Example from the readme doc fails with Jackson, works with Yasson

[sothawo]

I have set up a minimal Java application to test the client (https://github.com/sothawo/elastic-java-test) It's basically the code from the readme showing how to use the Elastisearch Client.

I have Elasticsearch 7.12.1 running in docker on port 9002 and am using an intercepting proxy on port 8080 to check what's going over the wire.

So this simple code

public class App {

    public static void main(String[] args) throws IOException {

        // Create the low-level client
        RestClient restClient = RestClient.builder(new HttpHost("localhost", 9200))
            .setHttpClientConfigCallback(builder -> {
                builder.setProxy(new HttpHost("localhost", 8080));
                return builder;
            })
            .build();

        // Create the transport that provides JSON and http services to API clients
        Transport transport = new RestClientTransport(restClient, new JacksonJsonpMapper());

        // And create our API client
        ElasticsearchClient client = new ElasticsearchClient(transport);

        // Search all items in an index that contains documents of type AppData
        SearchResponse<AppData> search = client.search(s -> s
                .index("appdata-index"),
            AppData.class
        );

        if (search.hits().hits().isEmpty()) {
            System.out.println("No match");
        } else {
            for (Hit<AppData> hit : search.hits().hits()) {
                processAppData(hit._source());
            }
        }
    }

    private static void processAppData(AppData appData) {
        if (appData != null) {
            System.out.println(appData.toString());
        }
    }
}

leads to this error:

20:06:06: Executing task 'App.main()'...

> Task :compileJava UP-TO-DATE
> Task :processResources NO-SOURCE
> Task :classes UP-TO-DATE

> Task :App.main()
Exception in thread "main" java.lang.NullPointerException: took
	at java.base/java.util.Objects.requireNonNull(Objects.java:233)
	at co.elastic.clients.elasticsearch._global.SearchResponse.<init>(SearchResponse.java:105)
	at co.elastic.clients.elasticsearch._global.SearchResponse$Builder.build(SearchResponse.java:381)
	at co.elastic.clients.elasticsearch._global.SearchResponse$Builder.build(SearchResponse.java:365)
	at co.elastic.clients.json.JsonpObjectBuilderParser.parse(JsonpObjectBuilderParser.java:43)
	at co.elastic.clients.json.JsonpValueParser.parse(JsonpValueParser.java:91)
	at co.elastic.clients.base.RestClientTransport.getHighLevelResponse(RestClientTransport.java:175)
	at co.elastic.clients.base.RestClientTransport.performRequest(RestClientTransport.java:65)
	at co.elastic.clients.elasticsearch.ElasticsearchClient.search(ElasticsearchClient.java:1227)
	at co.elastic.clients.elasticsearch.ElasticsearchClient.search(ElasticsearchClient.java:1246)
	at com.sothawo.elasticjavatest.App.main(App.java:39)

That's when parsing the response, not even on parsing the returned data.

In the proxy I see the following request

POST http://localhost:9200/appdata-index/_search HTTP/1.1
Content-Length: 2
Content-Type: application/json; charset=UTF-8
Proxy-Connection: Keep-Alive
User-Agent: elasticsearch-java/7.12.1-SNAPSHOT (Java/16.0.1)
X-Elastic-Client-Meta: es=7.12.1-SNAPSHOT,jv=16,t=7.12.1-SNAPSHOT,hc=4.1.4
Host: localhost:9200

{}

and this response:

HTTP/1.1 200 OK
content-type: application/json; charset=UTF-8
content-length: 408

{
    "took": 2,
    "timed_out": false,
    "_shards": {
        "total": 1,
        "successful": 1,
        "skipped": 0,
        "failed": 0
    },
    "hits": {
        "total": {
            "value": 2,
            "relation": "eq"
        },
        "max_score": 1.0,
        "hits": [
            {
                "_index": "appdata-index",
                "_type": "_doc",
                "_id": "5sko2HkB1yiMr4eS5Dmo",
                "_score": 1.0,
                "_source": {
                    "foo": "foo1",
                    "bar": "bar1"
                }
            },
            {
                "_index": "appdata-index",
                "_type": "_doc",
                "_id": "58ko2HkB1yiMr4eS-jlu",
                "_score": 1.0,
                "_source": {
                    "foo": "foo2",
                    "bar": "bar2"
                }
            }
        ]
    }
}

So the request and response over the wire are ok. Taking the proxy out yields the same result.

What could be the reason for this error?

[sothawo]

Addition: When I change to the Yasson jsonb processing by using this:

Transport transport = new RestClientTransport(restClient, new JsonbJsonpMapper());

instead of the JacksonJsonpMapper() the call succeeds.

[swallez]

Thanks for trying out the new Java client! Still early days, but feedback is very welcome!

There's an issue in the JacksonJsonpParser class that converts Jackson parser events into JSON-P events. I'm currently working on it, and will update once I've fixed it.

[sothawo]

Looks great up to now. I wrote reactive counterparts to ApiClient, Transport and ElasticsearchClient (the last one just for the first search method) and can reuse the Endpoints and part of the code from the RestClientTransport to send the requests and parse the responses over the wire for imperative and reactive code. That will definitely allow me to clean up the codebase in Spring Data Elasticsearch when we use this for reactive and imperative code.
My biggest problem seems to be that I already have a class named ReactiveElasticsearchClient and I need to support them both until version 8 of ES.

[swallez]

Fixed in 3bef3fd that also adds tests. I've pushed a new snapshot that also includes your changes from #6. Thanks again!