Hi All
When we initially built the Registry/Repository support for Synapse (and
the WSO2 ESB), we allowed the runtime to dynamically re-load changed
resources at runtime. We even made some of these changes visible
atomically to a message (i.e. if during the inSequence a message saw the
revision 344 of a resource, and the resource changed to 345 on the
remote registry when the response processing began, we let the same
version seen by this message earlier [344] be seen during the
outSequence as well)
However, this has added quite a bit of complexity to the code, and
probability for bugs and uncertainty. For example, if someone changed an
XSLT and XSD at the same time on the registry, its possible for a
message to see one version of the XSLT and another version of the XSD etc..
Allowing configuration elements (such as Sequences and Endpoints) to be
stored in the Registry has added some confusion as well. Typically a
production configuration is static, and any updates (esp in Production)
is controlled by manual human interaction. Thus I do not see much value
in allowing the configuration elements to be updated without the
explicit knowledge and control of the ESB admins.. this also creates
problems for us developers, who want to improve the JMX support and
other features of Synapse, as we cannot let a definition just vanish to
thin air and another configuration element to become available
automatically.. I am ready to accept the proposed changes to support
"includes" within a synapse.xml, and also the suggested JAR type
archives as a mechanism to update/manage the configuration.
So my proposal about Registry caching, is to always cache forever any
resources referred to from the Registry. We will then expose a new JMX
function which will allow us to clear the full cache. This gives:
1) Full human control for resources loaded from the registry
2) Allows someone to update content on the Registry, and still make
Synapse see the updated copies after a manual cache reset - when required
3) Allows some level of disconnected operation (e.g. once resources are
loaded - e.g. WSDLs), i.e. the services on Synapse can continue even if
the Registry becomes inaccessible
Your thoughts are welcome
asankha
--
Asankha C. Perera
WSO2 - http://wso2.org
http://esbmagic.blogspot.com
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