 | ISAPIZip Frequently Asked Questions |
| | | | | General
What is ISAPIZip?
How does ISAPIZip work?
Who benefits by using ISAPIZip?
How will ISAPIZip save me money?
Compatibility
What browsers/clients are support?
What content types are supported?
Do I, or my users, need any special hardware or special plugins?
Does ISAPIZip support scripted languages?
Does ISAPIZip handle both POST and GET requests?
Does ISAPIZip support Secure Socket Layers (SSL/HTTPS)?
Can I use ISAPIZip with my proxy server?
Does ISAPIZip support HTTP 1.0?
Does ISAPIZip support ColdFusion 4/5?
Does ISAPIZip cache files?
Does ISAPIZip work with other products from ISAPILabs?
Compression
Does ISAPIZip also decompress data?
Does ISAPIZip recompress every page upon request?
What are the best compression settings to use?
What is the average amount of compression that should be expected from ISAPIZip?
What type of compression does ISAPIZip use?
Can ISAPIZip be configured to handle compression per-page and/or per-site?
Can ISAPIZip compress my Adobe Reader PDF files?
Does ISAPIZip support white space compression?
Can I use ISAPIZip to resample images on my website?
How do I know if I'm getting any compression savings?
If IIS already provides compression, why should I buy an added compression program?
What if I get blank pages using Secure Socket Layer (SSL)?
Performance
How fast is ISAPIZip?
Does ISAPIZip slow down my server response time?
How much system resources are required?
Installation
Is ISAPIZip easy to install and uninstall?
I get an error activeds.dll when installing on Windows NT 4.0
Purchasing
How much does ISAPIZip cost?
Where can I purchase the full-version of ISAPIZip?
How much does it cost to upgrade ISAPIZip?
How do I know if I have the latest version of ISAPIZip?
Are there any discounts for educational or not-for-profit institutions?
What is ISAPIZip?
ISAPIZip is an Internet Server Application Programming Interface (ISAPI) filter for Internet Information Server (IIS) that compresses data requested from a web server. ISAPIZip effectively reduces the amount of bandwidth required to transfer data from a web server to an end user.
How does ISAPIZip work?
ISAPIZip takes advantage of the latest technology built into most modern web browsers and uses that technology to compress data that is requested from those who access your web server. When the user's browser requests data from an IIS server running ISAPIZip, it will indicate to ISAPIZip if it supports compression. If that browser supports compression, ISAPIZip will compress the data and send it to the end user. If the browser does not support compression, then the IIS server will send data in its original (uncompressed) form.
Who benefits by using ISAPIZip?
Anyone who manages an IIS HTTP server will benefit because ISAPIZip reduces the amount of bandwidth required to transfer data. Servers that use less bandwidth cost less money to operate. Users who access your web server will also benefit from ISAPIZip because data will be sent and displayed to them much faster.
How will ISAPIZip save me money?
The more bandwidth you use, the more money you pay. ISAPIZip reduces the amount of bandwidth being used on your IIS HTTP server, which helps you reduce the amount of money you spend on bandwidth.
What browsers/clients are supported?
All modern browsers (such as Internet Explorer, Netscape, Mozilla, and Opera) are supported. If a user whose browser does not support compression tries to access your website, ISAPIZip will not compress the data. This allows compatibility with browsers that do not support content encoding.
What content types are supported?
ISAPIZip supports all content types and it can also be configured to meet your needs. In general, compression is best on text files, such as HTML pages, TXT files, etc.
Do I, or my users, need any special hardware or special plugins?
No special hardware or plugins are required by either you or the people who view your website in order for ISAPIZip to operate. ISAPIZip takes advantage of existing technology built into all modern web browsers.
Does ISAPIZip support scripted languages?
ISAPIZip supports all scripted languages, including PHP, ASP, ASP.NET, CGI, Perl, ColdFusion, Javascript/JSP, and VBScript.
Does ISAPIZip handle both POST and GET requests?
ISAPIZip supports POST, GET, and almost all other requests.
Does ISAPIZip support Secure Socket Layers (SSL/HTTPS)?
ISAPIZip supports Secure Socket Layers, which also reduces the amount of data that has to be sent. Reducing the amount of data improves overall performance when running an IIS with ISAPIZip installed.
Can I use ISAPIZip with my proxy server?
ISAPIZip provides an option that supports proxy servers. This option can be activated using the ISAPIZip configuration tool. However, it is normally deactivated because some caching servers do not handle compressed content properly.
Does ISAPIZip support HTTP 1.0?
ISAPIZip supports HTTP 1.0. By default, this option is disabled due to the fact that content encoding was not introduced until HTTP 1.1. This feature can be enabled through the ISAPIZip configuration tool if needed.
Does ISAPIZip support ColdFusion 4/5?
According to Macromedia, ColdFusion versions 5 and eariler have problems when using HTTP compression with IIS. This occurs because ColdFusion sends out a second set of headers which is not caught by the user's browser and therefore ends up getting displayed to the user in their browser. ISAPIZip has a special mode that was specifically designed to handle this problem produced by ColdFusion. You can fix this problem by creating a URL filter for the CFM file extension, that supports the "dangling headers" option. This will catch the second set of headers that ColdFusion produces and should also fix any problems with produced by ColdFusion when used in conjection with URLScan as stated by Macromedia.
Does ISAPIZip cache files?
ISAPIZip does not cache files because many web pages feature dynamic content. Since dynamic web pages change constantly, they are unsuitable to be cached. In some instances, caching can actually reduce the server response time of dynamic pages, such as those created with ASP, PHP, and Perl. ISAPIZip does not have any internal caching, but it can work with any third-party caching software.
