Monday, November 22, 2010

Script: PB backup – Using PB ORCA to export PBLs

A basic Operating system level unit in Powerbuilder is a library file (.PBL). Each PBL file is a self contained directory in itself, with the objects stored inside in a proprietary binary format. You need Powerbuilder to view and work with this directory structure (System tree, Library painter etc).

Sometimes, it would be nice to be able to work with individual objects as text files at the OS level. This will enable us to use any text utilities to work with the objects as files (like you would a Java or C++ file). For e.g., I have a Perl script to grep through the exported text files. With text files, you can store away these source files in any version control systems (PVCS, SVN etc) easily. And you can easily diff 2 versions of an object by using any text diff tool (Of course, there are tools available to do these from inside PB, but it's just lot easier to work text files). PB allows the source code to be exported to text files with extensions, *.sr? (.srw for windows, .srd for datawindows etc.).

PB ORCA is an API that Powersoft developed early on for 3rd Party CASE tool vendors to work with PB objects. With PB ORCA, you can write programs to work PB libraries and objects from OS command line. Several object level operations available in PB IDE are also available in this API. Incidentally, there is a command line utility available with the same name (pborca.exe) on Google Code. The tool has several commands that correspond to API functions. You can create a ORCA script file (with .orc extension) and run it in batch mode using the tool. See here for a complete list of commands supported by the tool.

Below script uses pborca.exe in a DOS batch file to export all the objects in all the PBLs in a project directory to a corresponding directory structure. The batch file first loops on a list of .pbl files in a directory (passed in), and creates an ORCA script (latax.orc) with export commands. Then it runs the generated ORCA script using pborca.exe to export the object files (.*sr?). When the script finishes, you will have directory with several sub-directories, one for each PBL file exported.

This script uses several advanced features (%~ modifiers, ENABLEDELAYEDEXPANSION) of DOS Batch file. DOS scripts do several things a Unix script does, but it’s almost like an after thought! More on these later.

I use this script for daily backup of my development environment. Often times only a handful of files change on the developer's PC. Once I export the PBLs to a directory, I can diff 2 different versions using a diff tool. (I use Winmerge). The files can be optionally zipped up as well.

Pborca.exe can also handle the reverse (known as bootstrapping). Exported PB object files are only useful for performing file level operations. To be useful in a PB application, they will have to be imported back in to a PBL file again which can then be opened inside Powerbuilder. As of version 9, PB ORCA can be used to bootstrap as well. See here for the idea.

REM 12,2009 Sam V
REM script to export PBLS using pborca.exe (ORCA interface to PB)
REM this copies all the folders from source (typically Z:) to target.
REM then it creates an ORCA script to export each pbl to the subdirectories.
REM Finally it runs the generated orca script in pborca
REM @echo off

echo %0 %1, %2
@REM copy all the directories from the powerbuilder root to the export directory
@REM if a x.PBL is already in x subdirectory, you may not need MKD1 below.

@echo creating the target directory; just copy the entire path with empty sub-directories
xcopy /t /e /I %1 %2

@REM Here we start generating the orca file to be used with <a href="">PBORCA</a>.
@echo session begin pborc100.dll > latax.orc

@echo off
@FOR /f "usebackq delims=" %%a IN (`dir /s /b %1*.pbl`) DO (
@set a1=%%~dpa
@REM echo a1=%a1%
@call set "a1=!a1:%~1=%~2!"
@REM This creates a sub-directory with the same name as PBL file
mkdir "!a1!"
@echo export %%~fa,,,!a1! >> latax.orc)

@echo session end >> latax.orc


@echo on
@echo run the script in pborca
pborca latax.orc

REM end of script

Thursday, November 11, 2010

More about PB from my Hello World post

In my earlier post, I wrote a very simple program in Powerbuilder (PB) to print/show Hello World. I tried to compare with many other programming languages there. In that post, there were several concepts introduced. But, being a simple post, I ignored most of the details. We will try to analyze the details here and this way explain what it means to program in PB.

