Pro/WebLink: Tips On Getting Started

Pro/WebLink is one of the free PFC based API's available for automating Pro/Engineer. Although the documentation and marketing literature is focused on using Javascript with Pro/WebLink, VBScript can be used if that is more to your taste.

Developers interested in writing Pro/WebLink application have to overcome a number of hurdles. Most of these are related to the Internet Explorer and Mozilla security models, because Pro/WebLink applications typically must run within the context of the Pro/Engineer embedded web browser. This differs from the VB API (new with Wildfire 4.0), which runs outside of the Pro/Engineer process and has far fewer security issues to worry about.

While security is not the only problem facing Pro/WebLink developers, it is the most common problem in my experience. In this article I'll discuss the necessary steps in setting up your environment to run Pro/WebLink applications.

Pro/ENGINEER Configuration

Use of Pro/WebLink requires that the config.pro option WEB_ENABLE_JAVASCRIPT be set to ON (the default is OFF). In Windows, if this option is set to ON when Pro/ENGINEER is started, pfcscom.dll will be registered as a COM server. This contains all of the Pro/WebLink functionality.

Generally this works very well, but I have seen problems where the DLL doesn't get registered, or some other similar problem occurs preventing the Pro/WebLink application from functioning. The workaround is to run the application as an administrative user first, then the program works for everyone. Fortunately, I have only seen one user affected like this, otherwise the workaround would get really annoying.

None of that is relevant in Unix, as the required XPCOM technology is already present in the embedded Mozilla browser. However, I have seen rare instances where the Mozilla profile in the user's unix home directory has become corrupted. The resolution is to delete the profile. Pro/Engineer will recreate it upon startup.

HTML SCRIPT Tag

When setting up your Pro/WebLink programs, you are likely to include one or more files containing your Javascript code. A common one to use, although it is not absolutely necessary, is the PTC supplied pfcUtils.js file. If you are going to use such functions as pfcCreate() and pfcGetProESession(), you need to make sure you include pfcUtils.js correctly to avoid confusing errors, such as "Object Expected".

You also need to ensure that the SCRIPT tag entry in your HTML code correctly locates the pfcUtils.js file. For example, this entry will find the bom2excel.js file if it is placed in the same folder as the HTML file, and the pfcUtils.js file if it is in the parent folder:

<SCRIPT LANGUAGE="JavaScript" type=text/javascript src="../pfcUtils.js"></SCRIPT>
<SCRIPT LANGUAGE="JavaScript" type=text/javascript src="bom2excel.js"></SCRIPT>

 

Your web browser may not complain in an obvious way if it cannot find one of your Javascript programs, making the resulting errors hard to diagnose. If using a web server, make sure that the web server process has sufficient permissions to read the HTML and JS files, otherwise you'll wind up with the same problems, but it will that much harder to diagnose.

Web Browser Security Models

Overcoming the security requirements of Wildfire's various supported web browsers is often frustrating because the requirements are not inherently obvious and the documentation can be hard to find. With Wildfire 4.0, Mozilla is the supported browser on Unix platforms and Internet Explorer is the browser for Windows. Both have different mechanisms and rules concerning security.

Using digitally signed applications allow the developer to bypass some security roadblocks by requesting enhanced functionality based on the user's "trust" of the developer. Digital signatures are far beyond the scope of this article however.

Internet Explorer Security

Internet Explorer security is based on zones: Internet, Local intranet, Trusted sites, and Restricted sites. Each zone has it own security settings enabling or disabling certain functionalities. Using the "Custom Level" button, each option can be enabled or disabled selectively. If you change any of the security options, you may need to restart Pro/Engineer for the changes to take effect in the embedded web browser.
It is recommended that you do not reduce security for the Internet zone. It would be better to add the web site to the Trusted sites zone, then adjust the security for that zone.

Internet Explorer will decide to which zone your application applies depending on how you access it. If you access your program from a web server using a fully qualified domain name (i.e. www.yahoo.com) for a site that is not in your Trusted sites list, Internet Explorer will consider it part of the Internet zone. Using an internal web server (i.e. without top level domain: .com, .org, .co.uk, etc) or accessing the program from your hard drive or a network hard drive, will cause Internet Explorer to use the Local intranet zone. Not surprisingly, the Trusted sites zone will apply to a site that is in the Trusted sites list, even if it is an internal web server.

