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| </script></nav></div><div class="container mainContainer"><div class="wrapper"><div class="post"><header class="postHeader"><h1 class="postHeaderTitle">Heron Topologies</h1></header><article><div><span><!-- |
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| <blockquote> |
| <p><strong>Don't want to manually create spouts and bolts? Try the Heron Streamlet API.</strong>. If you find manually creating and connecting spouts and bolts to be overly cumbersome, we recommend trying out the <a href="topology-development-streamlet-api">Heron Streamlet API</a> for Java, which enables you to create your topology logic using a highly streamlined logic inspired by functional programming concepts.</p> |
| </blockquote> |
| <p>A Heron <strong>topology</strong> is a <a href="https://en.wikipedia.org/wiki/Directed_acyclic_graph">directed acyclic |
| graph</a> (DAG) used to process |
| streams of data. Topologies can be stateless or |
| <a href="heron-delivery-semantics#stateful-topologies">stateful</a> depending on your use case.</p> |
| <p>Heron topologies consist of two basic components:</p> |
| <ul> |
| <li><a href="topology-development-topology-api-java#spouts">Spouts</a> inject data into Heron topologies, potentially from external sources like pub-sub messaging systems (Apache Kafka, Apache Pulsar, etc.)</li> |
| <li><a href="topology-development-topology-api-java#bolts">Bolts</a> apply user-defined processing logic to data supplied by spouts</li> |
| </ul> |
| <p>Spouts and bolts are connected to one another via <strong>streams</strong> of data. Below is a |
| visual illustration of a simple Heron topology:</p> |
| <p><img src="/docs/assets/topology.png" alt="Heron topology"></p> |
| <p>In the diagram above, spout <strong>S1</strong> feeds data to bolts <strong>B1</strong> and <strong>B2</strong> for |
| processing; in turn, bolt <strong>B1</strong> feeds processed data to bolts <strong>B3</strong> and |
| <strong>B4</strong>, while bolt <strong>B2</strong> feeds processed data to bolt <strong>B4</strong>. This is just a |
| simple example; you can create arbitrarily complex topologies in Heron.</p> |
| <h2><a class="anchor" aria-hidden="true" id="creating-topologies"></a><a href="#creating-topologies" 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>Creating topologies</h2> |
| <p>There are currently two APIs available that you can use to build Heron topologies:</p> |
| <ol> |
| <li>The higher-level <a href="topology-development-streamlet-api">Heron Streamlet API</a>, which enables you to create topologies in a declarative, developer-friendly style inspired by functional programming concepts (such as map, flatMap, and filter operations)</li> |
| <li>The lower-level <a href="topology-development-topology-api-java">topology API</a> , based on the original <a href="http://storm.apache.org/about/simple-api.html">Apache Storm</a> API, which requires you to specify spout and bolt logic directly</li> |
| </ol> |
| <h2><a class="anchor" aria-hidden="true" id="topology-lifecycle"></a><a href="#topology-lifecycle" 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>Topology Lifecycle</h2> |
| <p>Once you've set up a Heron cluster, you |
| can use Heron's <a href="user-manuals-heron-cli">CLI tool</a> to manage the entire |
| lifecycle of a topology, which typically goes through the following stages:</p> |
| <ol> |
| <li><a href="user-manuals-heron-cli#submitting-a-topology">Submit</a> the topology |
| to the cluster. The topology is not yet processing streams but is ready to be |
| activated.</li> |
| <li><a href="user-manuals-heron-cli#activating-a-topology">Activate</a> the |
| topology. The topology will begin processing streams in accordance with |
| the topology architecture that you've created.</li> |
| <li><a href="user-manuals-heron-cli#restarting-a-topology">Restart</a> an |
| active topology if, for example, you need to update the topology configuration.</li> |
| <li><a href="user-manuals-heron-cli#deactivating-a-topology">Deactivate</a> the |
| topology. Once deactivated, the topology will stop processing but |
| remain running in the cluster.</li> |
| <li><a href="user-manuals-heron-cli#killing-a-topology">Kill</a> a topology to completely |
| remove it from the cluster. It is no longer known to the Heron cluster and |
