An API service for a small bank.
- Main Framework: Node.js with Express.js
- Dependencies Management: Yarn
- Database: MongoDB
- In-Memory Storage (for queue): Redis
- Testing: Supertest, Mocha
- Container Library: Docker
[Prerequisite]
- Node.js
- Docker
[Installation with Docker]
- Clone the repository: git clone https://www.github.com/IkwhanChang/transaction-service.git
- Go to transaction-service folder
- chmod 707 ./app.sh
- Make sure you're running Docker
- run "./app.sh run" -> will set up both redis, mongodb, and this service, and will run everything inside docker.
- Go and test via http://localhost:5000/accounts
[Installation without Docker]
(More prerequisites: MongoDB, Redis on your machine)
- Clone the repository: git clone https://www.github.com/IkwhanChang/transaction-service.git
- Go to transaction-service folder
- Install dependencies: npm i or npm install (make sure you already installed the node)
- Run Mongod and redis-server on other terminal
- npm run start
- Test http://localhost:5000/accounts
- I'm using Mocha and Supertest. Once you're done to setup, try to run "npm run test". It has every scenario of apis. See /test/api.test.js file. Will test like below:
✓ return 200 code (79ms)
Get balance of ACT310
✓ should 100.0
Withdraw 50.0 to ACT310
✓ return 200 code (48ms)
Get balance of ACT310
✓ should 50.0
Withdraw 55.0 to ACT310
✓ return not enough balance error (57ms)
Transfer from ACT310 to ACT320
Deposit 200.0 to ACT320
✓ return 200 code (67ms)
Deposit 100.0 to ACT310
✓ return 200 code (56ms)
Get balance of ACT320
✓ should 200.0
Transfer 170 from ACT310 to ACT320
✓ Should be not enough balance error of ACT310 (53ms)
Transfer 50 from ACT310 to ACT320
✓ Return 200 code (66ms)
Get balance of ACT320 and ACT310
✓ should be ACT320 = 250.0 and ACT310 = 100
Transfer 10 from ACT310 to ACT330 (not existed account)
✓ Should be error with invaild toId (39ms)
Transfer 10 from ACT330 to ACT310 (not existed account)
✓ Should be error with invaild fromId
Freeze Test
Freeze ACT330 (not existed account)
✓ Should be error with Cannot found accountId (38ms)
Freeze ACT320
✓ return 200 code
Deposit ACT320
✓ shoud be error
Withdraw ACT320
✓ shoud be error
Transfer 50 from ACT320 to ACT310
✓ Should be error with freeze fromId
Transfer 50 from ACT310 to ACT320
✓ Should be error with freeze toId (50ms)
Thaw Test
Thaw ACT330 (not existed account)
✓ Should be error with invaild accountId
Thaw ACT320
✓ return 200 code (50ms)
Deposit ACT320
✓ shoud be working (69ms)
Withdraw ACT320
✓ shoud be working (53ms)
Transfer 50 from ACT320 to ACT310
✓ Should be working (69ms)
Transfer 50 from ACT310 to ACT320
✓ Should be working (54ms)
GET /accounts
✓ return accounts- Warning: to add account, I modified "DEPOSIT" command that account will be created if there are no account with accountId.
// @route GET accounts
// @desc Get list of account detail
// @access Public
router.get("/", (req, res) => {
const accountIds = req.query.accountId;
if (accountIds === undefined) return res.status(200).json({});
AccountAPI.getAccounts({
cmd: "ACCOUNTS",
accountIds: typeof accountIds === "string" ? [accountIds] : accountIds
})
.then(details => {
res.send(details.filter(d => d !== undefined));
})
.catch(e => {
console.error(e);
res.status(500).json(e);
});
});// @route GET transactions
// @desc Execute command
// @access Public
router.post("/", (req, res) => {
const worker = new Worker(req.body.length);
//worker.start();
req.body.forEach(({ cmd, ...rest }) => {
const params = JSON.stringify({
cmd: `CMD_${cmd}`,
params: { cmd, ...rest }
});
worker.send(params, (messageCnt, isError, errors) => {
if (messageCnt === 0) {
if (isError) {
res.json({ errors });
} else {
res.send("OK");
}
}
});
});
});const AccountSchema = new Schema(
{
accountId: {
type: String,
unique: true
},
balance: {
type: Number
},
freeze: {
type: Boolean
},
createdAt: {
type: Date,
default: Date.now
}
},
{ timestamps: true }
);- MongoDB for the main database.
- Used Redis Simple Message Queue (https://github.com/smrchy/rsmq) to maintain the concurrent transaction request.
- Every transaction request will be sent to the worker, which is maintain the message queue with multiple transactions.
- Once transactions are sent to worker, worker.send will add the message into MQ, then MQ will automatically hooked in every 100ms via setInterval function (Worker.start())
- In every 100ms, rsmq.receiveMessage will catch the message and call the TransactionAPI with specific parameters
class Worker {
constructor(messageCnt) {
this.rsmq = new RedisSMQ({
host: process.env.REDIS_HOST || "127.0.0.1",
port: process.env.REDIS_PORT || 6379,
ns: "rsmq"
});
...
}
init() {...}
createQueue() {...}
start() {
this.listener = setInterval(() => {
this.receive();
}, 50);
}
stop() {
clearInterval(this.listener);
}
receive() {
const { rsmq, deleteMessage } = this;
rsmq.receiveMessage({ qname }, (err, res) => {
if (err) {
console.error(err);
return;
}
if (res.id) {
const { cmd, params } = JSON.parse(res.message);
TransactionAPI.exec(cmd, params)
.then(() => {
console.log("done");
deleteMessage(res.id);
})
.catch(e => {
console.error("Error while handling command", e);
this.isError = true;
this.errors.push(e);
deleteMessage(res.id);
});
}
});
}
send(message, successCallback) {
this.successCallback = successCallback;
this.rsmq.sendMessage({ qname, message }, function(err, resp) {
if (err) {
console.error(err);
return;
}
});
}
deleteMessage(id) {...}
}...
exec(cmd, params) {
switch (cmd) {
case CMD_DEPOSIT:
return this.deposit(params);
case CMD_WITHDRAW:
return this.withdraw(params);
case CMD_XFER:
return this.xfer(params);
case CMD_FREEZE:
return this.freeze(params);
case CMD_THAW:
return this.thaw(params);
default:
return Promise.reject();
}
}- TransactionAPI.exec() will run the command with parameters.