# Tomcat IIS HowTo

By Gal Shachor `<shachor@il.ibm.com>`

This document explains how to set up IIS to cooperate with Tomcat. Normally IIS can not execute Servlets and Java Server Pages (JSPs), configuring IIS to use the Tomcat redirector plugin will let IIS send servlet and JSP requests to Tomcat (and this way, serve them to clients).

## Document Conventions and Assumptions

<tomcat_home> is the root directory of tomcat. Your Tomcat installation should have the following subdirectories:

1. <tomcat_home>\conf - Where you can place various configuration files
2. <tomcat_home>\webapps - Containing example applications
3. <tomcat_home>\bin - Where you may place web server plugins

In all the examples in this document <tomcat_home> will be c:\jakarta-tomcat.

A `worker` is defined to be a tomcat process that accepts work from the IIS server.

## Supported Configuration

The IIS-Tomcat redirector was developed and tested on:

1. Win2k SP2, WinNT4.0-i386 SP4/SP5/SP6a, and Win98
2. IIS 5.0, PWS 5.0, IIS4.0 and PWS4.0
3. Tomcat3.0 - Tomcat3.3

Note: Due to some feature additions, the IIS-Tomcat redirector from earlier Tomcat's can't be used with Tomcat 3.3. Only use the IIS-Tomcat redirector from Tomcat 3.3, or newer versions from the jakarta-tomcat-connectors Jakarta project.

The redirector uses ajp13 or ajp12 to send requests to the Tomcat containers. There is also an option to use Tomcat in process, more about the in-process mode can be found in the in process howto.

## Installation

As of Tomcat 3.2, a pre-built version of the Tomcat redirector plugin, `isapi_redirect.dll`, is available under the win32/i386 directory where you downloaded the Tomcat binary distribution. For those using Netscape as your browser, try downloading a zip version of the file, if available. There can be problems using Netscape to download DLL files.

You can also build a copy locally from the source in Tomcat's source distribution.

The Tomcat redirector requires three entities:

1. isapi_redirect.dll - The Tomcat redirector plugin, either obtain a pre-built DLL or build it yourself (see the build section).
2. workers.properties - A file that describes the host(s) and port(s) used by the workers (Tomcat processes). A sample `workers.properties` can be found under the `conf/jk` directory.
3. uriworkermap.properties - A file that maps URL-Path patterns to workers. A sample `uriworkermap.properties` can be found under the `conf/jk` directory as well. Also, this is one of the files generated by the IISConfig module included by default in the `server.xml` file. The `uriworkermap.properties` file it generates is written to the `conf/auto` directory.

The installation includes the following parts:

1. Start Tomcat 3.3 with the "jkconf" specified so configuration files are written.
2. Configure the Tomcat redirector plugin with the configuration files and check that you can serve servlets and JSPs with IIS.
3. Repeat the appropriate portions of the previous steps when changes to configuration or contexts occur.

### Creating the Configuration Files

The default installation of Tomcat 3.3 includes the IISConfig module in the `server.xml` file. This module is responsible for writting the configuration files used for Tomcat redirector plugin installation and operation.

In Tomcat 3.3, configuration files are written on demand. You must start Tomcat 3.3 with the "jkconf" option specified. Tomcat 3.3 will initialize, write the configuration files, and then exit. This may be done, while an instance of Tomcat 3.3 is running. This differs from prior versions of Tomcat where the configuration files are written each time Tomcat is started.

The IISConfig module in Tomcat 3.3 writes two configuration files. The first is the registry configuration file, which by default will be `conf/auto/iis_redirect.reg`. The second is the worker map configuration file, which by default will be `conf/auto/uriworkermap.properties`.

The IISConfig module in Tomcat 3.3.1 writes a third configuration file. This file contains the same settings as the registry configuration file and provides an alternate means of configuring the Tomcat redirector plugin without relying on the registry. It defaults to writing `conf/auto/isapi_redirect.properties`.