| can no longer be activated. Once killed, the only way to run that topology is |
| to re-submit and re-activate it.</li> |
| </ol> |
| <h2><a class="anchor" aria-hidden="true" id="logical-plan"></a><a href="#logical-plan" 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>Logical Plan</h2> |
| <p>A topology's <strong>logical plan</strong> is analagous to a database <a href="https://en.wikipedia.org/wiki/Query_plan">query |
| plan</a> in that it maps out the basic |
| operations associated with a topology. Here's an example logical plan for the |
| example Streamlet API topology <a href="#streamlet-api-example">below</a>:</p> |
| <p><img src="https://www.lucidchart.com/publicSegments/view/4e6e1ede-45f1-471f-b131-b3ecb7b7c3b5/image.png" alt="Topology logical Plan"></p> |
| <p>Whether you use the <a href="#the-heron-streamlet-api">Heron Streamlet API</a> or the <a href="#the-topology-api">topology |
| API</a>, Heron automatically transforms the processing logic that |
| you create into both a logical plan and a <a href="#physical-plan">physical plan</a>.</p> |
| <h2><a class="anchor" aria-hidden="true" id="physical-plan"></a><a href="#physical-plan" 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>Physical Plan</h2> |
| <p>A topology's <strong>physical plan</strong> is related to its logical plan but with the |
| crucial difference that a physical plan determines the "physical" execution |
| logic of a topology, i.e. how topology processes are divided between containers. Here's a |
| basic visual representation of a |
| physical plan:</p> |
| <p><img src="https://www.lucidchart.com/publicSegments/view/5c2fe0cb-e4cf-4192-9416-b1b64b5ce958/image.png" alt="Topology Physical Plan"></p> |
| <p>In this example, a Heron topology consists of two <a href="topology-development-topology-api-java#spouts">spout</a> and five |
| different <a href="topology-development-topology-api-java#bolts">bolts</a> (each of which has multiple instances) that have automatically |
| been distributed between five different containers.</p> |
| <h2><a class="anchor" aria-hidden="true" id="window-operations"></a><a href="#window-operations" 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>Window operations</h2> |
| <p><strong>Windowed computations</strong> gather results from a topology or topology component within a specified finite time frame rather than, say, on a per-tuple basis.</p> |
| <p>Here are some examples of window operations:</p> |
| <ul> |
| <li>Counting how many customers have purchased a product during each one-hour period in the last 24 hours.</li> |
| <li>Determining which player in an online game has the highest score within the last 1000 computations.</li> |
| </ul> |
| <h3><a class="anchor" aria-hidden="true" id="sliding-windows"></a><a href="#sliding-windows" 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>Sliding windows</h3> |
| <p><strong>Sliding windows</strong> are windows that overlap, as in this figure:</p> |
| <p><img src="https://www.lucidchart.com/publicSegments/view/57d2fcbb-591b-4403-9258-e5b8e1e25de2/image.png" alt="Sliding time window"></p> |
| <p>For sliding windows, you need to specify two things:</p> |
| <ol> |
| <li>The length or duration of the window (length if the window is a <a href="#count-windows">count window</a>, duration if the window is a <a href="#time-windows">time window</a>).</li> |
| <li>The sliding interval, which determines when the window slides, i.e. at what point during the current window the new window begins.</li> |
| </ol> |
| <p>In the figure above, the duration of the window is 20 seconds, while the sliding interval is 10 seconds. Each new window begins five seconds into the current window.</p> |
| <blockquote> |
| <p>With sliding time windows, data can be processed in more than one window. Tuples 3, 4, and 5 above are processed in both window 1 and window 2 while tuples 6, 7, and 8 are processed in both window 2 and window 3.</p> |
| </blockquote> |
| <p>Setting the duration of a window to 16 seconds and the sliding interval to 12 seconds would produce this window arrangement:</p> |
| <p><img src="https://www.lucidchart.com/publicSegments/view/44bd4835-a692-44e6-a5d8-8e47151e3167/image.png" alt="Sliding time window with altered time interval"></p> |
