wt_config.xml

<!--
    Wt Configuration File.

    The Wt configuration file manages, for every Wt application, settings
    for session management, debugging, directory for runtime information
    such as session sockets, and some security settings.

    Settings may be specified globally, or for a single application path.

    The path should be as configured in the Wt build process, where it
    defaults to /etc/wt/wt_config.xml. It can be overridden in the environment
    variable WT_CONFIG_XML, or with the -c startup option of wthttpd.

    The values listed here are the default values, which are used when the
    declaration is missing or no configuration file is used.
  -->

<server>

    <!-- Default application settings

      The special location "*" always matches. See below for an example
      of settings specific to a single application.
      -->
    <application-settings location="*">

        <!-- Session management. -->
        <session-management>
            <!-- Every session runs within a dedicated process.

               This mode guarantees kernel-level session privacy, but as every
               session requires a seperate process, it is also an easy target
               for DoS attacks if not shielded by access control.

               It is also a convenient mode during development, as it is easy
               to enable disable debugging using valgrind, and it always starts
               the latest deployed executable for a new session.

               Note: currently only supported using the FastCGI connector
              -->
            <!--
               <dedicated-process>
                 <max-num-sessions>100</max-num-sessions>
               </dedicated-process>
            -->

            <!-- Multiple sessions within one process.

               This mode spawns a number of processes, and sessions are
               allocated randomly to one of these processes (you should not
               use this for dynamic FCGI servers, but only in conjunction
               with a fixed number of static FCGI servers.

               This requires careful programming, as memory corruption in one
               session will kill all of the sessions in the same process. You
               should debug extensively using valgrind. Also, it is your
               responsibility to keep session state not interfering and
               seperated.

               On the other hand, sessions are inexpensive, and this mode
               suffers far less from DoS attacks than dedicated-process mode.
               Use it for non-critical and well-debugged web applications.

               Note: wthttpd always uses exactly one process
              -->


            <shared-process>
                <num-processes>1</num-processes>
            </shared-process>


            <!-- Session tracking strategy.

               Possible values:
                 Auto: cookies is available, otherwise URL rewriting
                 URL:  only URL rewriting
              -->
            <tracking>Auto</tracking>

            <!-- How reload should be handled.

               When reload should (or rather, may) spawn a new session, then
               even in the case cookies are not used for session management,
               the URL will not be cluttered with a sessionid.
               However, WApplication::refresh() will never be called.
              -->
            <reload-is-new-session>false</reload-is-new-session>

            <!-- Session timeout (seconds).

               When a session remains inactive for this amount of time, it is
               cleaned up.
              -->
            <timeout>600</timeout>

            <!-- Server push timeout (seconds).

               When using server-initiated updates, the client uses
               long-polling requests. Proxies (including reverse
               proxies) are notorious for silently closing idle
               requests; the client therefore cancels the request
               periodically and issues a new one. This timeout sets
               the frequency.
              -->
            <server-push-timeout>50</server-push-timeout>
        </session-management>

        <!-- Settings that apply only to the FastCGI connector.

           To configure the wthttpd connector, use command line options, or
           configure default options in /etc/wt/wthttpd
          -->
        <connector-fcgi>
            <!-- Valgrind path

               If debugging is enabled and this path is not empty, then valgrind
               will be started for every shared process, or for every session
               which has ?debug appended to the command line.

               The variable is slighly misnamed. Not only a path can be set,
               but also options, like for example:

                 /usr/bin/valgrind - -leak-check=full
             -->
            <valgrind-path></valgrind-path>

            <!-- Run directory

               Path used by Wt to do session management.
              -->
            <run-directory>${RUNDIR}</run-directory>

            <!-- Number of threads per process

               This configures the size of the thread pool. You may
               want to change this value if you would like to support
               reentrant event loops, where you block one event loop
               using WDialog::exec() or related static
               methods. Everytime you enter such an event loop, one
               thread is blocked, and therefore the total number of
               sessions that reliably can do this is limited to the
               number of thread you have (minus one to unblock).

               For the built-in http connector, there is a similar
               config option that is specified in the whttpd config
               file or on the command line (-t).

               The default value is 1.
              -->
            <num-threads>1</num-threads>

        </connector-fcgi>

        <!-- Settings that apply only to the MS IIS ISAPI connector.

