This Refcard will help Java developers working with multi-threaded programs to understand core concurrency concepts and how to apply them. Overview the. This Refcard covers JVM internals, class loading (updated to reflect the new Metaspace in Java 8), garbage collection, troubleshooting, monitoring, concurrency. This Refcard focuses on the design, deployment, service discovery, and management of Java applications on the open-source project called Docker so that you.
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Java Enterprise Edition allows programmers to write less and focus on delivering clean business logic. Enterprise software development is inherently complex; multi-user systems open the door to concerns such as transactional integrity, security, persistence integration, and interaction between components.
Very simply put, the mission of the Java Enterprise Edition is to enable an out-of-the-box set of configurable services and functionality, which allow the programmer to write less and focus on delivering clean business logic.
Java EE 7 is in fact an aggregate of many interoperable technologies designed to deliver a unified experience. Application Servers which are certified to the standards defined by the Java Community Process are intended to service applications written to the specifications within the platform. This umbrella specification ties together the various subsystems that comprise the platform, and provides additional integration support where necessary.
The Java EE 7 platform added the following new subsystems:. Several other technologies were updated to provide improved productivity and features:.
WebSocket provides a full-duplex, bi-directional communication over a single TCP channel. This overcomes a basic limitation of HTTP where a server can send updates to the client and a TCP connection is maintained between client and server until one of them explicitly closes it.
WebSocket is also a very lean protocol and requires minimal framing on the wire. Client endpoints are defined with ClientEndpoint and can be connected to a server endpoint via:. Batch Applications allows developers to easily define non-interactive, bulk-oriented, long-running tasks in item-oriented and task-oriented ways. It provides a programming model for batch applications and a runtime for scheduling and executing batch jobs.
It supports item-oriented processing using Chunks and task-oriented processing using Batchlets. Each item is read, processed, and aggregated for writing. JSON is a lightweight data-interchange format and is the common format of the web for consuming and creating web services data.
The event-based parser allows an application developer to ask for an event using parser. Event which consists of values that indicate the start of an object, end of an object, and other similar events.
This gives more procedural control over processing the JSON. A new default instance of these objects is available for injection in the following JNDI namespace:. An application-specific ManagedExecutor can be created by adding the following fragment to web. The standard principles of REST, such as—identifying a resource via URI; defining a set of methods to access the resource; and allowing for multiple representation formats of a resource—can be easily marked in a POJO via annotations.
The Client API also permits retrieval of the response asynchronously by adding an async method call before the method invocation. JAX-RS enables the creation of server-side endpoints using annotations.
Core Java Reference Card
JAX-RS 2 introduces asynchronous endpoints that may be defined to suspend the client connection if the response is not readily available and later resume when it is. Here, an Executor is used to perform work in a separate thread:.
A synchronous endpoint that uses PathParam to identify a single book. Filters are mainly used to modify or process incoming and outgoing request or response headers.
An interceptor is defined by implementing ReaderInterceptor or WriterInterceptor, or both. Message-oriented middleware MOM allows sending and receiving messages between distributed systems.
The newly introduced, simplified API is very fluent, uses refcad exceptions, is annotation-driven, and makes use of CDI to reduce the boilerplate code. Queues may refcaed injected using the Resource annotation:. CDI manages the lifecycle and interactions of stateful components bound to well-defined contexts. CDI provides typesafe dependency injection between components and defines: The following are examples of beans that would be automatically enabled for injection using default settings.
By default, CDI interceptors are disabled.
They can be enabled and ordered via the javax. Priority annotation as shown rrefcard same can be done for decorators and alternatives:. Expanded in Java EE 7, the Bean Validation Specification provides for unified declaration of validation constraints upon bean data. It may be used to maintain the integrity of an object at all levels of an application: Here we show how we may apply Bean Validation constraints in a declarative fashion to ensure the integrity of a User object.
Custom constraints can be created to provide reusable annotations with specific validation definitions:. To enable internationalization and localization, custom constraint messages may reference resource bundle properties:.
Custom constraints may also rffcard custom ConstraintValidators. This is specified using the validatedBy attribute:. The ReadListener interface defines three callbacks:. Most enterprise applications will need to deal with persistent data, and interaction with relational databases can be a tedious and difficult endeavor. We may use the new NamedStoredProcedureQuery annotation atop an entity to define a stored procedure:. In JPA 2, the persistence context is synchronized refcarc the jsva resource manager.
