Github user haoch commented on the issue:
https://github.com/apache/incubator-eagle/pull/323
I think ApplicationProvider is just for providing a package of static
application process/metadata/extensions but not for runtime.
As following typical example, for different scope of memory/mysql,
`ISecurityMetadataDAO` should bind to different implementation
`InMemMetadataDaoImpl`/ `JDBCSecurityMetadataDAO`, and caller just need to
inject with `@Inject ISecurityMetadataDAO dao`.
~~~
@Override
public void register(ModuleRegistry registry) {
registry.register(MemoryMetadataStore.class, new AbstractModule() {
@Override
protected void configure() {
bind(ISecurityMetadataDAO.class).to(InMemMetadataDaoImpl.class);
}
});
registry.register(MySQLMetadataStore.class, new AbstractModule() {
@Override
protected void configure() {
bind(ISecurityMetadataDAO.class).to(JDBCSecurityMetadataDAO.class);
}
});
}
~~~
While if register with current metadata store instance, then the code have
to be as following, it will bind the register interface with MetadataStore and
not extensible enough.
~~~
@Override
public void register(MetadataStore store, ModuleRegistry registry) {
if(store instance of MemoryMetadataStore){
registry.register(MemoryMetadataStore.class, new
AbstractModule() {
@Override
protected void configure() {
bind(ISecurityMetadataDAO.class).to(InMemMetadataDaoImpl.class);
}
});
} else if (store instance of MySQLMetadataStore){
registry.register(new AbstractModule() {
@Override
protected void configure() {
bind(ISecurityMetadataDAO.class).to(JDBCSecurityMetadataDAO.class);
}
});
}
}
~~~
I think both maybe ok, and have similar implementation code, but the first
implementation should be more flexible, especially in future we may be able to
extend more than MetadataStore.
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