To use the "properties" file instead of registry settings, the "properties" file must have the same name as the redirector plugin DLL, except with a ".properties" extension. It must also be located in the same directory as the DLL. If both the "properties" file and registry settings exist, the "properties" file will be used.

### Configuring the ISAPI Tomcat Redirector

The following steps show how to configure the Tomcat redirector plugin.

1. Build or download the Tomcat redirector plugin DLL, `isapi_redirect.dll`, and place it in a suitable location. A typical location is `TOMCAT_HOME\bin\native`. If you are installing on WinNT or Win2k, make sure IIS runs with a user that can access this directory.
2. Use either of the following two methods to provide configuration settings to the redirector plugin DLL.
   1. Copy the `IISConfig` generated "proprties" file, `isapi_redirect.properties`, or a manually created one, to the directory where the redirector plugin DLL is found. Rename this file to have the same base name as the redirector plugin DLL should they happen to be different.
   2. Enter the registry settings from the registry configuration file into the registry. This can be done from Windows Explorer by double-clicking the file or by right-clicking the file and selecting `Open` or `Merge`.
   Note: If both are done, the "properties" file takes priority.
3. Using the IIS management console, add a new virtual directory to your IIS/PWS web site. The name of the virtual directory must be jakarta. Its physical path should be the directory where you placed the redirector plugin DLL, `isapi_redirect.dll` (for example c:\jakarta-tomcat\bin\native). While creating this new virtual directory, assign it with execute access.
4. Add the redirector plugin DLL, `isapi_redirect.dll`, as a filter to your IIS/PWS web site. The name of the filter should reflect its task (for example, "Jakarta Redirector"). Its executable must be the redirector plugin DLL, `isapi_redirect.dll`.
   On WinNT and Win2k, you can use the IIS Management console to add the filter.
   For PWS on Win98, you'll need to use regedit and add/edit the "Filter DLLs" key under `HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\W3SVC\Parameters.` This key contains a comma separated list of dlls ( full paths ). You need to add the full path to redirector plugin DLL, isapi_redirect.dll, to this key.
5. Restart IIS/PWS (stop + start the IIS service). If you are using WinNT or Win2k, you can make sure that the jakarta filter is successfully loaded by checking for a green up-pointing arrow.
   On Win98, to properly stop and restart PWS, you should open an MS-DOS window, navigate to the `WINDOWS\SYSTEM\inetsrv` directory and execute `PWS /stop`. Then execute `PWS` to start it again.

That's all, you should now start Tomcat and ask IIS to serve you the /examples context. Try http://localhost/examples/jsp/index.html for example and execute some of the JSP examples. If this does not work successfully, refer to the Troubleshooting section below for help on correcting the problem.

### Adding additional Contexts

The examples context is useful for verifying your installation, but you will also need to add your own contexts. Adding a new context requires two operations:

1. Adding the context to Tomcat (This is covered in the Tomcat User's Guide).
2. Adding the context to the Tomcat redirector plugin.

Adding a context to the Tomcat redirector plugin is simple, all you need to do is to start Tomcat 3.3 with "jkconf" option specified again. After the worker map file is rewritten, restart IIS/PWS.

If you are using a manually modified URI to worker map file, edit the file to add a line that looks like:

`/context/*=worker_name`

Workers and their name are defined in workers.properties, by default workers.properties comes with 2 pre-configured workers named "ajp13" and "ajp12" so you can use it. As an example, if you want to add a context named "shop", the line that you should add to `uriworkermap.properties` will be:

`/shop/*=ajp13`

After saving `uriworkermap.properties` restart IIS/PWS and it will serve the new context.

