Slides for a talk on Java clients for elasticsearch for Singapore JUG. Covers the TransportClient, RestClient, Jest and Spring Data Elasticsearch

1. Java Clients for
Florian Hopf
@fhopf

2. elasticsearch

3. Elasticsearch?
„Elasticsearch is a distributed,
JSON-based search and
analytics engine, designed for
horizontal scalability,
maximum reliability, and easy
management.“

4. Elasticsearch?
„Elasticsearch is a distributed,
JSON-based search and
analytics engine, designed for
horizontal scalability,
maximum reliability, and easy
management.“

5. Elasticsearch?

6. Installation
# download archive
wget https://artifacts.elastic.co/downloads/
elasticsearch/elasticsearch-5.0.0.zip
unzip elasticsearch-5.0.0.zip
# on windows: elasticsearch.bat
elasticsearch-5.0.0/bin/elasticsearch

7. Accessing Elaticsearch
curl -XGET "http://localhost:9200"
{
"name" : "LI8ZN-t",
"cluster_name" : "elasticsearch",
"cluster_uuid" : "UvbMAoJ8TieUqugCGw7Xrw",
"version" : {
"number" : "5.0.0",
"build_hash" : "253032b",
"build_date" : "2016-10-26T04:37:51.531Z",
"build_snapshot" : false,
"lucene_version" : "6.2.0"
},
"tagline" : "You Know, for Search"
}

8. Indexing
curl -XPOST "http://localhost:9200/food/dish" -d'
{
"food": "Hainanese Chicken Rice",
"tags": ["chicken", "rice"],
"favorite": {
"location": "Tian Tian",
"price": 5.00
}
}'

9. Indexing
curl -XPOST "http://localhost:9200/food/dish" -d'
{
"food": "Ayam Penyet",
"tags": ["chicken", "indonesian"],
"spicy": true
}'

10. Search
curl -XGET
"http://localhost:9200/food/dish/_search?q=chicken"
...
{"total":2,"max_score":0.3666863,"hits":
[{"_index":"food","_type":"dish","_id":"AVg9cMwARrBlrY9
tYBqX","_score":0.3666863,"_source":
{
"food": "Hainanese Chicken Rice",
"tags": ["chicken", "rice"],
"favorite": {
"location": "Tian Tian",
"price": 5.00
}
}},
...

11. Search using Query DSL
curl -XPOST "http://localhost:9200/food/dish/_search" -d'
{
"query": {
"bool": {
"must": {
"match": {
"_all": "rice"
}
},
"filter": {
"term": {
"tags.keyword": "chicken"
}
}
}
}
}'

12. Elasticsearch?
„Elasticsearch is a distributed,
JSON-based search and
analytics engine, designed for
horizontal scalability,
maximum reliability, and
easy management.“

13. Distributed

14. Distributed

15. Recap
●
Java based search server
●
HTTP and JSON
●
Search and Filtering Query-DSL
●
Faceting, Highlighting, Suggestions, …
●
Nodes can form a cluster

16. Transport-Client

17. Transport-Client
dependencies {
compile group: 'org.elasticsearch.client',
name: 'transport',
version: '5.0.0'
}

18. Transport-Client
TransportAddress address =
new InetSocketTransportAddress(
InetAddress.getByName("localhost"), 9300);
Client client = new PreBuiltTransportClient(Settings.EMPTY)
addTransportAddress(address);

19. Search using Query DSL
curl -XPOST "http://localhost:9200/food/dish/_search" -d'
{
"query": {
"bool": {
"must": {
"match": {
"_all": "rice"
}
},
"filter": {
"term": {
"tags.keyword": "chicken"
}
}
}
}
}'

20. Search using Search Builders
SearchResponse searchResponse = client
.prepareSearch("food")
.setQuery(
boolQuery().
must(matchQuery("_all", "rice")).
filter(
termQuery("tags.keyword", "chicken")))
.execute().actionGet();
assertEquals(1, searchResponse.getHits().getTotalHits());
SearchHit hit = searchResponse.getHits().getAt(0);
String food = hit.getSource().get("food").toString();

21. Indexing
XContentBuilder builder = jsonBuilder()
.startObject()
.field("food", "Roti Prata")
.array("tags", new String [] {"curry"})
.startObject("favorite")
.field("location", "Tiong Bahru")
.field("price", 2.00)
.endObject()
.endObject();
IndexResponse resp = client.prepareIndex("food","dish")
.setSource(builder)
.execute()
.actionGet();

22. Indexing

23. Transport-Client
●
Connects to an existing cluster
●
Uses the binary protocol also used for inter
cluster communication

24. Transport-Client

25. Sniffing

26. Sniffing
●
State of the cluster can be requested from
elasticsearch
●
Client side loadbalancing
TransportAddress address =
new InetSocketTransportAddress(
InetAddress.getByName("localhost"), 9300);
Settings settings = Settings.builder()
.put("client.transport.sniff", true)
.build();
Client client = new PreBuiltTransportClient(settings)
addTransportAddress(address);

27. Transport-Client
●
Full API-Support
●
Efficient communication
●
Client side loadbalancing

28. Transport-Client Gotchas
●
Compatibility between elasticsearch versions
●
Elasticsearch dependency

29. REST-Client

30. Elasticsearch 5 REST-Client

31. Elasticsearch 5 REST-Client
dependencies {
compile group: 'org.elasticsearch.client',
name: 'rest',
version: '5.0.0'
}