           To configure the wthttpd connector, use command line options, or
           configure default options in /etc/wt/wthttpd
          -->
        <connector-isapi>
            <!-- Number of threads per process

               This configures the number of threads that will be used
               to handle Wt requests. The IIS internal threads are never
               used to do any processing; all requests are forwarded to
               be handled in this threadpool. Rather than to configure a
               so-called 'web-garden' in IIS, increase this number. The
               ISAPI connector will not work correctly when a web-garden
               is configured.

               You may want to change this value if you would like to
               support more reentrant event loops, where you block one
               event loop using WDialog::exec() or related static
               methods. Everytime you enter such an event loop, one
               thread is blocked, and therefore the total number of
               sessions that reliably can do this is limited to the
               number of thread you have (minus one to unblock).

               You may also want to increase this number if your Wt
               application is regularly waiting for IO (databases, network,
               files, ...). If this number is too low, all threads could
               be waiting for IO operations to complete while your CPU
               is idle. Increasing the number of threads may help.

               Computing intensive applications may also increase this number,
               even though it is better to offload computations to a helper
               thread and user server push or a WTimer to check for
               completion of the task in order to keep your GUI responsive
               during the computations.

               The default value is 10.
              -->
            <num-threads>10</num-threads>

            <!-- Maximum Request Size spooled in memory (Kb)

               Normally, Wt keeps incoming requests (POST data) in memory.
               However, malicious users could send a big POST and as such
               use up all memory of your HTTP server. With this parameter,
               you tune how big a request can be before Wt spools it in a
               file before processing it. Legitimate big POST messages may
               occur when users are expected to upload files.

               See also max-request-size.

               The default value is 128K, which is more than enough for
               any interactive Wt event.
              -->
            <max-memory-request-size>128</max-memory-request-size>
        </connector-isapi>

        <!-- Javascript debug options

             Values:
             - true: JavaScript errors are not caught but the browser
                     built-in debug options are used
             - stack: JavaScript errors are caught but also a stack trace
                      is printed, useful for diagnosing a problem in production
             - false: JavaScript errors are caught and a simple error message
                      is printed to indicate that something is terribly wrong
          -->
        <debug>true</debug>

        <!-- Log file

           When the log file is empty, or omitted, logging is done to
           stderr. This may end up in the web server error log file
           (e.g. for apache + fastcgi module), or on stderr (e.g. for
           the built-in httpd).
         -->
        <log-file></log-file>

        <!-- Logger configuration

           This configures the logger. With the default configuration,
           everything except for debugging messages are logged.

           The configuration is a string that defines rules for
           enabling or disabling certain logging. It is a white-space
           delimited list of rules, and each rule is of the form:

             [-]level : enables (or disables) logging of messages of
             the given level; '*' is a wild-card that matches all
             levels

             [-]level:scope : enables (or disables) logging of
             messages of the given level and scope; '*' is a wild-card
             that matches all levels or scopes.  The default
             configuration is "* -debug", i.e. by default everything
             is logged, except for "debug" messages.

           Some other examples:

             "* -debug debug:wthttp": logs everything, including
             debugging messages of scope "wthttp", but no other
             debugging messages.

             "* -info -debug": disables logging of info messages
             in addition to debugging messages.

           Note debugging messages are only emitted when debugging
           has been enabled while building Wt.
          -->
        <log-config>* -debug</log-config>

        <!-- Maximum HTTP request size (Kb)

           Maximum size of an incoming POST request. This value must be
           increased when the user is allowed to upload files.
         -->
        <max-request-size>40960</max-request-size>

        <!-- Session id length (number of characters) -->
        <session-id-length>16</session-id-length>

        <!-- DoS prevention: limit plain HTML sessions

           This is a simple measure which avoids Denial-of-Service
           attacks on plain HTML sessions, which are easy to mount in
           particular in the case of progressive bootstrap mode.

           This setting may be used to keep the ratio of plain HTML
           versus Ajax sessions under a certain ratio. Typically, most
           of your sessions will be Ajax sessions, and only a tiny
           fraction (e.g. less than 5%) will be plain HTML
           sessions. This ratio is only enforced when more than 20 sessions
           have been created.
          -->
        <plain-ajax-sessions-ratio-limit>1</plain-ajax-sessions-ratio-limit>

        <!-- DoS prevention: adds a puzzle to validate Ajax sessions

           This is a simple measure which avoids Denial-of-Service
           attacks on Ajax sessions.

           When enabled, a puzzle needs to be solved in the first Ajax
           request which eliminates agents that do not build a proper
           DOM tree.
          -->
        <ajax-puzzle>false</ajax-puzzle>

        <!-- Do strict serialization of events.

