| Links User Guide Reference Apache Tomcat Development | Apache Tomcat 6.0Apache Portable Runtime (APR) based Native library for Tomcat| Introduction |  | 
  
      Tomcat can use the Apache Portable Runtime to 
      provide superior scalability, performance, and better integration with native server 
      technologies. The Apache Portable Runtime is a highly portable library that is at 
      the heart of Apache HTTP Server 2.x. APR has many uses, including access to advanced IO
      functionality (such as sendfile, epoll and OpenSSL), OS level functionality (random number
      generation, system status, etc), and native process handling (shared memory, NT
      pipes and Unix sockets).
   
      These features allows making Tomcat a general purpose webserver, will enable much better 
      integration with other native web technologies, and overall make Java much more viable as
      a full fledged webserver platform rather than simply a backend focused technology.
   | 
 | Installation |  | 
    
      APR support requires three main native components to be installed:
       
        APR libraryJNI wrappers for APR used by Tomcat (libtcnative)OpenSSL libraries | Windows |  | 
    
    
      Windows binaries are provided for tcnative-1, which is a statically compiled .dll which includes
      OpenSSL and APR. It can be downloaded from here
      as 32bit or AMD x86-64 binaries.
      In security conscious production environments, it is recommended to use separate shared dlls
      for OpenSSL, APR, and libtcnative-1, and update them as needed according to security bulletins.
      Windows OpenSSL binaries are linked from the Official OpenSSL 
      website (see related/binaries).
     | 
 | 
 | APR Components |  | 
  
    Once the libraries are properly installed and available to Java (if loading fails, the library path
    will be displayed), the Tomcat connectors will automatically use APR. Configuration of the connectors
    is similar to the regular connectors, but have a few extra attributes which are used to configure
    APR components. Note that the defaults should be well tuned for most use cases, and additional
    tweaking shouldn't be required.
   
    When APR is enabled, the following features are also enabled in Tomcat:
     
      Secure session ID generation by default on all platforms (platforms other than Linux required
          random number generation using a configured entropy)OS level statistics on memory usage and CPU usage by the Tomcat process are displayed by
          the status servlet | 
 | APR Connectors Configuration |  | 
    | HTTP |  | 
    
    
      When APR is enabled, the HTTP connector will use sendfile for handling large static files (all such
      files will be sent asynchronously using high performance kernel level calls), and will use 
      a socket poller for keepalive, increasing scalability of the server.
     
      The following attributes are supported in the HTTP APR connector in addition to the ones supported
      in the regular HTTP connector:
     | Attribute | Description | 
|---|
 | keepAliveTimeout | The number of milliseconds this Connector will wait for
       another HTTP request before closing the connection.
       The default value is to use the value that has been set for the
       connectionTimeout attribute. This value also controls the timeout interval which
       is used for Comet connections. |  | pollTime | Duration of a poll call. Lowering this value will slightly decrease latency of connections 
      being kept alive in some cases, but will use more CPU as more poll calls are being made. The
      default value is 2000 (5ms). |  | pollerSize | Amount of sockets that the poller responsible for polling kept alive connections can hold at a
      given time. Extra connections will be closed right away. The default value is 8192, corresponding to
      8192 keepalive connections. |  | pollerThreadCount | Number of threads used to poll kept alive connections. On Windows the
      default is chosen so that the sockets managed by each thread is
      less than 1024. For Linux the default is 1. Changing the default on
      Windows is likely to have a negative performance impact. |  | useSendfile | Use kernel level sendfile for certain static files. The default value is true. |  | sendfileSize | Amount of sockets that the poller responsible for sending static files asynchronously can hold 
      at a given time. Extra connections will be closed right away without any data being sent 
      (resulting in a zero length file on the client side). Note that in most cases, sendfile is a call
      that will return right away (being taken care of "synchronously" by the kernel), and the sendfile
      poller will not be used, so the amount of static files which can be sent concurrently is much larger
      than the specified amount. The default value is 1024. |  | sendFileThreadCount | Number of threads used service sendfile sockets. On Windows the
      default is chosen so that the sockets managed by each thread is
      less than 1024. For Linux the default is 1. Changing the default on
      Windows is likely to have a negative performance impact. | 
 | 
 | HTTPS |  | 
    
    
      When APR is enabled, the HTTPS connector will use a socket poller for keepalive, increasing 
      scalability of the server. It also uses OpenSSL, which may be more optimized than JSSE depending
      on the processor being used, and can be complemented with many commercial accelerator components.
      Unlike the HTTP connector, the HTTPS connector cannot use sendfile to optimize static file
      processing.
     
