Quarkus server-side http-cache - resteasy

Question

I tried to find out how to config. a server-side rest client (i.e. microservice A calls other microservice B using rest) to used a http cache.
The background is, that the binary entities transfered over the wire can be quite large. Overall performance can benefit from a cache on microservice A side which employs http caching headers and etags provided by microservice B.
I found a solution that seems to work, but I'm not sure it that is a proper solution, that work together with current requests, that can occur on microservice A at any time.
#Inject
/* package private */ ManagedExecutor executor;
//
// Instead of using a declarative rest client we create it ourselves, because we can then supply a server-side cache: See ctor()
//
private ServiceBApi serviceClientB;
#ConfigProperty(name="serviceB.url")
/* package private */ String serviceBUrl;
#ConfigProperty(name="cache-entries")
/* package private */ int cacheEntries;
#ConfigProperty(name="cache-entrysize")
/* package private */ int cacheEntrySize;
#PostConstruct
public void ctor()
{
// Create proxy ourselves, because we can then supply a server-side cache
final CacheConfig cc = CacheConfig.custom()
.setMaxCacheEntries(cacheEntries)
.setMaxObjectSize(cacheEntrySize)
.build();
final CloseableHttpClient httpClient = CachingHttpClientBuilder.create()
.setCacheConfig(cc)
.build();
final ResteasyClient client = new ResteasyClientBuilderImpl()
.httpEngine(new ApacheHttpClient43Engine(httpClient))
.executorService(executor)
.build();
final ResteasyWebTarget target = (ResteasyWebTarget) client.target(serviceBUrl);
this.serviceClientB = target.proxy(ServiceBApi.class);
}
#Override
public byte[] getDoc(final String id)
{
try (final Response response = serviceClientB.getDoc(id)) {
[...]
// Use normally and no need to handle conditional gets and caching headers and other HTTP protocol stuff here, because this does underlying impl.
[...]
}
}
My questions are:
Is my solution ok as server-side solution, i.e. can it handle concurrent requests?
Is there a declarative (quarkus) way (#RegisterRestClient. etc) to achieve the same?
--
Edit
To make things clear: I want service B to be able to control the caching based on the HTTP get request and the specific resource. Additionally I want to avoid the unnecessary transmission of the large documents service B provides.
--
Mik

Answer 1

Assuming that you have worked with the declarative way of using Quarkus' REST Client before, you would just inject the client in your serviceB-consuming class. The method, that will invoke Service B, should be annotated with #CacheResult. This will cache results depending on the incoming id. See also Quarkus Cache Guide.
Please note: As Quarkus and Vert.x are all about non-blocking operations, you should use the async support of the REST Client.
#Inject
#RestClient
ServiceBApi serviceB;
...
#Override
#CacheResult(cacheName = "service-b-cache")
public Uni<byte[]> getDoc(final String id) {
return serviceB.getDoc(id).map(...);
}
...