Nonblocking Database Access in Helidon SE

Copyright © 2019 Oracle and/or its affiliates.
Nonblocking Database Access
in Helidon SE
Oracle
September 16, 2019
Dmitry Kornilov /Tomas Langer

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Safe Harbor

Dmitry Kornilov
Senior Product Development Manager
Oracle

Tomas Langer
Helidon Architect
Oracle

• Introduction to Helidon
• Helidon DB Client
• Demo
• Q & A
Agenda

Helidon Introduction

Helidon (Χελιδόνι) = Swallow (Greek)

A set of Java libraries
for developing microservices

Project Helidon
• Open
• Innovative
• Support standards
• Supported active project

Open Source
• Hosted on GitHub
• https://github.com/oracle/helidon
• Apache 2.0 License

Supported Active Project
• Open Source support
• Web Site with guides and tutorials: https://helidon.io
• Public Slack channel: https://helidon.slack.com
• GitHub issues tracker: https://github.com/oracle/helidon/issues
• Management has committed to commercial support of Helidon
• AnyWebLogic licensed customer is automatically supported for
Helidon use

Landscape

• Microframework
• Tiny Footprint
• Functional style
• Reactive
• Transparent
• MicroProfile 3.0
• Small Footprint
• Declarative style
• Dependency Injection
• CDI, JAX-RS, JSON-P/B

Routing routing =
Routing.builder()
.get("/hello", (req, res) ->
res.send("Hello World"))
.build();
WebServer.create(routing)
.start();
@Path("hello")
public class HelloWorld {
@GET
public String hello() {
return "Hello World";
}
}

Helidon SE Components
Reactive Web
Server
Config
Security Tracing
Metrics
Health Check gRPC
MP
MP
MP
MP
MP
MP
Helidon DB Client

Helidon DB Client

Database access in Helidon SE
• Without Helidon DB Client...
• JDBC and most no-SQL drivers are blocking
• Backpressure implementation is complicated
• Support for tracing, metrics and health has to be programmed
• Configuration specific for each driver

Helidon DB Client – Reactive
• Non-blocking
• "native" if supported by driver (MongoDb, Cassandra and Redis have
reactive driver!)
• Using an executor service when wrapping a blocking driver (e.g. JDBC)
• Flow API
• Uses Flow.Publisher and Flow.Subscriber to process streams of data
• Backpressure
• records are read from the database only when requested by consumer
• in Helidon, this is propagated all the way to theTCP layer

Helidon DB Client - Observable
• Implemented as configurable interceptors
• all, or named statements ("select-all"), or statements by type (Insert,
Update, Delete...)
• either in a builder, or in configuration file
• Tracing
• Adds a trace to OpenTracing
• Metrics
• Counter, Meter,Timer
• Health
• "ping" operation for liveliness health check

Helidon DB Client - Configurable
• Statements in configuration
• All statements are named (including ad-hoc)
• Does not define a new query language
• Simple to modify a statement when needed
• Metrics, Health Checks in configuration
• Connectivity and database type in configuration
• Simple to switch to a different database

Helidon DB Client - Databases
• JDBC
• Using standard JDBC APIs, so any JDBC driver will work
• Support for local transactions
• MongoDB
• Using reactive MongoDB driver
• Basic operations usable for relational and other types of DBs
• CRUD operations

Helidon DB Client Configuration
# JDBC - MySQL
db:
source: "jdbc"
url: "jdbc:mysql://127.0.0.1:3306/pokemon?useSSL=false"
statements:
insert-mon: "INSERT INTO pokemons VALUES(:name, :type)"
# Mongo database:
db:
source: "mongoDb"
url: "mongodb://127.0.0.1:27017/pokemon"
statements:
insert-mon: '{"collection": "pokemons",
"value": {"_id": $name, "type": $type}}'

Helidon DB Client Usage
DbClient dbClient = DbClient.create(config.get("db"));
//...
private void insertPokemon(ServerResponse response, Pokemon pokemon) {
dbClient.execute(exec -> exec
.createNamedInsert("insert-mon")
.namedParam(pokemon)
.execute())
.thenAccept(count -> response.send("Inserted: " + count + " values"))
.exceptionally(throwable -> sendError(throwable, response));
}

Demo

Demo
Branch on Helidon: 581-helidon-db
https://github.com/oracle/helidon/tree/581-helidon-db

Q & A

Helidon-related Sessions on CodeOne 2019
Monday, Sep 16
01:30 PM - 02:15 PM
Helidon Flies Faster on GraalVM
Moscone South - Room 203
05:00 PM - 07:00 PM Hands on Lab: Building Microservices
with Helidon
MosconeWest - Room 3024B
Thursday, Sep 19
09:00 AM - 09:45 AM Helidon MicroProfile: Managing
Persistence with JPA
12:15 PM - 01:00 PM Migrating a Single Monolithic
Application to Microservices

Helidon-related Sessions on OOW 2019
Tuesday, Sep 17
02:00 PM - 02:20 PM
Building Helidon Applications
The Exchange (Moscone South) -Theater 4
Wednesday, Sep 18
09:00 AM - 09:45 AM BuildingCloud Native Applications with
Helidon

Thank You
Helidon Team
September 16, 2019
Dmitry Kornilov /Tomas Langer

Nonblocking Database Access in Helidon SE

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