xADL Developing Components:
Using XArchADTProxy

XArchADTProxy Overview

The IXArchADT is a distributable interface that provides additional low-level functionality that is not available when using the xArch/xADL Data Binding Library directly. However, it uses strings to specify (indirectly) method calls. Thus, errors that are normally detected by the compiler when type- checking (when using the native Data Binding Libray interface) will show up only at run-time as exceptions (when using the IXArchADT).

This can make it difficult to manage source code that takes advantage of the IXArchADT . It can be especially difficult to maintain source code so that it adheres to changes in one of the Data Binding Library's underlying XML schemas. Recompiling will not indicate that a removed method no longer exists, or that method signatures have changed. In addition, using the IXArchADT prevents one from using the code assist features (e.g., AutoComplete) that are available in many modern integrated development environments.

XArchADTProxy addresses these problems by providing a layer on top of the IXArchADT that exposes interfaces nearly identical to those exposed by the xArch/xADL Data Binding Library (e.g., Component ). Thus, calls using the XArchADTProxy mechanism will appear (and compile) like calls made to the data binding library directly. In reality, however, these calls will be dynamically translated to IXArchADT calls "under the covers." As such, this allows you to combine the ease of use of the data binding library's interface with the distributability and loose coupling provided by the IXArchADT.

Please read throught the IXArchADT and the Data Binding Library Example that shows how to write a program that manipulates an architecture description directly using the Data Binding Library. It also shows how to write the same example using the XArchADTProxy.


XArchADTProxy is somewhat more limited than using the data binding library or the IXArchADT directly, namely:

  • XArchADTProxy users cannot directly add themselves as XArchADTModelListeners and receive XArchADTModelEvents.

Let's look at how to use XArchADTProxy . Using this mechanism imposes certain minor constraints on your code:

  • You must access documents using data binding interfaces (e.g., Component), not implementation types (e.g., ComponentImpl). (NB: You shouldn't be using Impl classes in any case )

Working with XArchADTProxy

A program that was previously written to use the DOM-based Data Binding Library should be modified to:

  1. Use interfaces (if it did not already do so);
  2. Use proxied versions of EFactorys; and
  3. Use proxied versions of EObjects

To interact with ArchStudio (e.g., XArchModelEvents) it is occassionally necessary to convert between ObjRefs and EObjects. The following code converts an ObjRef to its corresponding EObject:

	IXArchADT xarch = ...;
	ObjRef componentRef = ...;

	// convert an ObjRef to an EObject
	Component component = XArchADTProxy.proxy(xarch, componentRef);

The following code converts an EObject back to an ObjRef:

	Component component = ...

	// convert an EObject to an ObjRef
	ObjRef componentRef = XArchADTProxy.unproxy(component);

The following code proxies an EFactory:

	// create a proxied EFactory
	String structureNsUri = Structure_3_0Package.eINSTANCE.getNsURI();
	Structure_3_0Factory structureFactory = XArchADTProxy.proxy(xarch, structureNsUri);

For a complete example, look at the Data Binding Library Example

Contact Us

If you have questions not answered by this website, please feel free to contact the software architectures group at UC Irvine through the ArchStudio developer's (mailman protected) email list at: archstudio-dev [@] uci [.] edu. (Note: You must subscribe to the mail list before you can post to it.)

Portions of this site Copyright © The Regents of the University of California. All Rights Reserved Worldwide. The development of ArchStudio was initially funded by the DARPA DASADA (Dynamic Assembly for Systems Adaptability, Dependability, and Assurance) program. The site now includes results from projects supported in part by National Science Foundation grants IIS-0205724 and CCF-0430066, The Boeing Company, and IBM.

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