Merge pull request MicrosoftDocs#36144 from kgremban/mar23-5346

Clarifying routing queries for issue 5346
bennage · Mar 23, 2018 · 64fb41a · 64fb41a
2 parents f572749 + e784868
commit 64fb41a
Showing 1 changed file with 13 additions and 24 deletions.
diff --git a/articles/iot-edge/module-composition.md b/articles/iot-edge/module-composition.md
@@ -8,7 +8,7 @@ author: kgremban
 manager: timlt
 
 ms.author: kgremban
-ms.date: 03/14/2018
+ms.date: 03/23/2018
 ms.topic: article
 ms.service: iot-edge
 
@@ -139,32 +139,21 @@ The source specifies where the messages come from. It can be any of the followin
 ### Condition
 The condition is optional in a route declaration. If you want to pass all messages from the sink to the source, just leave out the **WHERE** clause entirely. Or you can use the [IoT Hub query language][lnk-iothub-query] to filter for certain messages or message types that satisfy the condition.
 
-Azure IoT messages are formatted as JSON and always have at least a **body** parameter. For example:
+The messages that pass between modules in IoT Edge are formatted the same as the messages that pass between your devices and Azure IoT Hub. All messages are formatted as JSON and have **systemProperties**, **appProperties**, and **body** parameters. 
 
-```json
-"message": {
-    "body":{
-        "ambient":{
-            "temperature": 54.3421,
-            "humidity": 25
-        },
-        "machine":{
-            "status": "running",
-            "temperature": 62.2214
-        }
-    },
-    "appProperties":{
-        ...
-    }
-}
-```
+You can build queries around all three parameters with the following syntax: 
+
+* System properties: `$<propertyName>` or `{$<propertyName>}`
+* Application properties: `<propertyName>`
+* Body properties: `$body.<propertyName>` 
 
-Given this sample message, there are a number of conditions that can be defined, such as:
-* `WHERE $body.machine.status != "running"`
-* `WHERE $body.ambient.temperature <= 60 AND $body.machine.temperature >= 60`
+For examples about how to create queries for message properties, see [Device-to-cloud message routes query expressions](../iot-hub/iot-hub-devguide-query-language.md#device-to-cloud-message-routes-query-expressions).
 
-The condition can also be used to sort message types, for example, in a gateway that wants to route messages that come in from leaf devices. Messages that come from modules contain a specific property called **connectionModuleId**. So if you want to route messages from leaf devices directly to IoT Hub, use the following route to exclude module messages:
-* `FROM /messages/* WHERE NOT IS_DEFINED($connectionModuleId) INTO $upstream`
+An example that is specific to IoT Edge is when you want to filter for messages that arrived at a gateway device from a leaf device. Messages that come from modules contain a system property called **connectionModuleId**. So if you want to route messages from leaf devices directly to IoT Hub, use the following route to exclude module messages:
+
+```sql
+FROM /messages/* WHERE NOT IS_DEFINED($connectionModuleId) INTO $upstream
+```
 
 ### Sink
 The sink defines where the messages are sent. It can be any of the following values: