conjure-java-example

A small recipe application that demonstrates the simple usage of conjure tooling.

Overview

Tools and Libraries

This example project uses the following tools and libraries, please consult their respective documentation for more information.

conjure - IDL for defining APIs once and generating client/server interfaces in different languages.
- conjure-java-runtime - conjure libraries for HTTP&JSON-based RPC using Retrofit, Feign, OkHttp as clients and Jetty/Jersey as servers
- conjure-java - conjure generator for java clients and servers
- conjure-typescript - conjure generator for typescript clients
gradle - a highly flexible build tool. Some of the gradle plugins applied are:
- gradle-conjure - a gradle plugin that contains tasks to generate conjure bindings.
- gradle-baseline - a gradle plugin for configuring code quality tools in builds and projects.
dropwizard - a simple framework for building web services

Project Structure

recipe-example-api - a sub-project that defines recipe-example APIs in Conjure and generates both java and typescript bindings.

This is what the api project looks like:
```
├── recipe-example-api
│   ├── build.gradle
│   ├── recipe-example-api-jersey
│   ├── recipe-example-api-objects
│   ├── recipe-example-api-typescript
│   └── src
│       └── main
│           └── conjure
│               └── recipe-example-api.yml
```
- build.gradle - a gradle script that
  1. configures sub-projects with needed dependencies to generate java bindings. e.g. recipe-example-api-jersey
  2. configures publishTypescript task to generate .npmrc in the generated root folder, recipe-example-api-typescript/src for publishing the generated npm module.
  3. modifies the conjure extension to specify the package name under which the npm module will be published.
- recipe-example-api-jersey - the sub-project where all generated service interfaces live.
- recipe-example-api-objects - the sub-project where all generated object classes live.
- recipe-example-api-typescript - the sub-project where all generated typescript bindings live.
- src/main/conjure - directory containing conjure definition yml files where recipe APIs are defined, please refer to specification.md for more details.
recipe-example-server - a dropwizard application project that uses conjure generated jersey binding for resource class implementation

This is what the server project looks like:
```
├── recipe-example-server
│   ├── build.gradle
│   ├── src
│   │   ├── main/java
│   │   └── test/java
│   └── var
│       └── conf
│           └── recipes.yml
```
- build.gradle - configures the project with needed dependencies and applies the gradle-conjure and application plugins, so we can run the server locally or in IDE.
- src/main/java - source classes for the dropwizard application. e.g. RecipeBookResource.java class implements the generated Jersey interface.
- test/main/java - test source classes for simple integration tests that uses generated jersey interface for client interaction.
- var/conf/recipes.yml - the dropwizard application configuration yml file
build.gradle - the root level gradle script where a set of gradle plugins are configured, including gradle-conjure.
settings.gradle - the gradle settings file where all sub projects are configured.
versions.props - a property file of the nebula version recommender plugin with which we can specify versions of project dependencies, including conjure generators.

Development

Useful Gradle Commands:

./gradlew tasks for tasks available in this project.
./gradlew idea for IntelliJ
./gradlew eclipse for Eclipse
./gradlew run for running the server or use IDE to debug it

Generate New or Modify Existing APIs

Modify existing APIs

To modify the existing bindings in this project:

Make changes to the recipe-example-api.yml file
Run ./gradlew compileConjure or a more specific task such as ./gradlew compileConjureObjects, to check if the changes compile
Or run ./gradlew idea or ./gradlew eclipse to update the bindings for your IDE

Generate new binding for a different language

To generate bindings for a new language. Note that currently gradle-conjure plugin only supports generation of java, typescript, and python bindings.

Add a new sub project under recipe-example-api by modifying the settings.gradle file.

 ...
 include 'example-api:example-api-typescript'
+include 'example-api:example-api-python'

Optional: use the gradle script configure closure in recipe-example-api/build.gradle to configure project specific settings for the new sub project.
Specify conjure python dependency versions in versions.props
```
+com.palantir.conjure.python:* = 3.4.0
```
run ./gradlew compileConjure to generate new bindings for python.

Generate Java retrofit interfaces

Similar to how we add the conjure generation for python above, we can add a new project to generate java retrofit interfaces

add a new sub project under recipe-example-api by modifying the settings.gradle file.

 ...
 include 'example-api:example-api-typescript'
+include 'recipe-example-api:recipe-example-api-retrofit'

Optional: use the gradle script configure closure in recipe-example-api/build.gradle to configure project specific settings for the new sub project.
run ./gradlew compileConjureRetrofit to generate new bindings for retrofit2.

Writing Clients

Please see the following subsections for examples of writing recipe clients in different languages. To dev against this recipe application, you can either run the server locally via ./gradlew run or spin up a docker container using the palantir/recipe-example-server:latest image.

Java client

The tests in recipe-example-server/src/test/java illustrate simple examples of how you would use a Conjure jaxrs client to interact with the application. E.g.

RecipeBookService recipeBook = JaxRsClient.create(
       RecipeBookService.class,
       UserAgent.of(Agent.of("test", "0.0.0")),
       NoOpHostEventsSink.INSTANCE,
       ClientConfigurations.of(ServiceConfiguration
               .builder()
               .addUris(String.format("http://localhost:%d/examples/api/", RULE.getLocalPort()))
               .security(SslConfiguration.of(Paths.get(TRUSTSTORE_PATH)))
               .build()));

Recipe recipe = recipeBook.getRecipe(recipeName);

Typescript client

Please refer to conjure-typescript-example for an example implementation.

nkulkarni/conjure-java-example