Global SpelExpressionParser Suport [INT-3562]

Gary Russell opened INT-3562 and commented

The SpEL compiler can be enabled globally or on individual SpEL parsers.

Currently Spring Integration components do not provide support at the parser level, they each instantiate their own parser.

It would be useful if components can obtain an appropriate parser during initialization. Perhaps via some central registry; something like:

<int:spel-parser id="mixed" compiler-mode="MIXED" pattern="foo*, myAdapter.source, *.handler" />
<int:spel-parser id="immediate" compiler-mode="IMMEDIATE" pattern="bar" />

together with registry.getParserFor(getBeanName()).

Components that use several expressions may want to use a different parser for each; so some solution is needed for that situation.

It might not be too bad to support a Map under a well-known bean name:

<util:map id="integrationExpressionParsers">
    <entry key="ftpOut.remoteDirectoryExpression" value-ref="immediate" />
</util:map>

and registry.getParserFor(getBeanName(), "remoteDirectoryExpression").

The previous work to enable central configuration of the evaluation context means that all components that evaluate expressions should now have access to the BeanFactory so this should not be too hard to implement.

Reference URL: http://docs.spring.io/spring-framework/docs/current/spring-framework-reference/html/expressions.html#expressions-spel-compilation

Start by reviewing the Spring Integration components that instantiate their own SpEL parsers and the existing BeanFactory-based evaluation-context configuration. Read the linked Spring Framework SpEL compilation reference for parser behavior. Done would require an agreed design supporting centrally configured parsers, including selection by component and by expression where needed.