32. Elasticsearch 5 REST-Client
+--- org.apache.httpcomponents:httpclient:4.5.2
+--- org.apache.httpcomponents:httpcore:4.4.5
+--- org.apache.httpcomponents:httpasyncclient:4.1.2
+--- org.apache.httpcomponents:httpcore-nio:4.4.5
+--- commons-codec:commons-codec:1.10
--- commons-logging:commons-logging:1.1.3

33. Elasticsearch 5 REST-Client
RestClient restClient = RestClient.builder(
new HttpHost("localhost", 9200, "http"),
new HttpHost("localhost", 9201, "http")).build();

34. Elasticsearch 5 REST-Client
HttpEntity entity = new NStringEntity(
"{ "query": { "match_all": {}}}",
ContentType.APPLICATION_JSON);
// alternative: performRequestAsync
Response response = restClient.performRequest("POST",
"/_search", emptyMap(), entity);
String json = toString(response.getEntity());
// ...

35. Elasticsearch 5 REST-Client
●
Less dependent on elasticsearch version
●
Clean separation network application/cluster
●
Minimal dependency
●
Sniffing
●
Error handling, timeout config, basic auth,
headers, …
●
No query support (for now)

36. Jest – Http Client

37. Jest
dependencies {
compile group: 'io.searchbox',
name: 'jest',
version: '2.0.0'
}

38. Client
JestClientFactory factory = new JestClientFactory();
factory.setHttpClientConfig(new HttpClientConfig
.Builder("http://localhost:9200")
.multiThreaded(true)
.build());
JestClient client = factory.getObject();

39. Searching Jest
String query = jsonStringThatMagicallyAppears;
Search search = new Search.Builder(query)
.addIndex("library")
.build();
SearchResult result = client.execute(search);
assertEquals(Integer.valueOf(1), result.getTotal());

40. Searching Jest
JsonObject jsonObject = result.getJsonObject();
JsonObject hitsObj = jsonObject.getAsJsonObject("hits");
JsonArray hits = hitsObj.getAsJsonArray("hits");
JsonObject hit = hits.get(0).getAsJsonObject();
// ... more boring code

41. Searching Jest
public class Dish {
private String food;
private List<String> tags;
private Favorite favorite;
@JestId
private String id;
// ... getters and setters
}

42. Suche mit Jest
Dish dish = result.getFirstHit(Dish.class).source;
assertEquals("Roti Prata", dish.getFood());

43. Jest
●
Alternative HTTP implementation
●
Queries as Strings or via Elasticsearch-Builder
●
Indexing and searching Java beans
●
Node Discovery

44. Spring Data Elasticsearch

45. Spring Data
●
Abstractions for different data stores
●
Speciality of each store available
●
Dynamic Repository implementations
●
Popular modules
●
Spring Data JPA
●
Spring Data MongoDB

46. Dependency
dependencies {
compile group: 'org.springframework.data',
name: 'spring-data-elasticsearch',
version: '2.0.4.RELEASE'
}

47. Entity
@Document(indexName = "spring_dish")
public class Dish {
@Id
private String id;
private String food;
private List<String> tags;
private Favorite favorite;
// more code
}

48. Repository
public interface DishRepository
extends ElasticsearchCrudRepository<Dish, String> {
}

49. Configuration
<elasticsearch:transport-client id="client" />
<bean name="elasticsearchTemplate"
class="o.s.d.elasticsearch.core.ElasticsearchTemplate">
<constructor-arg name="client" ref="client"/>
</bean>
<elasticsearch:repositories
base-package="de.fhopf.elasticsearch.springdata" />

50. Indexing
Dish mie = new Dish();
mie.setId("hokkien-prawn-mie");
mie.setFood("Hokkien Prawn Mie");
mie.setTags(Arrays.asList("noodles", "prawn"));
repository.save(Arrays.asList(hokkienPrawnMie));

51. Searching
Iterable<Dish> dishes = repository.findAll();
Dish dish = repository.findOne("hokkien-prawn-mie");

52. Repository
public interface DishRepository
extends ElasticsearchCrudRepository<Dish, String> {
List<Dish> findByFood(String food);
List<Dish> findByTagsAndFavoriteLocation(String tag,
String location);
List<Dish> findByFavoritePriceLessThan(Double price);
@Query("{"query": {"match_all": {}}}")
List<Dish> customFindAll();
}

53. Recap
●
High level abstraction
●
Entity beans
●
dynamic repository implementation
●
HTTP support in the making
●
Slower feature development

54. Recap
●
Transport-Client
●
Full API support
●
Elasticsearch dependency
●
REST-Client
●
Uses HTTP
●
currently lacking search API

55. Recap
●
Jest
●
Http client
●
Support for Java beans
●
Spring-Data-Elasticsearch
●
High level abstraction
●
Dynamic repositories

56. Links
●
http://elastic.co
●
https://github.com/searchbox-io/Jest
●
https://github.com/spring-projects/spring-
data-elasticsearch
●
https://github.com/fhopf/singajug-examples
●
http://blog.florian-hopf.de