# Blocks with message input and output only

**URL:** <https://www.ruby-forum.com/t/blocks-with-message-input-and-output-only/239539>\
**Category:** GNU Radio\
**Created:** [March 4, 2014, 1:10am UTC](https://www.ruby-forum.com/t/blocks-with-message-input-and-output-only/239539 "2014-03-04T01:10:11Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![musicdenotation](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ea666f/32.png) [@musicdenotation](https://www.ruby-forum.com/u/musicdenotation)\
**Post date:** [March 4, 2014, 1:10am UTC](https://www.ruby-forum.com/t/blocks-with-message-input-and-output-only/239539/1 "2014-03-04T01:10:11Z")

</div>

Hi Guys,

How to write blocks that have only message input and outputs only? I  
have derived from gr:block, and in most cases it seems to work, but if  
I put together a test that has no streams, then the whole graph stops  
I think prematurely. How to ensure that a flow graph works with  
messages only?

Miklos

---

<div class="post-metadata">

**Author:** ![Miklos\_M](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/57b2e6/32.png) [@Miklos\_M](https://www.ruby-forum.com/u/Miklos_M)\
**Post date:** [March 4, 2014, 1:24am UTC](https://www.ruby-forum.com/t/blocks-with-message-input-and-output-only/239539/2 "2014-03-04T01:24:18Z")

</div>

Sorry, everything works as expected (needs a little wait at the  
beginning). Miklos