# 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 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. WinNT4.0-i386 SP4/SP5/SP6a (it should be able to work on other versions of the NT service pack.) and Win98
2. IIS4.0 and PWS4.0
3. Tomcat3.0 - Tomcat3.2

The redirector uses 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 ISAPI redirector server 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 IIS server 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` directory.
3. uriworkermap.properties - A file that maps URL-Path patterns to workers. A sample `uriworkermap.properties` can be found under the `conf` directory as well.

The installation includes the following parts:

1. Configuring the ISAPI redirector with a default /examples context and checking that you can serve servlets with IIS.
2. Adding more contexts to the configuration.

### Configuring the ISAPI Redirector

In this document I will assume that isapi_redirect.dll is placed in c:\jakarta-tomcat\bin\win32\i386\isapi_redirect.dll and that you created the properties files are in c:\jakarta-tomcat\conf.

1. In the registry, create a new registry key named
   `"HKEY_LOCAL_MACHINE\SOFTWARE\Apache Software Foundation\Jakarta Isapi Redirector\1.0"`
2. Add a string value with the name `extension_uri` and a value of /jakarta/isapi_redirect.dll
3. Add a string value with the name `log_file` and a value pointing to where you want your log file to be (for example `c:\jakarta-tomcat\logs\isapi.log)`.
4. Add a string value with the name `log_level` and a value for your log level (can be `debug`, `info`, `error` or `emerg`).
5. Add a string value with the name `worker_file` and a value which is the full path to your workers.properties file (for example `c:\jakarta-tomcat\conf\workers.properties`)
6. Add a string value with the name `worker_mount_file` and a value which is the full path to your uriworkermap.properties file (for example `c:\jakarta-tomcat\conf\uriworkermap.properties`)
7. 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 isapi_redirect.dll (in our example it is c:\jakarta-tomcat\bin\win32\i386). While creating this new virtual directory assign it with execute access.
8. Using the IIS management console, add isapi_redirect.dll as a filter in your IIS/PWS web site. The name of the filter should reflect its task (I use the name jakarta), its executable must be our `c:\jakarta-tomcat\bin\win32\i386\isapi_redirect.dll`. For PWS, 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 "," separated list of dlls ( full paths ) - you need to insert the full path to isapi_redirect.dll.
9. Restart IIS (stop + start the IIS service), make sure that the jakarta filter is marked with a green up-pointing arrow.
   (costin)Under Win98 you may need to cd WINDOWS\SYSTEM\inetsrv and type PWS /stop ( the DLL and log files are locked - even if you click the stop button, PWS will still keep the DLLs in memory. ). Type 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 (I am not going to talk about this).
2. Adding the context to the ISAPI redirector.

Adding a context to the ISAPI redirector is simple, all you need to do is to edit your `uriworkermap.properties` and 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 a single pre-configured worker named "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/*=ajp12`

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

As a new feature in Tomcat 3.2, a `uriworkermap.properties-auto` is automatically written each time Tomcat is started. This file includes settings for each of the contexts that Tomcat will serve during its run. Each context has settings to have Tomcat handle servlet and JSP requests, but by default static content is left to be served by IIS. Each context also has a commented out setting to have Tomcat handle all requests to the context. You can rename this file (so it won't be overwritten the next time Tomcat is started) and uncomment this setting or make other customizations. You may also use this file as is in your `worker_mount_file` setting.

## Building the redirector

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

The steps that you need to take are:

1. Change directory to the isapi 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 load 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 transfer the request to the extension.
3. The extension collects the request parameters and forwards them to the appropriate worker using the ajp12 protocol.
4. The extension collects the response from the worker and returns it to the browser.

## Advanced Context Configuration

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/*=ajp12`

with the following two lines:

`/examples/*.jsp=ajp12
/examples/servlet/*=ajp12`

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 automically written to the `uriworkermap.properties-auto` file for each context.

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

`/example/servletname=ajp12`

that instructs the redirector to redirect request whose URL-Path equals `/example/servletname` to the worker named ajp12.

### 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, ajp12second`
2. Entries that define the host and port associated with these workers. For example:
   `worker.ajp12.host=localhost
   worker.ajp12.port=8007
   worker.ajp12second.host=otherhost
   worker.ajp12second.port=8007`

The above examples defined two 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
/webpages/*=ajp12second`

As you can see the examples context is served by ajp12 while the webpages context is served by ajp12second.

## Troubleshooting

It is easy to have the ISAPI 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 uriworkermap.properties file. Results may be misleading if `worker_mount_file` points to a modified uriworkermap.properties or the uriworkermap.properties-auto file. It is also assumed that the "/examples" context works correcly if you access Tomcat directly.

### Win98

1. Make sure web site activity is being logged. For PWS 4.0 make sure "Save Web Site Activity Log" is checked in the Advanced Options of the Personal Web Manager.
2. Start the IIS service and Tomcat.
3. Check for the presence of the ISAPI 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 insure the directory in which the log file will appear already exists.
   If the above are set correctly, the ISAPI 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 in Tomcat 3.2. The characters following "localhost" in the URL must be lower case. If the page fails to appear, stop the IIS service (required to view the IIS log file). Then examine the last line in the IIS 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 ISAPI 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 ISAPI 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 ISAPI 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 `worker.ajp12.port` is the same as the port specified in the server.xml for the "Apache AJP12 support".
      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

1. Make sure web site activity is being logged. For PWS 4.0 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 ISAPI 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 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 insure the directory in which the log file will appear already exists.
   If the above are set correctly, the ISAPI 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 in Tomcat 3.2. 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 ISAPI 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 `worker.ajp12.port` is the same as the port specified in the server.xml for the "Apache AJP12 support".
      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.

## Feedback

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