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This Week in Spring - September 29, 2015

Engineering | Josh Long | September 30, 2015 | ...

Welcome to another installation of This Week in Spring! To those of you reading from the US, let me be the first to wish you a very happy national coffee day! As usual, we've got a lot to cover so let's get to it!

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React.js and Spring Data REST: Part 3 - Conditional Operations

Engineering | Greg L. Turnquist | September 29, 2015 | ...
To see updates to this code, visit our React.js and Spring Data REST tutorial.

In the previous session, you found out how to turn on Spring Data REST’s hypermedia controls, have the UI navigate by paging, and dynamically resize based on changing the page size. You added the ability to create and delete employees and have the pages adjust. But no solution is complete with taking into consideration updates made by other users on the same bit of data you are currently editing.

Feel free to grab the code from this repository and follow along. This session is based on the previous session’s app with extra things added.

To PUT or not to PUT, that is the question

When you fetch a resource, there is risk is that it might go stale if someone else updates it. To deal with this, Spring Data REST integrates two technologies: versioning of resources and ETags.

By versioning resources on the backend and using ETags in the frontend, it is possible to conditially PUT a change. In other words, you can detect if a resource has changed and prevent a PUT (or a PATCH) from stomping on someone else’s update. Let’s check it out.

Versioning REST resources

To support versioning of resources, define a version attribute for your domain objects that need this type of protection.

src/main/java/com/greglturnquist/payroll/Employee.java
@Data
@Entity
public class Employee {

private @Id @GeneratedValue Long id;
private String firstName;
private String lastName;
private String description;

private @Version @JsonIgnore Long version;

private Employee() {}

public Employee(String firstName, String lastName, String description) {
	this.firstName = firstName;
	this.lastName = lastName;
	this.description = description;
}



}

  • The version field is annoated with javax.persistence.Version. It causes a value to be automatically stored and updated everytime a row is inserted and updated.

When fetching an individual resource (not a collection resource), Spring Data REST will automatically add an ETag response header with the value of this field.

Fetching individual resources and their headers

In the previous session you used the collection resource to gather data and populate the UI’s HTML table. With Spring Data REST, the _embedded data set is considered a preview of data. While useful for glancing at data, to get headers like ETags, you need to fetch each resource individually.

In this version, loadFromServer is updated to fetch the collection and then use the URIs to retrieve each individual resource.

src/main/resources/static/app.jsx - Fetching each resource
loadFromServer: function (pageSize) {
    follow(client, root, [
        {rel: 'employees', params: {size: pageSize}}]
    ).then(employeeCollection => {
        return client({
            method: 'GET',
            path: employeeCollection.entity._links.profile.href,
            headers: {'Accept': 'application/schema+json'}
        }).then(schema => {
            this.schema = schema.entity;
            this.links = employeeCollection.entity._links;
            return employeeCollection;
        });
    }).then(employeeCollection => {
        return employeeCollection.entity._embedded.employees.map(employee =>
                client({
                    method: 'GET',
                    path: employee._links.self.href
                })
        );
    }).then(employeePromises => {
        return when.all(employeePromises);
    }).done(employees => {
        this.setState({
            employees: employees,
            attributes: Object.keys(this.schema.properties),
            pageSize: pageSize,
            links: this.links
        });
    });
},
  1. The follow() function goes to the employees collection resource.
  2. The then(employeeCollection ⇒ …​) clause creates a call to fetch JSON Schema data. This has a sub-then clause to store the metadata and navigational links in the <App/> component.
    • Notice that this embedded promise returns the employeeCollection. That way, the collection can be passed onto the next call while letting you grab the metadata along the way.
  3. The second then(employeeCollection ⇒ …​) clause converts the collection of employees into an array of GET promises to fetch each individual resource. This is what you need to fetch an ETag header for each employee.
  4. The then(employeePromises ⇒ …​) clause takes the array of GET promises and merges them into a single promise with when.all(), resolved when all the GET promises are resolved.
  5. loadFromServer wraps up with done(employees ⇒ …​) where the UI state is updated using this amalgamation of data.

This chain is implemented in other places as well. For example, onNavigate(), which is used to jump to different pages, has been updated to fetch individual resources. Since it’s mostly the same as what’s shown above, it’s been left out of this session.

Updating existing resources

In this session, you are adding an UpdateDialog React component to edit existing employee records.

src/main/resources/static/app.jsx - UpdateDialog component
var UpdateDialog = React.createClass({

handleSubmit: function (e) {
    e.preventDefault();
    var updatedEmployee = {};
    this.props.attributes.forEach(attribute =&gt; {
        updatedEmployee[attribute] = React.findDOMNode(this.refs[attribute]).value.trim…
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Check out the new "Creating CRUD UI with Vaadin" guide

Engineering | Greg L. Turnquist | September 28, 2015 | ...

Greetings Spring community,

Today we have published a new guide: Creating CRUD UI with Vaadin.

This guide, written by the Vaadin team, shows how to nicely build a UI that taps into Spring Data, but doesn't require writing a single line of JavaScript or HTML code.