           By default events are queued at the client-side, and
           transmitted to the server so that at any time only one
           request/response is pending. This scheme has a quality that
           resembles TCP: on a low-latency link you allow the
           transmission of many smaller requests, while on a high
           latency link, events will be propagated less often, but in
           batches.

           In any case, this scheme does not drop events, no matter
           how quickly they are generated.

           In rare cases, the scheme may result in unwanted behaviour,
           because the client-side is allowed to be slighly out of
           sync at the time an event is recorded with the server-side
           (and more so on high-latency links). The drastic
           alternative is to discard events while a response is
           pending, and can be configured by setting this option to
           true.
          -->
        <strict-event-serialization>false</strict-event-serialization>

        <!-- Enables web socket.

           By default Ajax and long polling are used to communicate
           between server and browser.

           By enabling web socket support, if the browser supports
           WebSockets, then WebSocket is the protocol used for
           communication between client and server. WebSockets are
           currently only supported by the built-in httpd Connector,
           which acts as both an HTTP and WebSocket server. The WebSocket
           protocol is intentionally not compatible with HTTP, through
           a special hand-shake mechanism, and requires
           that all (reverse) proxy servers also have explicit support
           for this protocol.

           This feature is still experimental: the Web Sockets RFC is
           still a draft. Wt implements up to version 17 of the draft
           (latest as of November 2011).
          -->
        <web-sockets>false</web-sockets>

        <!-- Redirect message shown for browsers without JavaScript support

           By default, Wt will use an automatic redirect to start the
           application when the browser does not support
           JavaScript. However, browsers are not required to follow
           the redirection, and in some situations (when using XHTML),
           such automatic redirection is not supported.

           This configures the text that is shown in the anchor which
           the user may click to be redirected to a basic HTML version
           of your application.
          -->
        <redirect-message>Load basic HTML</redirect-message>

        <!-- Whether we are sitting behind a reverse proxy

           When deployed behind a reverse proxy (such as Apache or Squid),
           the server location is not read from the "Host" header,
           but from the X-Forwarded-For header, if present.
          -->
        <behind-reverse-proxy>true</behind-reverse-proxy>

        <!-- Whether inline CSS is allowed.

           Some Wt widgets will insert CSS rules in the the inline
           stylesheet when first used. This can be disabled using this
           configuration option.

           Note: some widgets, such as WTreeView and WTableView,
           dynamically manipulate rules in this stylesheet, and will
           no longer work properly when inline-css is disabled.
          -->
        <inline-css>true</inline-css>

        <!-- The timeout before showing the loading indicator.

           The value is specified in ms.
          -->
        <indicator-timeout>500</indicator-timeout>

        <!-- The timeout for processing a double click event.

           The value is specified in ms.
          -->
        <double-click-timeout>200</double-click-timeout>

        <!-- Ajax user agent list

           Wt considers three types of sessions:
           - Ajax sessions: use Ajax and JavaScript
           - plain HTML sessions: use plain old server GETs and POSTs
           - bots: have clean internal paths and no persistent sessions

           By default, Wt does a browser detection to distinguish between
           the first two: if a browser supports JavaScript (and has it
           enabled), and has an Ajax DOM API, then Ajax sessions are chosen,
           otherwise plain HTML sessions.

           Here, you may indicate which user agents should or should
           not receive an Ajax session regardless of what they report as
           capabilities.

           Possible values for 'mode' or "white-list" or "black-list". A
           white-list will only treat the listed agents as supporting Ajax,
           all other agents will be served plain HTML sessions. A black-list
           will always server plain HTML sessions to listed agents and
           otherwise rely on browser capability detection.

           Each <user-agent> is a regular expression.
          -->
        <user-agents type="ajax" mode="black-list">
          <!-- <user-agent>.*Crappy browser.*</user-agent> -->
        </user-agents>

        <!-- Bot user agent list

           Here, you can specify user agents that should be should be
           treated as bots.

           Each <user-agent> is a regular expression.
          -->
        <user-agents type="bot">
          <user-agent>.*Googlebot.*</user-agent>
          <user-agent>.*msnbot.*</user-agent>
          <user-agent>.*Slurp.*</user-agent>
          <user-agent>.*Crawler.*</user-agent>
          <user-agent>.*Bot.*</user-agent>
          <user-agent>.*ia_archiver.*</user-agent>
          <user-agent>.*Twiceler.*</user-agent>
        </user-agents>

        <!-- Configures different rendering engines for certain browsers.

