Re: [gyrex-dev] How to use the INodeState

[Gunnar Wagenknecht <gunnar@xxxxxxxxxxxxxxx>]

Hi,

Am 21.11.2014 um 11:20 schrieb Jürgen Albert <j.albert@xxxxxxxxxxxxxxxxxx>:
> I stumbled upon the INodeState but I have no idea how to use it properly.  Can somebody give me an explanation or even better a short example for this? I found nothing about this in the gyrex code…

I just realized that there are no examples at all. One more thing for our todo list. Anyway, here is the general idea:

The state provider (some node) does:

Map<String, String> properties = …;
properties.put(“service.pid”, “cool.search.service.info”)
properties.put(“url”, “https://thishostname...”)
properties.put(“available.indices”, “books”)
…registerOsgiService (INodeState.class, INodeState.INSTANCE, properties);


The state consumer does:

INodeStateQueryService stateQueryService = getOsgiService(INodeStateQueryService.class);
List<INodeStateInfo> availableInfos = stateQueryService.findByServicePid(“cool.search.service.info”);

while(true) {

  INodeStateInfo info = pickRandomServiceForIndexAndRemoveItFromList(availableInfos, “books”);
  Map<String, String> properties = info.getDate();
  String url = properties.get(“url”);
  Object result = doSearch(url, keywords)
  if(result != null)
    return result;

  // re-try

}


pickRandomServiceForIndexAndRemoveItFromList can implement some round robin pattern or whatever. It should fail if the list is empty and/or no service is available.

-Gunnar

-- 
Gunnar Wagenknecht
gunnar@xxxxxxxxxxxxxxx