merlimat closed pull request #1503: Pulsar Functions triggering overview
URL: https://github.com/apache/incubator-pulsar/pull/1503
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diff --git a/site/docs/latest/functions/deployment.md
b/site/docs/latest/functions/deployment.md
index 8901347039..25c0c2fc9c 100644
--- a/site/docs/latest/functions/deployment.md
+++ b/site/docs/latest/functions/deployment.md
@@ -104,9 +104,9 @@ $ bin/pulsar-admin functions update \
--functionConfigFile function-config.yaml
```
-## Triggering functions
+## Triggering Pulsar Functions {#triggering}
-Whether a Pulsar Function is running in [local run](#local-run) or
[cluster](#cluster-mode), you can **trigger** the function at any time using
the command line. Triggering a function means that you send a message with a
specific value to the function.
+If a Pulsar Function is running in [cluster mode](#cluster-mode), you can
**trigger** it at any time using the command line. Triggering a function means
that you send a message with a specific value to the function and get the
function's output (if any) via the command line.
{% include admonition.html type="info" content="Triggering a function is
ultimately no different from invoking a function by producing a message on one
of the function's input topics. The [`pulsar-admin functions
trigger`](../../CliTools#pulsar-admin-functions-trigger) command is essentially
a convenient mechanism for sending messages to functions without needing to use
the [`pulsar-client`](../../CliTools#pulsar-client) tool or a language-specific
client library." %}
diff --git a/site/docs/latest/functions/overview.md
b/site/docs/latest/functions/overview.md
index ffee467d65..c3cf23d65d 100644
--- a/site/docs/latest/functions/overview.md
+++ b/site/docs/latest/functions/overview.md
@@ -62,8 +62,6 @@ If you were to implement the classic word count example using
Pulsar Functions,
-Here, sentences are produced on the `sentences` topic. The Pulsar Function
listens on that topic and whenever a message arrives it splits the sentence up
into individual words and increments a [counter](#counters) for each word every
time that word is encountered. The value of that counter is then available to
all [instances](#parallelism) of the function.
-
If you were writing the function in [Java](../api#java) using the [Pulsar
Functions SDK for Java](../api#java-sdk), you could write the function like
this...
```java
@@ -193,7 +191,7 @@ Pulsar Functions can currently be written in
[Java](../../functions/api#java) an
* SerDe (built-in vs. custom)
* Pulsar messages are always just bytes, but Pulsar Functions handles data
types for you *unless* you need custom types
-## Function context {#context}
+### Function context {#context}
Each Pulsar Function created using the [Pulsar Functions SDK](#sdk) has access
to a context object that both provides:
@@ -347,6 +345,33 @@ public class ConfigMapFunction implements Function<String,
Void> {
}
```
+### Triggering Pulsar Functions {#triggering}
+
+Pulsar Functions running in [cluster mode](#cluster-mode) can be
[triggered](../deployment#triggering) via the [command line](#cli). With
triggering you can easily pass a specific value to a function and get the
function's return value *without* needing to worry about creating a client,
sending a message to the right input topic, etc. Triggering can be very useful
for---but is by no means limited to---testing and debugging purposes.
+
+{% include admonition.html type="info" content="Triggering a function is
ultimately no different from invoking a function by producing a message on one
of the function's input topics. The [`pulsar-admin functions
trigger`](../../CliTools#pulsar-admin-functions-trigger) command is essentially
a convenient mechanism for sending messages to functions without needing to use
the [`pulsar-client`](../../CliTools#pulsar-client) tool or a language-specific
client library." %}
+
+Let's take an example Pulsar Function written in Python (using the [native
interface](../api#python-native)) that simply reverses string inputs:
+
+```python
+def process(input):
+ return input[::-1]
+```
+
+If that function were running in a Pulsar cluster, it could be triggered like
this:
+
+```bash
+$ bin/pulsar-admin functions trigger \
+ --tenant sample \
+ --namespace ns1 \
+ --name reverse-func \
+ --triggerValue "snoitcnuf raslup ot emoclew"
+```
+
+That should return `welcome to pulsar functions` as the console output.
+
+{% include admonition.html type="success" content="Instead of passing in a
string via the CLI, you can also trigger a Pulsar Function with the contents of
a file using the `--triggerFile` flag." %}
+
## Processing guarantees {#guarantees}
The Pulsar Functions feature provides three different messaging semantics that
you can apply to any function:
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