Any updates made to the persistence context are propagated to the resource manager. Here is how you can create a container-managed unsynchronized persistence context:. Its primary function is to provide a component-based toolset for easily displaying dynamic data to the user.
It also integrates a rich set of patterns to help manage state and promote code reuse. View files may be placed in subdirectories.
Below is an example of a CDI managed bean referred rdfcard as a backing bean gefcard provides the required functionality for the view:. This module has well-defined entry and exit points defined by the application developer. Flow XML files may be empty if no configuration is required. A configurable set of views in the application will be able to declare themselves as template-clients of any template in the resource library contract.
The API defines a high-level interface, annotation, and scope to demarcate transaction boundaries in an application. The UserTransaction interface enables the application to control transaction boundaries programmatically by explicitly starting and committing or rolling back a transaction.
Transactional annotation that enables one to declaratively refcqrd transaction boundaries on POJOs. This annotation can be specified at both the class and method level, where method-level annotations jsva those at the class level. All methods of this bean are executed in a transaction managed by the container.
This support is provided via an implementation of CDI interceptors that conduct the necessary suspending, resuming, etc. This scope defines a bean instance whose lifecycle is scoped to the currently active JTA transaction.
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Core Java Concurrency
Refcard Java Enterprise Edition 7. Streamlining Modern Java Development Java Enterprise Edition allows programmers to write less and focus on delivering clean business logic. PDF for easy Reference. JSR This umbrella specification ties together the various subsystems that comprise the platform, and provides additional integration jaav where necessary.
The Java EE 7 platform added the following new subsystems: Several other technologies were updated to provide improved productivity and features: Contexts and Dependency Injection 1. Annotated server endpoints can be defined as: JSR Batch Applications allows developers reccard easily define non-interactive, bulk-oriented, long-running tasks in item-oriented and task-oriented ways.
Different elements define the sequence of a job: Defcard and sequential phase of a job Flow: Sequence of execution elements that execute together as a unit Split: Set of flows that execute concurrently Decision: Customized way javz determining sequencing among step, flows, and splits Public API from javax. Class Name Description BatchRuntime Represents the JSR runtime JobOperator Interface for operating on batch jobs ItemReader Batch artifact that reads item for chunk processing ItemProcessor Batch artifact that operates on an input item and produces an output item for chunk processing ItemWriter Batch artifact that writes to a list of item for chunk processing Batchlet Batch step for item-oriented processing BatchProperty Annotation to define a batch property injected from Job XML JobListener Interface that intercepts job javaa StepListener Interface that intercepts step execution ChunkListener Interface that intercepts chunk processing CheckpointAlgorithm Provides a custom checkpoint policy for chunk steps PartitionMapper Provide unique batch properties for each batch execution PartitionReducer Unit of work demarcation across partitions.
JSR JSON is a lightweight data-interchange format and is the common format of the web for consuming and creating web services data. Four managed objects are provided: Here, an Executor is used to perform work in a separate thread: A message can be jva sent as the following example: A message can be received as: Queues may be injected using the Resource annotation: All types in the archive are considered for injection.
Priority annotation as shown the same can be done for decorators and alternatives: Support for AroundConstruct lifecycle callback for constructors Binding interceptors to constructors Interceptor binding moved to the interceptors spec, allowing for reuse by other specifications Support for decorators on built in beans EventMetadata to allow inspection of event metadata Vetoed annotation allowing easy programmatic disablement of classes Many improvements for passivation capable beans, including Nava allowing instances to be retained only for use within the invoked method or constructor Scope activation and destruction callback events AlterableContext allowing bean instances to be explicitly destroyed Class exclusion filters to beans.
New in the 1. This is specified using the validatedBy attribute: Refcarr enhancements Applying run-as security roles to init and destroy methods Added HttpSessionIdListener to enable detection of session fixation attacks, and enabled deterrence of session fixation attacks by enabling changing the session ID via HttpServletRequest. In addition, Servlet 3.
This will allow a URL to be specified without a scheme. In this case the scheme of the corresponding request will be used. JSR Most enterprise applications refcarrd need to recfard with persistent data, and interaction with relational databases can be a tedious and jaava endeavor.
A spec example of a bulk update may look like: