reduces the chances of getting errors when deployed. You can check all the possible scenarios through unit testing — and for that, some of the most commonly used React test frameworks you can use are JEST and ENZYMES.
    6. \n
\n

Good Commenting Practices

\n
    \n
  1. Use comments to explain why you did something, not how you did it. If you find yourself explaining how you did something, then it's time to make your code self-explanatory.
    2. \n
  2. Another point is not to write comments that are obvious and redundant — for example:
    3. \n
\n
// Prints out the sum of two numbers\nconsole.log(sum);
\n
    \n
  1. Write comments that are legal, informative, explanatory of intent, and offer clarification,
    2. \n
\n

ES6

\n
    \n
  1. Always destructure your props. Destructuring your props helps make your code cleaner and more maintainable. It also makes assigning object properties to variables feels like much less of a chore.
    2. \n
  2. Know where to use spread/rest operators. You shall read about it before actually using it.
    3. \n
  3. Try using optional chaining if possible.
    4. \n
  4. Use const instead of var or let . const lets you check that a variable should always stay constant. let indicates that the values of the variables can be changed.
    5. \n
  5. Start preferring arrow functions (= >) for more cleaner code. Arrow functions allow simplifying your code to a single line.
    6. \n
\n

Basics

\n
    \n
  1. Always ensure that your app is responsive.
    2. \n
  2. Your app should contain a proper README.md file that clearly details or explains your app. Clearly mention the features, functionalities, contributions guidelines, installation process, guide, etc.
    3. \n
  3. Do check that your app runs without any errors.
    4. \n
  4. Use EsLint throughout your codebase and other automation tools so that most of the best practices are maintained automatically for you.
    5. \n
  5. Consolidate duplicate code throughout the codebase.
    6. \n
\n

Please note that I haven't talked about automation extension and tools that can help you maintain most of the best practices easily without looking into separately. But, I wanted to bring this into consideration. Anyhow, you can use extensions like prettier, EsLint, EditorConfig, PLOP etc., to maintain your codebase efficiently.

\n

These are the best practices that I've learned practically over time by working in a team, reviewing my mates' codebase, observing open-source projects and repositories, and reading great resources, such as the offical React docs.

\n

Conclusion

\n

I hope you gained valuable insights. If you have more suggestions or practices that the React or dev community can follow, please to let us know.

\n

Until next time, keep learning, build awesome stuff, and uplift the community.

\n

By the way, if you want to add user registration and authentication to your React apps, you can use LoginRadius. It helps you become more efficient and focus more on the core business features of your React apps.

\n","frontmatter":{"date":"October 26, 2021","updated_date":null,"description":"Important React best practices every React developer should follow before, during, & after writing the code. To ensure code maintainability, keep these React coding best practices handy.","title":"32 React Best Practices That Every Programmer Should Follow","tags":["React"],"pinned":null,"coverImage":{"childImageSharp":{"fluid":{"aspectRatio":1.5037593984962405,"src":"/static/ad3a41474714ff1458856a6c47795b66/58556/Best-Practices.webp","srcSet":"/static/ad3a41474714ff1458856a6c47795b66/61e93/Best-Practices.webp 200w,\n/static/ad3a41474714ff1458856a6c47795b66/1f5c5/Best-Practices.webp 400w,\n/static/ad3a41474714ff1458856a6c47795b66/58556/Best-Practices.webp 800w,\n/static/ad3a41474714ff1458856a6c47795b66/99238/Best-Practices.webp 1200w","sizes":"(max-width: 800px) 100vw, 800px"}}},"author":{"id":"Anjali Rohira","github":"rohiraanjali","avatar":null}}}},{"node":{"excerpt":"A Progressive Web App (PWA) is a more dynamic web application that can run as a standalone. It offers benefits such as: performance; the…","fields":{"slug":"/engineering/guest-post/how-to-build-a-progressive-web-app-with-react/"},"html":"

A Progressive Web App (PWA) is a more dynamic web application that can run as a standalone. It offers benefits such as:

\n\n
\n

You can learn more about the differences between native apps and PWAs here.

