# Apache Tomcat 6.0

Version 6.0.51, Mar 9 2017

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# Apache Tomcat Configuration Reference

## System Properties

Table of Contents

> - Introduction
> - Clustering
> - Expression Language
> - Jasper
> - Security
> - Specification
> - Sessions
> - Logging
> - Other

Introduction

> The following sections list the system properties that may be set to modify the default Tomcat behaviour.

Clustering

> Property | Description
> --- | ---
> `org.apache.catalina. tribes.dns_lookups` | If `true`, the clustering module will attempt to use DNS to resolve any host names provided in the cluster configuration. If not specified, the default value of `false` will be used.

Expression Language

> Property | Description
> --- | ---
> `org.apache.el.BeanELResolver. CACHE_SIZE` | The number of javax.el.BeanELResolver.BeanProperties objects that will be cached by the EL Parser. If not specified, the default of `1000` will be used.
> `org.apache.el.ExpressionBuilder. CACHE_SIZE` | The number of parsed EL expressions that will be cached by the EL Parser. If not specified, the default of `5000` will be used.
> `org.apache.el.parser. COERCE_TO_ZERO` | If `true`, when coercing EL expressions to numbers `""` and `null` will be coerced to zero as required by the specification. If not specified, the default value of `true` will be used.
> `org.apache.el.parser. SKIP_IDENTIFIER_CHECK` | If `true`, when parsing EL expressions, identifiers will not be checked to ensure that they conform to the Java Language Specification for Java identifiers. If not specified, the default value of `true` will be used.

Jasper

> Property | Description
> --- | ---

> `org.apache.jasper.compiler. Generator.POOL_TAGS_WITH_EXTENDS`

> By default, JSPs that use their own base class via the extends attribute of the page directive, will have Tag pooling disabled since Jasper cannot guarantee that the necessary initialisation will have taken place. This can have a negative impact on performance. Providing the alternative base class calls _jspInit() from Servlet.init(), setting this property to `true` will enable pooling with an alternative base class. If the alternative base class does not call _jspInit() and this property is `true`, NPEs will occur when attempting to use tags.

> If not specified, the default value of `false` will be used.

> `org.apache.jasper.compiler. Generator.VAR_EXPRESSIONFACTORY` | The name of the variable to use for the expression language expression factory. If not specified, the default value of `_el_expressionfactory` will be used.
> `org.apache.jasper.compiler. Generator.VAR_INSTANCEMANAGER` | The name of the variable to use for the instance manager factory. If not specified, the default value of `_jsp_instancemanager` will be used.
> `org.apache.jasper.compiler. Generator.STRICT_GET_PROPERTY` | If `true`, the requirement to have the object referenced in `jsp:getProperty` action to be previously "introduced" to the JSP processor, as specified in the chapter JSP.5.3 of JSP 2.0 and later specifications, is enforced. If not specified, the specification compliant default of `true` will be used.
> `org.apache.jasper.compiler. Parser.STRICT_QUOTE_ESCAPING` | If `false` the requirements for escaping quotes in JSP attributes will be relaxed so that an unescaped quote will not cause an error. If not specified, the specification compliant default of `true` will be used.
> `org.apache.jasper.runtime. BodyContentImpl.LIMIT_BUFFER` | If `true`, any tag buffer that expands beyond `org.apache.jasper.Constants.DEFAULT_TAG_BUFFER_SIZE` will be destroyed and a new buffer created of the default size. If not specified, the default value of `false` will be used.
> `org.apache.jasper.runtime. JspFactoryImpl.USE_POOL` | If `true`, a ThreadLocal `PageContext` pool will be used. If not specified, the default value of `true` will be used.
> `org.apache.jasper.runtime. JspFactoryImpl.POOL_SIZE` | The size of the ThreadLocal `PageContext`. If not specified, the default value of `8` will be used.
> `org.apache.jasper.Constants. JSP_SERVLET_BASE` | The base class of the Servlets generated from the JSPs. If not specified, the default value of `org.apache.jasper.runtime.HttpJspBase` will be used.
> `org.apache.jasper.Constants. SERVICE_METHOD_NAME` | The name of the service method called by the base class. If not specified, the default value of `_jspService` will be used.
> `org.apache.jasper.Constants. SERVLET_CLASSPATH` | The name of the ServletContext attribute that provides the classpath for the JSP. If not specified, the default value of `org.apache.catalina.jsp_classpath` will be used.
> `org.apache.jasper.Constants. JSP_FILE` | The name of the request attribute for `<jsp-file>` element of a servlet definition. If present on a request, this overrides the value returned by `request.getServletPath()` to select the JSP page to be executed. If not specified, the default value of `org.apache.catalina.jsp_file` will be used.
> `org.apache.jasper.Constants. PRECOMPILE` | The name of the query parameter that causes the JSP engine to just pregenerate the servlet but not invoke it. If not specified, the default value of `jsp_precompile` will be used, as defined by JSP specification (JSP.11.4.2).
> `org.apache.jasper.Constants. JSP_PACKAGE_NAME` | The default package name for compiled jsp pages. If not specified, the default value of `org.apache.jsp` will be used.
> `org.apache.jasper.Constants. TAG_FILE_PACKAGE_NAME` | The default package name for tag handlers generated from tag files. If not specified, the default value of `org.apache.jsp.tag` will be used.
> `org.apache.jasper.Constants. ALT_DD_ATTR` | The servlet context attribute under which the alternate deployment descriptor for this web application is stored. If not specified, the default value of `org.apache.catalina.deploy.alt_dd` will be used.
> `org.apache.jasper.Constants. TEMP_VARIABLE_NAME_PREFIX` | Prefix to use for generated temporary variable names. If not specified, the default value of `_jspx_temp` will be used.
> `org.apache.jasper.Constants. USE_INSTANCE_MANAGER_FOR_TAGS` | If `true`, the instance manager is used to obtain tag handler instances. If not specified, the default value of `false` will be used.

