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httpZip Documentation

httpZip IIS Web server performance by transparently compressing Web pages. When installed on an IIS server, httpZip replaces the native HTTP compression mechanism that comes with IIS.

Installation

Installing httpZip is very simple. Once you have downloaded the installer executable from the Port80 Web site, double click on the file to begin the httpZip setup program.

The httpZip setup program will guide you through the steps necessary to complete the installation. You will be asked to accept the license agreement and to choose an installation destination. The default installation location is C:\Program Files\Port80\httpZip.

Note: During the installation process, you will also be given the option to install a copy of the CacheRight sample rules file in each Web site's Web root directory. Whether or not you make use of this option, a copy of the sample rules file is always installed in the CacheRight installation directory for later redistribution.

Files Installed by httpZip

httpZip installs the following files in the following default locations:

C:\%SystemRoot%\System32\inetsrv\

zip_isapi.dll httpZip ISAPI filter DLL

In C:\Program Files\Port80\httpZip\

zip_dialog.exe httpZip Settings Manager
w3svcupd.exe Installer utility for updating metabase
zip_com.dll httpZip COM object interface
Uninstall.exe Uninstaller
Unwise.exe Wise Uninstaller
Setacl.exe ACL Utility
Activation.txt Activation Message Text
Install.log Installation log file
documentation httpZip HTML Documentation
ReleaseHistory.htm httpZip Release History
TechSupport.htm Shortcut to online technical support

C:\Program Files\Port80\httpZip\files\

Supporting files for documentation, ReleaseHistory.htm, and TechSupport.htm

C:\Program Files\Port80\httpZip\reporting\

Master copy of HTML template for Web-based reporting

C:\Program Files\Port80\httpZip\reporting\images\

Supporting images for Web-based reporting template

C:\Program Files\Port80\httpZip\images\

Miscellaneous supporting image files

C:\Program Files\Port80\httpZip\logs\

Default directory for storage of Web-based reports and temporary log dumps
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Using the Settings Manager

The Settings Manager can be launched from the Port80/httpZip program group in the Start menu, or directly by running zip_dialog.exe. The Settings Manager controls the operation of httpZip for any Web site (virtual server) provisioned on the computer. On the left side of the Settings Manager is a list of all the Web Sites (virtual servers) that are available on the computer. Use this list to select the Web site whose settings you want to change.

  • To enable or disable httpZip for a given Web site: Select the site to enable (or disable) from the Web sites list and check (or uncheck) the Enable httpZip Compression checkbox located above the configuration settings tabs, on the right side of the interface.
  • To configure httpZip settings for a particular Web site: Select the site from the Web Sites list. The controls on the Settings Manager will reflect the current settings for that Web site. Any changes you make will take effect only for the site that is selected.
  • To configure httpZip's default settings for new Web sites: Select Default Settings from the Web Sites list. The controls on the Settings Manager will reflect the current default settings. Any changes you make will take effect for any new Web sites that are added in IIS.
  • To configure httpZip settings for two or more Web sites: Select the sites from the Web Sites list (optionally including Default Settings) using the Shift key (for two or more contiguous Web sites) or the Control key (for two or more discontinuous Web sites). In this case, the controls on the Settings Manager will reflect the current settings for the first Web site selected -- which will also be the one pointed to by the arrow indicator. Any changes you make will take effect for all the sites that are selected.
  • To replicate settings from one site to another: To propagate the settings of one site (or the Default Settings) to one or more additional sites, use the multiselect feature to select both (or all) of the sites, making sure that the first site selected is the one whose settings you wish to propagate (verify this by seeing that the arrow indicator is pointing to the source site). Without making any configuration changes, simply click Apply to propagate the settings to the target site(s).
  • To replicate settings from one server to another: To migrate all configuration settings (including Default Settings) from one server to another, use the File/Export Settings menu option on the source machine to save out a .zeg file (Port80 Registration file) to disk. Next, copy this file to the target machine(s) and then use the File/Import Settings menu option to read the file and import the settings. All existing settings on the target machine will be erased. The Settings Export/Import option assumes that all relevant metabase and file system settings on the target machine are an exact mirror of those on the source machine.

