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| </script></nav></div><div class="container mainContainer"><div class="wrapper"><div class="post"><header class="postHeader"><h1 class="postHeaderTitle">Heron Design Goals</h1></header><article><div><span><!-- |
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| <p>From the beginning, Heron was envisioned as a new kind of stream processing |
| system, built to meet the most demanding of technological requirements, to |
| handle even the most massive of workloads, and to meet the needs of organizations |
| of all sizes and degrees of complexity. Amongst these requirements:</p> |
| <ul> |
| <li>The ability to process billions of events per minute</li> |
| <li>Extremely low end-to-end latency</li> |
| <li>Predictable behavior regardless of scale and in the face of issue like extreme traffic spikes and pipeline congestion</li> |
| <li>Simple administration, including: |
| <ul> |
| <li>The ability to deploy on shared infrastructure</li> |
| <li>Powerful monitoring capabilities</li> |
| <li>Fine-grained configurability</li> |
| </ul></li> |
| <li>Easy debuggability</li> |
| </ul> |
| <p>To meet these requirements, a few core design goals have guided---and continue to |
| guide---Heron's development:</p> |
| <ul> |
| <li><a href="#modularity">Modularity</a></li> |
| <li><a href="#extensibility">Extensibility</a></li> |
| <li><a href="#isolation">Isolation</a></li> |
| <li><a href="#constrained-resource-usage">Constrained resource usage</a></li> |
| <li><a href="#apache-storm-compatibility">Apache Storm compatibility</a></li> |
| <li><a href="#backpressure-handling">Backpressure handling</a></li> |
| <li><a href="#multiple-delivery-semantics">Multiple delivery semantics</a></li> |
| </ul> |
| <h3><a class="anchor" aria-hidden="true" id="modularity"></a><a href="#modularity" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Modularity</h3> |
| <p>Heron was designed to serve a wide range of requirements, use cases, platforms, |
| programming languages and so on. In order to suit varying---and often |
| unforeseeable---needs, Heron provides support for mulitple:</p> |
| <ul> |
| <li><a href="heron-architecture#schedulers">schedulers</a></li> |
| <li>metrics sinks</li> |
| <li>operating systems and platforms</li> |
| <li>topology <a href="heron-architecture#uploaders">uploaders</a></li> |
| </ul> |
| <h3><a class="anchor" aria-hidden="true" id="extensibility"></a><a href="#extensibility" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Extensibility</h3> |
| <p>Due to its fundamentally <a href="#modularity">modular</a> character, Heron is remarkably |
| easy to extend to meet your needs, with simple APIs that you can use to add |
| support for new schedulers, programming languages (for topologies), topology |
| uploaders, etc.</p> |
| <h3><a class="anchor" aria-hidden="true" id="isolation"></a><a href="#isolation" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Isolation</h3> |
| <p>Heron topologies should be process based rather than |
| thread based, and each process should run in isolation for the sake of easy |
| debugging, profiling, and troubleshooting.</p> |
| <h3><a class="anchor" aria-hidden="true" id="constrained-resource-usage"></a><a href="#constrained-resource-usage" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Constrained resource usage</h3> |
| <p>Heron topologies should use only those resources that they are |
| initially allocated and never exceed those bounds. This makes Heron safe to run |
| in shared infrastructure.</p> |
| <h3><a class="anchor" aria-hidden="true" id="apache-storm-compatibility"></a><a href="#apache-storm-compatibility" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Apache Storm compatibility</h3> |
| <p>Although Heron has a <a href="topology-development-streamlet-api">Functional API</a> |
| that we recommend for all future topology development, Heron is fully API and |
| data model compatible with <a href="http://storm.apache.org">Apache Storm</a>, making it |
| easy for developers to transition from Storm to Heron.</p> |
| <h3><a class="anchor" aria-hidden="true" id="backpressure-handling"></a><a href="#backpressure-handling" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Backpressure handling</h3> |
| <p>In a distributed system like Heron, there are no guarantees that all system |
| components will execute at the same speed. Heron has built-in <a href="heron-architecture#stream-manager">back pressure |
| mechanisms</a> to ensure that topologies can |
| self-adjust in case components lag.</p> |
| <h3><a class="anchor" aria-hidden="true" id="multiple-delivery-semantics"></a><a href="#multiple-delivery-semantics" aria-hidden="true" class="hash-link"><svg class="hash-link-icon" aria-hidden="true" height="16" version="1.1" viewBox="0 0 16 16" width="16"><path fill-rule="evenodd" d="M4 9h1v1H4c-1.5 0-3-1.69-3-3.5S2.55 3 4 3h4c1.45 0 3 1.69 3 3.5 0 1.41-.91 2.72-2 3.25V8.59c.58-.45 1-1.27 1-2.09C10 5.22 8.98 4 8 4H4c-.98 0-2 1.22-2 2.5S3 9 4 9zm9-3h-1v1h1c1 0 2 1.22 2 2.5S13.98 12 13 12H9c-.98 0-2-1.22-2-2.5 0-.83.42-1.64 1-2.09V6.25c-1.09.53-2 1.84-2 3.25C6 11.31 7.55 13 9 13h4c1.45 0 3-1.69 3-3.5S14.5 6 13 6z"></path></svg></a>Multiple delivery semantics</h3> |
| <p>Heron provides support for |
| <a href="heron-delivery-semantics#available-semantics">at-most-once</a>, |
| <a href="heron-delivery-semantics#available-semantics">at-least-once</a>, and |
| <a href="heron-delivery-semantics#available-semantics">effectively-once</a> processing |
| semantics.</p> |
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