Interpreted or Compiled

From that list of examples I had, there is one thing that stands out. PB looks a lot more like C/C++/Java, at least in commenting style. But, then we see it has the simplicity of Basic program that it's usually thought of as originating from. It also has a lot of similarities with Visual Basic (For that matter with other flavors of BASIC such Power basic as well). PB is actually the tool and it uses proprietary language called PowerScript. Like BASIC this is an interpreted language, but not interactive (In a BASIC interpreter, results were displayed as soon as you type a command (or a command block) and press ENTER.). In PB, though the  code is interpreted, it's not the original code that you typed in, but an intermediate code it generated when you compiled (generated) or ran. More on this below.


Object Orientedness:

PB is at the very least, an Object based language. Windows environment contains windows with several controls or widgets on each window. The various controls and windows (objects) talk to each other through events and methods (functions). Now, this itself doesn't make it object oriented, but definitely object based. In PB (as in VB) an application is made up of several objects such as Application, Windows, Buttons, Text Boxes (and Data windows - more on this later). You cannot have a program without an application and you cannot communicate with the users without windows or buttons. So essentially when we build a PB application, we are reusing these "objects" as templates to make our own objects. Thus, by the very nature PB is Object based.

Real Object orientation came to it in later versions. A rudimentary "user object " was introduced as early as ver 3.0 and by Ver 5.0 Pb introduced Object-oriented concepts such as function overloading. Many of us still write object based code in PB, but there have been some movements to make it more and more object oriented. There were several frameworks developed for PBincluding PFC, which is still strong in the Client/Server world. A more sophisticated EAF was developed for PB in an enterprise n-tier world.  A lot more companies seem to be dusting off their old PB programs and try to upgrade latest versions of PB. So, as a developer you will see both object-based and object-oriented code out there. This is different from Java perspective which is Object Oriented to the core, but not unlike C++ where people continue(d) to code C style programs.

User Interface (IDE)

When we did the hello world, we mentioned what we coded and what we saw. But, we did not mention how or where we coded it. A Java program can be coded in a simple text editor like Notepad or more sophisticated Eclipse or Netbeans. It can then compiled and executed in a DOS (or unix/linux) command line. Or like in Eclipse, all these functionality can be done in one tool. Such tools are called IDE - Integrated Development Environment. PB has been IDE from the beginning. In fact, you cannot code or compile PB outside Powerbuilder (not exactly true, particularly the compiling part). Unlike other tools, PB is a more complete IDE and allows you, as a developer, to debug and run from within itself. Also, the code that you put into PB is actually stored in files with the extension .pbl in proprietary format. More on these later.

[caption id="attachment_95" align="alignnone" width="300" caption="Powerbuilder Workspace"]PB Workspace[/caption]

Types of Applications built in PB

What is not revealed in the Hello World program is what kind of programs can be written in PB. Apart from the windows programs, PB can also be a great Client/Server tool. In fact, in corporate environments it is mostly used as a Database programming tool. It's strength lies wholly on the simplicity of database connectivity with the use of Datawindows.  With the advent of EA Server, PB can be a great n-tier development tool as well, like Java J2EE. (More on these later).

PB portability

As mentioned above, PB runs in an interpreted mode. When you compile a PB program, it gets compiled into p-code, a proprietary bytecode. In this regard PB is very much like Java. Just like Java, there are options to compile into native machine code, but typically p-code is preferred. Thus, to run a PB application, you need to install a PB runtime. This is very much like a Java VM. (In fact in EA Server terminology, this is called PB VM). So, theoretically, PB application can be ported and run anywhere PB runtime was available. There were Unix versions of PB available. But, you need a specific version of PB runtime to run a program generated with a specific version of PB. Here it is different from Java, where future runtimes are guaranteed to be backward compatible and thus can run older versions of Java classes.This makes PB less portable. Also, by the windowing nature of it, it naturally fits into Microsoft Windows. The direction Sybase is taking, seems to confirms this. PB12 is, apart from being a windows application builder, also an IDE for .Net plaform.

Starting from my next post, I will go into more details about using the product.

