mirror of https://github.com/apache/jmeter.git
410 lines
20 KiB
XML
410 lines
20 KiB
XML
<?xml version="1.0"?>
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<!--
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$Header$
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Copyright 2001-2004 The Apache Software Foundation
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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<document prev="component_reference.html" next="glossary.html" date="$Date$">
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<properties>
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<title>User's Manual: Introduction</title>
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</properties>
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<body>
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<section name="15. Functions" anchor="functions">
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<p>
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JMeter functions are special values that can populate fields of any Sampler or other configuration
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element in a test tree. A function looks like this:</p>
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<p><code>${__functionName(var1,var2,var3)}</code></p>
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<p>Where "__functionName" matches the name of an existing built-in or user-defined function.<br/>
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Parentheses surround the parameters sent to the function. The actual parameters vary from function
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to function. Functions that require no parameters can leave off the parentheses. The function itself
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is wrapped in ${}.</p>
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<subsection name="15.1 What can functions do" anchor="what_can_do">
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<p>There are two kinds of functions: user-defined static values, and built-in functions.<br/>
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User-defined static values allow the user to define variables to be replaced with their static value when
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a test tree is compiled and submitted to be run. This replacement happens once at the beginning of the test
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run. This could be used to replace the DOMAIN field of all HTTP requests, for example - making it a simple
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matter to change a test to target a different server with the same test.
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</p>
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<p>This type of replacement is possible without functions, but was less convenient and less intuitive.
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It required users to create default config elements that would fill in blank values of Samplers. User-defined
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functions allow one to replace only part of any given value, not just filling in blank values.</p>
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<p>
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With built-in functions users can compute new values at run-time based on previous response data, which
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thread the function is in, the time, and many other sources. These values are generated fresh for every
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request throughout the course of the test. </p>
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</subsection>
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<subsection name="15.2 Where can functions be used?" anchor="where">
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<p>A user-defined function can be written into any field of any test component. Some fields do not allow random strings
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because they are expecting numbers, and thus will not accept a function. However, most fields will allow
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functions.</p>
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<p>Built-in functions can be written into any field of non-controller test components. This includes
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Samplers, Timers, Listeners, Modifiers, Assertions, Pre-Processors, Post-Processors and Config Elements.</p>
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</subsection>
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<subsection name="15.3 Writing the function string" anchor="how">
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<p>User-defined functions take the form: <code>${varName}</code>. In the TestPlan tree element, a two-column table
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of user-defined values is kept, matching up variable names with static values. Referencing the
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variable in a test element is done by bracketing the variable name with '${' and '}'.</p>
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<p>Built-in functions are written in the same manner, but by convention, the names of built-in
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parameters begin with "__" to avoid conflict with user value names<sup>*</sup>. Some functions take arguments to
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configure them, and these go in parentheses, comma-delimited. If the function takes no arguments, the parentheses can
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be left out. A further complication for argument values that themselves contain commas is that the value
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should be escaped as necessary. Thus, if you need to include a comma in your parameter value, escape it like so: '\,'. JMeter provides a tool to help you construct
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function calls for various built-in functions, which you can then copy-paste. It will not automatically escape values for you, since functions can be parameters to other functions, and you should only escape values you intend as literal.</p>
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<note><sup>*</sup>If you define a user-defined static variable with the same name as a built-in function, your static
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variable will override the built-in function.</note>
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</subsection>
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<subsection name="15.4 The Function Helper Dialog" anchor="function_helper">
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<p>The Function Helper dialog is available from JMeter's Tools menu.</p>
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<figure image="function_helper_dialog.png">Function Helper Dialog</figure>
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<p>Using the Function Helper, you can select a function from the pull down, and assign
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values for its arguments. The left column in the table provides a brief description of the
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argument, and the right column is where you write in the value for that argument. Different
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functions take different arguments.</p>
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<p>Once you have done this, click the "generate" button, and the appropriate string is generated
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for you to copy-paste into your test plan wherever you like.</p>
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</subsection>
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<subsection name="15.5 Functions" anchor="functions">
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<component index="15.5.1" name="__regexFunction">
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<description><p>The Regex Function is used to parse the previous response using any regular
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expression (provided by user). The function returns the template string with variable values filled
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in.</p>
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<p>The __regexFunction stores values for future use. In the sixth parameter, you can specify
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a reference name. After this function executes, the same values can be retrieved at later times
