Merge pull request #6514 from segmentio/DOC-911

Source overview updates [DOC-911]

Author: forstisabella

src/connections/sources/images/source-overview.jpeg

@@ -49,7 +49,7 @@ analytics.identify('user_123', {
 {% endcomment %}
 
 > info "If you don't see the source you're looking for in our catalog"
-> If a tool is not listed as a supported source in our [catalog](https://segment.com/catalog/){:target='_blank’}, then it is not possible to incorporate the integration out-of-the-box within a Segment workspace. However, as an alternative, you can use the [HTTP API](/docs/connections/sources/catalog/libraries/server/http-api/) source to collect data from the tool's API. You can also use [Functions](/docs/connections/functions/) to send or receive data from other tools.
+> If a tool is not listed as a supported source in Segment's [catalog](https://segment.com/catalog/){:target='_blank’}, then it is not possible to incorporate the integration out-of-the-box within a Segment workspace. However, as an alternative, you can use the [HTTP API](/docs/connections/sources/catalog/libraries/server/http-api/) source to collect data from the tool's API. You can also use [Functions](/docs/connections/functions/) to send or receive data from other tools.
 
 ## Types of sources
 
@@ -79,18 +79,30 @@ Event streams sources collect data from your website or app to monitor user acti
 
 ### Source Overview
 
-When viewing the Source Overview page for an event stream source, you can view a line chart and breakdown table that reflects the volume and details of the events that Segment ingested from your source.
+The Source Overview page for an event stream source shows you a [pipeline view](#pipeline-view) of all events Segment receives from your source, events that failed on ingest, events that are filtered at the source level, and "eligible events", which are the events that will flow into your destinations. If you select one of the steps in the pipeline view, you can see a line chart that reflects the fluctuations in volume alongside a [breakdown table](#breakdown-table) that has more details about the events impacted by the selected step.
 
-You can use the time picker located on the Source Overview page to specify a time period (last 10 minutes, 1 hour, 24 hours, 7 days, 2 weeks, or a custom date range over the last two weeks) for which you’d like to see data.
+#### Pipeline view
 
-![A screenshot of the Source Overview page for an Android source.](images/source-overview.jpeg)
+The pipeline view shows each of the four steps Segment encounters when processing data from your source: 
 
-The breakdown table displays the following details:
-* **Event type**: The Segment Spec event type (Track call vs. Identify call, for example).
-* **Event name**: The event name, provided by you or the source. You should only expect to see track calls with event names. If you see unnamed events in the breakdown table, it's because for other specs, you're either identifying users/groups or tracking what page/screen the user is on. Both of which do not have event names. The exception to this is if you provide a name in the Page call. Named Page calls also show up in this section with the name of the Page as the event name. 
-<!-- NOT SUPPORTED IN CURRENT VERSION: ADD IN ONCE THIS IS SUPPORTED* **App version**: The app/release version, provided by you or the source-->
-* **Event count**: How many of each event was successfully received by your source.
-* **% Change**: Insight into how the event counts differ from the last comparable time range as a percentage.
+- **Events successfully received**: All events that Segment received from your source.
+- **Failed on ingest**: Events that failed at the Tracking API level. For more information about errors that might cause events to fail on ingest, see Delivery Overview's [Troubleshooting](/docs/connections/delivery-overview/#troubleshooting) documentation.
+- **Filtered at source**: Events that were filtered out by source schema controls, Tracking Plans, or a common JSON schema.
+- **Eligible events**: Eligible events are the events that flow downstream to your Segment destinations. This value is read-only, but you can see the events that flow downstream to a particular destination using [Delivery Overview](/docs/connections/delivery-overview).
+
+> success ""
+> You can use the time picker located on the Source Overview page to specify a time period (last 10 minutes, 1 hour, 24 hours, 7 days, 2 weeks, or a custom date range over the last two weeks) for which you’d like to see data. Segment sets the time picker to show data for the last 24 hours by default. 
+
+![A screenshot of the Source Overview page for an Go source, with the Failed on ingest step selected.](images/source-overview.png)
+
+#### Breakdown table
+
+The breakdown table displays three tabs, **Event type**, **Event name**, and **App version**. 
+* **Event type**: The Segment Spec event type (Track call vs. Identify call, for example). _This tab also contains a "% change" metric, which displays how the event counts differ from the last comparable time range, represented as a percentage._
+* **Event name**: The event name, provided by you or the source.
+* **App version**: The app/release version, provided by you or the source. 
+
+Each of these tabs displays an event count, which is the total number of events that Segment received in a particular step. 
 
 ### Website libraries