Security

> Property | Description
> --- | ---
> `org.apache.catalina.connector. RECYCLE_FACADES` | If this is `true` or if a security manager is in use a new facade object will be created for each request. If not specified, the default value of `false` will be used.
> `org.apache.catalina.connector. CoyoteAdapter.ALLOW_BACKSLASH` | If this is `true` the '\' character will be permitted as a path delimiter. If not specified, the default value of `false` will be used.
> `org.apache.tomcat.util.buf. UDecoder.ALLOW_ENCODED_SLASH` | If this is `true` '%2F' and '%5C' will be permitted as path delimiters. If not specified, the default value of `false` will be used.
> `org.apache.coyote. USE_CUSTOM_STATUS_MSG_IN_HEADER` | If this is `true`, custom HTTP status messages will be used within HTTP headers. If a custom message is specified that is not valid for use in an HTTP header (as defined by RFC2616) then the custom message will be ignored and the default message used. If not specified, the default value of `false` will be used.

Specification

> Property | Description
> --- | ---

> `org.apache.catalina. STRICT_SERVLET_COMPLIANCE`

> If this is `true` the following actions will occur:
> - any wrapped request or response object passed to an application dispatcher will be checked to ensure that it has wrapped the original request or response. (SRV.8.2 / SRV.14.2.5.1)
> - a call to `Response.getWriter()` if no character encoding has been specified will result in subsequent calls to `Response.getCharacterEncoding()` returning `ISO-8859-1` and the `Content-Type` response header will include a `charset=ISO-8859-1` component. (SRV.15.2.22.1)
> - every request that is associated with a session will cause the session's last accessed time to be updated regardless of whether or not the request explicitly accesses the session. (SRV.7.6)
> - cookies will be parsed strictly, by default v0 cookies will not work with any invalid characters.
>   If set to `false`, any v0 cookie with invalid character will be switched to a v1 cookie and the value will be quoted.
> - the path in `ServletContext.getResource` / `getResourceAsStream` calls must start with a "/".
>   If set to `false`, code like `getResource("myfolder/myresource.txt")` will work.

> If this is `true` the default value will be changed for:

> - `org.apache.catalina.connector.Request. ALLOW_EMPTY_QUERY_STRING` property
> - `org.apache.tomcat.util.http.ServerCookie. PRESERVE_COOKIE_HEADER` property
> - The `webXmlValidation` attribute of any Context element.
> - The `webXmlNamespaceAware` attribute of any Context element.
> - The `tldValidation` attribute of any Context element.

> If not specified, the default value of `false` will be used.

> `org.apache.catalina.connector. Request.ALLOW_EMPTY_QUERY_STRING` | If this is `true` Tomcat will return an empty string rather than `null` for empty query strings - i.e. query strings where only `?` is present. If not specified, the value of `org.apache.catalina.STRICT_SERVLET_COMPLIANCE` will be used as the default.
> `org.apache.catalina.session. StandardSession.ACTIVITY_CHECK` | If this is `true` or if `org.apache.catalina.STRICT_SERVLET_COMPLIANCE` is `true` Tomcat will track the number of active requests for each session. When determining if a session is valid, any session with at least one active request will always be considered valid. If not specified, the default value of `false` will be used.
> `org.apache.tomcat.util.http. ServerCookie.ALLOW_EQUALS_IN_VALUE` | If this is `true` Tomcat will allow '`=`' characters when parsing unquoted cookie values. If `false`, cookie values containing '`=`' will be terminated when the '`=`' is encountered and the remainder of the cookie value will be dropped. If not specified, the default specification compliant value of `false` will be used.
> `org.apache.tomcat.util.http. ServerCookie.ALWAYS_ADD_EXPIRES` | If this is `true` Tomcat will always add an expires parameter to a SetCookie header even for cookies with version greater than zero. This is to work around a known IE6 and IE7 bug that causes IE to ignore the Max-Age parameter in a SetCookie header. If not specified, the default value of `true` will be used.
> `org.apache.tomcat.util.http. ServerCookie.PRESERVE_COOKIE_HEADER` | If this is `true` Tomcat will ensure that cookie processing does not modify cookie header returned by `HttpServletRequest.getHeader()`. If `org.apache.catalina.STRICT_SERVLET_COMPLIANCE` is set to `true`, the default of this setting will be `true`, else the default value will be `false`.

