SiMPLE

SIMPLE is the name for the gcs platform technology which founds the basis for its Web caching and acceleration applications. SIMPLE technology was built with portability and efficiency in mind and thus also enables integration in embedded solutions (like modems, routers, etc.). SIMPLE is a modular architecture to build solutions that exactly fit the needs of our customers. Based on a modular design principle, SiMPLE can be used to build solutions for many different usage scenarios, by combining and configuring a set of SiMPLE modules together with specialized application logic (if needed).

Key characteristics of the SiMPLE platform:

• Supports HTTP/1.1 and IPv6
• Available as dedicate appliances or software packages
• Runs on Windows (XP, Vista, Win7), Linux and misc. other POSIX-compatible operating systems
• Easy integration in devices from third-party vendors (modems, routers, etc.) through high portability and efficiency

HTTP Proxy

Provides the HTTP interface towards user clients.

HTTP Fetcher

It features an optimizing HTTP Transaction Engine for communication with upstream proxies and web servers. Its main features are:

• Efficient scheduling of connections and requests
• Protocol translation between user and server
• Utilization of server-features like persistent connections, pipelining and compression

Dynamic Cache

The cache module implements a scalable disk/memory buffer for storing all kinds of Web resources. It can handle cache sizes of up to 100 Gigabytes.

Static Cache

This module maintains a set of (immutable) Website snapshots which pre-loaded (e.g. on DVD) and/or distributed over the network via multicast with support for incremental or full updates. The Static Cache module is able to serve content requested by clients from matching archives. If content is not located in one of the archives, it will be provided by some other means, e.g. from the Dynamic Cache or the HTTP Fetcher.

Prefetcher

Long-delay links induce long page load times. The SIMPLE Prefetcher module on the server/backbone-side of the link analyzes the page structure and pro-actively transmits resources needed for rendering. This is called ÒprefetchingÓ. The sequence of these transmissions follows typical browser request patterns. The Prefetcher keeps track of objects already transmitted and suppresses re-transmissions, as these objects will likely already be contained in the client cache. Scheduled transmissions of objects are cancelled by a client-side version of the Prefetcher module, if the objects are already in the client cache, because of earlier requests or by some other means (via multicast). The client-side Prefetcher also delays requests from user clients until scheduled (prefetched) transmissions arrive at the client-side, to avoid unnecessary retransmissions.

YTP Transport

YTP is the communication protocol used for data transfers. It is based on UDP and optimized for long-delay links. It massively reduces the overhead compared to conventional HTTP/TCP based Web accesses. The YTP Transport module (consisting of a client- and a server-side version) handles all communication aspects related to SiMPLE client/server associations. It also copes with announcing and selecting available SiMPLE servers.