\n
\n

In this article, you're going to learn how to build a PWA using React. As React is a popular web framework, this article starts by going over the setup, development process, and spinning it up to see how it looks. For this example, you'll create a simple Counter Page that simply adds or subtracts a number based on button controls.

\n

Create a React App with the Progressive Web App Template

\n

Before you can begin coding, you need to set up your project. Let's start by ensuring you can use React (if you're already familiar with coding in React, you can probably skip this section!). You need to use Node.js with any development using web frameworks such as Angular, React, or Vue -- especially if you wish to use libraries and packages to assist in developing your project.

\n

A popular utility in using such packages and libraries is the Node Package Manager, simply referred to as \"npm\". This utility allows you to install/uninstall packages, start your React application build using webpack, and many more other features. For your needs, you can take advantage of npm to create a React application with a PWA template, which allows you to code right away. Whenever you start building a React app, you can use templates offered by Facebook using the 'create-react-app' command with npm.

\n

Let's build the PWA starter app by running the following command:

\n
npx create-react-app name-of-our-PWA-app --template cra-template-pwa
\n

The above command can be broken down as follows:

\n\n

Hitting 'Enter' after this command should initiate the build of your starter PWA React application. You should see a stream of prompts in your command-line interface. It may take a few minutes, but if you can see this screen after the command, you have created the project.

\n

\"cra-pwa.webp\"

\n

\"pwa-folder-structure.webp\"

\n

Here, you can see the following folder structure of your application so far. There are a few files that you shall pay attention to when it comes to PWA's:

\n\n

Adding a Simple React Component

\n

For your project, you'll build a simple Counter component, similar (if not exactly the same) to the example provided in the React docs: Hooks State

\n

Let's start by creating a Counter component. Here, it is named as Counter.jsx and placed in a components folder.

\n

To speed things up, you can copy and paste the following code in your specific files. Here, it is built out as a simple page and some generic stylings for the component.

\n
//Counter.jsx\nimport React, { useState } from 'react';\nimport Button from '@mui/material/Button';\n\nfunction Counter(props) {\n    let [count, setCount] = useState(0)\n\n    function increment() {\n        setCount(count + 1);\n    }\n\n    function decrement() {\n        setCount(count - 1);\n    }\n\n    return(\n        <div style={{textAlign: 'center'}}>\n            <h3>Counter App</h3>\n            <div>\n                <Button variant="contained" onClick={increment}>+</Button>\n                <span> {count} </span>\n                <Button variant="contained" onClick={decrement}>-</Button>\n            </div>\n        </div>\n    );\n};\n\nexport default Counter;
\n

Note: Here, Material UI's Button component is used. You don't need to and can substitute the Button component with:

\n
<button onClick={increment}>+</button>
\n

To use Material UI, run the following npm commands:

\n
npm install @mui/material\nnpm install @emotion/react @emotion/styled //these are additional dependencies for me to get Material UI working with the Counter component
\n

Running Your Application

\n

In your command prompt, entering 'npm start' can spin up your application to a specific http://localhost url. You can start to see what work you've done so far.

\n

With these simple components, let's try to spin this application up and ensure it is working.

\n

Enter the command:

\n
npm start
\n

This starts the application at a set http://localhost URL. Once the dev server is working and live on the command prompt, go to the URL to view the application. You should see something similar to this:

\n

\"counter-base-app.webp\"

\n

Now, it's all good and ready to have the app live and working, but more interested in the PWA aspect.

\n

Running Your Progressive Web Application

\n

Focus back on the index.js file. Make the following change:

\n
// If you want your app to work offline and load faster, you can change\n// unregister() to register() below. Note this comes with some pitfalls.\n// Learn more about service workers: https://cra.link/PWA\nserviceWorkerRegistration.register(); //change the service worker registration from 'unregistered' to 'registered'
\n

Essentially, changing the service worker from unregistered to registered will allow you to utilize the app even when it's offline, a key benefit when it comes to PWAs. Check Google's explanation on this topic for more information: Service Worker Registration

\n

With the PWA files setup, in order to view the difference, you can deploy your application to a static server using the serve package that will serve your application to localhost. In a nutshell, make sure you have the serve package by installing, building the application again, and using serve to deploy the application:

\n
npm install serve\nnpm run build\nserve -s build //if you encounter an error with this command, try 'npx serve -s build'
\n

Once you use the serve command, you should see the following message, having your application deployed to http://localhost:5000. It automatically adds the URL to your clipboard as well for quick pasting in your browser.