After making any changes on the httpZip Settings Manager, you must press either the "Apply" or the "OK" button in order for the changes to take effect. OK dismisses the Settings Manager dialog, Apply does not. Click "Cancel" (or use the File/Exit menu option) to abandon any changes and exit the Settings Manager.

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Default Compression Settings

By design, httpZip will never compress the output of a file unless the request for that file includes an explicit indication from the browser (or other HTTP client) that it is able to decompress a compressed response. This means that the standard HTTP Accept-Encoding header, along with a value indicating support for either gzip or deflate encoding (or both), must be present in the request for compression to happen. If this capability is not conveyed through the HTTP request, httpZip will not compress the content of the response.

In addition to the prerequisite of the Accept-Encoding header with a gzip or deflate value, httpZip's configuration settings control which files and files types are compressed, for which browsers, and at what level of compression. All of these settings can be altered in the Settings Manager. Detailed instructions on how to change the default compression settings can be found under the Configuration Options topic.

However, the default compression settings represent the results of considerable research on our part to determine the highest safe level of compression, consistent with a high average throughput, and reasonable CPU demands, under a wide range of conditions and in a wide variety of application environments. It is quite possible that you will find a more optimal mix of settings than the default ones, since the latter are designed for a balanced set of trade-offs in the most general case. This is why httpZip exposes as many of its configuration settings as possible. We do, however, recommend caution in making changes to the default settings and suggest that any changes be tested carefully in your environment to confirm the expected results.

Compression is configured and controlled primarily through a list of MIME Types. The default list of MIME Types is viewable under the Compression tab in the Settings Manager. This MIME Types list is the first determinant of which files will or will not get compressed.

Because many of the popular Web browsers in use today have well-known bugs in the way they handle some specific MIME types, there is a list of Browser Exceptions for each MIME type. Through these exceptions, only the specific browsers that mishandle compressed content of a particular MIME type need to be excluded (or, conversely, a MIME type that, when compressed, is mishandled by most browsers can still be compressed for those browsers that handle it correctly.) This allows compressed content to be served safely to the greatest possible number of browsers. For example, default settings include the disabling of compression for text/css and text/xml for Internet Explorer 5.x, which is required for reliable support of Outlook Web Access.

Some Web applications will require a specific file or directory of files to be excluded for all browsers. This can be configured through the Exclusions tab in the Settings Manager. By default httpZip excludes the compression of all files using the extensions .exe, .tar, .gzip and .rar. This is because these files are generally already tightly compressed and are not good candidates for additional gzip or deflate compression. Also, since files of this kind do not always generate reliable MIME types, it is more reliable to block them by extension rather than MIME type.

Finally, the size of an uncompressed file is also used to determine whether the response should be compressed. Exceedingly small or large files can be excluded from compression despite their MIME type or file extension. These limits are included because if a file is too small then it becomes unlikely to benefit from compression because of a lack of repetitive data. If a file is very large then the processing time could in principle exceed any improvement in transfer speed gained by sending a compressed file over a narrow bandwidth connection. These limits are set through the Response Size Limits section of the Exclusions (for compression, not caching) tab in the Settings Manager. The default values of 500 bytes as a minimum for compression and 1,000,000 bytes as a maximum for compression. You may be able to increase this maximum without any undesirable consequences, depending on your available CPU capacity.

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Configuration Options

The httpZip Settings Manager consists of a Web Sites list to select which sites to configure and a series of tabs where the configuration controls are located for various areas of httpZip functionality. These tabs are where httpZip is configured for each Web site. Changes made on a tab apply only to the highlighted Web sites. After making any changes on these tabs, you must press either the "Apply" or the "OK" button on the Settings Manager in order for the changes to take effect. The functional areas represented by the various tabs include:

Compression

These settings determine which types of files httpZip will and will not compress based on the MIME type of the response and the browser making the request. The main control on this tab is the MIME Type list, which is a tree of parent nodes representing top-level MIME types such as "text" and child nodes representing MIME sub-types such as "html." Compression is set to "On" or "Off" for each parent and child node.

