Uploads have always historically been a major pain point for web applications, due to poor performance, spotty reliability, and framework-specific limitations. As more and more websites rely on social networking, user generated content, and in general storing data in the cloud, the ability to support reliable and scalable uploads is rapidly becoming more critical than ever.
After working with many clients to help solve these problems, LeanServer is announcing ScaleUP – a breakthrough web upload solution for the Microsoft IIS platform that finally enables fast, reliable, and super-scalable HTTP uploads to any web application.
Making uploads work
We designed ScaleUP to power uploads in some of the largest web sites in the world – such as myspace.com’s media farm that handles over 25M photo, song, and video uploads a day – while significantly reducing server costs.
ScaleUP is unique in that it is able to fundamentally replace the platform’s upload process, enabling upload reliability and scalability characteristics that existing upload managers simply could not attain.
As a result, ScaleUP allows any existing ASP.NET, ASP, PHP, or other IIS 7.0 compatible application to achieve:
- Up to 20x faster upload speeds 
- Reliable uploads of unlimited size (4Gb+)
- Reduced application impact (no thread starvation, lower disk usage, etc)
- Scaling to THOUSANDS of active uploads on a single server
- Full support for streaming, filtering, server-side progress reporting, and other common upload features 
- Transparent support for ASP, ASP.NET, PHP, and any other IIS 7.0-compatible application (regardless of framework upload limitations)
To make this happen, we had to fundamentally redesign the platform’s upload process, leveraging the IIS 7.0 low level extensibility layer to handle request uploads with our own high-performance upload engine.
Here are some of the challenges that ScaleUP addresses:
Upload thread starvation. Uploads block application threads, causing thread starvation and destroying application performance at even medium load. This affects any application, be it ASP, ASP.NET, PHP, or even an IIS 6.0 ISAPI extension – and any third party upload manager built for ASP.NET or previous versions of IIS.
Upload size limitations. Uploads on ASP.NET/IIS have been limited to 2Gb/4Gb, and typically much less due to resource impact of handling large uploads.
Severely limited scalability. Thread starvation and heavy resource impact of handling uploads today prevents handling more than a small number of active uploads per server. In production, many sites quickly experience dropping upload speeds, quickly followed by errors and timeouts.
Making it work for any existing application. We wanted to provide excellent upload support to any existing ASP.NET, ASP, PHP or other IIS 7.0 compatible application, regardless of framework-specific limitations, and without cumbersome browser plugins.
You can read more about these challenges, and the history of the upload support in the Microsoft web platform, in my Brief History of Web Uploads post.
Definitely check out the results for yourself on www.leanserver.com/scaleup.
Why it works
There are dozens of available upload IIS and ASP.NET upload components that provide upload processing features, and client plugins that support progress reporting and retries, but neither could previously address the core upload limitations imposed by the platform. All of these components receive uploads from the ASP.NET or IIS API, which imposes the aforementioned performance limitations.
The secret behind ScaleUP is its use of the IIS 7.0’s native extensibility layer to completely replace the platform’s upload handling with its own high-performance preload engine. This allows it to eliminate the pre-existing upload limitations, while allowing any existing IIS-compatible application to handle web uploads with virtually no application changes.
At the heart of ScaleUP’s upload engine is fully asynchronous request preload, which eliminates thread starvation and enables us to fully take advantage of multi-core power provided by today’s servers.
The entire engine is fully asynchronous from reading network data, to parsing multipart/form-data uploads, streaming entity filters, and disk storage. Internally, we use advanced Windows performance technologies like async unbuffered IO, advanced cache management and pretty much every IIS 7.0 trick in the book to significantly boost upload throughput, and reduce resource usage on the server.
This architecture allows us to handle hundreds of uploads without using more than a few threads, and completely isolate the impact of large, slow, or many uploads from the application. The result is a lot faster and more reliable uploads, and a lot less application impact.
In addition to performance, ScaleUP is designed to be flexible and facilitate many common upload processing scenarios including progress reporting, streaming, filtering, and so on.
We are currently making ScaleUP commercially available to a limited number of customers, to make sure we can work closely with them in deploying ScaleUP and observe its impact. To learn more, see more performance results, and evaluate it for your application, check out http://www.leanserver.com/scaleup.
This marks the first public release of one of our performance tools, and we are going to be making more publicly accessible shortly. If you are interested in learning what betas we have going on now – or have a tough scalability problem you’d like solved – let us know on http://www.leanserver.com/.
 Streaming and filtering currently available only in .NET.
 Simulated load test involving 3Mb, 50Mb, 200Mb, and 1Gb uploads and application requests, performed on a DELL PowerEdge T300 with 16Gb of RAM and 2Gbit dedicated test network.
 Simulated load test involving 3Mb uploads and application requests, performed on a DELL PowerEdge T300 with 16Gb of RAM and 2Gbit dedicated test network.