Asynch REST

Examine Spring MVC & Jersey as REST API framework within Spring Boot

Playing with various asynchronous & parallel processing options

Running the examples

Spring MVC will run using the following URL path

localhost:8888/springmvc/hello

localhost:8888/springmvc/invoice/find/?storeNumber=100&trailerNumber=1

Jersey/JAX-RS will run using the following URL path

localhost:8888/jaxrs/hello

localhost:8888/jaxrs/invoice/find/?storeNumber=100&trailerNumber=1

Testing stream

In order to see the stream in action, update the SlowInvoiceDao so that it returns 5000 invoices. Also update the Thread.sleep to 100 ms.

curl localhost:8888/jaxrs/invoice/find/stream?storeNumber=100

The resulting array of JSON objects will start to be returned before the method has completed.

Using Jersey as JAX-RS provider instead of Spring MVC

Typically a Spring Boot application will use the web starter, which sets up the container for Spring MVC REST development.

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-web</artifactId>
</dependency>

Switch that starter out for the following Jersey one (or in our case leave them both in, since we are comparing them)

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-starter-jersey</artifactId>
</dependency>

Issue w/ Jersey and Spring Boot

Jersey doesn't always work with Spring Boot fat jars (1468)

This issue presented when adding the packages() to JerseyConfig

@Configuration
@ApplicationPath("/jaxrs")
public class JerseyConfig extends ResourceConfig {

    public JerseyConfig() {
        register(HelloJerseyController.class);
        register(JaxRsInvoiceController.class);
        register(JaxRsAsynchInvoiceController.class);
        //packages("codesmell.invoice.rest.jaxrs.mappers");
    }
}

To get around it the ExceptionMapper classes were registered directly.

building and running the application

The simulator can be run from Maven command line:

mvn spring-boot:run

It can also be built and run as a "fat jar"

mvn package spring-boot:repackage

This builds the JAR file that contains all of the dependencies, including the container.

java -jar target/rx-invoice-[version].jar

The scenario being solved

Imagine that we are storing invoices in an Apache Cassandra database.

Assume a keyspace that has two tables. One allows queries to retrieve all of the invoices going to the same place and on the same trailer.

CREATE TABLE IF NOT EXISTS "invoices_by_destination" (
	invoice_id TEXT,
	destination_name TEXT,
	destination_type TEXT,
	trailer TEXT,
	PRIMARY KEY ((destination_name, destination_type), trailer, invoice_id));

Another stores the JSON document with all of the details for a single invoice.

CREATE TABLE IF NOT EXISTS "invoice_detail" (
	invoice_id TEXT,
	json_doc TEXT,
	PRIMARY KEY ((invoice_id)));	

Now we have a scenario where we are searching for a list of invoices and then want to return JSON that contains an array of invoice documents. Note: the sample code uses a small JSON representation of an invoice.

[
	{"invoice": {
		"id": "1",
		"foo": "bar"}
	},
	{"invoice": {
		"id": "2",
		"foo": "fighters"}
	}
]