Pro/WebLink applications need a couple of settings defined for the zone that will be used by your application. Some of these may already be the default for you. As PTC recommends in the documentation, the option "Initialize and script ActiveX controls not marked safe for scripting" should be set to "Prompt". If you are interacting with Excel from Pro/WebLink, this option may need to be set to "Enable".

Ensure that the option "Active Scripting" is set to "Enable".

Mozilla Security

Mozilla has some good security functionality in which a script can request enhanced functionality allowing the user to accept or deny the request. That's why you see some UniversalXPConnect requests in Pro/WebLink examples. The code has to ask for enhanced privileges to connect to Pro/Engineer and do something useful.

When the Pro/WebLink application is served from a web server, the code and HTML must be digitally signed (together) for this request process to work. To make matters worse, a very unusual jar:http: URL must be used to interact with the resulting JAR file that contains the code and HTML.

A workaround is not to use a web server, but instead access the code and HTML from the file system using a file: type URL. For Pro/WebLink applications, the user is generally prompted only once for enhanced privileges, then is good to from then on.

Review

Keeping some of these issues in mind will help you get up and running with Pro/WebLink avoiding many of the pitfalls and frustrations.

• Set WEB_ENABLE_JAVASCRIPT to ON in your config.pro file
• Ensure that HTML and JS files are located correctly
• Make sure that the web browser security requirements are satisfied

Pro/E VB API: Not Just for Visual Basic Anymore

In a previous article entitled "WebLink: What is it anyway?", I discussed Pro/WebLink and how it's not exactly a Javascript interface. Now it's the VB API's turn. The VB API is newly released by PTC with Wildfire 4. It is billed as a Visual Basic interface to PTC's PFC libraries, which is the same core that J-Link and Pro/WebLink are built upon.

While this is true, it's not that limited. Don't let the name scare you away from using your favorite COM accessible programming or scripting language to write Pro/Engineer applications. This is a good thing because it opens the API to a much wider range of applications.

In this article, I'll walk through sample applications written in Visual Basic, VBScript (using Windows Script Host), Perl, and Javascript (in a HyperText Application), all using the VB API. The sample application will connect to a Pro/Engineer session, obtain the session object, display the name of the current model, then disconnect from the Pro/Engineer session. Each program will display the model name in a different way.

Suggested reading is the section on the importance of disconnecting from Pro/Engineer in Pro/E VB API: A First Look.

Excel Macro

This is the standard and documented approach to the sample program. Objects are declared up front, the connection to Pro/Engineer is made, then the session object is obtained. The model name is displayed both in cell A1 and in a MsgBox.

Sub Macro1()

Dim asynconn As New pfcls.CCpfcAsyncConnection
Dim conn As pfcls.IpfcAsyncConnection
Dim session As pfcls.IpfcBaseSession
Dim mdlname

Set conn = asynconn.Connect("", "", ".", 5)
Set session = conn.session

mdlname = session.CurrentModel.Filename
Range("A1").Select
ActiveCell.FormulaR1C1 = mdlname
MsgBox ("Name: " & mdlname)
conn.Disconnect(2)

End Sub

 

VBScript

The VBScript code is almost identical except that VBScript doesn't seem to allow for the type declaration of the objects. As a result, the CreateObject() call is used to instantiate a pfcAsyncConnection object.

The program is executed using the following command line:

  cscript vbapi_script.vbs

 

Dim asynconn
Dim conn
Dim session
Dim mdlname

Set asynconn = CreateObject("pfcls.pfcAsyncConnection")
Set conn = asynconn.Connect("", "", ".", 5)
Set session = conn.session

mdlname = session.CurrentModel.Filename
MsgBox ("Name: " & mdlname)
conn.Disconnect(2)

 

Perl

As with most COM applications, the Perl syntax is also very similar to the VBScript code, but with Perl's own syntactical flavor. Win32::OLE->new() is the Perl equivalent to VBScript's CreateObject(). The Perl program outputs the model name to the command prompt (or standard output).

use Win32::OLE;
$asynconn = Win32::OLE->new("pfcls.pfcAsyncConnection");
$conn = $asynconn->Connect( "", "", ".", 5 );
$session = $conn->Session;
$mdlName = $session->CurrentModel->FileName;

print "mdlName: $mdlName", "\n";
$conn->Disconnect(2);

 

Javascript

Pro/WebLink applications can finally break out of the embedded browser jail using the VB API. This example uses a "Hypertext Application", which is a web page with a special HTA tag and with a file extension of ".hta" instead of ".htm". The pfcUtils.js file cannot be used as-is because it tries to use COM objects with "pfc." prefixes, instead of those associated with VB API which have "pfcls." prefixes.

