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<a href="http://community.jboss.org/index.jspa" style="text-decoration: none; color: #E1E1E1">Community</a></h1>
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Implementing a non-flat deployment for Weld Integration
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reply from <a href="http://community.jboss.org/people/flavia.rainone%40jboss.com">Flavia Rainone</a> in <i>JBoss Microcontainer Development POJO Server</i> - <a href="http://community.jboss.org/message/542347#542347">View the full discussion</a>
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<div class="jive-rendered-content"><p>Pete and I had a face-to-face meeting where we discussed all my questions and what would be the best way to implement this.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Regarding the assumptions I wanted to validate, both are correct.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>But, regarding visibility of deployments. He told me that the best approach is to mirror the ClassLoader structure. The point is that one BDA A can see another BDA B if the module it represents, say A', can see classes from the module B', that corresponds to BDA B.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>So, instead of reinventing the wheel, we should use the already existent ClassLoader structure to implement this correspondence in the BDA structure. These are the steps that Pete suggested:</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>1) Find Modules which are BDA's</p><p>2) List <Module>, List<ClassLoader>, Map<ClassLoader, Module></p><p>3) Iterate over classes and build graph of modules</p><p>4) Module -> BDA</p><p>   a) Explore CL graph & for each CL & Module</p><p>   b) Convert</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>A few examples of complex things that we would have to implement if we don't use the ClassLoader structure:</p><p>- we would have to able to see if a deployment is scoped or not, so we can define the visibility it has from other modules and to which modules it is visible</p><p>- we need to keep track of modules being deployed and undeployed, so to know when it becomes visible and when it becomes invisible</p><p>- we need to support Class-path attributes in manifest files</p><p>- we need to define when a previously defined archive is available to a archive being deployed now</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>So, these features that we need to support provide the arguments as to why we should mirror the ClassLoader structure instead of implementing this from scratch.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>Pete also pointed out an important behaviour that should be fixed. In a nutshell, all archives visible to a BDA are scanned. In the given scenario:</p><p>  ejb.jar A reaches lib2. In lib2 we have a ClassPath reference in the manifest to lib3, which is not in the classpath of the server... it is somewhere in the filesystem. In this case, for what I understood from Pete's explanations, lib3 is going to be scanned for CDI stuff. But this shouldn't happen, so we would also need a way of differentiating lib3 from lib2. I'll stop my explanation here, as I think Pete can fill in the blanks and explain this much better :-)</p><p>Anyway, this would be a future step, as the priority is to first mirror the CL structure effectively.</p><p style="min-height: 8pt; height: 8pt; padding: 0px;"> </p><p>So, Ales, how do you think this should be done? I think we have plenty of code in the ClassPools that do exactly that, mirror the ClassLoader structure in a way that allows us to find the classes and xml files in META-INF dirs. Maybe there is a way of reusing part of the ClassPool code to do this?</p></div>
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