\n

\"pwa-serve.webp\"

\n

If you enter the http://localhost URL in your browser, you should see something similar to this:

\n

\"pwa-service-worker.webp\"

\n

PWA Features

\n

With the PWA React application live, let's take a look under the hood and open up the Developer Tools (for Google Chrome, entering F12 opens the Dev Tools).

\n

After registering your service worker from index.js, you should be able to see it running in the Application tab. Inside that tab, on the left side you should see a Service Workers section. From here, you can see for http://localhost:5000. You have a Service Worker from your service-worker.js file and is activated/running.

\n

In the section above, you can see Manifest -- opening that should show you the relevant details you listed from your manifest.json files.

\n

\"pwa-manifest.webp\"

\n

With your PWA app running using React, you've successfully built your first PWA React application! From here, you can test many PWA features, such as installation, offline viewing, and Lighthouse audit testing.

\n

\"pwa-install.webp\"

\n

If you hit the '+' symbol on the right side of the URL ba,r you can install your PWA, just as done here.

\n

\"pwa-lighthouse.webp\"

\n

Use Workbox Lighthouse for testing the capabilities of your PWA: Lighthouse

\n

Conclusion

\n

You've learned about what PWAs are and how to build a PWA with React.

\n

If you want to quickly add user registration and authentication to your React PWA, you can use LoginRadius. It eliminates the burden of building and maintaining user authentication from scratch and helps you focus entirely on building your app's core features.

\n","frontmatter":{"date":"October 22, 2021","updated_date":null,"description":"Follow this article to understand how to develop a simple React PWA. It explains the step-by-step process to help you easily follow along.","title":"How to Build a Progressive Web App (PWA) with React","tags":["React","PWA","npm"],"pinned":null,"coverImage":{"childImageSharp":{"fluid":{"aspectRatio":1.5037593984962405,"src":"/static/a95efcae02df125860df9cb572a3e517/58556/blog-image.webp","srcSet":"/static/a95efcae02df125860df9cb572a3e517/61e93/blog-image.webp 200w,\n/static/a95efcae02df125860df9cb572a3e517/1f5c5/blog-image.webp 400w,\n/static/a95efcae02df125860df9cb572a3e517/58556/blog-image.webp 800w,\n/static/a95efcae02df125860df9cb572a3e517/99238/blog-image.webp 1200w","sizes":"(max-width: 800px) 100vw, 800px"}}},"author":{"id":"Abdullah Pathan","github":"aonepathan","avatar":null}}}},{"node":{"excerpt":"Introduction Bootstrap is an open-source tool collection for creating responsive web pages and web apps. It is the combination of HTML, CSS…","fields":{"slug":"/engineering/guest-post/bootstrap4-vs-bootstrap5/"},"html":"

Introduction

\n

Bootstrap is an open-source tool collection for creating responsive web pages and web apps. It is the combination of HTML, CSS, and JavaScript framework that makes it easy to develop responsive, mobile-first websites. It mainly aims to resolve the cross-browser compatibility issue. Bootstrap is at the core of every website that is perfect for all screen sizes and looks perfect in every modern browser.

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Getting Started with Bootstrap

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In order to start using Bootstrap in your web pages, you need to add a few CSS and JS tags in your template file.

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CSS Link tag\n\n<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
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JS Link tag\n\n<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>\n\n<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js" integrity="sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q" crossorigin="anonymous"></script>\n\n<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js" integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl" crossorigin="anonymous"></script>
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NOTE: Always add the jquery script first, followed by the popper and bootstrap scripts. Then you can add any of your custom scripts below them.

