wt_config.xml.example

<!--
    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 wthttp.

    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.

            Note: currently only supported by the wtfcgi and wthttp
            connectors.
        -->

        <!--
            <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: the wthttp connector will ignore the num-processes
            setting and use only 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

            It is recommended to stick to URL rewriting for session
            tracking as this is more secure (it avoids the risk of attacks
            like CSRF or BREACH), and also provides proper support for
            concurrent sessions in a single browser.
        -->
        <tracking>URL</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>true</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 wthttp 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>/var/run/wt</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 wthttp 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:
        - naked: JavaScript errors are not caught at all
        - false: JavaScript errors are caught and a simple error message
        is printed to indicate that something is terribly wrong
        - stack: equivalent to 'false'
        - true: JavaScript errors are rethrown after server-side logging

        Unless the value is 'naked',
        WApplication::handleJavaScriptError() is called which by
        default logs the error and terminates the session.
    -->
    <debug>false</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>128</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>true</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>

    <!-- Enables the detection of webgl-capabilites.

        When this is enabled, the browser will try to create a
        webgl-context when loading to verify that it is possible. This
        is neccesary when using WGLWidget.

        This can take up some load time. When your application does not
        use WGLWidget, this option can be set to false. It will improve
        the initial loading time of the web-application.
    -->
    <webgl-detection>true</webgl-detection>

    <!-- 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.

        This option is required to make e.g. clientAddress() return the
        correct address.
    -->
    <behind-reverse-proxy>false</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
        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>false</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>false</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>

    <!-- Configure meta headers

        The user-agent allows optional filtering based on the
        user-agent, using a regular expression. You can have multiple
        set-meta-headers definitions.
    -->
    <meta-headers user-agent=".*MSIE.*">
      <meta name="robots" content="noindex" />
    </meta-headers>

    <!-- 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">favicon.ico</property>
        
        <!-- Email notifications

            These configure the email address used to send emails
        -->
        <!--
            <property name="auth-mail-sender-name">WP4 Mail Bot</property>
            <property name="auth-mail-sender-address">foo@bar.com</property>
        -->
    </properties>

    </application-settings>


</server>