On 11/29/2012 01:47 AM, Adam Zedan wrote:
I am trying to understand batch fetching with the following practical example.Currently My Qpid Broker has 70 items in it. I am trying to implement batch fetching however I am not having any success. Here is what I am doing in C# receiver.Receiver rx = session.CreateReceiver("QueueA"); rx.Capacity = 20000 ; while (rx.Fetch(ref message_n, timeout_n)) { uint val = rx.Available; //Value is 69. So does this mean only 1 item was fetched ? //Some code to process the message session.Acknowledge(); } As it can be seen that only one item was fetched reducing the content from 70 to 69 in the broker. I thought with batch fetching you could retrieve all the 70 items at one time since my count is set to 20000. Am i missing something here ?
The fetch call returns at most one message. The way prefetch works is by allowing the broker to send messages to the client that the client library will hold in anticipation of further fetch calls.
In your case, if available is reporting 70 messages, then the next 70 calls to fetch are just returning messages from a local, client side buffer. There is no round trip involved. (Of course were there any more messages on the broker those could be sent at any time providing the client had capacity).
In other words the prefetch is not so much a batch interface as a way to prevent having to do a network round-trip per fetch.
Any suggestions would help. Also how do I acknowledge batch messages.
Just call its less frequently then every message. The acknowledge call without parameters will acknowledge all previously fetched messages.
I want to reduce network load by making minimum trip to the broker that is why I am trying to use batch fetching (prefetch)
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