### The Tomcat Redirector Plugin Configuration Settings

The following is an example isapi_redirect.properties file which contains the default settings for Tomcat 3.3.

    extension_uri=/jakarta/isapi_redirect.dll
    log_file=E:\Jakarta\Tc33x\jakarta-tomcat\dist\tomcat\logs\iis_redirect.log
    log_level=emerg
    worker_file=E:\Jakarta\Tc33x\jakarta-tomcat\dist\tomcat\conf\jk\workers.properties
    worker_mount_file=E:\Jakarta\Tc33x\jakarta-tomcat\dist\tomcat\conf\auto\uriworkermap.properties

The Tomcat redirector plugin for Tomcat 3.3.1 supporta an additional setting with the following default.

    uri_select=parsed

The following table describes the use of each of these settings:

Setting | Description | Default
--- | --- | ---
extension_uri | The URI used by the redirector plugin's filter to redirect the request to the extension. This setting consists of the name of the virtual directory followed by the name of the DLL. | /jakarta/isapi_redirect.dll
log_file | The path of the log file for the redirector plugin DLL | must be specified
log_level | The quantity of log output desired. Valid values are debug, info, error, and emerg. | emerg
worker_file | The path to the workers definition file, typically named `worker.properties` | must be specified
worker_mount_file | The path to the URI to worker map file, typically named `uriworkermap.properties`. | must be specified
uri_select [Tomcat 3.3.1] | This settings controls which of several forms of the URI is passed to Tomcat. The following are the valid values:
Value | Description
--- | ---
parsed | Internally, the redirector plugin normalizes and decodes the request URI before checking the request against the URI to worker mappings. This value passes this normalized/decoded version of the URI to Tomcat.
unparsed | Passes the original (i.e. unnormalized and undecoded) request URI to Tomcat.
escaped | Passes a re-encoded version normalized/decoded request URI to Tomcat.
Setting this value properly is important so that request data, such as HttpServletRequest.getRequestURI(), are returned with the proper encoding. Tomcat 3.3 and later requires the `parsed` setting. Tomcat 3.2.x can use either `unparsed` or `escaped`. For Tomcat 3.2.1 and earlier, `escaped` should be used since it does not do its own normalization. | parsed

## Building the Tomcat redirector

The Tomcat redirector was developed using Visual C++ Ver.6.0, so having this environment is a prerequisite if you want to perform a custom build.

The steps that you need to take are:

1. Change directory to the isapi redirector plugins source directory.
2. Execute the following command:
   `MSDEV isapi.dsp /MAKE ALL`
   If msdev is not in your path, enter the full path to msdev.exe

This will build both release and debug versions of the redirector plugin.

An alternative will be to open the isapi workspace file (isapi.dsw) in msdev and build it using the build menu.

## How does it work?

1. The IIS-Tomcat redirector is an IIS plugin (filter + extension), IIS loads the redirector plugin and calls its filter function for each in-coming request.
2. The filter then tests the request URL against a list of URI-paths held inside `uriworkermap.properties`, If the current request matches one of the entries in the list of URI-paths, the filter transfers the request to the extension.
3. The extension collects the request parameters and forwards them to the appropriate worker using the ajp1X protocol.
4. The extension collects the response from the worker and returns it to the browser.

## Advanced Context Configuration

Unlike prior versions, Tomcat 3.3 writes config files which default to sending all requests, including those for static pages, to Tomcat for processing. This gives the best chance for the web application configuration specified in the `web.xml` file to work successfully.

Also, unlike prior versions, the default worker map file does not try to add servlet or JSP operation to the IIS/PWS main virtual directory. To see how to control the manner in which Tomcat writes the worker map file see the reference information on the IISConfig module.

Sometimes it is better to have IIS serve the static pages (html, gif, jpeg etc.) even if these files are part of a context served by Tomcat. For example, consider the html and gif files in the examples context, there is no need to serve them from the Tomcat process, IIS will suffice.

Making IIS serve static files that are part of the Tomcat contexts requires the following:

1. Configuring IIS to know about the Tomcat contexts
2. Configuring the redirector to leave the static files for IIS

Adding a Tomcat context to IIS requires the addition of a new IIS virtual directory that covers the Tomcat context. For example adding a /example IIS virtual directory that covers the c:\jakarta-tomcat\webapps\examples directory.