MIME types (parent nodes) are overridden by settings for MIME sub-types (child nodes), if one of the latter is present. Thus, there are cases in which a top-level MIME type has compression disabled, while one or more of its MIME sub-types has compression enabled. The converse is also true -- a top-level MIME type can have compression disabled as a general rule, but enabled for one or more specific MIME sub-types.

The following are the operations that can be performed on the MIME type list using the controls on this dialog:

  1. To add a new top-level MIME type to the list, select the root-level "MIME types" node from the list and click the "New" button to launch the Add MIME type dialog. Enter the top-level MIME type in the text box and, if you wish to compress files having this MIME type, place a check in the box labeled "Compress".
  2. To add a new MIME sub-type to the list, select the appropriate top-level MIME type (whose child the sub-type will be) and click the "New" button to launch the Add MIME Type dialog. Enter the MIME sub-type in the text box labeled "MIME Type" and, if you wish to compress files matching this MIME type, place a check in the box labeled "Compress".
  3. To remove a top-level MIME type or sub-type from the list, simply select the appropriate node from the tree list and click the "Delete" button.
  4. To edit a MIME type name, highlight the entire row in the MIME Type list, and then click within that row, in the MIME Types column. A text box will appear, allowing the name to be edited.
  5. To edit a MIME type's compression status, highlight the entire row in the MIME Type list, then click within the row under the Compression column. A drop down list of values will appear. Select "On" or "Off" from the list.
  6. To restore the default compression settings for all MIME types (top-level and sub-types), simply click the "Restore Defaults" button.

Each MIME type in the MIME Types list includes an optional list of Browser Exceptions. This Browser Exceptions list is made up of two columns -- the Browser Names and the Search String values used to identify browsers that should not be served compressed content for the given MIME type. These Search Strings are sub-strings that are matched at request time against the value of the HTTP User-Agent header sent by the browser making the request (known as the "user agent string"). If the Search String occurs anywhere in the user agent string, the match is positive, and the compression setting for the MIME type is changed to its logical opposite for that request (i.e., "On" becomes "Off", and vice-versa).

The special "!" token, when it appears in a Search String, provides a way to exclude browsers whose user agent strings would otherwise positively match the Search String, but which are not the real target browsers (for example, the user agent string may contain "Mozilla" but the browser may in reality be something else). Everything to the left of the "!" token is the regular Search String; everything to the right of it is a negative-match string. In effect it means, "If the user-agent string contains the following sub-string, it is not a match."

  1. To add a new Browser Exception for a MIME type, select "New" and, in the Add Browser Exception dialog, enter a Browser Name for the browser in the text box labeled "Browser Name." Next, enter the search string text used to identify the browser in the text box labeled "Search String". You can also select from the list of previously added Browser Names and Search Strings, optionally editing either the Browser Name or the Search String, or both, before clicking OK.
  2. To remove a Browser Exception for a MIME type, simply select the Browser Name and click the "Remove" button.
  3. To edit a Browser Exception, simply click on the "Browser Name" or "Search String" text to enable editing of the text.
Exclusions

The "Exclusions" tab manages exclusions for compression and also for the compression cache in httpZip. You can specify one or more file names, file extensions or containing directories that should be excluded from compression, or compression caching. These exclusions will override any other settings in httpZip, with the exception of the In-Page Directives.

To add files to one of the Exclusion Lists, first select either the Compression Exclusions or Caching Exclusions radio button to pick a mode of exclusion to configure. Then, in the Exclusion text box, type the name of the file, or (to exclude all files of the same type) a wildcard plus the file extension (for instance "*.exe"), or (to exclude all the files in or below a certain directory) the full path to a directory followed by a wildcard ("F:/www/cart/*"). Finally, click the "Add" button to add the new exclusion to the list.

