Using or Replacing the Private Web Server

Limitations on Windows

Windows-based Apache installations use a special multi-threaded form of the Apache Multi-Processing Module (MPM) which is better suited to the way the operating system is optimized. Therefore, the behavior of the private web server under Windows is similar to that of a production grade Apache build as far as the ability to handle concurrent load is concerned.

If high availability and production-grade security is a requirement, or there is a need to integrate with other sources of web information, or a need for a high degree of control over the web server, a separate production-grade build of Apache is recommended — ideally operating on its own server. If, on the other hand, low volumes of HTTP traffic are expected, and there are limited demands for high availability and security, then the private web server may be suitable for deployment under these circumstances.

Building the Private Web Server

The (default) full Apache server is usually created with the following sequence of commands:

./configure --prefix=<install-dir>
make
make install

The minimal Apache build is typically created as follows:

./configure --prefix=/usr/iris/httpd --with-port=57773
            --with-pcre=$srcdir/pcre
            --enable-mods-static="log_config mime alias unixd authz_core"
            --disable-ssl
            --enable-so --without-gdbm --without-ndbm
            --without-berkeley-db --with-included-apr --with-expat=builtin
            --with-mpm=prefork --disable-shared
make
make install

Notice that many of the services that are normally required for a production grade installation are excluded.

While this server can be used to host other web applications it is strongly recommended that a full, independent web server installation is used for this purpose. It should be remembered that any changes made to the configuration of the Management Portal Apache installation are overwritten when the hosting InterSystems IRIS installation is upgraded.

Limitations on UNIX®

The private web server defaults to using the Apache Group’s prefork Multi-Processing Module (MPM). This is a non-threaded server model: the number of requests that can be concurrently served is directly related to the number of Apache worker processes in the pool.

The private web server is configured to occupy the smallest possible footprint by allowing a maximum of two worker processes to be created for the pool. The following settings are found in the Apache configuration (httpd.conf) for the private web server:

MinSpareServers 1
MaxSpareServers 2

By contrast, the default Apache configuration for a production grade build is usually as follows:

StartServers       5
MinSpareServers    2
MaxSpareServers   20
ServerLimit      256
MaxRequestWorkers       256

This configuration allows Apache to create 5 worker processes at start-up, increasing to a maximum of 256 as the concurrent load increases. Because of these differences in configuration, the performance of the private web server is noticeably inferior to that of a production grade Apache build. This performance deficit becomes more noticeable as the concurrent load increases. However, it is possible to change the configuration of the private web server to match that of a full Apache installation (shown above). Apache must be completely restarted after changing these parameters.

Note

The Management Portal Apache installation uses the following Web Gateway modules for communicating with InterSystems IRIS:

• Windows: CSPa24.dll and CSPa24Sys.dll

• UNIX®: CSPa24.so and CSPa24Sys.so

Making Configuration Changes

The configuration file for the private web server is located at: install_dir/httpd/conf/httpd.conf. However, edits made to this file do not persist through a software upgrade. The configuration file install_dir/httpd/conf/httpd-local.conf is provided for configuration changes you want to retain on upgrade. It is created on a new install or on upgrade if it does not already exist. If it does exist, upgrade makes no changes to its content.

Managing the Private Web Server on Windows

Start the private web server:

<install-dir>\httpd\bin\httpd -k start -n <instname>httpd
  -c "Listen port"

Stop the private web server:

<install-dir>\httpd\bin\httpd -k stop -n <instname>httpd

For example, suppose that InterSystems IRIS is installed in: C:\iris

InterSystems IRIS instance name: IRIS

TCP port for Apache: 52773

Start:

C:\iris\httpd\bin\httpd -k start -n IRIShttpd -c "Listen 52773"

And you can stop it as follows:

C:\iris\httpd\bin\httpd -k stop -n IRIShttpd

Managing the Private Web Server on UNIX®

Start the private web server:

<install-dir>/httpd/bin/httpd -d <install-dir>/httpd
  -c "Listen port"

Stop the private web server:

kill `cat <install-dir>/httpd/logs/httpd.pid`

For example, suppose that InterSystems IRIS installed in /usr/iris, and the TCP port for Apache is 8972. In this case, you can start the Private Web Server as follows:

/usr/iris/httpd/bin/httpd -d /usr/iris/httpd -c "Listen 8972"

And you can stop it as follows:

kill `cat /usr/iris/httpd/logs/httpd.pid`