Other than those differences, it's essentially a Pro/WebLink application. As with the other examples, because it's an asynchronous application, the code must connect to the Pro/Engineer session. This is a step that embedded browser based Pro/WebLink applications don't have to worry about.

<html>
<head>
<title>VB API Test</title>

<HTA:APPLICATION 
     ID="vbapi-test"
     APPLICATIONNAME="VB API Test"
     SCROLL="auto"
     SINGLEINSTANCE="yes"
>
</head>

<body>

<SCRIPT LANGUAGE="JavaScript">

function HitMe ( ) {
    var obj = null;
    var elem = document.getElementById("mesg");

    if (obj == null) {
        try {
            obj = new ActiveXObject("pfcls.pfcAsyncConnection");
        }
        catch (e) {
            elem.innerHTML = "Failed to create object";
            return;
        }
    }

    var conn = obj.Connect( "", "", ".", 5 );
    var session = conn.Session;
    var mdlName = session.CurrentModel.FileName;

    elem.innerHTML = "mdlName: " + mdlName;
    conn.Disconnect(2);
}

</SCRIPT>

<form name="f">
  <INPUT name="a" type=button value="Hit me!" onclick="HitMe()">
  <br><a id="mesg"></a><br>
</form>

</body>
</html>

 

These are just a few of the possibilities. As you can see, there is nothing really Visual Basic specific about the VB API. It's just an API.

Pro/WebLink: Send Excel Data To Pro/ENGINEER Drawing Tables, and Back Again - Part 2

In part 1, the transfering of data from Excel to Pro/ENGINEER drawing tables was discussed. In this second part, the discussion will focus on the other direction, sending Pro/ENGINEER drawing table data to an Excel workbook.

TableToExcel Function

The TableToExcel() function is also pretty simple. After resetting the status fields, it uses ArrayFromProETable() to obtain an array of data from a user selected drawing table, then uses ArrayToExcel() to populate a new Excel workbook with the data from the array.

function TableToExcel ( ) {

    var mesg = document.getElementById("mesg");
    var errmesg = document.getElementById("errmesg");
    mesg.innerHTML = "";
    errmesg.innerHTML = "";

    var array = ArrayFromProETable();
    if (array == null) {
        mesg.innerHTML = "null array";
        return;
    }

    if (array != null) { ArrayToExcel(array); }
}

 

ArrayFromProETable Function

The ArrayFromProETable() function gathers drawing table data into an array. It's main steps are: Get the Pro/Engineer session object, obtaining the current model object and ensure a drawing is active, request a drawing table selection from the user, and iterate through the table cells to populate the array elements. After the table is selected by the user, UnHighlight() is used to repaint the table with its normal colors.

The table cell iteration code cycles first through the table rows, then the columns of each row, then through the lines of text in each cell. When there is more than one line of text in a table cell, a linefeed character is added as a line separator. This is correctly interpreted by Excel as multi-line data.

It's important to note that while in Javascript (as in many programming languages) arrays are indexed starting with zero, both drawing tables and Excel cells are indexed starting with one.

Once the iteration of the table cells has completed and the array has been populated, the array is returned.

function ArrayFromProETable ( ) {

    var mesg = document.getElementById("mesg");
    var errmesg = document.getElementById("errmesg");
    var session = null;
    var drawing = null;


    // Get ProE session object
    //
    try {
        session = pfcGetProESession();
    }
    catch (e) {
        errmesg.innerHTML = "Unable to connect to Pro/Engineer";
        return null;
    }


    // Get model object and ensure it's a drawing
    //
    try {
        drawing = session.CurrentModel;

        if (drawing == null || drawing.Type != pfcCreate("pfcModelType").MDL_DRAWING) {
            errmesg.innerHTML = "A drawing must be active!";
            return null;
        }
    }
    catch (e) {
        errmesg.innerHTML = "A drawing must be active.";
        return null;
    }