History of PB

Powerbuilder grew from the modest beginnings in the early 80's to where it is now. Those of us who have worked with it for a long time know that it's come a long way as a product. But how many of know it's real history (sort of like the history PC programming world itself)? It was originally conceived and produced by a company called Powersoft. Now it is owned by Sybase. We all knew that it was "bought out" by Sybase in the 90's and what it did to the product. But how many of us know the background of it? Both Powersoft, the company, and Powerbuilder, the product had their fair share of competitions from big giants, threat of hostile takeovers. After initial days of glory, it did lie in the dumps for some time and several wrote death sentence for it. Yet, time and again it came back up again and with PB 12 seems to have gained a new life. I can write about all those here. But, I won't try to re-invent the wheel as there have been several nice posts about the subject. I am listing a few, that I liked, here:

An Article by Chris Pollach


History of Powerbuilder from the maker of PBLPeeper

A nice blog about Powerbuilder and other tools

The displaced guy or your personal IT guy on the web!

Hello World!

This is my real first post in Powerbuilder. (I wrote a lot about PB and my association with it before). Like it is customary for any tutorial or book on programming to start with a program to print Hello World, I will try to do the same in Powerbuilder.

Before I jump into it, let's some simple ones: (I am only including the actual lines and not full program code here,  please refer to the really interesting site that prints hello world in various languages - here)

In a Pascal program, you can just say,

[sourcecode language="delphi"]
{Hello World in Pascal}
writeln(&quot;Hello world&quot;);

(In Delphi which is based on Pascal, it is written as,

[sourcecode language="delphi"]
{Hello World in Delphi}
WriteLn('Hello World');

In C, you can do

[sourcecode language="cpp"]
/*Hello World in C*/
puts(&quot;Hello World!&quot;);

In Basic Language, (which contributed to  Powerbuilder's Powerscript) you can do

[sourcecode language="vb"]
10 REM Hello World in BASIC
20 PRINT &quot;Hello World!&quot;

Coming to the more Object oriented world,

In C++ you can write,

[sourcecode language="cpp"]
/*Hello World in C++*/
cout &lt;&lt; &quot;Hello World!&quot; &lt;&lt; endl;

And in Java, this would be,

[sourcecode language="java"]
/*Hello World in Java*/
System.out.println(&quot;Hello World!&quot;);

Well, almost of all of them print to a console - a text based screen, like in DOS, Unix, Linux. The same task of showing hello world to the user takes a bit more, when it comes to a windowing world (like MS windows, X-windows, Apple mac interface). The presentation becomes little more important. After all, in such an operating environment, everything is shown inside a window, so our program needs to write into one such too! In a windowing environment, simplest way to present a text is using some type of message box, which is a small window showing the text (and may be some question buttons).  Luckily windows API offers functions to create such a messagebox with ease. Let's see how we could do the same in Java, for a windowing environment:

[sourcecode language="java"]
/*Hello World in Java -windowing version*/
javax.swing.JOptionPane.showMessageDialog(null,&quot;Hello world!&quot;);

Swing is a package available in Java to create an application for a windowing environment.
Coming back to what we started with, to print Hello World in Powerbuilder, we could do something like above using a messagebox. Luckily PB offers a function for that - MessageBox. So, in the simplest form, we will do,

[sourcecode language="cpp"]
/*Hello World in Powerbuilder-Simple*/
MessageBox(&quot;Hi from Powerbuilder&quot;, &quot;Hello World!&quot;)

We are almost done. Like almost all of the examples above (except BASIC which was interpreted, you just type that one line and it did print it), we need to wrap this line in a program. In the java example above,
we would do,

[sourcecode language="java"]
// Hello World in Java using Swing GUI
class HelloWorldSwing {
static public void main(String args[]) {
javax.swing.JOptionPane.showMessageDialog(null,&quot;Hello world!&quot;);

Notice the main function. That is the entry point in various languages like C, C++, Java. This is the function that is called when the program is executed.

Powerbuilder is built slightly differently. It does have an entry point function - actually an event. This will be the open even of an Application object. Just like the class with main function becomes entry point object in Java, an Application object is the entry point object in Powerbuilder. So in it's simplest form, we simply add the messagebox function in the application open event and just run the application. When run, this is what you will see,

Well, that's for showing the simplest way. But a typical PB application is built not just with application object, but with one or more windows as well. We will see about that in a later post.