Products and Services - Image Server

Image Server: Turbo-charging Your Web Pages

What is the Image Server? The Image Server is an image accelerator designed with one clear purpose. Deliver content negotiated images faster than traditional multipurpose web servers and do so with little or no cpu overhead. With the Image Server, existing web servers can deliver pages faster then ever before while still keeping the existing investment of computer hardware and web software. To hosting companies, the Image Server will increase the performance for your customers, conserve existing hardware resources, and increase profit to your bottom line.

Why do I need to use the Image Server? For most traditional web sites, images can make up 90% of the system overhead of fetching most pages. This results in an explosion of requests to any web server as it attempts to satisfy these requests. For example, if a page contained 10 unique graphics, then a single individual could request 10 simultaneous connections to deliver these graphics. Many current server implementations have attempted to solve this problem with pre-forking or threaded servers. The Image Server is a non-blocking image scheduling cop for any modern UNIX Kernel. There is no need to run extra copies to gain the same performance advantage to maximize socket throughput.

Why is an image accelerator faster than traditional web servers? Traditional web servers such as Apache 1.1.1 are full functional servers. Some are very fast and full featured like Apache and others are a little slower offering more exotic features. The Image Server pales in comparison to the features of these other servers. This lack of features however is what creates the speed advantage as it only has to deliver images and this is a very accelerated code path. It does have many advanced features not currently available from existing servers but these are simple and optimized for returning graphics only. For example, image throttling allows a webmaster to set performance quotas on images.

Who would be a good candidate for the Image Server? The performance gain is very similar to the fastest web servers such as Apache 1.1.1 but the conservation of resources can offer compelling reason to use an image accelerator if you want to conserve system resources. For example, high level language web servers written in Perl, Java, TCL, and Python can now deliver impressive performance while using their native strengths to generate incredible dynamic pages. Smaller web sites running on meager hardware or bandwidth can offload their images to image accelerators at hosting facilities for an increase in web page delivery without penalty to resources.

Are there security issues relating to this server? The Image server is inherently more secure than traditional web servers as it only handles the HTTP commands of GET and HEAD. In additional, it will not serve up any HTML pages or execute any CGI scripts. It can't as it only knows how to deliver JPEG and GIF images.

How stable is this server in a production environment? This is another advantage to having a small server with very specific features. With less then 1000 lines of C code, finding problems is much easier than with general purpose full featured web servers. Exhaustive performance testing and quality assurance testing has shown no current issues. Our testing includes checks for memory leaks, stability, torture testings, and performance checks specifically for users on low bandwidth links or requests coming in from congested networks. Anyone who has maintained a web server will appreciate how this server responds under these extreme conditions. We have used it at Aesir extensively in support of our Connections online travel resource.

Webstone 1.1+ Benchmark results Below, we show a comparison between the current fastest web server we have found to date which is Apache 1.1.1 and our Image Server. Testing was done with servers connected at 10Mb/s.
Apache 1.1.1
clients connections/sec Mb/s
16 59.60 3.08
32 65.53 3.53
48 62.98 3.33
Image Server 1.03
clients connections/sec Mb/s
16 65.83 3.43
32 64.83 3.44
48 65.34 3.58

Image Server Characteristics The current release of the Image Server has the following characteristics:

  • High performance. The server was designed with the highest performance in mind. There are no slave processes, forked processes, or threads. There is no start-up time waiting for a process to be created to handle an incoming connection and multiple incoming connections are handled in parallel. This is a true non-blocking server using existing kernel primitives to schedule the work. And yes, its performance is faster and more consistent than Apache 1.1.1 as measured by Webstone 1.1+ for all client sizing.

  • True Image Negotiation Virtual images are supported. This allows the web page designer to specify an image and allow the server to determine the best possible image for that browser. Simply specify the image without any extension and the Image Server will supply the correct image depending upon what image format is available for that name and whether the browser is capable of handling that image type.

  • Performance Throttling With this feature, it is possible to design a site where one customer or graphic hurts performance for other customers or graphics during bandwidth shortfall. For hosting companies, performance throttling allows control over customers that generate more traffic than others. The throttling only takes effect during a bandwidth shortfall, otherwise described as peak times. This allows you to use your current resources more economically.

  • Extended Logging Standard features of logging contain time, method, graphic file requested, bytes transferred, status, browser, referrer, and email address (if contained in the request) for every graphic transferred. In addition, extended logging such as new mime headers are reported as warnings and the IP address are reported for cases where hackers attempt to test the security of the server by using common practices such as stack overflows. The logging is available in both syslog and non-syslog styles. Both formats are identical. The non-syslog format only writes records during high water marks, thereby saving additional system resources which would be used should logging occur for every graphic retrieved. The logs can be restarted without requiring the server to exit.

  • Tiny Virtual Footprint The server uses less them 2MB of memory and requires only one instance to deliver full performance of a socket. Many Image Servers can be run on a machine on different ports or different IP addresses with little impact on system performance. Use additional servers when you need to use the full bandwidth of your connection. For example, 3 image servers are required to use the full 10Mb/s of ethernet.

  • Secure The Image Server is only capable of answering an HTTP GET or HEAD request. It can not return anything but graphics. It is not capable of executing any external programs such as CGI scripts. Assertion points are present to log the IP address of attempts at probing the security of the server. The server can run as root or non-root and in a chrooted environment if required. This level of security makes it a nice complement to web sites that wish to run normal operations behind a firewall and images outside.

  • Status The server has its own built in ping protocol which allows it to be tested for availability and latency of new connection. In addition, the current number of connections, and status of existing connections are available. Since connections are very light weight with this server, it is possible to build dynamic load balancing server farms using this feature.

Service Options The Image Server is available as two distinct options: a hosting service through Aesir and direct sales of the software product. High speed, high performance image hosting is available from Aesir Computing, Inc. with service via a dual-processor Sparc 20 on a 100Mb/s network connected to the MAE-East NAP. The Image Server is also available to those companies who wish to manage their hardware/software resources inhouse.
Contact Information For more information and specifics of the Image Server pricing plans, contact our office at:

Aesir Computing, Inc.
Telephone: (703) 406-4440
Email: sales@aesir.com

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