You can also use the Exclusion Builder to browse for a file or folder whose contents you would like to exclude from compression or caching. The Exclusion Builder will populate the Exclusion text field for you. You will still need to click "Add" to add the new exclusion to the list however.

To remove an exclusion from one of the Exclusion Lists, highlight the exclusion and click "Delete".

The "Response Size Limits" area contains only two controls for exclusions -- a pair of text boxes for setting the minimum and maximum file sizes to compress (in bytes). To change one of these settings, simply type the new value into the appropriate text box and click "OK." Note that streamed content (including chunked encoded content) will not be bound by the Maximum Response Size limit for compression.

The HTTP Exclusions section manages exclusions for both HTTP 1.0 user agents (browsers and proxies) and also HTTP 1.1 proxies. The default settings are generally safe, but you may have a need to exclude these requests from compression based on your particular browser/user base.

Caching

The "Caching" tab allows you to set httpZip's compressed content caching preferences. For a detailed description of httpZip's compressed content cache, see the topic Understanding the httpZip Cache.

To enable or disable caching, use the checkbox at the top of the Caching settings tab.

To have the cache use the HTTP Expires header (in addition to comparing the last-modified date/time of the file in the cache with that of the file in the Web site directory) to determine the freshness of cached compressed content, select the radio button labeled "expiration time and last modification" To instead have the cache rely solely on the comparison of last-modification times, select the radio button labeled "last modification time only."

To limit the size of the cache in memory, place a check in the box labeled "Limit cache size" and specify the maximum number of bytes in the text box labeled "Max Cache Size (bytes)."

Normally, streamed content, including chunked encoded data, is presumed to be dynamic and is not cached. However, caching of such content (which entails buffering it such that it is no longer streamed) can be forced by placing a check in the box labeled "Enable Caching of Streamed Files"

To change which file types are cached after being compressed, click the "Cached Files" button. This will launch the "Cacheable File Types" dialog. Files that have one of the file extensions in this list will be cached after being compressed. Use the "Add", "Remove", and "Edit" buttons to modify the list of cacheable file types.

The files in the cache for a specific Web site can be cleared by clicking the button labeled "Clear Cache Now."

httpZip can cache dynamic content based on a specified Cookie header value, or on unique query string information, or on a combination of the two. To cache dynamically generated pages based on a Cookie value, select the checkbox beside "Based on cookie value" and type the name of the cookie in the text box. This is the cookie whose value will indicate a unique copy of the page should be cached. To cache a dynamically generated page based on unique query string data, select the checkbox beside "Based on unique query stings". Any uniqueness in the query string will now create a unique cached copy of a given (cacheable) file.

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Optimization

The settings on the "Optimization" tab allow one to set the preferences for optional integrated HTML/CSS Code Optimization. For a detailed description of httpZip's integrated code optimization, see the topic Integrated Code Optimization.

To enable or disable Code Optimization, use the checkbox at the top of the Optimization settings.

There are three HTML code compression options (Remove White Space, Remove Comments and Lower Case Tags) and two CSS code compression options (Remove White Space and Remove Comments). You may enable all or none of these options, or enable and disable individual options selectively. To enable a Code Optimization option, place a check in the box labeled with the name of that option. To disable one, clear its check box.

Advanced

The Advanced tab on the Settings Manager includes configuration settings that affect how responses should be compressed.

The "Streamed Content" and "Chunked Transfer Encoded Content" areas allow for the configuration of how httpZip will apply compression to streamed responses, including chunked transfer encoded responses. In both cases, the responses can either be compressed transparently as a stream (which in most cases will result in a faster time-to-first-byte), or else buffered and then compressed (which normally results in tighter compression, but with a slower time-to-first-byte). Note: Disabling transparent compression of streams also disables transparent compression of chunked transfer encoded data, but the reverse is not true -- compression of chunked streams can be disabled (that is, buffering and dechunking of such data, prior to its being compressed, can be forced) without disabling compression of non-chunked streamed data.