      The HTTPS APR connector has the same basic attributes than the HTTP APR connector, but adds 
      OpenSSL specific ones. For the full details on using OpenSSL, please refer to OpenSSL documentations
      and the many books available for it (see the Official OpenSSL 
      website). The SSL specific attributes for the connector are:
     | Attribute | Description | 
|---|
 | SSLEnabled | 
      Enable SSL on the socket, default value is false. Set this value to true
      to enable SSL handshake/encryption/decryption in the APR connector.
     |  | SSLProtocol | 
      Protocol which may be used for communicating with clients. The default is "all", with
      other acceptable values being "SSLv2", "SSLv3", "TLSv1", and "SSLv2+SSLv3".
     |  | SSLCipherSuite | 
      Ciphers which may be used for communicating with clients. The default is "ALL", with
      other acceptable values being a list of ciphers, with ":" used as the delimiter
      (see OpenSSL documentation for the list of ciphers supported).
     |  | SSLCertificateFile | 
      Name of the file that contains the server certificate. The format is PEM-encoded.
     |  | SSLCertificateKeyFile | 
      Name of the file that contains the server private key. The format is PEM-encoded.
      The default value is the value of "SSLCertificateFile" and in this case both certificate
      and private key have to be in this file (NOT RECOMMENDED).
     |  | SSLPassword | 
      Pass phrase for the encrypted private key. If "SSLPassword" is not provided, the callback function
      should prompt for the pass phrase.
     |  | SSLVerifyClient | 
      Ask client for certificate. The default is "none", meaning the client will not have the opportunity
      to submit a certificate. Other acceptable values include "optional", "require" and "optionalNoCA".
     |  | SSLVerifyDepth | 
      Maximum verification depth for client certificates. The default is "10".
     |  | SSLCACertificateFile | 
      See the mod_ssl documentation.
     |  | SSLCACertificatePath | 
      See the mod_ssl documentation.
     |  | SSLCertificateChainFile | 
      See the mod_ssl documentation.
     |  | SSLCARevocationFile | 
      See the mod_ssl documentation.
     |  | SSLCARevocationPath | 
      See the mod_ssl documentation.
     | 
 
    An example SSL Connector declaration can be:
     |  |  |  |  |  | 
    <Connector port="443" maxHttpHeaderSize="8192"
               maxThreads="150"
               enableLookups="false" disableUploadTimeout="true"
               acceptCount="100" scheme="https" secure="true"
               SSLEnabled="true" 
               SSLCertificateFile="${catalina.base}/conf/localhost.crt"
               SSLCertificateKeyFile="${catalina.base}/conf/localhost.key" /> |  |  |  |  |  | 
 | 
 | AJP |  | 
    
    
      When APR is enabled, the AJP connector will use a socket poller for keepalive, increasing 
      scalability of the server. As AJP is designed around a pool of persistent (or almost
      persistent) connections, this will reduce significantly the amount of processing threads 
      needed by Tomcat. Unlike the HTTP connector, the AJP connector cannot use sendfile to optimize
      static file processing.
     
      The following attributes are supported in the AJP APR connector in addition to the ones supported
      in the regular AJP connector:
     | Attribute | Description | 
|---|
 | pollTime | Duration of a poll call. Lowering this value will slightly decrease latency of connections 
      being kept alive in some cases, but will use more CPU as more poll calls are being made. The
      default value is 2000 (5ms). |  | pollerSize | Amount of sockets that the poller responsible for polling kept alive connections can hold at a
      given time. Extra connections will be closed right away. The default value is 8192, corresponding to
      8192 keepalive connections. | 
 | 
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