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Bootstrap Versions

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The developers have been working continuously to enrich the developer experience of using Bootstrap for customizing the web pages quite easily. They've released many minor and major versions. But the major releases that are the most popular are the Bootstrap v4.x and Bootstrap v5.x. Let's look at what all v4.x offered and how those things evolved in the v5.x release with additional features.

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Bootstrap v4.x

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Bootstrap 4 was launched back in January 2018, and it was a great improvement over the existing previous versions. However, the most loved features included the following.

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Bootstrap v5.x

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Bootstrap 5 came into play back in May 2021. This release was launched after several iterations of alpha and beta releases and hence had a stack of major additions and new features. Some of the most talked about features are listed below.

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Let's dive into its features by comparing how things changed in Bootstrap 5 and understanding what better design perspectives it offers for developers.

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Bootstrap 5 vs. Bootstrap 4

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The above section talked about the features of both Bootstrap 4 and Bootstrap 5. This section talks about the upgrades that Bootstrap 5 provides over Bootstrap 4.

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Enhanced Grid System

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The grid system is retained in Bootstrap 5. However, an extra grid tier xxl has been introduced to minimize the effort in making the pages responsive on higher resolution displays.

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Columns don't have a default relative position in Bootstrap 5.

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Classes have been added to address vertical spacing.

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Enhanced Form Elements

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The form elements in Bootstrap 4 have defaulted to the browser-provided view. However, in Bootstrap 5, the form elements have a custom design that enables them to have a consistent look and feel in all browsers.

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The new form controls are based on completely semantic, standard form controls. This helps developers to avoid adding extra markups for form controls.

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Utilities API

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Unlike Bootstrap 4, Bootstrap 5 enables the developers to modify and create their own utilities.

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You can simply use sass to create your own utilities.

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You can use the state option to generate dummy class variations like hover and focus.

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$utilities: (\n  "opacity": (\n    property: opacity,\n    class: opacity,\n    state: hover,\n    values: (\n      0: 0,\n      25: .25,\n      50: .5,\n      75: .75,\n      100: 1,\n    )\n  )\n);
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Support for IE

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Bootstrap 5 no longer supports Internet Explorer 10 and 11 like its predecessor, Bootstrap 4.

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Extended Colors

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Bootstrap 4 had limited color options. But Bootstrap 5 has included many new color options to its color palette, enabling you to choose from the various shades available. You can find some of the color shades below.

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\"Bootstrap

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Bootstrap Icons

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Bootstrap 4 didn't have an SVG icon library. You had to use other third-Party libraries like Font Awesome to use icons in your applications. But Bootstrap 5 has taken care of this issue by introducing its own SVG library with 1000+ icons.

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It also includes a web font version in the stable version release of the icon library.

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\"Bootstrap

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Site Generation Strategy

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Bootstrap 5 has moved to Hugo for its static site generation over Jekyll. Hugo is a fast static site generator implemented in Go and is quite popular. You can learn more about Hugo here.

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Popper.js Update

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Bootstrap 5 update brings in an update for Popper.js as well, Popper.js v2. Popper.js generally helps to design the tooltips and popovers. With v2, the following changes come in:

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Placeholder Components

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Bootstrap 5 allows loading placeholders in your pages. This means that you can utilize the space of the components by showing placeholders in their place while they're still loading the actual content.

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\"Placeholder

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Floating Labels

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Bootstrap 5 adds support for floating labels in forms for the input fields. You can simply use the form-floating class to enable a floating label. When you enter some value into the input fields, they automatically adjust their position to their floated area.

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\"Floating

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RTL Support

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Bootstrap 5 has added support for RTL (Right-to-Left), which means you can develop content that needs writing from the right side of the page and continues to the left. As a result, websites in languages like Arabic, Sindhi, and Urdu can easily be developed.

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\"RTL

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jQuery Deprecation

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Bootstrap used jQuery from the very beginning as a dependency to offer dynamic features. With Bootstrap 5, jQuery is dropped, and Vanilla JS is introduced as its replacement.

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NOTE: There are still JS dependencies that depend on Popper and Vanilla JS modules. However, jQuery is optional and can be added based on the requirement of the project.