The "Compression Levels" area allows compression level to be assigned for responses based on file extension. Assigning compression level based on a file's extension is helpful because it allows dynamic files to be compressed at a lower rate than static files of the same MIME type, thereby mitigating the overhead of compressing dynamic files while still achieving maximum compression for static files. Note: The higher the compression level, the greater the file size reduction, but also the more CPU cycles required to compress the content.

Clicking on the "File Extensions" button launches the "Compression Level Dialog". Three operations are possible here:

  1. To add a new file extension to the list, click the "Add" button to open the Add File Extension dialog. Type the file extension into the text box labeled "Extension" (it is not necessary to type the ".") and set the slider bar to the desired compression level. Click "OK" when finished.
  2. To remove a file extension from the list, highlight the extension by clicking on it in the list and click the "Remove" button. Click "OK" to accept the change.
  3. To change the compression level for a given file extension already in the list, click on the extension to highlight it and click the "Edit" button. On the Edit File Extension dialog, adjust the slider bar control to the desired compression level. Click "OK" when finished.

The "Deflate Option" allows you to direct httpZip to send only deflate content when both gzip and deflate are supported by the browser. Deflate is slightly more efficient than gzip but, historically speaking, not as widely or consistently supported. It can be a good choice when your browser audience is controlled and known to support deflate without difficulty.

Reporting

The configuration settings on the Reporting tab allow you to set httpZip's Web-based reporting preferences. For a detailed description of the reporting functionality, see the topic Using httpZip's Web-based Reporting.

To enable or disable Web-based reporting for a particular site, use the checkbox labeled "Enable httpZip Reports," located at the top of the Reporting settings tab.

To open the report for the currently-selected Web site in the default Web browser, click the "Go" button.

To specify the storage location for the hard copy of the report.htm file that is generated when the report page is requested, type a full path to the appropriate directory in the text box labeled "Location of the report snapshot."

To restrict which IP addresses are allowed to request the online report, click the "IP List" button. This will pop-up a list control that allows you to specify the IP addresses that are authorized to view the httpZip Web-based report page. All other IP addresses will receive a 404 error message.

To specify the length of time for which report data should be accumulated, choose an interval from the drop-down list labeled "Refresh logs after." By default, the in-memory logs that supply the report data are recycled every month. There is no size penalty for using a longer logging period, it is simply a question of how long of a logging period you wish to see represented in the report.

To immediately clear all log data for the currently-selected site, click the "Clear Log" button.

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Integrated Code Optimization

httpZip provides integrated Code Optimization as an option for added compression. The code optimizer is a functionally separate utility that has been incorporated into httpZip. Linear white space and comments removal help to increase file size savings, by reducing HTML and/or CSS code by approximately 10% prior to gzip/deflate compression.

Please Note: Since the code optimizer is applied to outgoing responses, enabling it means that the server will need to do extra work prior to compressing the file. This can be costly in terms of page delivery times, especially for large files, or dynamic files that are not cached after being compressed. For this reason, it is recommended that highly dynamic sites use the optional In-page Directives to selectively invoke the code optimizer, rather than relying on the site-wide settings discussed here.

For a detailed description of the In-Page Directives, see the topic Using the In-page Directives.

The code optimizer has five optional features which you may enable or disable as you wish. The optional features are:

  • Remove HTML white space
  • Remove HTML comments
  • Lower-case HTML tags
  • Remove CSS white space
  • Remove CSS comments

Although the code optimizer has been extensively tested, please verify as part of your standard QA process that the white space reduced page renders correctly. There should be no visible difference between it and the pre-reduced page.

The code optimizer does not overwrite existing HTML or CSS code. If for any reason you do not want to keep the changes made by the white space remover, just disable the remover and clear your compressed content cache.

