Resin provides a fast servlet runner for Apache 1.3 or greater, allowing Apache to run servlets and JSP files.
If you have not yet done so, we suggest you use the Resin standalone web server option first.
Before integrating Resin with Apache, it is valuable to configure Resin as a standalone server , especially with more complicated setups such as those involving virtual hosts. Doing so isolates the steps and makes troubleshooting easier.
Many users find that the performance, flexibility, and features of Resin make Resin a desirable replacement for Apache.
When used with Apache, Resin serves JSPs and Servlets and Apache serves static content like html and images. Apache is a frontend server, it handles the request from the browser. Resin's mod_caucho plugin integrates with Apache, it dispatches requests for JSPs and Servlets to one or more backend Resin servers.
mod_caucho queries the backend server to distinguish the URLs going to Resin from the URLs handled by Apache. The backend server uses the <servlet-mapping> directives to decide which URLs to send. Also, any *.war file automatically gets all its URLs. Other URLs stay with Apache.
There's a more complete discussion of the URL dispatching in the How the Plugins Dispatch to Resin page.
Resin needs Apache 1.3.x or greater and DSO support.
To configure Resin with Apache, you must follow the following steps:
You need a version of Apache with DSO support enabled. Apache has full documentation at their website . To check if your apache has DSO support, you can check for in your your httpd
Many distributions, e.g. Red Hat Linux, will have Apache preinstalled. However, because the standard distribution has files all over the place, some people prefer to recompile Apache from scratch.
Once you untar Apache, build it like:
Solaris versions of Apache may need additional flags, otherwise you'll get some linking errors when trying to load Resin. You may need to refer to the Apache documentation if you get linking errors. Here's an example configuration on Solaris:
To compile and installon Unix, you'll need to run Resin's configure and then make. This step will create mod_caucho.so and put it in the Apache module directory. Usually, mod_caucho.so will end up in /usr/local/apache/libexec/mod_caucho.so.
If you know where yourexecutable is, you can use --with-apxs. is a little Perl script that the Apache configuration makes. It lets modules like Resin know how all the Apache directories are configured. It is generally in /usr/local/apache/bin/apxs or /usr/sbin/apxs. It's usually easiest to use --with-apxs so you don't need to worry where all the Apache directories are.
Even if you don't know whereis, the configure script can often find it:
As an alternative to --with-apxs, if you've compiled Apache yourself, or if you have a simple configuration, you can generally just point to the Apache directory:
The previous --with-apxs or --with-apache should cover most configurations. For some unusual configurations, you can have finer control over each directory with the following arguments to ./configure. In general, you should use --with-apache or --with-apxs, but the other variables are there if you know what you're doing.
If you don't already have Java installed, you'll need to download a JDK and set some environment variables.
Here's a typical environment that you might put in ~/.profile or /etc/profile
The setup.exe program installs the mod_caucho.dll plugin for any Apache it finds, and modifies the Apache httpd.conf file.
The httpd.conf file is also easily modified manually:
The communication between mod_caucho and the backend Resin server takes place using anport.
The resin.conf for the backend server contains an srun to enable the port. The default resin.conf has an srun listener on port 6802.
The resin.conf and the layout of your webapps should match the layout that Apache expects. The mapping of urls to filesystem locations should be consistent between Apache and the backend Resin server.
The default resin.conf looks in resin-3.0.x/webapps/ROOT for JSP files and resin-3.0.x/webapps/ROOT/WEB-INF/classes for servlets and java source files. To tell Resin to use Apache's document area, you configure an explicitwith the appropriate document-directory:
Now you need to start the backend Resin server. Starting Resin is the same with Apache or standalone. See the httpd page for a detailed description.
Resin will print every port it's listening to. In the above example, Resin has an http listener on port 8080 and an srun listener on port 6802 (using its custom `hmux' protocol). mod_caucho establishes connections to Resin using port 6802, and a web browser can connect using port 8080. Usually the 8080 port will be unused, because web browsers will make requests to Apache, these requests get dispatched to Resin as needed by mod_caucho. A Resin configured http listener on port 8080 is a useful debugging tool, it allows you to bypass Apache and make a request straight to Resin.
The following snippet shows theand configuration for the above example.
Create a test file '/usr/local/apache/htdocs/test.jsp'
Browse http://localhost/test.jsp again. You should now get
The installation process above automatically changes the httpd.conf file. You can also configure the httpd.conf file manually, or modify the default configuration created by the installation process.
The ResinConfigServer is used to tell mod_caucho how to contact the backend Resin server. The backend Resin server tell's mod_caucho which urls should be dispatched.
caucho-status is optional and probably should be avoided in a production site. It lets you ask the Caucho Apache module about it's configuration, and the status of the backend server(s), valuable for debugging.
After any change to httpd.conf, restart Apache. Now browse http://localhost/caucho-status.
You can also dispatch to Resin directly from the httpd.conf. Instead of relying on the ResinConfigServer directive to determine which url's to dispatch to the backend server, Apache handler's are used to specify the url's to dispatch.
Requests dispatched directly from the Apache httpd.conf will not appear in /caucho-status.
The virtual host topic describes virtual hosts in detail. If you're using a single JVM, you only need to configure the resin.conf.
If you want a different JVM for each virtual host, your httpd.conf can specify a different srun port for each host.
The Reliability and Load Balancing section provides an introduction to the concepts of load balancing.
mod_caucho recognizes cluster configurations for load balancing. Requests are distributed to all machines in the cluster, all requests in a session will go to the same host, and if one host goes down, Resin will send the request to the next available machine. Optional backup machines only receive requests if all of the primaries are down.
mod_caucho only needs to know about one of the backend servers. It will query that backend server, and learn about all of the other members of the cluster.
mod_caucho keeps a local cache of the configuration information, so if the backend server becomes unavailable then the cached configuration will be used until the backend server becomes available again.
The httpd.conf file can also specify more than one backend server, when mod_caucho checks for configuration updates, it will check each in turn, and only if none of them are available will it use the local cached copy.
Manual dispatching in httpd.conf can also specify the backend hosts and the backend backup hosts, as an alternative to using ResinConfigServer.