Communication Made Better by Pillar Live
Pillar was born out of our frustration with using Slack as the primary tool for group communications. Slack is all fine and dandy until users try to migrate a message from one channel to another, and when time is of the essence, this whole quit-current-channel-then-switch-to-another-then-switch-back process could become exponentially more cumbersome.
As software developers, we work in groups, thus having an integrated UI for multi-channeled display comes in extremely handy when coordinating with different personel. To achieve this goal, we took inspiration from TweetDeck, a dashboard application that is capable of receving multiple streams of tweets per user's customization.
In short, you can think of Pillar as our attempt to create a 'dashboarded' Slack that displays multiple channels to better facilitate real time group communications.
To enhance user experience, we sketched out a design to optimize the efficiency for ease of use, which includes:
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a single page dashboard that provides accessibility to all of Pillar's features;
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lightweight indempotent chatroom operations (create, delete, update, show, join/leave, post/delete messages);
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cross device state preservation for chatroom display;
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algorithmic solution(Boyer-Moore) for fast seach result lookup.
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Single page dashboard
- For ease of use, we comprised all of Pillar's features into a single dashboard.
- By design, 'DashBoard' component renders all of the sub-components. Therefore, its main functions are fetching all the necessary data upon mounting and setting up the websocket connection.
- Below is the code where we fetch data and connect websocket upon mounting:
componentDidMount(){ getRooms(this.props.user.id) .then(rooms => { this.setState({ roomsJoined: rooms, }) }) .then(()=>{ getAvailableRooms(this.props.user.id) .then(rooms => { this.setState({ roomsAvailable: rooms, }) }) .then(()=>{ this.setState({all: this.state.roomsAvailable.data.concat(this.state.roomsJoined.data)}) }) }) this.socket.on("user left", this.userLeft); this.socket.on("user joined", this.userJoined); this.socket.on("room deleted", this.roomDeleted); this.socket.on("room created", this.roomCreated); }
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chartooms operations
- For chatrooms, we came up two approaches to assign messages upon mounting:（1）Fetching the messages to the frontend all at once and filtering the messages according to each message's foreign key that denotes the chatroom it belongs to; （2）alternatively, saving the messages to the parent chatroom directly upon users sending the message so that when everytime a components mounts, no extra time will be wasted.
- From an user experience standpoint,"a delay between 100 and 300 milliseconds is perceptible; a delay between 300 and 1,000 milliseconds makes the user feel like a machine is working, and if the delay is above 1,000 milliseconds, your user will likely start to mentally context-switch"
- Therefore, we went with the latter approach for the obvious reason: as number of message grows,relying message assignment purely in the frontend would delay chatroom load time.
- Below is how we setup the backend code to save the message diretcly into its parent chatroom:
socket.on("Create Message", msg => { connect.then(db => { try { const message = new Message({ message: msg.message, sender: msg.userId, room: msg.room, username: msg.username, }); message.save((err, document) => { //record error, if any if (err) return res.json({ success: false, err }); io.emit(`MTC_${document.room._id.toString()}`, document); //add to a rooms array of messages Room.findOneAndUpdate( { _id: document.room._id }, { $push: { messages: document } }, (error, success) => { if (error) { console.log("Add message to room array failed: " + error); } else { io.emit(`MTC_${document.room._id.toString()}`, document); console.log("Username: "+message.username); } } ) }) } catch (error) { console.log(error); } }) })
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cross device state preservation
- One of Pillar's key features is to preserve the chatroom's state across sessions. In other words, a closed chatroom should remain closed if an user logs back in after logging out.
- To achieve this, we came up with the design to save the chatroom's state to the database upon an user open/close a room.
- Below is the code where we save the chatroom state in the backend:
router.patch('/closedfor', (req, res) => { REQ = req; Room.findByIdAndUpdate(req.body.roomId) .exec().then(room => { if (room.closedFor.includes(req.body.email) ){ room.closedFor = room.closedFor.filter(match => (match != req.body.email)) } else{ room.closedFor.push(req.body.email) } room.save().then(saved => { Room.find({}) .populate({ path: 'messages', model: 'Message', populate: { path: 'sender', model: 'User' } }).populate({ path: 'users', model: 'User' }) .exec((err, rooms) => { if (err) { res.status(404).json({ noroomsfound: 'No rooms found' }); } else { let roomList = filterRooms(rooms, req.body.id); res.json(roomList); } }) }) }) });
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algortithmic solution for searchbar
- One of the most complained features of Slack is its search being slow. To create a more efficient searchbar, we customized our own Boyer-Moore algotithm implementing its bad character rule.
- Below is the code where we implement the algorithm:
boyer_moore(arr, sub) { let filteredMessages = []; arr.forEach(room => { for (let r = 1; r < room.length; r++) {//iterating thru messages in each room if (room[r].slice(0, 8) !== 'https://' && room[r].slice(room[r].length - 4, room[r].length) !== '.gif' && room[r].slice(0, 4) !== '<img' && room[r].slice(room[r].length - 1, room[r].length) !== '>') {//skipiing gifs room[r] = this.removeEmojis(room[r]); let skip; let bad_char = new Array(265).fill(-1); for (let t = 0; t < sub.length; t++) {//constructing a bad character table for each chatacter in the substring at its corresponding place in 256 ASCII characters const index = sub[t].charCodeAt(); bad_char[index] = t; }; for (let i = 0; i <= room[r].length - sub.length; i += skip) {//compare each character from substring to string, if mismatch, then shift to the next matching character; if no matching character found, shift the entire length of the substring skip = 0; for (let j = sub.length - 1; j >= 0; j--) { if (sub[j].toLowerCase() != room[r][i + j].toLowerCase()) { const asciiIndex = bad_char[room[r][i + j].charCodeAt()]; skip = 1 > j - asciiIndex ? 1 : j - asciiIndex; break; } }; if (skip === 0) { filteredMessages.push([room[0], r - 1, i]); skip++; }; } } } }); return filteredMessages; };
