What is Application Delivery?
Application delivery is a new take on content delivery. As, content delivery is limited to ensuring application static content is optimized, application delivery uses a stack of technologies to ensure that applications are available, scalable and robust.
What is an Application Delivery Network?
Application delivery networks comprise a set of technologies that aim to maximize application availability, acceleration, security and visibility. They are a holistic and broad based approach to content delivery, and performance optimization for remote applications.
Application Delivery Network vs CDN
Application delivery networks were born out of the need for a more robust and broad based content delivery solution. CDNs were perfect for the static webpages of the early internet. Newer trends, such as SaaS, remote application hosting and increasing personalization of webpages, have forced CDNs to come up with alternative solutions to the problem of dynamic content delivery.
The concept behind a CDN is quite simple. They work by caching frequently accessed content at geographically distributed edge locations. Whenever a client browser requests that content it is served from the nearest edge location. This results in significant performance improvements for static websites. However, for remote applications that are accessed over the public internet, merely caching content at edge locations doesn’t yield the same performance improvements.
Remote applications are dynamic, and require the delivery of real time data, analytics and user preferences from the application server to clients. The data and analytics are different for every client, and every request is fetched from the origin server. They also require an intelligent traffic monitoring and management solution to distribute network traffic over multiple application servers. Application Delivery networks combine both elements to provide a holistic dynamic content delivery and performance optimization solution.
Components of an Application Delivery Network
Delivery networks can be broken down into two components: Application Delivery Controller and WAN Optimization Controller.
Application Delivery Controller
The Application Delivery Controller is an advanced load balancing apparatus that sits in data center facilities in front of application servers. It serves to distribute web traffic over multiple distributed application servers, so that no one server is overwhelmed by requests. Application delivery controllers also perform other functions such as caching, compression, traffic shaping and SSL offload.
WAN Optimization Controller
WAN Optimization Controllers (WOCs) are typically located at both the data center facilities and the client device. WOCs use a variety of techniques including compression, caching, de-duplication, protocol spoofing and latency optimization to improve application performance.
Both components of delivery networks work together to improve application performance including speed, availability and scalability. Below we take a closer look at some of these techniques.
Application networks use compression technologies to speed up data transfer and improve the end user experience. One frequently used compression technique is HTTP compression. It can be integrated into both application servers and clients and optimizes data transfer and bandwidth usage.
Load balancers are also an important component. They sit in front of application servers and distribute traffic using different indicators. These factors include health checks and availability. Load balancers prevent request delays and server downtime.
Another crucial component of delivery networks is failover. Application resources are mirrored across multiple servers. Continuous health checks monitor these servers and in the event that a server goes down, requests are automatically re-routed to another server.
Security is an overriding concern for today’s applications. Delivery networks use techniques like IP filtering, delayed binding, application firewalls and SSL encryption to ensure application security.
Download the Anycast Whitepaper to learn more about Anycast load balancing and failover.