Configuring the redirector is somewhat harder, you will need to specify the exact URL-Path pattern(s) that you want Tomcat to handle (usually only JSP files and servlets). This requires a change to the `uriworkermap.properties`. For the examples context it requires to replace the following line:

`/examples/*=ajp13`

with the following two lines:

`/examples/*.jsp=ajp13
/examples/servlet/*=ajp13`

As you can see the second configuration is more explicit, it actually instruct the redirector to redirect only requests to resources under `/examples/servlet/` and resources under `/examples/` whose name ends with `.jsp`. This is similar to what is automatically written to the `uriworkermap.properties-auto` file for each context.

You can even be more explicit and provide lines such as:

`/example/servletname=ajp13`

that instructs the redirector to redirect request whose URL-Path equals `/example/servletname` to the worker named ajp13.

### Protecting the WEB-INF Directory

Each servlet application (context) has a special directory named WEB-INF, this directory contains sensitive configurations data and Java classes and must be kept hidden from web users. Using the IIS management console it is possible to protect the WEB-INF directory from user access, this however requires the administrator to remember that. To avoid this need the redirector plugin automatically protects your WEB-INF directories by rejecting any request that contains WEB-INF in its URL-Path.

## Advanced Worker Configuration

Sometimes you want to serve different contexts with different Tomcat processes (for example to spread the load among different machines). To achieve such goal you will need to define several workers and assign each context with its own worker.

Defining workers is done in `workers.properties`, this file includes two types of entries:

1. An entry that lists all the workers defined. For example:
   `worker.list=ajp12, ajp13, ajp13second`
2. Entries that define the host and port associated with these workers. For example:
   `worker.ajp12.host=farhost
   worker.ajp12.port=8007
   worker.ajp13.host=localhost
   worker.ajp13.port=8009
   worker.ajp13second.host=otherhost
   worker.ajp13second.port=8009`

The above examples defined three workers, now we can use these workers to serve two different contexts each with its own worker. For example look at the following `uriworkermap.properties` fragment:

`/examples/*=ajp12
/webapp1/*=ajp13
/webapp2/*=ajp13second`

As you can see the examples context is served by ajp12 while the webapp1 context is served by ajp13, and the webapp2 context is served by the ajp13second worker.

## Troubleshooting

It is easy to have the Tomcat redirector not work the first time you try to install it. If this happens to you, here are some steps to follow to try to correct the problem. These steps aren't guaranteed to cover all possible problems, but they should help find the typical mistakes. If you make any corrections during these steps, restart the IIS service as described above in the last step of the installation, then retry the step.

Note: These steps assume your `worker_mount_file` setting points to an unmodified copy of the `conf/auto/uriworkermap.properties` file. Results may be misleading if `worker_mount_file` points to a modified version of the file. It is also assumed that the "/examples" context works correctly if you access Tomcat directly.