| <p>Here, the sliding interval determines that a new window is always created 12 seconds into the current window.</p> |
| <h3><a class="anchor" aria-hidden="true" id="tumbling-windows"></a><a href="#tumbling-windows" 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>Tumbling windows</h3> |
| <p><strong>Tumbling windows</strong> are windows that don't overlap, as in this figure:</p> |
| <p><img src="https://www.lucidchart.com/publicSegments/view/881f99ee-8f93-448f-a178-b9f72dce6491/image.png" alt="Tumbling time window"></p> |
| <p>Tumbling windows don't overlap because a new window doesn't begin until the current window has elapsed. For tumbling windows, you only need to specify the length or duration of the window but <em>no sliding interval</em>.</p> |
| <blockquote> |
| <p>With tumbling windows, data are <em>never</em> processed in more than one window because the windows never overlap. Also, in the figure above, the duration of the window is 20 seconds.</p> |
| </blockquote> |
| <h3><a class="anchor" aria-hidden="true" id="count-windows"></a><a href="#count-windows" 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>Count windows</h3> |
| <p><strong>Count windows</strong> are specified on the basis of the number of operations rather than a time interval. A count window of 100 would mean that a window would elapse after 100 tuples have been processed, <em>with no relation to clock time</em>.</p> |
| <p>With count windows, this scenario (for a count window of 50) would be completely normal:</p> |
| <table> |
| <thead> |
| <tr><th style="text-align:left">Window</th><th style="text-align:left">Tuples processed</th><th style="text-align:left">Clock time</th></tr> |
| </thead> |
| <tbody> |
| <tr><td style="text-align:left">1</td><td style="text-align:left">50</td><td style="text-align:left">10 seconds</td></tr> |
| <tr><td style="text-align:left">2</td><td style="text-align:left">50</td><td style="text-align:left">12 seconds</td></tr> |
| <tr><td style="text-align:left">3</td><td style="text-align:left">50</td><td style="text-align:left">1 hour, 12 minutes</td></tr> |
| <tr><td style="text-align:left">4</td><td style="text-align:left">50</td><td style="text-align:left">5 seconds</td></tr> |
| </tbody> |
| </table> |
| <h3><a class="anchor" aria-hidden="true" id="time-windows"></a><a href="#time-windows" 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>Time windows</h3> |
| <p><strong>Time windows</strong> differ from <a href="#count-windows">count windows</a> because you need to specify a time duration (in seconds) rather than a number of tuples processed.</p> |
| <p>With time windows, this scenario (for a time window of 30 seconds) would be completely normal:</p> |
| <table> |
| <thead> |
| <tr><th style="text-align:left">Window</th><th style="text-align:left">Tuples processed</th><th style="text-align:left">Clock time</th></tr> |
| </thead> |
| <tbody> |
| <tr><td style="text-align:left">1</td><td style="text-align:left">150</td><td style="text-align:left">30 seconds</td></tr> |
| <tr><td style="text-align:left">2</td><td style="text-align:left">50</td><td style="text-align:left">30 seconds</td></tr> |
| <tr><td style="text-align:left">3</td><td style="text-align:left">0</td><td style="text-align:left">30 seconds</td></tr> |
| <tr><td style="text-align:left">4</td><td style="text-align:left">375</td><td style="text-align:left">30 seconds</td></tr> |
| </tbody> |
| </table> |
| <h3><a class="anchor" aria-hidden="true" id="all-window-types"></a><a href="#all-window-types" 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>All window types</h3> |
| <p>As explained above, windows differ along two axes: sliding (overlapping) vs. tumbling (non overlapping) and count vs. time. This produces four total types:</p> |
| <ol> |
| <li><a href="#sliding-windows">Sliding</a> <a href="#time-windows">time</a> windows</li> |
| <li><a href="#sliding-windows">Sliding</a> <a href="#count-windows">count</a> windows</li> |
| <li><a href="#tumbling-windows">Tumbling</a> <a href="#time-windows">time</a> windows</li> |
| <li><a href="#tumbling-windows">Tumbling</a> <a href="#count-windows">count</a> windows</li> |
| </ol> |
| <h2><a class="anchor" aria-hidden="true" id="resource-allocation-with-the-heron-streamlet-api"></a><a href="#resource-allocation-with-the-heron-streamlet-api" 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>Resource allocation with the Heron Streamlet API</h2> |
