Re: [wildfly-dev] IMPORTANT: First overview of changes to jboss-ejb-client 3.0 for WildFly 10 (probably)

I don't want to commit this to a specific WildFly release but I guess and hope it'll come in around WildFly 10 or so (definitely not 9). As previously discussed, the EJB client architecture is undergoing the following substantial changes: • Introduction of URIAffinity, and URI-based invocation • Expansion of the 'ejb' JNDI initial context to auto-associate the PROVIDER_URL as the URI affinity for looked-up proxies

• Elimination of all "nested" EJB client context functionality • Integration with Elytron for client identity management

• Deferral to Remoting for automatic connection management • Unification of client configuration, so the Elytron authentication client, Remoting connection management, remote transaction client, and EJB client configurations all can be configured in one file or deployment descriptor

As such, I've introduced a 2.x branch for upstream where continued development of the 2.x series will take place. The "master" branch is being re-purposed towards this new development, targeted for 3.x of this library. There are a number of compatibility considerations from 2.x to 3.x. Most (I hope) existing client code (which avoids specialized manual configuration or nested client contexts) should continue to function as-is, with the following exceptions: • The following classes and interfaces are currently removed in my working copy: • ClusterContext - replaced with discovery (?) • ClusterNodeManager - replaced with discovery • ClusterNodeSelector - replaced with discovery • DeploymentNodeSelector - replaced with discovery

• ContextSelector - replaced with general selector class • ConstantContextSelector • IdentityEJBClientContextSelector • ThreadLocalContextSelector • EJBClientContextInitializer - no replacement • DefaultInterceptorsClientContextInitializer • TransactionRecoveryContextInitializer • EJBClientContextIdentifier - no replacement • NamedEJBClientContextIdentifier • DefaultCallbackHandler - no replacement • EJBClientConfiguration - replaced with context builder • PropertiesBasedEJBClientConfiguration • EJBClientContextListener - no replacement • EJBClientInterceptor.Registration - no replacement (interceptor set cannot be changed) • EJBClient*TransactionContext - replaced by wildfly-transaction-client facility • EJBReceiverContext - no replacement • ReceiverInterceptor - no replacement (internal class) • ALL public classes in the org.jboss.ejb.client.remoting package including ReconnectHandler • The following changes will be made to these core classes and interfaces: • EJBClient • Added more createSession() variants to support new affinity types • Change createSession() methods to throw CreateException instead of Exception • Remove createProxy() and createSession() variants which accept EJBClientContextIdentifier • Remove getEJBClientContextIdentifierFor() method • Attachable • Remove getAttachments() method • EJBClientContext • No longer implements Closeable

• Remove close() method • Remove all static create() methods, replaced with Builder class • Remove finalize() method • Remove getClusterContext(), getEJBClientConfiguration(), getOrCreateClusterContext(), removeCluster() • Remove selector-related methods, replaced with general Selector class • Remove register*() and unregister*() methods (providers are added to Builder) • Remove require() method which accepts EJBClientContextIdentifier • Add getInvocationTimeout() method • Affinity • Add forUri() factory method • EJBClientInvocationContext • Add getCompressionLevel(), isClientAsync(), and isIdempotent() query methods • Remove finalize() • EJB*Locator classes • Additional constructors which also accept an affinity • Additional "copy" constructors which accept a locator and affinity, to change the target affinity • EJBReceiver class • openSession() method changed to accept a stateless EJB locator • Constructor changed to no args • Remove all send*() and other methods related to transactions • Remove associate(), getNodeName(), [de]registerModule(), exists() • EJBReceiverInvocationContext • Remove retryInvocation() method • Remove getEjbReceiverContext() method • Remove getNodeName() method • EJBMetaDataImpl • Deprecated, changed to not use raw types • RequestSendFailedException • Replaced constructor with standard exception four-constructor setup • The following API classes are added: • EJBClientPermission - a general permission class • AbstractEJBMetaData - type-safe hierarchical version of EJBMetaDataImpl • EJBClientContext.Builder - forwards-compatible builder for EJBClientContext • EJBDiscoveryProvider - an interface to provide pluggable discovery • EJBTransportProvider - an interface to provide URI-compatible transport (factory for EJBReceivers) • URIAffinity - a type of affinity which has a URI for a target Note in particular that most of the cluster-support infrastructure is presently removed with no replacement. It is my hope and intent that the discovery infrastructure will be able to take over this function. How much of the code will be new, compared to how much of the code can be forward-ported and reintroduced from 2.x, remains to be discussed. At present, the plan is for wire compatibility to be supported for 2.x clients talking to 3.x servers and vice-versa. Transaction handling will be relegated to a separate wildfly-transaction-client API. However the getUserTransaction(node) method will continue to be supported as a deprecated delegation to the transaction-client API. In addition, when talking to a 2.x server, it is expected that a wildfly-transaction-client SPI implementation will piggyback on the existing EJB protocol transaction messages.

If any of these API changes seems unacceptable, now is the time to discuss it. All the code that was removed was determined to be tied too tightly to the previous location or configuration strategy, and thus couldn't sensibly be supported going forward. I have hopefully been adequately upfront about what I intended to remove or support going forward. In addition, by supporting the 2.x client, most migration concerns can hopefully be mitigated. But it's possible that some classes or methods could indeed be reintroduced with sensible semantics and in such a way as to not cause problems; if you have any thoughts along these lines, please share them and we can discuss them on a case-by-case basis. I've pushed up the proposed baseline 3.0 API at https://github.com/dmlloyd/jboss-ejb-client/tree/uri_invocation for review. I intend for pull requests that are relevant to both old and new code bases to be applied to both if possible, to avoid increasing the incompatibility window even further.