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using the syntax for user-defined values. For instance, if you enter "refName" as the sixth
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parameter you will be able to use:
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<ul>
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<li>${refName} to refer to the computed result of the second parameter ("Template for the
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replacement string") parsed by this function</li>
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<li>${refName_g0} to refer to the entire match parsed by this function.</li>
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<li>${refName_g1} to refer to the first group parsed by this function.</li>
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<li>${refName_g#} to refer to the n<sup>th</sup> group parsed by this function.</li>
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</ul>
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</p></description>
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<properties>
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<property name="First arguement" required="Yes">The first argument is the regular expression
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to be applied to the response data. It will grab all matches. Any parts of this expression
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that you wish to use in your template string, be sure to surround in parentheses. Example:
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&lt;a href="(.*)"&gt;. This will grab the value of the link and store it as the first group (there is
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only 1 group). Another example: &lt;input type="hidden" name="(.*)" value="(.*)"&gt;. This will
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grab the name as the first group, and the value as the second group. These values can be used
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in your template string</property>
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<property name="Second argument" required="Yes">This is the template string that will replace
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the function at run-time. To refer to a group captured in the regular expression, use the syntax:
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$[group_number]$. Ie: $1$, or $2$. Your template can be any string.</property>
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<property name="Third argument" required="Yes">The third argument tells JMeter which match
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to use. Your regular expression might find numerous matches. You have four choices:
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<ul><li>An integer - Tells JMeter to use that match. '1' for the first found match, '2' for the
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second, and so on</li>
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<li>RAND - Tells JMeter to choose a match at random.</li>
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<li>ALL - Tells JMeter to use all matches, and create a template string for each one and then
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append them all together. This option is little used.</li>
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<li>A float number between 0 and 1 - tells JMeter to find the Xth match using the formula:
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(number_of_matches_found * float_number) rounded to nearest integer.</li>
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</ul></property>
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<property name="Fourth argument" required="No">If 'ALL' was selected for the above argument
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value, then this argument will be inserted between each appended copy of the template value.</property>
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<property name="Fifth argument" required="No">Default value returned if no match is found</property>
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<property name="Sixth argument" required="No">A reference name for reusing the values parsed by this function.<br></br>
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Stored values are ${refName} (the replacement template string) and ${refName_g#} where "#" is the
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group number from the regular expression ("0" can be used to refer to the entire match).</property>
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</properties>
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</component>
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<component index="15.5.2" name="__counter">
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<description><p>The counter generates a new number each time it is called, starting with 1
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and incrementing by +1 each time. The counter can be configured to keep each simulated user's values
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separate, or to use the same counter for all user. If each user's values is incremented separately,
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that is like counting the number of iterations through the test plan. A global counter is like
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counting how many times that request was run.</p></description>
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<properties>
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<property name="First argument" required="Yes">TRUE if you wish each simulated user's counter
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to be kept independent and separate from the other users. FALSE for a global counter.</property>
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<property name="Second argument" required="Yes">A reference name for reusing the value created by this function.<br></br>
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Stored values are of the form ${refName}. This allows you to keep one counter and refer to its value in
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multiple places.</property>
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</properties>
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</component>
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<component index="15.5.3" name="__threadNum">
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<description><p>The thread number function simply returns the number of the thread currently
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being executed. These numbers are independent of ThreadGroup, meaning thread #1 in one threadgroup
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is indistinguishable from thread #1 in another threadgroup, from the point of view of this function.</p>
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<p>There are no arguments for this function.</p>
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</description>
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</component>
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<component index="15.5.4" name="__intSum">
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<description><p>The intsum function can be used to compute the sum of two or more integer values.
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</p></description>
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<properties>
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<property name="First argument" required="Yes">The first int value.</property>
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<property name="Second argument" required="Yes">The second int value.</property>
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<property name="nth argument" required="No">The nth int value.</property>
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<property name="last argument" required="Yes">A reference name for reusing the value
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computed by this function.</property>
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</properties>
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</component>
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<component index="15.5.5" name="_StringFromFile">
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<description>
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<p>
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The StringFromFile function can be used to read strings from a text file.
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This is useful for running tests that require lots of variable data.
