Build a Virtual Waiting Room with Amazon DynamoDB and AWS Lambda at SeatGeek

As retail sales, products, and customers continue to expand online, we’ve seen a trend towards releasing products in limited quantities to larger audiences. Demand of these products can be high, due to limited production capacity, venue capacity limits, or product exclusivity. Providers can then experience spikes in transaction volume, especially when multiple event sales occur simultaneously. This increased traffic and load can negatively impact customer experience and infrastructure.

To enhance the customer experience when releasing tickets to high demand events, SeatGeek has introduced a prioritization and queueing mechanism based on event type, venue, and customer type. For example, Dallas Cowboys’ tickets could have a different priority depending on seat type, or whether it’s a suite or a general admission ticket.

SeatGeek previously used a third-party waiting room solution, but it presented a number of shortcomings:

• Lack of configuration and customization capabilities
• More manual process that resulted in limiting the number of concurrent events could be set up
• Inability to capture custom insights and metrics (for example, how long was the customer waiting in the queue before they dropped?)

Resolving these issues is crucial to improve the customer experience and audience engagement. SeatGeek decided to build a custom solution on AWS, in order to create a more robust system and address these third-party issues.

Virtual Waiting Room overview

Our solution redirects overflow customers waiting to complete their purchase to a separate queue. Personalized content is presented to improve the waiting experience. Public services such as school or voting registration can use this solution for limited spots or time slot management.

Figure 1. User path through a Virtual Waiting Room

During a sale event, all customers begin their purchase journey in the Virtual Waiting Room (see Figure 1). When the sale starts, they will be moved from the Virtual Waiting Room to the ticket selection page. This is referred to as the Protected Zone. Here is where the customer will complete their purchase. The Protected Zone is a group of customized pages that guide the user through the purchasing process.

When the virtual waiting room is enabled, it can operate in three modes: Waiting Room mode, Queueing mode, or a combination of the two.

In Waiting Room mode, any request made to an event ticketing page before the designated start time of sale is routed to a separate screen. This displays the on-sale information and other marketing materials. At the desired time, users are then routed to the event page at a predefined throughput rate. Figure 2 shows a screenshot of the Waiting Room mode:

Figure 2. Waiting Room mode

In Queueing mode, the event can be configured to allow a preset number of concurrent users to access the Protected Zone. Those beyond that preconfigured number wait in a First-In-First-Out (FIFO) queue. Exempt users, such as the event coordinator, can bypass the queue for management and operational visibility.

Figure 3. Queueing mode flow

Figure 4. Queueing mode

In some cases, the two modes can work together sequentially. This can occur when the Waiting Room mode is used before a sale starts and the Queueing mode takes over to control flow.

Once the customers move to the front of the queue, they are next in line for the Protected Zone. A ticket selection page, shown in Figure 5, must be protected from an overflow of customers, which could result in overselling.

Figure 5. Ticket selection page

Virtual Waiting Room implementation

In the following diagram, you can see the AWS services and flow that SeatGeek implemented for the Virtual Waiting Room solution. When a SeatGeek customer requests a protected resource like a concert ticket, a gate keeper application scans to see if the resource has an active waiting room. It also confirms if the configuration rules are satisfied in order to grant the customer access. If the customer isn’t allowed access to the protected resource for whatever reason, then that customer is redirected to the Virtual Waiting Room.

Figure 6. Architecture overview

SeatGeek built this initial iteration of the gate keeper service on Fastly’s Computer@Edge service to leverage its existing content delivery network (CDN) investment. However, similar functionality could be built using Amazon CloudFront and AWS Lambda@Edge.

The Bouncer, handling the user flow into either the protected zone or the waiting room, consists of 3 components – Amazon API Gateway, AWS Lambda, and a Token Service. The token service is at the heart of the Waiting Room’s core logic. Before a concert event sale goes live at SeatGeek, the number of access tokens generated is equivalent to the number of available tickets. The order of assigning access tokens to customers in the waiting room can be based on FIFO or customer status (VIP customers first). Tokens are allocated when the customer is admitted to the waiting room and expire when tickets are purchased or when the customer exits.

For data storage, SeatGeek uses Amazon DynamoDB to monitor protected resources, tokens, and queues. The key tables are:

• Protected Zone table: This table contains metadata about available protected zones
• Counters table: Monitors the number of access tokens issued per minute for a specific protected zone
• User Connection table: Every time a customer connects to the Amazon API Gateway, a record is created in this table recording their visitor token and connection ID using AWS Lambda
• Queue table: This is the main table where the visitor token to access token mapping is saved

For analytics, two types of metrics are captured to ensure operational integrity:

• System metrics: These are built into the AWS runtime infrastructure, and are stored in Amazon CloudWatch. These metrics provide telemetry of each component of the solution: Lambda latency, DynamoDB throttle (read and write), API Gateway connections, and more.
• Business metrics: These are used to understand previous user behavior to improve infrastructure provisioning and user experiences. SeatGeek uses an AWS Lambda function to capture metrics from data in a DynamoDB stream. It then forwards it to Amazon Timestream for time-based analytics processing. Metrics captured include queue length, waiting time per queue, number of users in the protected zone, and more.

For historical needs, long-lived data can be streamed to tiered data storage options such as Amazon Simple Storage Service (S3). They can then be used later for other purposes, such as auditing and data analysis.

Considerations and enhancements for the Virtual Waiting Room

• Tokens: We recommend using first-party cookies and token confirmations to track the number of sessions. Use the same token at the same time to stop users from checking out multiple times and cutting in line.
• DDoS protection: Token and first-party cookies usage must also comply with General Data Protection Regulation (GDPR) and California Consumer Privacy Act (CCPA) guidelines depending on the geographic region. This system is susceptible to DDoS attacks, XSS attacks, and others, like any web-based solution. But these threats can be mitigated by using AWS Shield, a DDoS protection service, and AWS WAF – Web Application Firewall. For more information on DDoS protection, read this security blog post.
• Marketing: Opportunities to educate the customer about the venue or product(s) while they wait in the Virtual Waiting Room (for example, parking or food options).
• Alerts: Customers can be alerted via SMS or voice when their turn is up by using Amazon Pinpoint as a marketing communication service.

Conclusion

We have shown how to set up a Virtual Waiting Room for your customers. This can be used to improve the customer experience while they wait to complete their registration or purchase through your website. The solution takes advantage of several AWS services like AWS Lambda, Amazon DynamoDB, and Amazon Timestream.

While this references a retail use case, the waiting room concept can be used whenever throttling access to a specific resource is required. It can be useful during an infrastructure or application outage. You can use it during a load spike, while more resources (EC2 instances) are being launched. To block access to an unreleased feature or product, temporarily place all users in the waiting room and let them in as needed per your own configuration.

Providing a friendly, streamlined, and responsive user experience, even during peak load times, is a valuable way to keep existing customers and gain new ones.

Be mindful that there are costs associated with running these services. To be cost-efficient, see the following pages for details: AWS Lambda, Amazon S3, Amazon DynamoDB, Amazon Timestream.