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Why We Chose to Build SeatGeek Open on .NET Core

players huddle in front of beautiful Children's Mercy Park

In July of 2016, SeatGeek announced that we would be the primary ticketer of Sporting Kansas City in the following Major League Soccer season. This entrance into primary ticketing was a landmark moment in the company’s history. We would partner with an Israeli company called TopTix to ticket all events for SKC and their minor league team, the Swope Park Rangers, with the first game taking place only eight months later in March of 2017. TopTix provided a SaaS system called SRO4 built on the .NET Framework that enabled teams to manage their events, tickets, and customers.

In August, we founded the SeatGeek Open team to build the integration between our clients (e.g. Sporting Kansas City) and our customers. This new team had an ambitious schedule: we would integrate with SRO’s complex and expressive API on a short and inflexible timeline. Our new service had to be reliable and scalable enough to handle major ticket sales and live events. Most importantly, the credibility of the company and our future in primary ticketing depended on it.

SeatGeek mostly works with Python, although we’re comfortable using new languages and platforms when the use case makes sense. We started by trying out some Python SOAP libraries and working around the issues and inconsistencies that came up. The SRO API exposes hundreds of methods and thousands of classes, so development was slow and minor bugs were multiplied many times over. We also ran into performance issues when fetching the available listings in a stadium, which took up to two minutes to deserialize.

To meet our scalability and performance goals, we had to find a new approach. Because of its compatibility with SRO’s .NET Framework API, we began to consider .NET, but we had some misgivings. First, our team had limited experience with .NET. Second, even if we were willing to commit to C♯, it still wasn’t obvious whether we should use .NET Framework or .NET Core. If we used .NET Framework, we would have had to adopt not only a new language in C♯, but also a new operating system in Windows. On the other hand, .NET Core would run on Linux but was relatively unproven. These concerns would have required careful thought for any production service, but we were building the foundation of the company’s future and we needed to be sure it was solid.

We decided to build a proof of concept to evaluate the viability of this approach. We exported a WSDL of the SRO API and used that to generate a C♯ reference file. Using this, we began to build a .NET Core app that could communicate with SRO via SOAP in a strongly-typed manner. Having code completion made understanding and exploring the features of the API much easier. After we had successfully built out a few scenarios, .NET Core started to seem more realistic. When we looked at the community growing around .NET Core, we saw that the maintainers were actively responding to and fixing issues, which boosted our confidence in the viability of the platform.

eager fans being efficiently scanned in to the stadium

The next hurdle was integrating .NET Core into our existing infrastructure and deployment systems. Because it runs on Linux, we were able to write C♯ code but still deploy it using a Debian container stack, so we could continue to use the same deployment and monitoring tools SeatGeek uses for other services. We were also able to find an Entity Framework provider for PostgreSQL that worked with .NET Core, allowing us to leverage our existing investments in that database.

There were some challenges along the way. The first problem we had to face was our lack of C♯ experience. Our first commits after the switch were basically Python with more curly braces, but over time we began to learn and appreciate idiomatic C♯. The more impactful issue we faced was a lack of tooling support for .NET Core, especially on macOS. Because most .NET developers use Windows and the .NET Framework, we initially had trouble finding .NET Core versions of some popular libraries and tools.

In October, we committed to .NET Core. Over the next several months, we ramped up on improving our C♯ and building out API features. By January we had our first primary ticket purchase. In March, less than five months after we started development, we had our first home game. The system scaled flawlessly, and all 19,000 fans were scanned into the stadium without issue. Since then, we’ve signed several more clients with some of the largest venues in the world, including AT&T Stadium and the Mercedes-Benz Superdome. Handling events of that size might never be easy, but we are confident that .NET Core won’t be what holds us back.

In retrospect, .NET Core was the right choice for the SeatGeek Open platform. It was the best way to meet our goals of quick integration, high performance, and flexible deployment options. We’ve been thrilled to see the meteoric growth of the .NET Core platform over the past year and a half, and we’re fascinated to see what the future will bring.