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Other Significant Changes

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\"Offcanvas

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Summary

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Bootstrap 4 used to do a great job providing all the flexibility and responsiveness for designing the web pages. However, Bootstrap 5 adds several new aspects that help to reduce the effort to do the same. But still, you need to keep certain parameters in mind before choosing either of these two.

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If you have an existing project that needs to support IE 10 and 11 or depends on jQuery, you should probably stick to Bootstrap 4. Bootstrap 5 can be overwhelming but might break your project structure if not migrated properly.

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But if you're starting a new project and want to provide a more immersive UI for the users, definitely opt for Bootstrap 5 to use its modern components, which this article discussed above.

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This is all for this blog post at the moment. I hope you had a great time reading this and learned something new. Do let me know in the comments if you liked the content.

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NOTE: All the images used in this blog post are taken from the official Bootstrap website and are used here for reference purposes only.

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\n","frontmatter":{"date":"October 21, 2021","updated_date":null,"description":"This article discusses the differences between Bootstrap 4 and Bootstrap 5 and helps you understand which version you should use for your projects.","title":"Bootstrap 4 vs. Bootstrap 5: What is the Difference?","tags":["Bootstrap","Frontend","Sass"],"pinned":null,"coverImage":{"childImageSharp":{"fluid":{"aspectRatio":1.5037593984962405,"src":"/static/b8214436ee2553d77f17b33b5fdb3112/58556/coverImage.webp","srcSet":"/static/b8214436ee2553d77f17b33b5fdb3112/61e93/coverImage.webp 200w,\n/static/b8214436ee2553d77f17b33b5fdb3112/1f5c5/coverImage.webp 400w,\n/static/b8214436ee2553d77f17b33b5fdb3112/58556/coverImage.webp 800w,\n/static/b8214436ee2553d77f17b33b5fdb3112/99238/coverImage.webp 1200w","sizes":"(max-width: 800px) 100vw, 800px"}}},"author":{"id":"Rutam Prita Mishra","github":"Rutam21","avatar":null}}}}]},"markdownRemark":{"excerpt":"Introduction Ever wondered how apps like Spotify, Netflix, or Slack manage seamless login experiences across devices? Many of them use JWT…","fields":{"slug":"/engineering/how-to-integrate-jwt/"},"html":"

Introduction

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Ever wondered how apps like Spotify, Netflix, or Slack manage seamless login experiences across devices? Many of them use JWT, or JSON Web Tokens, a compact, stateless method for securely transmitting user identity and session data across services.

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With JWT token authentication, identity information is embedded in a signed token, allowing you to maintain user sessions without server-side storage. This approach is highly scalable and ideal for modern architectures like SPAs, mobile apps, and microservices.

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In this blog, we’ll walk you through what is JWT, why use it, and how to implement JWT authentication using LoginRadius.

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You’ll learn what JWT is, why it’s effective, and how it works in real-world applications. We'll cover both integration methods (IDX and Direct API), generating your signing key, managing sessions, storing the JWT token securely, and applying best practices throughout.

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Whether you're a developer, product manager, or IAM architect, this guide offers a complete foundation for implementing JWT token authentication into your application stack.

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What is JWT?

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JSON Web Token (JWT) is an open standard (RFC 7519) used to transmit information securely between parties as a JSON object. It’s compact, self-contained, and digitally signed, making it a reliable format for authentication and authorization across modern applications.

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A JWT consists of three parts:

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  1. Header – Contains metadata like the type of token and signing algorithm (e.g., HS256).
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  2. Payload – Stores the actual data or “claims,” such as user ID, roles, and token expiry.
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  3. Signature – A cryptographic hash that ensures the token hasn’t been tampered with.
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Example of a token structure:

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<base64Header>.<base64Payload>.<signature>

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Why Use JWT?

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How JWT Works?

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\"Flowchart

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  1. A user logs in with credentials.
    2. \n
  2. Your app (or identity provider like LoginRadius) issues a signed JWT.
    3. \n
  3. The client stores the token and sends it with each request (usually in the Authorization header).
    4. \n
  4. The server validates the token’s signature and claims.
    5. \n
  5. If valid, access is granted — without any session stored on the backend.
    6. \n
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JWT simplifies identity verification, especially when you're building apps that talk to APIs or need to scale without centralized session storage.