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For example when testing a banking application, 100s or 1000s of different account numbers might be required.
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</p>
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<p>
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Each time it is called it reads the next line from the file.
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When the end of the file is reached, it will start reading again from the beginning.
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If there are multiple references to the function in a test script, each will open the file independently,
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even if the file names are the same.
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[If the value is to be used again elsewhere, use different variable names for each function call.]
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</p>
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<p>If an error occurs opening or reading the file, then the function returns the string "**ERR**"</p>
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</description>
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<properties>
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<property name="File Name" required="Yes">Path to the file name.
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(The path can be relative to the JMeter launch directory)
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If using optional sequence numbers, the path name should be suitable for passing to DecimalFormat.
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See below for examples.
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</property>
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<property name="Variable Name" required="No">
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A reference name - refName - for reusing the value created by this function. Stored values are of the form ${refName}.
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</property>
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<property name="Start sequence number" required="No">Initial Sequence number</property>
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<property name="End sequence number" required="No">Final sequence number (if omitted, seqence numbers can increase without limit)</property>
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</properties>
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<p>The file name parameter is resolved when the file is opened or re-opened.</p>
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<p>The reference name parameter (if supplied) is resolved every time the function is executed.</p>
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<p><b>Using sequence numbers:</b></p>
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<p>When using the optional sequence numbers, the path name is used as the format string for java.text.DecimalFormat.
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The current sequence number is passed in as the only parameter.
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If the optional sequence numbers are not used, the path name is used as is.
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Useful formatting sequences are:
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<pre>
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# - insert the number, with no leading zeros or spaces
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000 - insert the number packed out to 3 digits with leading zeros if necessary
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Examples:
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pin#.dat -> pin1.dat, ... pin9.dat, pin10.dat, ... pin9999.dat
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pin000.dat -> pin001.dat ... pin099.dat ... pin999.dat ... pin9999.dat
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</pre>
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If more digits are required than there are formatting characters, the number will be
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expanded as necessary. To prevent a formatting character from being interpreted,
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enclose it in single quotes. See the documentation for DecimalFormat for full details.
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<br></br>
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If the path name does not contain any special formatting characters,
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it will be unaffected by the current sequence number.
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In this case, specifying only a start sequence number will have no effect,
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but specifying a start and end sequence number will result in the file
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being used at mose end-start+1 times.
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</p>
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</component>
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<component index="15.5.6" name="__machineName">
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<description><p>The machineName function returns the local host name</p></description>
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<properties>
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<property name="Name of function" required="Yes">A reference name for reusing the value
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computed by this function.</property>
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</properties>
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</component>
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<component index="15.5.7" name="__javaScript">
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<description><p>The javaScript function executes a piece of JavaScript (not Java!) code and returns its value</p>
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</description>
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<properties>
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<property name="Expression" required="Yes">The JavaScript expression to be executed. For example:
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<ul>
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<li>new Date() - return the current date and time</li>
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<li>Math.floor(Math.random()*(${maxRandom}+1))
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- a random number between 0 and the variable maxRandom</li>
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<li>${minRandom}+Math.floor(Math.random()*(${maxRandom}-${minRandom}+1))
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- a random number between the variables minRandom and maxRandom</li>
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</ul>
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</property>
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<property name="Name of function" required="Yes">A reference name for reusing the value
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computed by this function.</property>
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</properties>
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</component>
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<component index="15.5.8" name="__Random">
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<description><p>The random function returns a random number that lies between the given min and max values.</p></description>
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<properties>
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<property name="Minimum value" required="Yes">A number</property>
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<property name="Maximum value" required="Yes">A bigger number</property>
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<property name="Name of function" required="Yes">A reference name for reusing the value
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computed by this function.</property>
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</properties>
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</component>
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<component index="15.5.8" name="__CSVRead">
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<description><p>The CSVFile function returns a string from a CSV file (c.f. <a href="#_StringFromFile">StringFromFile</a>)</p>
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<p>NOTE: versions up to 1.9.1 only supported a single file.
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JMeter versions since 1.9.1 support multiple file names.
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</p>
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<p>
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When a filename is first encountered, the file is opened and read into an internal
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array. If a blank line is detected, this is treated as end of file - this allows
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trailing comments to be used (N.B. this feature was introduced in versions after 1.9.1)
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</p>
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<p>All subsequent references to the same file name use the same internal array.
