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All extensions (scriptable variables and components) have access to a VU storage component that can pass seamlessly pass data between extensions.

Accessing the storage

Scriptable variables can access the VU storage through the SessionContext.SetObject() and SessionContext.GetObject() methods.

Components can access the VU storage through the RuntimeVU.SetObject(), RuntimeVU.GetObject(), RuntimeSession.SetObject(), and RuntimeSession.GetObject() methods.

Example

Suppose a test case with 2 requests:

  • /GetAvailableBooks returns a list of available books
  • /CheckoutBook checks out a book

The requirement is to call /GetAvailableBooks to get a list of books, and then for each available book, call /CheckoutBook

The strategy is to call /GetAvailableBooks, then create a Do...While loop around /CheckoutBook as shown below

The first step is to extract all the books from the /GetAvailableBooks response into a list and store the list in the VU storage under the key ListOfBooks. We will create a component for that:

Extract all books
class ExtractBooksComponent : IExternalComponent2
{
    //---- Implement IExternalComponent2 

    /// <summary>
    /// Fired after a response is received.
    /// </summary>
    /// <param name="session">The session object</param>
    public void OnAfterResponse(RuntimeSession session)
    {
		var listOfBooks = new List<string>();
		
		var body = session.GetResponseBody();
		
		var regex = new System.Text.RegularExpressions.Regex("{some regular expression}");
		
		//--- regex.Matches(body) ... Match all books and add them to listOfBooks
		
		session.SetObject("ListOfBooks", listOfBooks);		
    }
}

Set the Component hook property of the request to ExtractBooksComponent

The next step is to create a scriptable variable, ReturnFirstBook, that will be used to parameterize /CheckoutBook request. We will create a scriptable variable that will read the VU storage for the list of available books, remove the first one, and return it.

Return first book
class ReturnFirstBook : IExternalVariable
{
    public ReturnFirstBook()
    {
        //Do not edit this section.
    }

    #region IExternalVariable Members

    /// <summary>
    /// Return true if the variable will be evaluated once per VU iteration. Otherwise will be evaluated on every parameter.
    /// </summary>
    bool IExternalVariable.EvaluateOnIteration
    {
        get 
        {
            return false;
        }
    }

    /// <summary>
    /// Return a value for the given session context.
    /// </summary>
    /// <param name="session">The session context object of the request consuming the variable.</param>
    /// <returns>The source variable value.</returns>
    string IExternalVariable.GetValue(SessionContext context)
    {
		var listOfBooks = context.GetObject("ListOfBooks") as List<string>;
		
		string book = null;
		
		if (listOfBooks.Count > 0)
		{
			book = listOfBooks[0];
			listOfBooks.RemoveAt(0);
		}
		return book;
    }

    #endregion
}

Then use the scriptable variable as a parameter in /CheckoutBook.

Finally, we will add a scriptable variable that will return the number of available books remaining that have not yet been checked.

Any books left?
using System;
using StresStimulus.Extensibility;
using System.Data;
using System.Collections.Generic;
using System.Linq;

class NumberOfBooksLeft : IExternalVariable
{
    public NumberOfBooksLeft()
    {
        //Do not edit this section.
    }

    /// <summary>
    /// Return true if the variable will be evaluated once per VU iteration. Otherwise will be evaluated on every parameter.
    /// </summary>
    bool IExternalVariable.EvaluateOnIteration
    {
        get 
        {
            return false;
        }
    }

    /// <summary>
    /// Return a value for the given session context.
    /// </summary>
    /// <param name="session">The session context object of the request consuming the variable.</param>
    /// <returns>The source variable value.</returns>
    string IExternalVariable.GetValue(SessionContext context)
    {
        var listOfBooks = context.GetObject("ListOfBooks") as List<string>;
		
		return listOfBooks.Count.ToString();
    }
}

In the Do...While loop set the following properties:

  • Condition type: Match scriptable variable
  • Scriptable variable to match: NumberOfBooksLeft
  • Text-to-match: 0
  • Exit loop if match found: Yes


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