Sorry for late response. Yes, 'id' is is a fixed field that generated by drpc server and emitted by drpc spout. However it is not visible to drpc client.
On Wed, Oct 22, 2014 at 9:49 AM, Junfeng Chen <[email protected]> wrote: > Hi , thanks > > I found the following sentences:” The first bolt you declare will take in > as input 2-tuples, where the first field is the request id and the second > field is the arguments for that request. LinearDRPCTopologyBuilder > expects the last bolt to emit an output stream containing 2-tuples of the > form [id, result]. Finally, all intermediate tuples must contain the > request id as the first field.” > > > > I tried to add one more field in the *declareOutputFields* function, and > I get the following error message: “Output stream of last component in > LinearDRPCTopology must contain exactly two fields. The first should be the > request id, and the second should be the result.” > > > > Does that mean the ‘*id’* field is a fixed field in the tuple and be > ignored in the “*drpc.execute("exclamation", word)*”. The returned value > must be the second field. > > > > Is my word correnct? > > > > > > *发件人:* 肖康(Kang Xiao) [mailto:[email protected]] > *发送时间:* 2014年10月21日 23:24 > *收件人:* [email protected] > *主题:* Re: DRPC problem > > > > hi Junfeng, > > > > http://storm.apache.org/documentation/Distributed-RPC.html is useful for > you to understand how DRPC works. > > > > LocalDRPC is generated from clj code > https://github.com/apache/storm/blob/master/storm-core/src/clj/backtype/storm/LocalDRPC.clj > . > > > > On Mon, Oct 20, 2014 at 2:14 PM, Junfeng Chen <[email protected]> wrote: > > Hi, I am a newbie for the Storm. Now I meet a problem about DRPC. > > > > In the BasicDRPCTopology of sample code, drpc.execute("exclamation", word) > return a String as the result. I don’t understand how the DRPC return the > emitted value in ExclaimBolt as it declares two Tuples as output format, > while it just return "result" field. I tried to discover the source code > but no source file of the class “LocalDRPC” can be found in > storm-core\src\jvm\backtype\storm path. Could somebody explain for me? > Thanks a lot. > > > > Regard, > > Junfeng Chen > > > > > > > > -- > > Best Regards! > > Kang Xiao,<[email protected]> > Distributed Software Engineer > -- Best Regards! Kang Xiao,<[email protected]> Distributed Software Engineer