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Understanding the httpZip Cache

httpZip uses compressed-content caching for enhanced performance. For instructions on how to enable and disable httpZip caching, and how to configure the various options mentioned below, see "Caching" in the topic Configuration Options.

Unlike compression itself, which is based on MIME type, the caching of compressed content is controlled by file extension. The "Cached Files" list in the Caching tab of the httpZip Settings manager contains a list of these file extensions. A file's extension must be present in this list for that file's compressed version to be cached by httpZip.

By default, httpZip's rules for the caching of compressed content are very conservative. Only files having the extensions .css, .htm, .html, .js, .txt and .xml are eligible for compressed content caching by default. By design, the default list does not contain any extensions normally associated with dynamic pages (such as .asp or .aspx), which often contain user-specific content (e.g., shopping carts or other user-configured content). Such extensions may be added to the cached files list, providing there is no danger of user-specific content being cached and served to the wrong users.

Alternatively, if only a small subset of files of a given type should not be cached, you can use the In-page Directives to override the normal caching behavior for those specific files. See the topic Using the In-page Directives.

If caching is enabled for a particular file type, httpZip will store a copy of the compressed page. In the future, httpZip will check if the page has been updated. If it has not been, the page will be read from the server's cache instead of being re-compressed.

Note: In deciding whether to use its cached compressed copy, httpZip first checks the modification date of the original file. This will not have changed in the case of a dynamic page whose content changes based on an included file or database query. By default, pages that are cacheable by httpZip also make use of the HTTP Expires header, in addition to the file's last-modification time. Provided that the Expires header is set to the true expiration time of the content produced by the file, the cached copy of the page will expire when the data is no longer fresh, even if the file itself has not been updated on disk.

By enabling the "dynamic caching" feature, it is possible to use caching in the case of dynamic pages that output different content depending on query-string parameters and/or cookie values. With this feature enabled, the unique query string, or unique value of a specified cookie, or both, will be cached along with the name of the compressed file. Thus, multiple versions of the page can be cached, and the correct one can be served, based on the request identifiers contained in the query parameters and/or cookie values. For example, suppose you have a page productdetails.asp that shows different content depending on a product ID that is passed to it as a query parameter and a region identifier passed in a cookie. With dynamic caching, multiple compressed versions of this page can be cached--one for each unique product/region combination.

The compressed content cache used by httpZip is an in-memory cache, so there is no storage of the cached files on disk and no disk access is required in order to read those files. The cache is cleared whenever the Web service is restarted. In addition, httpZip also offers the option of restricting the amount of system memory consumed by the compressed content cache. This option may be enabled to specify how large the compressed content cache should be allowed to grow. Once the memory cache reaches that size, httpZip stops adding files to the cache, until space is created by the requesting of cached file that has reached its expiration time, or that has been modified on disk since it was cached. It is also possible to manually clear the cache of all its contents at any time, by using the "Clear Cache" button in the Caching tab of the httpZip Settings Manager.

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Using httpZip's Web-based Reporting

httpZip includes a comprehensive Web-based reporting mechanism for tracking the amount of bandwidth savings achieved through compression, on both a per-page and a site-wide basis. The reporting mechanism makes use of httpZip logs which are stored in memory. The report itself consists of an HTML page called report.htm that is created (or recreated) whenever a user makes a request for a URL of the form:

http://[hostname]/httpzipreport/report.htm

When report.htm is requested (and httpZip is running with reporting enabled) the data in the log is used to populate the data fields in the report page. The report page includes both site-wide compression data, as well as page-specific data for each page that has been compressed since the log was last recycled. To see an updated version of the report, you need only to refresh the report page in the browser.

The Reporting tab of the Settings Manager provides a number of configuration options for the logging and reporting mechanisms. For detailed instructions on how to set these logging and reporting options, see "Reporting" in the topic Configuration Options.

