[pulsar-dotpulsar] branch master updated: modified the "hello world" to fix first run issue (#110)

[bl...@apache.org]

This is an automated email from the ASF dual-hosted git repository.

blankensteiner pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/pulsar-dotpulsar.git


The following commit(s) were added to refs/heads/master by this push:
     new 3ca870e  modified the "hello world" to fix first run issue (#110)
3ca870e is described below

commit 3ca870ed6c4a67f54fc54849287f0101a1a27ab1
Author: Joshua Lapinski <ai...@users.noreply.github.com>
AuthorDate: Fri Sep 30 14:33:17 2022 -0700

    modified the "hello world" to fix first run issue (#110)
    
    * modified the "hello world" to fix first run issue
    
    the current "hello world" will not show a consumed message the very first time it is run. On subsequent runs, it will work, but it isn't entirely clear from the code alone why it works on subsequent runs.
    
    I don't entirely understand why the order matters here, but I believe it isn't showing the consumed message on the first run because the subscription is created after the producer sends a message. It seems that by default, a new subscription will not consume messages that are created before it.
    
    An alternative solution would be to create the consumer with the "InitialPosition" option set to Earliest (".InitialPosition(SubscriptionInitialPosition.Earliest"), but I think it's preferable to minimize optional configuration in a hello world like this.
    
    * Revised "Hello World" update
    
    Per feedback, revised the "Hello World" code to use the optional "InitialPosition" configuration setting on the consumer.
---
 README.md | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/README.md b/README.md
index d031189..56a860b 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@ Have a look at the [changelog](CHANGELOG.md).
 
 ## Getting Started
 
-Let's take a look at a "Hello world" example, where we first produce a message and then consume it.
+Let's take a look at a "Hello world" example, where we first produce a message and then consume it. Note that the topic and subscription will be created if they don't exist.
 
 First, we need a Pulsar setup. Have a look [here](https://pulsar.apache.org/docs/en/standalone-docker/) to see how to setup a local standalone Pulsar instance.
 Install the NuGet package [DotPulsar](https://www.nuget.org/packages/DotPulsar/) and copy/paste the code below (you will be needing using declarations for 'DotPulsar' and 'DotPulsar.Extensions').
@@ -32,6 +32,7 @@ _ = await producer.Send("Hello World"); // Send a message and ignore the returne
 await using var consumer = client.NewConsumer(Schema.String)
                                  .SubscriptionName("MySubscription")
                                  .Topic(myTopic)
+                                 .InitialPosition(SubscriptionInitialPosition.Earliest)
                                  .Create();
 
 await foreach (var message in consumer.Messages())