Vaadin is real cool:

  • Comes with its own Spring Boot starter
  • Works nicely with constructor injection
  • Makes it dirt simple to plugin persistence solutions like Spring Data
  • Is armed with an arsenal of plugins to grow into real applications

Check out this newly minted guide and have fun!

As a follow up to SpringOne 2GX, we have identified some more guides that need to be written. The story of cloud native is sweeping the development community, and people are asking for more solutions. Our job shouldn't be racking and stacking servers or building infrastructure. Instead, we should focus on smooth and easy solutions. Coding things cloud native…

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This Week in Spring - September 22nd, 2015

Engineering | Josh Long | September 22, 2015 | ...

Welcome to another installment of This Week in Spring! This week, fresh after an incredible SpringOne2GX 2015, I'm.. a little burnt if I'm honest! :D BUT, Spring endures and I'm this week in Amsterdam with our pal Martin Deinum helping a large group of developers make the cloud native journey with Spring Boot, Spring Cloud and Cloud Foundry.

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Java DSL for Spring Integration 1.1 GA is Available

Engineering | Artem Bilan | September 22, 2015 | ...

Dear Spring Community!

On behalf of Spring Integration team I'm pleased to announce that the 1.1 GA of Spring Integration Java DSL is now available from the Release Repository and Maven Central:

For Gradle use this dependency:

'org.springframework.integration:spring-integration-java-dsl:1.1.0.RELEASE'

For Maven this:

<dependency>
     <groupId>org.springframework.integration</groupId>
     <artifactId>spring-integration-java-dsl</artifactId>
     <version>1.1.0.RELEASE</version>
</dependency>

First of all a big thanks to everyone who visited my talk at the SpringOne 2GX 2015 last week…

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Spring for Apache Hadoop 2.3 Milestone 3 released

Releases | Thomas Risberg | September 22, 2015 | ...

We are pleased to announce the Spring for Apache Hadoop 2.3 M3 milestone release.

The most important enhancements in this release:

  • Update build to use Spring Framework 4.2.1, Boot 1.3.0.M5, Batch 3.0.5 [SHDP-509]
  • Move annotation config to separate sub-project to reduce dependencies for spring-data-hadoop-boot [SHDP-525]
  • Add additional properties to Spark Tasklet [SHDP-397]
  • Upgrade build to use to Spark 1.5.0 [SHDP-521]

See the release changelog for details.

We continue to provide version specific artifacts with their respective transitive dependencies in the Spring IO milestone repository:

  • 2.3.0.M3 (default - Apache Hadoop stable 2.7.1)
  • 2.3.0.M3-hadoop26 (Apache Hadoop 2.6.0)
  • 2.3.0.M3-phd30 (Pivotal HD 3.0)
  • 2.3.0.M3-phd21 (Pivotal HD 2.1)
  • 2.3.0.M3-cdh5 (Cloudera CDH 5.4)
  • 2.3.0.M3-hdp23 (Hortonworks HDP 2.3)
    • …
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Single-page web apps with Vaadin Spring 1.0

Engineering | Stéphane Nicoll | September 17, 2015 | ...

This post is a guest post by community member Matti Tahvonen (@MattiTahvonen), who works as a developer advocate in Vaadin Ltd, the company that originally developed Vaadin Framework and provides commercial services and extensions for it.

The Spring integration library for Vaadin has been in beta stage since May and has already been used by several production applications. Today we are proud to announce that the beta flag is dropped and the stable 1.0.0 release is out.

Vaadin is a component based web UI framework where your application state and logic lives in the memory of your Java…

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First Milestone of Spring Cloud Brixton Release Train is Available

Releases | Spencer Gibb | September 16, 2015 | ...

On behalf of the Spring Cloud team, I am pleased to announce the first milestone of the Spring Cloud Brixton release train. The milestone is available today and can be found in our Spring Milestone repository. We’ve made numerous enhancements and bug fixes, some of the highlights include:

  • Spring Boot 1.3.x and Spring 4.2.x support
  • Cluster Leadership election and locks
  • Hashicorp Consul support for service registration/discovery, configuration and bus
  • Apache Zookeeper support for service registration/discovery, configuration and leader election
  • Lattice support for service registration/discovery
  • Distributed tracing support
    • …
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This Week in Spring - September 15th, 2015 - SpringOne2GX 2015 edition!

Engineering | Josh Long | September 16, 2015 | ...

Welcome to another installment of This Week in Spring! This week, we're in beautiful Washington DC for the amazing SpringOne2GX 2015!

It's been an amazing event packed with amazing, pivotal moments that saw more than a thousand attendees - including engineers from some of the largest websites in the world - Rakuten, Alibaba, and Netflix, among others - join us here in Washington DC to learn and love what Pivotal is doing with and around Spring.

Here are some of my favorite moments:

get cloud native

  • this year saw Pivotal take cloud-native further and faster than anyone and SpringOne2GX has been a huge celebration of this drive: GET CLOUD NATIVE.
    • …
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