| <p>When creating topologies using the Streamlet API, there are three types of resources that you can specify:</p> |
| <ol> |
| <li>The number of containers into which the topology's <a href="#physical-plan">physical plan</a> will be split</li> |
| <li>The total number of CPUs allocated to be used by the topology</li> |
| <li>The total amount of RAM allocated to be used by the topology</li> |
| </ol> |
| <p>For each topology, there are defaults for each resource type:</p> |
| <table> |
| <thead> |
| <tr><th style="text-align:left">Resource</th><th style="text-align:left">Default</th><th style="text-align:left">Minimum</th></tr> |
| </thead> |
| <tbody> |
| <tr><td style="text-align:left">Number of containers</td><td style="text-align:left">1</td><td style="text-align:left">1</td></tr> |
| <tr><td style="text-align:left">CPU</td><td style="text-align:left">1.0</td><td style="text-align:left">1.0</td></tr> |
| <tr><td style="text-align:left">RAM</td><td style="text-align:left">512 MB</td><td style="text-align:left">192MB</td></tr> |
| </tbody> |
| </table> |
| <h3><a class="anchor" aria-hidden="true" id="allocating-resources-to-topologies"></a><a href="#allocating-resources-to-topologies" 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>Allocating resources to topologies</h3> |
| <p>For instructions on allocating resources to topologies, see the language-specific documentation for:</p> |
| <ul> |
| <li><a href="topology-development-streamlet-api#containers-and-resources">Java</a></li> |
| </ul> |
| <h2><a class="anchor" aria-hidden="true" id="data-model"></a><a href="#data-model" 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>Data Model</h2> |
| <p>Heron's original topology API required using a fundamentally tuple-driven data model. |
| You can find more information in <a href="guides-data-model">Heron's Data Model</a>.</p> |
| </span></div></article></div><div class="docs-prevnext"><a class="docs-prev button" href="/docs/0.20.1-incubating/heron-design-goals"><span class="arrow-prev">← </span><span>Heron Design Goals</span></a><a class="docs-next button" href="/docs/0.20.1-incubating/heron-streamlet-concepts"><span>Heron Streamlets</span><span class="arrow-next"> →</span></a></div></div></div><nav class="onPageNav"><ul class="toc-headings"><li><a href="#creating-topologies">Creating topologies</a></li><li><a href="#topology-lifecycle">Topology Lifecycle</a></li><li><a href="#logical-plan">Logical Plan</a></li><li><a href="#physical-plan">Physical Plan</a></li><li><a href="#window-operations">Window operations</a><ul class="toc-headings"><li><a href="#sliding-windows">Sliding windows</a></li><li><a href="#tumbling-windows">Tumbling windows</a></li><li><a href="#count-windows">Count windows</a></li><li><a href="#time-windows">Time windows</a></li><li><a href="#all-window-types">All window types</a></li></ul></li><li><a href="#resource-allocation-with-the-heron-streamlet-api">Resource allocation with the Heron Streamlet API</a><ul class="toc-headings"><li><a href="#allocating-resources-to-topologies">Allocating resources to topologies</a></li></ul></li><li><a href="#data-model">Data Model</a></li></ul></nav></div><footer class="nav-footer" id="footer"><div class="apache-disclaimer">Apache Heron is an effort undergoing incubation at <a target="_blank" href="https://apache.org/">The Apache Software Foundation (ASF)</a> sponsored by the Apache Incubator PMC. Incubation is required of all newly accepted projects until a further review indicates that the infrastructure, communications, and decision making process have stabilized in a manner consistent with other successful ASF projects. While incubation status is not necessarily a reflection of the completeness or stability of the code, it does indicate that the project has yet to be fully endorsed by the ASF.<br/><br/>Apache®, the names of Apache projects, and the feather logo are either <a rel="external" href="https://www.apache.org/foundation/marks/list/">registered trademarks or trademarks</a> of the Apache Software Foundation in the United States and/or other countries.<br/><br/><div class="copyright-box">Copyright © 2023 the Apache Software Foundation, Apache Heron, Heron, |
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