Does ISAPIZip work with other products from ISAPILabs?
Yes, all products from ISAPILabs are compatible and work harmoniously with each other to provide you with a reliable solution to all your ISAPI needs.
Does ISAPIZip also decompress data?
ISAPIZip only compresses data sent from your server. The end user's browser decompresses the data from the server. If a user whose browser does not support compression requests information from your server, the data will not be compressed.
Does ISAPIZip recompress every page upon request?
ISAPIZip does not recompress every page on the web server-only the pages requested by the user viewing your website. ISAPIZip only recompresses pages that are requested at the time that they are requested.
What are the best compression settings to use?
All compression settings are configurable in ISAPIZip. The configuration tool has several default configurations to allow you to customize your plugin to support your specific needs. If one of the default settings does not support your needs, you can configure ISAPIZip manually or from each page in your website.
What is the average amount of compression that should be expected from ISAPIZip?
Typically, 70% compression should be expected for most web pages. In some instances, depending on the file, compression can be anywhere from 80-90% of the original.
What type of compression does ISAPIZip use?
ISAPIZip uses Gzip and deflate compression encoding algorithms to compress data sent from your server.
Can ISAPIZip be configured to handle compression per page and/or per site?
ISAPIZip can be configured to handle compression on a per-page basis. It also features support for PHP and ASP headers that would turn off compression for a particular page. You can also configure ISAPIZip to handle compressed data through several parameters, including file name, extension, path, URL, etc.
Can ISAPIZip compress my Adobe Reader PDF files?
Yes, ISAPIZip can compress PDF files. However, the compression savings on Adobe PDF files is minimal.
Does ISAPIZip support white space compression?
In order to help ensure that your site looks the same for your users as it does for you, ISAPIZip does not support white space compression. In some instances, white space compression can actually alter the appearance of your site while not providing any significant reduction in download time.
Can I use ISAPIZip to resample images on my site?
ISAPIZip does not resample images on any website, which helps to deliver the site consistently to end-users looking exactly how you created it.
How do I know if I'm getting any compression savings?
There are two different ways you can go about finding out exactly how well ISAPIZip is compressing data on your site. The easiest way is to make sure logging is turned on, then view the log files; they contain the name of the file compressed, the original size followed by the compressed size. Another way would be to turn on realtime scriptable statistics, and place special scripting instructions on the bottom of each page to indicate how well the page was compressed. Keep in mind that you can script these to appear in HTML comments, so normal users of your site won't see the values.
If IIS already provides compression, why should I buy another compression program?
The compression ability provided by IIS is inadequate to suit the needs for most of today s web servers. The ISAPIZip plugin is faster, more stable, and it offers a higher rate of compression. And because ISAPIZip is completely configurable, you can adapt its many features to help meet the needs of any applications.
What if I get blank pages using Secure Socket Layer (SSL)?
When you get blank pages using SSL this means that the SSL filter priority is not set correctly. In order for the SSL filter (sspifilt.dll) to work properly in conjunction with ISAPIZip, the SSL filter must have priority over (it must be above) the ISAPIZip filter in the IIS filter list. ISAPIZip will automatically set this up for you when you use the Add to Webserver button in the QuickStart tab. For more information on how to setup an SSL server visit the support area.
How fast is ISAPIZip?
ISAPIZip compresses data on demand. In many cases, it takes less than a millisecond to compress data, and much less time to deliver that data to the requesting user. ISAPIZip can typically compress data to around 70% of its original size depending on the type of data being requested.
Does ISAPIZip slow down my server response time?
Initially, ISAPIZip requires overhead time to compress data. In most cases, this time is less than a millisecond. Keep in mind that the time it takes to send the data once it is compressed is dramatically reduced. The reduced sending time offsets the initial data compression time, which actually reduces the total amount of time it would take a web page to load without compression enabled.
How much system resources are required to run ISAPIZip?
ISAPIZip requires very little system resources during compression. At peak performance, about 1MB of RAM is all ISAPIZip needs to run because it was designed to run under the tightest system and memory constraints. Typical performance requires approximately 1MB of RAM, although having more users logged on and requesting data simultaneously can increase the amount of system resources required.
Is ISAPIZip easy to install and uninstall?
ISAPIZip is very easy to install and uninstall. To install ISAPIZip, simply double-click on the setup file and follow the setup routine. To uninstall ISAPIZip, select the Uninstall icon in the ISAPIZip Program Group in your Start menu.
I get an error activeds.dll when installing on Windows NT 4.0
If you get an error "This application has failed to start because ACTIVEDS.dll was not found. Re-installing the application may fix this problem," this is because you do not have Active Directory Services or Windows Script Host installed on your machine. Click on the links below to download the required software from Microsoft.
Download Windows Script Host 5.6 for Windows NT 4.0
Download Active Directory Service Interfaces (ADSI) for Windows NT 4.0
How much does ISAPIZip cost?
To find out how much ISAPIZip costs check out the price listing at http://www.isapilabs.com/.
Where can I purchase the full-version of ISAPIZip?
To purchase the full version of ISAPIZip, goto http://www.isapilabs.com/.
How much does it cost to upgrade ISAPIZip?
You may find the prices for all ISAPILabs products at http://www.isapilabs.com/.
How do I know if I have the latest version of ISAPIZip?
You can identify the version of ISAPIZip installed on your server through the ISAPIZip configuration tool.
Are there any discounts for educational or not-for-profit institutions?
Accredited organizations can receive ISAPIZip at discounted rates. For more information, please contact us.
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