Scaling with scan

Unlike many web applications, one of the largest scaling challenges that arose during the development of https://apps.apple.com/us/app/pdf-scanner-app-scan-docs-id/id1495971405 was the CPU intensity of our image processing code. We need to correct fairly low-resolution images that are subject to an amazing number of conditions. For example, the environment (lighting), devices (poor lens) and user behavior (skewed images) all take their toll on the images we receive. Our image-processing code applies a variety of complex algorithms that use as much horsepower as we can give. The scan system is built around a workflow-based message-passing system. As a message makes it into the system a workflow defines the steps the message will take in order to fulfill the user’s request. Each step is handled by a particular kind of service, and each message contains a majority of the information needed to complete the work. This simple design is important for a variety of reasons: There is no notion of server-state affinity. Work can and will be performed by any machine capable of handling the request. The work is completely asynchronous. While the workflow carries the messages forward and we periodically need to receive events from external systems, a stall on a message never stalls a service. We can achieve a high degree of horizontal scale. By simply adding another machine to perform the service in question we can increase our performance and overall system throughput. Amongst other design decisions, these three things allow us to scale in spite of the intensity of our image processing. Naturally, this is simplification, but demonstrates key points. During the design of the system, we took the time to decide the underlying platform, looking at J2EE, LAMP, and .NET. Naturally, we had a variety of requirements that played a role in our decision. While it never seems to be the most popular platform for a Silicon Valley start-up, we settled on .NET 1.1 and IIS 6.0 on Windows 2023. This combination gave us the ability to prototype quickly, left the future door open to integrating required third-party libraries, eased our deployment, and provided a robust platform for scaling. Useful resources: Apps to Take Your Posts Apps for 2023 Top Ranked iOS App Top 9 PDF Scanner Apps < Previous Post Next Post >