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N.B. the filename case is significant to the function, even if the OS doesn't care,
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so CSVRead(abc.txt,0) and CSVRead(aBc.txt,0) would refer to different internal arrays.
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</p>
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<p>
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The *ALIAS feature allows the same file to be opened more than once,
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and also allows for shorter file names.
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</p>
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<p>
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Each thread has its own internal pointer to its current row in the file array.
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When a thread first refers to the file it will be allocated the next free row in
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the array, so each thread will access a different row from all other threads.
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[Unless there are more threads than there are rows in the array.]
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</p>
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</description>
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<properties>
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<property name="File Name" required="Yes">The file (or *ALIAS) to read from</property>
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<property name="Column number" required="Yes">
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The column number in the file.
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0 = first column, 1 = second etc.
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"next" - go to next line of file.
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*ALIAS - open a file and assign it to the alias
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</property>
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</properties>
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</component>
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<component index="15.5.9" name="__property">
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<description><p>The property function returns the value of a JMeter property.
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If the property value cannot be found, and no default has been supplied, it returns the property name.
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When supplying a default value, there is no need to provide a function name - the parameter can be set to null, and it will be ignored.
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</p>For example:<p>
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<code>
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<pre>
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${__property(user.dir)} - return value of user.dir
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${__property(user.dir,UDIR)} - return value of user.dir and save in UDIR
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${__property(abcd,ABCD,atod)} - return value of property abcd (or "atod" if not defined) and save in ABCD
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${__property(abcd,,atod)} - return value of property abcd (or "atod" if not defined) but don't save it
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</pre>
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</code></p>
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</description>
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<properties>
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<property name="Property Name" required="Yes">The property name to be retrieved.</property>
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<property name="Name of function" required="No">A reference name for reusing the value
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computed by this function.</property>
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<property name="Default Value" required="No">The default value for the property.</property>
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</properties>
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</component>
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<component index="15.5.10" name="__P">
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<description><p>This is a simplified property function which is
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intended for use with properties defined on the command line.
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If the property is not found, the default is returned.
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If no default was provided, then returns 1.
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</p>For example:<p>
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<code>
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<pre>
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Define the property value:
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jmeter -Jgroup1.threads=7 -Jhostname1=www.realhost.edu
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Fetch the values:
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${__P(group1.threads)} - return the value of group1.threads
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${__P(group1.loops)} - return the value of group1.loops
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${__P(hostname,www.dummy.org)} - return value of property hostname or www.dummy.org if not defined
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</pre>
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In the examples above, the first function call would return 7,
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the second would return 1 and the last would return www.dummy.org
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(unless those properties were defined elsewhere!)
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</code></p>
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</description>
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<properties>
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<property name="Property Name" required="Yes">The property name to be retrieved.</property>
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<property name="Default Value" required="No">The default value for the property.
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If omitted, the default is set to "1".</property>
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</properties>
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</component>
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<component index="15.5.11" name="__log">
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<description>
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<p>
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The log function logs a message, and returns its input string
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</p>
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</description>
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<properties>
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<property name="String to be logged" required="Yes">A string</property>
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<property name="Log Level" required="No">DEBUG, INFO (default), WARN or ERROR</property>
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<property name="Throwable text" required="No">If non-empty, creates a Throwable to pass to the logger</property>
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</properties>
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</component>
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<component index="15.5.12" name="__logn">
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<description>
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<p>
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The logn function logs a message, and returns the empty string
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</p>
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</description>
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<properties>
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<property name="String to be logged" required="Yes">A string</property>
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<property name="Log Level" required="No">DEBUG, INFO (default), WARN or ERROR</property>
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<property name="Throwable text" required="No">If non-empty, creates a Throwable to pass to the logger</property>
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</properties>
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</component>
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<component index="15.5.13" name="__BeanShell">
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<description>
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<p>
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The BeanShell function evaluates the script passed to it, and returns the result.
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</p>
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</description>
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<properties>
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<property name="BeanShell script" required="Yes">A script</property>
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<property name="Name of variable" required="No">A reference name for reusing the value
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computed by this function.</property>
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</properties>
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</component>
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</subsection>
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</section>
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</body>
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</document> |