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https://issues.apache.org/jira/browse/SLING-4386?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14307368#comment-14307368
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Bertrand Delacretaz commented on SLING-4386:
--------------------------------------------
h2. Working proof of concept, February 5th, 2015
Revision 1657588 provides a reasonable proof of concept of the content model at
[1], with a few changes improvised during implementation. To test it, start the
sling launchpad and install the 3 bundles provided at [2].
The changes to Sling are minimal (see the resolver module at [2]), I'm just
using a custom {{MultiTenantScriptResolver}} instead of the default
{{SlingScriptResolver}} (but sharing a lot of code with it) for Resources that
adapt to {{ContentDrivenTenant}}. This means that existing Sling applications
that use content resources found outside of tenant subtrees should continue to
work unchanged.
This is definitely a prototype, there's lots of room for optimizations - it's
just meant to demonstrate the ideas and evaluate how much impact this has on
Sling.
h3. Tenants
The tenants are identified simply by having a {{sling:tenantRoot}} property
under {{/content/T}}. The {{/content/T/example.com}} node for example has such
a property, so it's the root of the example.com content-driven tenant. Such
tenants can be nested, see the {{subsite}} child node.
Resources found in such subtrees can be adapted to {{ContentDrivenTenant}}
which provides tenant-specific search and execution paths for scripts and
servlets.
Those paths are defined based on the modules listed in the tenant definition
resource, in this example:
{code}
curl -s http://localhost:8080/tenants.tidy.3.json | grep -v jcr
{
"example.com": {
"sling:tenant": {
"modules": [
"sling-default-servlets/1.0",
"blog/v42"
],
},
"subsite": {
"sling:tenant": {
"modules": ["blog/v43"],
}}}}
{code}
The {{example.com}} tenant lists two modules, one that gives access to the
Sling default servlets and v42 of a blog module.
The {{example.com/subsite}} tenant does not include the Sling default servlets,
the default {{.json}} rendering will not be available to render resources found
under there for example. It also uses a different version of the blog module.
The servlet search/executions paths are computed based on these module
references and the module definitions shown below, by the
{{ContentDrivenTenantImpl}} class. The new {{MultiTenantScriptResolver}} uses
these per-Resource search paths instead of the globally defined ones, allowing
tenant-specific scripts and (up to a point) servlets.
h3. Modules
The modules are defined under {{/modules}}:
{code}
curl -s http://localhost:8080/modules.tidy.6.json | grep -v jcr
{
"blog": {
"v42": {
"scripts": {
"blog": {
"homepage": {
"sling:resourceSuperType": "blog/page"
},
"page": {
"page.esp": {
}
}
}
}
},
"v43": {
"scripts": {
"blog": {
"homepage": {
"homepage.esp": {
}
},
"page": {
"page.esp": {
}
}
}
}
}
},
"sling-default-servlets": {
"1.0": {
"searchPath": "/libs",
"executionPath": "/libs/sling/servlet/default",
}
}
}
{code}
Module scripts have to be placed in a {{scripts}} subfolder, and we should
later enforce their resource types to start with the module name for
consistency. The blog module shows an example of that.
The sling-default-servlets module does not define any scripts, it only provides
an additional search path element with a limitation (only accept resources
under {{/libs/sling/servlet/default}}) to avoid exposing other script/servlet
resources found under {{/libs}}.
The tenant's custom scripts location is added in front of the search path, so
for example adding a homepage.esp script in the
{{/tenants/example.com/sling:tenant/scripts/blog/homepage}} folder would
replace the default {{blog/homepage}} GET rendering.
As the tenants point to specific versions of modules, those can easily be
upgraded or removed, as long as they consist of scripts only and maybe servlets
with specific mounting paths (which are big limitations).
h3. Interesting URLs in this prototype
http://localhost:8080/content/T/example.com.html rendered with the blog/v42
page.esp script which is the supertype of blog/homepage
http://localhost:8080/content/T/example.com/about.html rendered with the same
script, directly
http://localhost:8080/content/T/example.com/subsite.html also blog/homepage
resource type but renders with the blog/v43 script as the resource belongs to
the subsite tenant which points to the blog/v43 module.
http://localhost:8080/content/T/example.com/subsite/somepage.html rendered by
blog/v43 page script.
http://localhost:8080/content/T/example.com.json works as the example.com
tenant includes the sling-default-servlets module.
http://localhost:8080/content/T/example.com/subsite.json doesn't work as the
example.com/subsite tenant does not include the sling-default-servlets module.
[1]
https://cwiki.apache.org/confluence/display/SLING/Ideas+for+a+multi-tenant+and+multi-module+content+model
[2] https://svn.apache.org/repos/asf/sling/whiteboard/bdelacretaz/multisling2015
> Multi-tenant content model prototype
> ------------------------------------
>
> Key: SLING-4386
> URL: https://issues.apache.org/jira/browse/SLING-4386
> Project: Sling
> Issue Type: Task
> Components: General
> Reporter: Bertrand Delacretaz
> Assignee: Bertrand Delacretaz
>
> I'm working on a prototype for [1], will use this issue to keep track of
> progress.
> [1]
> https://cwiki.apache.org/confluence/display/SLING/Ideas+for+a+multi-tenant+and+multi-module+content+model
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