Sessions

> Property | Description
> --- | ---
> `org.apache.catalina.SESSION_COOKIE_NAME` | An alternative name for the session cookie. Defaults to `JSESSIONID`. Note that the Servlet specification requires this to be `JSESSIONID`. You should not rely on being able to change this.
> `org.apache.catalina.SESSION_PARAMETER_NAME` | An alternative name for the session path parameter. Defaults to `jsessionid`. Note that the Servlet specification requires this to be `jsessionid`. You should not rely on being able to change this.
> `org.apache.catalina.authenticator. Constants.SSO_SESSION_COOKIE_NAME` | An alternative name for the single sign on session cookie. Defaults to `JSESSIONIDSSO`.

Logging

> Property | Description
> --- | ---

> `org.apache.juli.logging. UserDataHelper.CONFIG`

> The type of logging to use for errors generated by invalid input data. The options are: `DEBUG_ALL`, `INFO_THEN_DEBUG`, `INFO_ALL` and `NONE`. When `INFO_THEN_DEBUG` is used, the period for which errors are logged at DEBUG rather than INFO is controlled by the system property `org.apache.juli.logging.UserDataHelper.SUPPRESSION_TIME`.

> The default value is `INFO_THEN_DEBUG`.

> The errors currently logged using this system are:
> - invalid parameters.
> Other errors triggered by invalid input data may be added to this system in later versions.

> `org.apache.juli.logging. UserDataHelper.SUPPRESSION_TIME`

> When using `INFO_THEN_DEBUG` for `org.apache.juli.logging.UserDataHelper.CONFIG` this system property controls how long messages are logged at DEBUG after a message has been logged at INFO. Once this period has elapsed, the next message will be logged at INFO followed by a new suppression period where messages are logged at DEBUG and so on. The value is measured in seconds.

> A value of `0` is equivalent to using `INFO_ALL` for `org.apache.juli.logging.UserDataHelper.CONFIG`.

> A negative value means an infinite suppression period.

> The default value is `86400` (24 hours).

Other

> Property | Description
> --- | ---
> `org.apache.coyote.ALLOWED_TRAILER_HEADERS` | Limits the names of trailing headers that will be accepted in the last chunk of a chunked HTTP request. The property should be set to a comma separated list of acceptable headers. Trailing headers not in the list will be ignored. If not specified, the default value of no headers will be used.
> `org.apache.coyote.MAX_EXTENSION_SIZE` | Limits the total length of extension data when using chunked encoding. If the value is `-1`, no limit will be imposed. If not specified, the default value of `8192` will be used.
> `org.apache.coyote.MAX_TRAILER_SIZE` | Limits the total length of trailing headers in the last chunk of a chunked HTTP request. If the value is `-1`, no limit will be imposed. If not specified, the default value of `8192` will be used.
> `org.apache.coyote.MAX_SWALLOW_SIZE` | Limits the length of a request body Tomcat will swallow if it is not read during normal request processing. If the value is `-1`, no limit will be imposed. If not specified, the default value of `2097152` (2MB) will be used.
> `catalina.useNaming` | If this is `false` it will override the `useNaming` attribute for all Context elements.
> `jvmRoute` | Provides a default value for the `jvmRoute` attribute of the Engine element. It does not override the value configured on the Engine element.

> `org.apache.catalina.loader. WebappClassLoader.ENABLE_CLEAR_REFERENCES`

> If `true`, Tomcat attempts to null out any static or final fields from loaded classes when a web application is stopped as a work around for apparent garbage collection bugs and application coding errors.

> There have been some issues reported with log4j when this option is `true`.

> Applications without memory leaks using recent JVMs should operate correctly with this option set to `false`.

> If not specified, the default value of `true` will be used.

> `catalina.config` | The URL for the catalina.properties configuration file.
> `tomcat.util.buf.StringCache.byte.enabled` | If `true`, the String cache is enabled for `ByteChunk`. If not specified, the default value of `false` will be used.
> `tomcat.util.buf.StringCache.char.enabled` | If `true`, the String cache is enabled for `CharChunk`. If not specified, the default value of `false` will be used.
> `tomcat.util.buf.StringCache.trainThreshold` | The number of times `toString()` must be called before the cache is activated. If not specified, the default value of `20000` will be used.
> `tomcat.util.buf.StringCache.cacheSize` | The size of the String cache. If not specified, the default value of `200` will be used.
> `tomcat.util.buf.StringCache.maxStringSize` | The maximum length of String that will be cached. If not specified, the default value of `128` will be used.
> `org.apache.tomcat.util. http.FastHttpDateFormat.CACHE_SIZE` | The size of the cache to use parsed and formatted date value. If not specified, the default value of `1000` will be used.
> `org.apache.tomcat.util. net.NioSelectorShared` | If `true`, use a shared selector for servlet write/read. If not specified, the default value of `true` will be used.
> `org.apache.catalina.startup. EXIT_ON_INIT_FAILURE` | If `true`, the server will exit if an exception happens during the server initialization phase. If not specified, the default value of `false` will be used.

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