           Currently this is only used to select IE7 compatible rendering
           engine for IE8, which solves problems of unreliable and slow
           rendering performance for VML which Microsoft broke in IE8.

           Before 3.3.0, the default value was IE8=IE7, but since 3.3.0
           this has been changed to an empty string (i.e. let IE8 use the
           standard IE8 rendering engine) to take advantage of IE8's
           improved CSS support. If you make heavy use of VML, you may need
           to revert to IE8=IE7.
          -->
        <UA-Compatible></UA-Compatible>

        <!-- Configures whether the progressive bootstrap method is used.

           The default bootstrap method first senses whether there is Ajax
           support, and only then creates the application.

           The progressive bootstrap method first renders a plain HTML
           version and later upgrades to an Ajax version.

           (Not to be confused with the Twitter Bootstrap theme)
          -->
        <progressive-bootstrap>true</progressive-bootstrap>

        <!-- Set session-ID cookie

           In its default (and recommended) configuration, Wt does not
           rely on cookies for session tracking.

           Wt has several mechanisms in place to prevent session ID stealing:
           - for an Ajax session, the session ID is not shown in the URL,
             avoiding session ID stealing through a referer attack.
           - in case the session ID is present in the URL (e.g. for a plain
             HTML session), Wt will redirect links to images or external
             anchors through an intermediate page that censors the session ID

           In case of the loss of a session ID, the impact is minimized:
           - a full page refresh is not supported if the client IP address
             changes or the user-agent changes
           - an Ajax update is protected by other state which is not exposed
             in the URL

           To still enable a full page refresh when the client IP address
           changes, an additional cookie may be set which is used only
           for this purpose, and can be enabled using this setting.
          -->
        <session-id-cookie>true</session-id-cookie>

        <!-- Configure cookie checks

         By default, Wt will test for cookie support using JavaScript.
         Because cookie manipulation from JavaScript is a common security
         risk vector, some prefer to disable these checks.
        -->
        <cookie-checks>true</cookie-checks>

        <!-- Runtime Properties

           These properties may be used to adapt applications to their
           deployment environment. Typical use is for paths to resources
           that may or may not be shared between several applications.
          -->
        <properties>
            <!-- baseURL property

               The absolute URL at which the application is deployed
               (known to the user). This is needed only in two scenarios.

               a) use of relative URLs in included XHTML

               When you use relative URLs for images, etc... in
               literal XHTML fragments (e.g. in WTemplate), which need
               to resolve against the deployment path of the
               application. This will not work as expected in the
               presence of an internal application path.  This URL is
               set as base URL in the HTML, against which relative
               URLs are resolved so that these work correctly
               regardless of the internal path. It is also used
               explicitly in any URL generated by the library.

               b) widgetset mode deployments

               Another situation in which you need to define the baseURL is
               when deploying a widgetset mode application behind a reverse
               proxy. A widgetset mode application uses only absolute URLs
               because it may be hosted in a web page from an entirely
               different domain.

               By default, no baseURL is specified, in which case Wt will
               avoid using absolute URLs. Relative URLs passed in API calls
               will be "fixed" so that they resolve against the location of the
               application deploy path, even in the presence of an
               internal path.
              -->
            <!-- <property name="baseURL">"http://mysite.com/app</property> -->

            <!-- resourcesURL property

               The URL at which the resources/ folder is deployed that
               comes distributed with Wt and contains auxiliary files
               used to primarily for styles and themes.

               The default value is 'resources/'
              -->
            <property name="resourcesURL">../resources/</property>

            <!-- extBaseURL property

               Used in conjunction with Ext:: widgets, and points to the
               URL of Ext JavaScript and resource files (css, images).
               See the documentation for the Ext namespace for details.

               The default value is 'ext/'
              -->
            <property name="extBaseURL">ext/</property>

            <!-- favicon property

               By default, a browser will try to fetch a /favicon.ico icon
               from the root of your web server which is used as an icon
               for your application. You can specify an alternative location
               by setting this property, or for an individual application
               entry point by passing a location to WServer::addEntryPoint().
              -->
            <!-- <property name="favicon">images/favicon.ico</property> -->
        </properties>

    </application-settings>


    <!-- Override settings for specific applications.

       Location refers to physical filesystem location of the
       application. The application prints this location (which
       corresponds to argv[0]) to the log file on startup, and this
       should match exactly.
      -->
    <!--
    <application-settings
       location="/var/www/localhost/wt-examples/hello.wt">
    </application-settings>
    -->
</server>