Getting started with scripting

A script is a simple computer program that communicates instructions to an application like Echoview. Scripts can save time because they enable you to automate repetitive tasks. This topic briefly discusses the things you need to know, or need to do, in order to begin writing scripts for Echoview. Examples are given for VBScript.

To use the Automation module you will need to have an installed copy of Echoview and be licensed for the Automation module and have registered Echoview COM.

To write a script you need to:

  1. Decide which tasks you want Echoview to carry out. This includes decisions about data files, EV files, EV file templates and desired analysis outputs.
  2. Select a scripting language or computer language that can create and use COM objects.
  3. Use the syntax of the selected language together with supported commands or COM objects to communicate with Echoview.

Echoview's scripting interface

COM object interface

The COM object interface (introduced with Echoview 4.10) offers COM objects. The automation of Echoview can come from a script, web page or other program.

Script languages

Choose a scripting language or computer language that can create and use COM objects. A general discussion about scripting languages can be found at https://en.wikipedia.org/wiki/Scripting_language.

VBScript

You can download example scripts from the Echoview website under Technical support > Scripts

The help file also provides example COM object scripts.

If you are going to use Windows Script Host to write scripts, you will need to have Windows Script Host installed on your computer. See Installing Windows Script Host.

Other languages

Other languages include (but are not limited to): Python®, R, MATLAB, JScript, Java script, Visual Basic, Visual Basic for Applications, Borland C++ Builder, Delphi, Visual C++, C# and Visual J++

Windows Script Files

Windows Script Files (.wsf) can be useful in a number of ways. In a WSF file you can:

The following is a .wsf script that consists of:

Multiple_scripts_WSF

WSF tag

Description

yellow

A definition for the Echoview type library, so that you can use Echoview COM enum names rather than enum values.

Blue

Multiple scripts.

Purple

Different script languages.

orangish

Job.

<job id="Multiple-language-example">
<reference object="EchoviewCom.EvApplication"/>
<script language="VBScript">
    Option Explicit
    Const fName = "C:/Echoview Software/Echoview/EchoviewN/EVFiles/FileA.EV"
               
    ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
    ' A simple example
    ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
    Dim EvApp
    Set EvApp = CreateObject("EchoviewCom.EvApplication")
    ' Open the EV file
    Dim EvFile
    Set EvFile = EvApp.OpenFile(fName)
    If Not EvFile Is Nothing Then
            MsgBox "Successfully opened EV file with VBScript:" & vbcrlf & EvFile.FileName
            EvFile.Close
    Else 
            MsgBox "Failed to open EV file '" & fName & "' with VBScript."
    End If
    
</script>
<script language="JScript">
    // Start of the JScript code
    // Note that we can still use constants And variables which were declared in the
    // VBScript code above, so we don't have to re-declare EvApp, EvFile, etc.
    // And we can still use the 'fName' constant for the file Name
    // Connect To Echoview - commented out because the EvApp Object from above
    // can still be used
    // var EvApp;
    // EvApp = new ActiveXObject("EchoviewCom.EvApplication");
    // This declaration also doesn't have to be made again
    // var fname = "C:/Echoview Software/Echoview/EchoviewN/EVFiles/FileA.EV";
    // var EvFile;
    EvFile = EvApp.OpenFile(fname);
    // Note that keywords like 'if', 'else' and 'null' are case-sensitive in JScript
      if (EvFile != null) {
      WScript.echo("Successfully opened EV file with JScript:\n"  + EvFile.FileName);
        EvFile.Close();
    } else {
        WScript.echo("Failed to open EV file '" + fName + "' with JScript.");
    }
</script>
</job>

Code snippet that you can copy/paste into a plain text editor and save as a *.wsf file.

"fname" can be edited to refer to a different EV file name and path.

To execute the job in this .wsf, simply double-click the file.

Note: You must have Windows Script Host installed on your computer to run .wsf.

For further information refer to:

Script editors

Text editor

Plain text editors (Notepad, for instance) provide a medium in which to view and write scripts quickly. However you can't do much more than write new scripts, or copy/paste snippets of code to customize your data. You save the script with an appropriate file extension. For example, a script file written using VBScript has a .vbs extension.

