title: Distributed Streaming Applications (Graph and Transaction) In Reallife
body: <p>I am currently studying distributed stream processing systems, e.g. Storm, Flink and Spark Streaming. I want to implement some applications in these systems and briefly compare them. I wonder if there is any company using these systems for processing the following situations and what's the scale of the data stream.</p>
  
  <ol>
  <li><p><strong>Graph</strong> where a large graph may be distributed to multiple machines and we handles some updates (add or remove vertices or edges) and queries on the graph. So far I can only find some streaming graph algorithms on a single machine.</p></li>
  <li><p><strong>Transaction</strong> where exactly-once message delivery is a must. There exists a <em>Leaderboard Maintenance Benchmark</em> in S-Store (Meehan, John, et al. "S-store: Streaming meets transaction processing." Proceedings of the VLDB Endowment 8.13 (2015): 2134-2145) but I cannot find how they generated the input data.</p></li>
  </ol>