### Win98

1. Make sure web site activity is being logged. For PWS make sure "Save Web Site Activity Log" is checked in the Advanced Options of the Personal Web Manager.
2. Start the PWS service and Tomcat.
3. Check for the presence of the Tomcat redirector log file you specified in the `log_file` setting. If not found, check the following:
   1. Check the "Filter DLLs" setting in the "HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\W3SVC\Parameters" key and make sure the path is correct.
   2. Check the spelling of the "HKEY_LOCAL_MACHINE\SOFTWARE\Apache Software Foundation\Jakarta Isapi Redirector\1.0" key. Case isn't important, but an incorrect letter will prevent the isapi_redirect.dll from finding its registry settings.
   3. Check the `log_file` setting for typos, name and data. Also ensure the directory in which the log file will appear already exists.
   If the above are set correctly, the Tomcat redirector should be able to create the log file.
4. Invoke the URL "http://localhost/examples/jsp/index.html" in your browser. Case is important. The characters following "localhost" in the URL must be lower case. If the page fails to appear, stop the PWS service (required to view the PWS log file). Then examine the last line in the PWS log file in found in SYSTEM/LogFiles/W3SVC1.
   1. If the last line contains: `GET "/examples/jsp/index.html HTTP/1.1" 404`, then the Tomcat redirector is not recognizing that it should be handling requests for the "/examples" context. Check the following:
      1. Check the `extension_uri` name for typos.
      2. Check the `worker_file` setting for typos, name and data.
      3. Check the `worker_mount_file` setting typos, name and data.
      If these are set correctly, the Tomcat redirector should recognize that it should handle requests for the "/examples" context.
   2. If the last line contains something like: `GET "/jakarta/isapi_redirect.dll HTTP1.1"`, then the Tomcat redirector is recognizing that it should handle the request, but is not successful at getting Tomcat to service the request.
      1. If the number following `GET "/..."` is 404, check the following:
         1. Make sure you entered the URL correctly.
         2. Make sure the virtual directory created was called "jakarta". It should display in Personal Web Manager as "/jakarta" (without the quotes).
         3. Make sure the `extension_uri` data begins with "/jakarta/" (without the quotes).
      2. If the number following `GET "/..."` is 500, check the following:
         1. Make sure that "isapi_redirect.dll" follows "/jakarta/" in the `extension_uri` setting.
         2. Check the workers.properties file and make sure the port setting for `workers used` is the same as the port specified in the server.xml for the ajp13 or ajp12 connectors, normally this ports are 8007 for ajp12 and 8009 for ajp13.
      3. If the number following `GET "/..."` is 200 or 403, make sure you have checked Execute Access for the jakarta virtual directory in the Advanced Options of the Personal Web Manager.
   If the above settings are correct, the index.html page should appear in your browser. You should also be able to click the Execute links to execute the JSP examples.

### WinNT/Win2k

1. Make sure web site activity is being logged. For IIS/PWS make sure "Save Web Site Activity Log" is checked in the Advanced Options of the Personal Web Manager.
2. Start the World Wide Web Publishing Service and Tomcat.
3. Check for the presence of the Tomcat redirector log file you specified in the `log_file` setting. If not found, check the following:
   1. Check the "executable" you set for the filter in the IIS Management Console and make sure the path is correct.
   2. Check the spelling of the "HKEY_LOCAL_MACHINE\SOFTWARE\Apache Software Foundation\Jakarta Tomcat Redirector\1.0" key. Case isn't important, but an incorrect letter will prevent the isapi_redirect.dll from finding its registry settings.
   3. Check the `log_file` setting for typos, name and data. Also ensure the directory in which the log file will appear already exists.
   If the above are set correctly, the Tomcat redirector should be able to create the log file.
4. Check the jakarta filter you added and make sure its status shows a green upward-pointing arrow. If not, check the following:
   1. Check the `worker_file` setting for typos, name and data.
   2. Check the `worker_mount_file` setting typos, name and data.
   If the above are set correctly, the green upward-pointing arrow should appear, even if the other settings are wrong.
5. Invoke the URL "http://localhost/examples/jsp/index.html" in your browser. Case is important. The characters following "localhost" in the URL must be lower case. If the page fails to appear, examine the last line in the IIS server log file in found in SYSTEM32/LogFiles/W3SVC1.
   1. The last line should contain something like: `GET "/jakarta/isapi_redirect.dll HTTP1.1"`, which indicates the Tomcat redirector is recognizing that it should handle the request.
      1. If the number following `GET "/..."` is 404, check the following:
         1. Make sure you entered the URL correctly.
      2. If the number following `GET "/..."` is 500, check the following:
         1. Make sure the virtual directory created was called "jakarta".
         2. Make sure that the `extension_uri` setting is correct.
         3. Check the workers.properties file and make sure the port setting for `workers used` is the same as the port specified in the server.xml for the ajp13 or ajp12 connectors, normally this ports are 8007 for ajp12 and 8009 for ajp13.
      3. If the number following `GET "/..."` is 200 or 403, make sure you have checked Execute Access for the jakarta virtual directory in the Advanced Options of the Personal Web Manager. If you created the "Filter DLLs" key in the registry, delete it. That registry key is only used on Win98.
   If the above settings are correct, the index.html page should appear in your browser. You should also be able to click the Execute links to execute the JSP examples.

## Feedback

Please send feedback, bug report or any additional information to `tomcat-user@jakarta.apache.org`