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2.6 Open Scripting Architecture

 


                                              



 
   Figure 32. OpenDoc Open Scripting Architecture 

   One of the major goals of OpenDoc is to increase the level of 
   customization that you can do with documents or applications. Experienced 
   users or system integrators want to do much more with components than just 
   assemble them.  Many tasks can be automated.  OSA provides the automation 
   technique done by scripts.  OSA defines also how components can 
   collaborate and communicate using events.  OSA enables collaboration 
   between components beyond the very basic mechanisms of layout and resource 
   negotiations OpenDoc is dealing with, as described in "Frames and Facets" 
   in topic 2.3.2.1.  These OSA events can be launched either directly or by 
   scripts.  Scripts can be attached to parts, and a user-interface control 
   such as a button might consist of nothing more than a part that executes a 
   script when activated. 

   Scripts are programs executed by interpreters.  Scripting forms a rich 
   medium for coordinating the work of parts in documents, and allows you and 
   parts to work together to perform tasks. 

   Today script programs are the base for an agent technology.  They can be 
   small pieces of code that can perfrom specific tasks such as buying or 
   selling shares.  They may be coded so that they control whether a stock is 
   bought or sold depending on its price.  They could also be coded to 
   collect infromation from different internet sites.  The scripting language 
   provided with OS/2 is REXX.  Because OS/2 TCP/IP is providing a socket API 
   and an OS/2 FTP API for REXX, it is possible to run REXX programs also on 
   the Internet. 

   REXX, with its extension to Object REXX as delivered with the The 
   Developer Connection for OS/2 Volume 9 Special Edition, can also be used 
   as a scripting language for OSA, to enable collaboration between parts or 
   to customize OSA-aware applications. 

   The implementation of this collaboration between parts in an OS/2 
   environment is called the interapplication communication (IAC).  The IAC 
   architecture comprises the following parts, as shown in the next figure 
   Figure 33: 

   1.   Open scripting architecture (OSA) provides a mechanism that allows 
       users to control multiple applications by means of scripts, or sets of 
       instructions, written in a variety of scripting languages.  Each 
       scripting language has a corresponding scripting component that is 
       managed by the Component Manager. When a user executes a script, the 
       scripting component sends OSA events to one or more applications to 
       perform the actions the script describes. 

   2.  OSA Event Manager allows applications to send and respond to OSA 
       events. 

   3.  Presentation Manager allows applications to send and respond to 
       high-level events other than OSA events. 



 


                                              



 
   Figure 33. Interapplication Communication 

   OSA is based on events. OSA extends the existing messaging mechanism 
   provided by Presentation Manager in OS/2 by semantic messages.  That means 
   the objects addressed by a message can be described in a semantic way. 
   For example in Figure 34 in topic 2.6.2. The script command: 

     copy table "Summary of Sales" to Totals 

    describes the object's table and totals in a very general semantic way. 
   For further explanation see also " Standard Events" in topic 2.6.2.  OSA 
   provides a set of common event suites the components collaborating can 
   agree on.  The scripting component provides human-language equivalents to 
   OSA event codes.  OSA allows users to record their actions in the form of 
   a script when using a scripting component that supports recording.  The 
   recording is not supported in the current release by REXX.  OSA allows 
   provides the infrastructure to manipulate and execute scripts via a script 
   editor.  These OSA events can be generated by scripting components as REXX 
   or sent directly by applications.  The most important requirement for 
   high-level communication among all applications is a common vocabulary of 
   events.  High-level events that conform to this protocol are called OSA 
   events. 

Subtopics:

   2.6.1 OSA Events
   2.6.2 Standard Events
   2.6.3 Event Objects
   2.6.4 Script

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