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JWT Authentication with LoginRadius: Overview

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LoginRadius provides robust support for JWT (JSON Web Token) authentication, which allows for flexible and secure access control across different digital platforms. Whether you're building a fully custom identity flow or using a pre-built interface, the platform supports various integration approaches depending on your architecture.

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If you're looking to understand how to implement JWT token authentication effectively, LoginRadius offers two primary implementation models that cater to different levels of customization and control:

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1. IDX Implementation – JWT through a Hosted Login Page

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The IDX-hosted login approach enables secure, standards-compliant, JWT-based authentication without requiring you to build a custom login interface. This is a strategic option for fast, compliant, and user-friendly deployments.

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Configuration Steps:

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  1. Enable JWT Login
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  2. Go to authentication configuration settings and enable JWT Login in the Admin Console.
    3. \n
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\"Screenshot

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  1. Specify your signing algorithm and expiry policy, and define your JWT Secret Key.
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  2. Input a secure JWT signing key.
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  3. Specify token expiry duration (e.g., 15–60 minutes)
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  4. Select the desired algorithm —HS256 for symmetric signing (same key signs and verifies)
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  5. RS256 for asymmetric signing, where LoginRadius securely stores the private key used to sign the JWT.
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  6. Your app or backend service uses the public key to validate the token signature.
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  7. LoginRadius provides a JWKS (JSON Web Key Set) endpoint to dynamically fetch and rotate public keys, ensuring trust without key exposure.
    8. \n
  8. Update IDX Template for Callback
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  9. Modify your IDX login page template to retrieve the JWT post-login. You can access the token via redirect URL parameters or secure JavaScript callbacks.
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Example Response:

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{

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\"access_token\": \"eyJhbGciOiJIUzI1NiIsInR...\",

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\"expires_in\": 1800

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}

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This integration approach works best for all teams that want effective identity workflows without the complexity of building proprietary login screens, something that is crucial for customer portals, onboarding of mobile applications, and even managing access for business partners.

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2. Direct API Implementation – Self Managed Login

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If you’re building a custom login UI or working in a headless environment, LoginRadius lets you generate and handle JWTs directly through its Authentication APIs. Here’s how you can programmatically perform token authentication using the classic method:

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Configuration Steps:

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Step 1: Authenticate via API:

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Include the user’s credentials (email + password) in the request body.

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Step 2: Get JWT in Response

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{

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\"access_token\": \"eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...\",

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\"expires_in\": 3600

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}

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Step 3: JWT Decoding and Validation

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Step 4: Set Custom Claims (Optional)

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With LoginRadius, it is possible to customize the payload to include user roles and/or any additional metadata. You can set custom JWT claims on the Admin Console.

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With this method, you have complete customization over login flows while using LoginRadius to issue signed JWTs for user session management.

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NOTE- With either method, LoginRadius ensures that JWTs are securely signed, optionally short-lived, and compatible with standard token validation libraries, making integration seamless for everyone.

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To get started with JWT implementation, you can read our complete developer documentation.

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Hosted Login vs Direct API

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\"Illustration

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What is Session Management and How It Works with JWT

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Session management is how your app keeps track of a user after they log in so they don’t have to prove who they are with every request.

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In traditional apps, sessions are stored on the server using session IDs. Every time a request comes in, the server checks that session ID to verify the user.

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In modern apps, especially SPAs and APIs, JWTs are used to manage sessions without needing server-side storage; this is called stateless session management. The token itself carries the user’s identity, roles, and expiration details. As long as the token is valid, the user stays logged in.

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Good session management ensures:

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How LoginRadius Handles Session Management with JWT:

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  1. \n

    User Logs In

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    2. \n
  2. \n

    Client Stores the Token

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    3. \n
  3. \n

    Access Token Expiry

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    4. \n
  4. \n

    Token Renewal

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    5. \n
  5. Logout and Token Revocation Strategy
    6. \n
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When the user logs out, both the access token and refresh token should be cleared from client storage.

