Support "Connection : Keep-Alive" header on Http operations

[roelofkemp]

When performing subsequent PUT operations without the "Connection : Close" header, the second PUT operation does not complete and times out after 60 seconds. Setting the Connection header to close avoids this problem, and introduces overhead of setting up a connection for each new request (especially SSL costs might be expensive).

Desired solution: subsequent PUTs work with the Keep-Alive header (note that this header doesn't need to be set explicitly, the server will take care of it)

See: com.dexels.navajo.resource.http/src/com/dexels/navajo/resource/http/impl/ResourceComponent.java line 99

	@Override
	public Single<ReactiveReply> put(String tenant, String bucket, String id, String type, Publisher<byte[]> data) {
		logger.info("Putting: {} type: {}",assembleURL(tenant,bucket, id),type);
		return client.callWithBody(assembleURL(tenant,bucket, id), 
					r->r.header("Authorization", this.authorization)
						.header("Connection", "Close")
						.method(HttpMethod.PUT)
						.idleTimeout(idle_timeout, TimeUnit.SECONDS)
						.timeout(timeout, TimeUnit.SECONDS)
				,Flowable.fromPublisher(data)
				,type)
				.timeout(timeout+1, TimeUnit.SECONDS)
				.firstOrError();
	}

[ghost]

Started working on branch _fix_E536_async_http_keepalive, with test scripts at navajo-basic-environment/_fix_E536_async_http_keepalive.

[ghost]

Wireshark appears to show that the data is properly traveling over the wire back and forth: two data packets to the server and one back to the client per request (both with and without the workaround).

[ghost]

To problem appears to be that only the status code of the HTTP response is used in the code, the content (data) of the HTTP response (presumably empty) is not consumed. A candidate solution is to attach a subscriber to the content publisher.

[ghost]

To problem appears to be that only the status code of the HTTP response is used in the code, the content (data) of the HTTP response (presumably empty) is not consumed. A candidate solution is to attach a subscriber to the content publisher.

[ghost]

Generalized the title since the problem also occurs with HTTP operations other than put (i.e., head and delete).