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Using httpZip's In-Page Directives

httpZip provides in-page directives to enable programmatic control over basic compression and cache settings. These directives allow any server-side scripting environment to override the configuration settings in the settings manager. This can be useful for treating dynamic pages differently than static pages, or for singling out particular dynamic files for special treatment, depending on their content or their role in an application.

There are two ways to use the in-page directives: You can inject HTTP headers into the HTTP response using whatever mechanism your server-side scripting environment provides for doing this. Alternatively, you can use httpZip's COM interface (if your environment supports COM), which encapsulates the process of injecting the headers.

To use the COM object interface in your server-side script, create an object named port80.httpzip. In ASP, for instance, the code will look like this:

Set comp= Server.CreateObject("port80.httpzip") Once the httpZip COM object is instantiated, invoke its compress method to have httpZip compress the file:

Comp.compress "compression_setting"

The compress method takes a single parameter -- a text string indicating the compression setting httpZip should use for the file in which the object is created. This string (compression_setting in the example) must be one of the following string constants:

  • "WHITESPACE-ONLY"
    This setting will cause the integrated code optimizer to be invoked on the file. The file will not be compressed, but it will have linear white space and comments removed, and tags lowercased.
  • "GZIP-ONLY" [Deprecated]
    This setting will cause the file to be compressed, but it will not invoke the code optimizer.
  • "FULL" [Deprecated]
    This setting will both invoke the code optimizer and compress the file.
  • "NONE"
    This setting will ensure that httpZip does nothing to the file; it will neither optimize the code nor compress the file. This setting is useful for overriding configuration settings that would otherwise have caused the file to be compressed and/or optimized.
  • "OVR-COMP-ONLY"
    This setting will override any compression restrictions and compress the file.
  • "OVR-FULL"
    This setting will override any compression and optimization restrictions and compress and optimize the file.
  • "OVR-COMP-ONLY-CACHE"
    This setting will override any compression and caching restrictions and both compress and cache the file.
  • "OVR-FULL-CACHE"
    This setting will override any compression, optimization and caching restrictions and will compress, optimize and cache the file.
  • "DEF-CACHE"
    This setting will override any caching restrictions and cache the file (if compressed).
  • "DEFLATE-ONLY"
    This setting will cause the file to be compressed using the deflate method.

To use the in-page directives without relying on the COM object, inject the HTTP headers directly into the response. In classic ASP, you would do this as follows:

Response.AddHeader "httpZip", "header-value"

where "header-value" is the appropriate in-page directive. Most of the directives have the same, or very similar syntax in the raw HTTP header format as they do in the COM parameter format. Here is the complete list, given in the same order as the COM parameters above:

  • "white-space-only"
  • "gzip-only"
  • "full-compression"
  • "no-compression"
  • "ovr-cmp"
  • "ovr-full"
  • "ovr-cmp-cache"
  • "ovr-full-cache"
  • "def-cache"
  • "deflate-only"

Note: The user whose security context IIS uses when accessing the file that instantiates the httpZip COM object must have read and execute permissions on the httpZip COM DLL (zip_com.dll). These permissions are granted to the Web Anonymous User at installation time. If you have receive "access denied" errors when trying to request the page that instantiates the httpZip COM object, make sure that the user whose security context is being used by IIS to request the file has these permissions.

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System Requirements

httpZip is compatible with the following:

  • IIS 4.0 (NT 4.0 Server)
  • IIS 5.0 (Windows 2000 Server)
  • IIS 5.1 (Windows XP)*
  • IIS 6.0 (Windows Server 2003)

* The Windows XP configuration is not recommended for use in production environments.

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Port80 Software Technical Support

support@port80software.com
www.port80software.com/support
888.4PORT80 (888.476.7880) toll free
858.268.7960 phone
858.268.7760 fax

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Port80 Software stands behind our products 100%. Given the nature of Web server utilities, various environments and third party applications may cause new and unforeseen conflicts. Therefore, Port80 pledges to work with you to ensure our products run in all testing and production environments - if you work with us, we will work with you to make your IIS Web server safer, faster and friendlier.