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Combining these strategies gives you greater control over token misuse and enables a robust, enterprise-grade logout flow.

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\"illustration

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How to Store JWT Tokens?

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When you implement JWT-based authentication, the client (browser or mobile app) needs a way to store the access token and, optionally, the refresh token after they are issued by the authentication server. This stored token is then attached to every subsequent request to prove the user's identity.

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Choosing where to store the JWT is a crucial security decision. The most common storage options are:

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Each option has trade-offs between security, accessibility, and persistence, and the right choice depends on your application's architecture and threat model.

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Recommended Storage Strategy

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Best Practices for Storing JWTs

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  1. Never store sensitive tokens (like refresh tokens) in localStorage or sessionStorage.
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  2. Use Secure and HttpOnly flags with cookies to prevent JavaScript access and ensure transmission only over HTTPS.
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  3. Set the SameSite=Strict or Lax attribute on cookies to protect against CSRF.
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  4. Use short-lived access tokens and rotate refresh tokens regularly.
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  5. Implement CSP (Content Security Policy) to reduce XSS risk.
    6. \n
  6. Avoid storing any tokens in frontend code (e.g., hardcoded in JS files).
    7. \n
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Conclusion

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JWT authentication with LoginRadius offers a modern, stateless approach to managing sessions across distributed systems. The IDX integration is ideal for rapid deployment, while the Direct API model is best for organizations needing deep customization and integration flexibility.

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With robust token signing, refresh capabilities, and centralized control, LoginRadius provides a future-ready foundation for secure, scalable identity architecture. Contact us to know more about JWT authentication and implementation guide.

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FAQs

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1. What is JWT authentication used for?

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A: JWT authentication securely verifies user identities, enabling stateless session management across web, mobile apps, and microservices without server-side session storage.

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2. How does LoginRadius simplify JWT integration?

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A: LoginRadius simplifies JWT integration by offering hosted IDX login pages and direct API-based authentication methods, enabling rapid deployment and deep customization.

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3. Is JWT authentication secure?

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A: Yes, JWT authentication is secure when implemented with best practices like short-lived tokens, secure storage methods, signature validation, and refresh token rotation.

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4. Can JWT tokens be revoked with LoginRadius?

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A: Yes, LoginRadius allows revocation of JWT refresh tokens explicitly, and supports strategies like short-lived tokens and key rotation to manage token lifecycles securely.

\n","frontmatter":{"date":"April 15, 2025","updated_date":null,"description":"Discover JWT (JSON Web Token) authentication, its advantages, and how to integrate it seamlessly using LoginRadius' hosted IDX and Direct API methods for secure, scalable identity management.","title":"JWT Authentication with LoginRadius: Quick Integration Guide","tags":["JWT","JSON Web Token","Authentication","Authorization"],"pinned":null,"coverImage":{"childImageSharp":{"fluid":{"aspectRatio":0.7782101167315175,"src":"/static/4cedb7829f98208cbc6d5a9aea4e983d/58556/how-to-integrate-jwt.webp","srcSet":"/static/4cedb7829f98208cbc6d5a9aea4e983d/61e93/how-to-integrate-jwt.webp 200w,\n/static/4cedb7829f98208cbc6d5a9aea4e983d/1f5c5/how-to-integrate-jwt.webp 400w,\n/static/4cedb7829f98208cbc6d5a9aea4e983d/58556/how-to-integrate-jwt.webp 800w,\n/static/4cedb7829f98208cbc6d5a9aea4e983d/1cc9f/how-to-integrate-jwt.webp 896w","sizes":"(max-width: 800px) 100vw, 800px"}}},"author":{"id":"Kundan Singh","github":null,"avatar":null}}}},"pageContext":{"limit":6,"skip":36,"currentPage":7,"type":"//engineering//","numPages":53,"pinned":"5c425581-f474-5ae9-abe7-cf5342db2aaa"}},"staticQueryHashes":["1171199041","1384082988","2100481360","23180105","528864852"]}