    // Prompt user to select an existing table
    //
    var selections = null;
    var table = null;

    try {
        selections = selectItems("dwg_table", 1);
        var tabnum = selections.Item(0).SelItem;
        table = drawing.GetTable(tabnum.Id);
    }
    catch (e) { // nothing selected
        errmesg.innerHTML = "A drawing table was not selected.";
        return null;
    }

    selections.Item(0).UnHighlight();


    mesg.innerHTML = "Selected Table: " 
                     + table.GetRowCount() + " rows, " 
                     + table.GetColumnCount() + " columns";


    // Gather data from table and populate into array
    //

    var array = new Array();

    for (var i=0; i<table.GetRowCount(); i++) {

        array[i] = new Array();

        for (var j=0; j<table.GetColumnCount(); j++) {

            // Table cell indexes start with one, arrays with zero
            var cell = pfcCreate("pfcTableCell").Create(i+1,j+1);
            var mode = pfcCreate("pfcParamMode").DWGTABLE_NORMAL;
            array[i][j] = "";

            try {
                var textseq = table.GetText(cell, mode);

                for (var k=0; k<textseq.Count; k++) {
                    var textitem = textseq.Item(k);
                    if (k > 0) { array[i][j] += "\n"; }
                    array[i][j] += textitem;
                }
            }
            catch (e) { // cell has no value
                // ignore
            }

        }

    }

    return array;
}

 

ArrayToExcel Function

The ArrayToExcel() function takes the two dimensional array and populates cells in a new Excel workbook. There are only three steps in this function: Get the Excel session object, Create a new workbook and get the active sheet object, Populate cells of the active sheet from data in the array.

As an alternative, a new Excel session could be started if an existing one can not be found.

function ArrayToExcel ( array ) {

    var oXL;
    var errmesg = document.getElementById("errmesg");


    // Try to access Excel and get Application object.
    //
    try {
        oXL = GetObject("","Excel.Application");
        if (oXL == null) {
            errmesg.innerHTML = "Failed to get Excel session object.";
            return null;
        }
    }
    catch (e) {
        // oXL = new ActiveXObject("Excel.Application");
        errmesg.innerHTML = "Excel must be running!";
        return;
    }


    // Make session visible, get Sheet object
    //
    try {
        oXL.Visible = true;
        var oWB = oXL.Workbooks.Add();
        var oSheet = oWB.ActiveSheet;
    }
    catch (e) {
        errmesg.innerHTML = "Problem creating new workbook.";
        return;
    }


    // Put the array data into the cells of the active sheet
    //
    for (var i=0; i < array.length; i++ ) {
        for (var j=0; j < array[i].length; j++ ) {
            // Excel cell indexes start with one, arrays with zero
            oSheet.Cells(i+1, j+1).Value = array[i][j];
        }
    }

}

 

selectItems Function

The selectItems() function is largely based on selectItems() from an example in the Pro/WebLink documentation. It is changed here to be slightly more generic. The function builds a pfcSelectionOptions object that defines the type and number of allowable items that can be selected. It also minimizes the browser window during the selection process.

A sequence of selections (or null if nothing was selected) is returned.

function selectItems ( options, max ) {

    // Setup options object
    selOptions = pfcCreate("pfcSelectionOptions").Create(options);
    selOptions.MaxNumSels = parseInt(max);


    var session = pfcGetProESession();
    var browserSize = session.CurrentWindow.GetBrowserSize();
    session.CurrentWindow.SetBrowserSize(0.0);


    var selections = null;

    try {
        selections = session.Select(selOptions, null);
        session.CurrentWindow.SetBrowserSize(browserSize);
    }
    catch (err) {
        session.CurrentWindow.SetBrowserSize(browserSize);
        // In case user didn't select expected item
        var errstr = pfcGetExceptionType(err);
        if (errstr == "pfcXToolkitUserAbort" || errstr == "pfcXToolkitPickAbove") {
            return null;
        }
    }

    if (selections == null || selections.Count == 0)
        return null;


    return selections;
}

 


As I've mentioned, interaction with Excel is easy and straightforward. Although the Pro/Engineer interaction code is much more complex, the PFC API's contain a rich set a classes and methods making automation, such as I have shown here, possible. It's a quantum leap beyond relying upon mapkeys.