edw/pubsubd

Simple pub-sub HTTP service

pubsubd

Note: This is an outdated version of this project hosted here for reference purposes. A significantly enhanced version is available at https://git.sr.ht/~edwin/pubsubd. The enhanced version supports multiple topics, maximum subscription queue sizes with dropping strategies, and features at least one important bug fix.

Pubsubd is a simple pub-sub server with a curl-friendly HTTP interface. All messages are posted to a single topic. Subscriptions are creared implicitly by performing a pull or ack operation. Pubsubd is poll-only: it does not support push operations.

Installing

$ go get poseur.com/pubsubd

Running

$ pubsubd --data-dir ./data --host 127.0.0.1 --port 8080

Subscribing

$ curl "http://localhost:8080/pull?sub=SUBNAME&n=0"

Sending messages

$ curl -X POST -D - \
    -d "message=foo&message=bar&message=42" \
    "http://localhost:8080/send"

Getting oldest unacknowledged messages

$ curl -D - "http://localhost:8080/pull?sub=SUBNAME&n=10"

Output:

HTTP/1.1 200 OK
Date: Wed, 22 Jul 2020 18:25:47 GMT
Content-Length: 58
Content-Type: text/plain; charset=utf-8

{"n_messages":3,"messages":{"0":"foo","1":"bar","2":"42"}}

Acknowledging messages

$ curl -X POST -D - "http://localhost:8080/ack?sub=SUBNAME&id=0"

This will result in another pull on sub SUBNAME excluding message id 0:

$ curl -D - "http://localhost:8080/pull?sub=SUBNAME&n=10"

Output:

HTTP/1.1 200 OK
Date: Wed, 22 Jul 2020 18:29:06 GMT
Content-Length: 48
Content-Type: text/plain; charset=utf-8

{"n_messages":2,"messages":{"1":"bar","2":"42"}}

Unsubscribing

$ curl -X POST -D - "http://localhost:8080/unsub?sub=SUBNAME"

A subsequent pull shows that there are no longer any waiting messages:

$ curl -D - "http://localhost:8080/pull?sub=SUBNAME&n=10"

Output:

HTTP/1.1 200 OK
Date: Wed, 22 Jul 2020 18:32:09 GMT
Content-Length: 30
Content-Type: text/plain; charset=utf-8

{"n_messages":0,"messages":{}}

Of course, that pull operation re-creeated the subscription, so be careful out there!

Testing

There is an included test.sh script that will fire up an instance of pubsubd and perform operations similar to the above to verify something approximating proper operation. The script assumes that the pubsubd binary exists in same directory.