See also Example scripts for COM automation.

Text editor with features

Enhanced editors can provide tools that help you modify, create and debug scripts. Tools can include a COM object browser, debugging features, an interactive display for COM object methods and properties and code snippets. Such editors can be open-source applications or be applications available for trial and/or purchase (such as VBSedit).

Script content and structure

Content

The content of a script is reflection of the tasks you are able to ask Echoview to do. Echoview supports a COM scripting model, it is easy to program with and continues to evolve.

With knowledge of the set of accessible settings and processes, you can then consider the tasks you want to automate. This includes decisions about data files, EV files, EV file templates, analyses and outputs.

Language syntax

The syntax of your chosen language allows you construct a script for the tasks that you want Echoview to perform.

A script consists of:

Statements Syntax elements or syntax elements with COM object syntax/export scripting commands.
Comments Text within the script for documentation.

VBScript statements that are useful include:

There are many training materials that cover language syntax. Examples of useful materials that can be found on the internet are:

ADOBE INTRODUCTION TO SCRIPTING

A useful overview of scripting with topics on COM objects. Examples are targeted towards ADOBE applications.

VBScript Tutorials - Herong's Tutorial Notes

Extensive tutorials and examples for the syntax available with VBScript.

VBScript Fundamentals for Windows Scripting – The Basics

Short treatment of the VBScript basics with two annotated script examples.

WSH Tutorial Light (Free Stuff)

Extensive tutorials and examples for the syntax available with VBScript (Appendix C) and JScript (Appendix D).

Visual Basic Guide

Microsoft Technet - Visual Basic guide.

Using Echoview scripting objects

Accessing object properties and methods

To access a COM object’s property or method, you type the object followed by a period and then the method or property.

To access the version number of your Echoview application, you would query the Version property of the EvApplication object:

EvApp.Version
EvApp refers to the object Echoview.EvApplication, which has been declared as a script variable earlier in a script.

To access an object’s method, you follow the same rules, but also add brackets around the parameters.

EvApp.OpenFile("C:\Program Files\Echoview Software\Echoview N\Echoview\AutoOpen.EV")

This example uses the  EvApplication method OpenFile to open AutoOpen.EV.

N is the Echoview version number.

In both of the previous examples script variables like EvApp can use the period modifier (with objects and their methods and properties) as well.

Dim and Set

In a VBScript, before you use Echoview scripting objects, you need to initiate access to the objects. The Dim and Set statements are important in initiating access to objects.

The script variables declared by the Dim/Set statements represent the objects, object properties and object methods that you want to work with. An incidental benefit of using script variables is that long COM object expressions can be referred to instead of being used as is through the script.

At the beginning of a script, Dim and Set are used to connect to Echoview using the EvApplication object. Refer to Scripting with COM objects - Creating_a_script.

Advancing through a script, access to other COM objects is managed in a similar way.

The following COM script snippet is from PickLine.vbs.

Dim EvApp: Set EvApp = CreateObject("EchoviewCom.EvApplication")
 fOut.WriteLine "Echoview version: " & EvApp.Version & " at " & Date & " " & Time
' Open the EV file
Dim EvFile: Set EvFile = EvApp.OpenFile(ScriptsFolder & "EVFiles\FileA.EV")
 If EvFile Is Nothing Then
   fOut.WriteLine "Could not open EV file - " & EvApp.GetLastLogMessage
   WScript.Quit
 End If 

 

The first Dim/Set pair connects to the Echoview COM scripting object EchoviewCom.EvApplication.

The second Dim/Set pair connects to the OpenFile method of the EvApplication object.

Using enums

Some object properties use enums to refer to specific Echoview settings. Script languages can require you to refer to enums in particular ways.

To use an enum name rather than the enum value:

Further script examples

If you have previous programming experience, example scripts can be useful as demonstration/learning and (script) templating tools.

Example COM scripts are discussed in Example scripts for COM automation. A selection of these scripts emulate the outcome of several export analysis scripts (see below). Other scripts demonstrate more advanced tasks.

See also

About automating Echoview
Scripting with COM objects
COM object hierarchy