29 November 2010

Working with the 90 Character Limit of Twitter

What?  Twitter has a 90 character limit?  No, it's 140.  Everyone knows that.

Mr Wikipedia says this about SMS length

"... resources in the system could be used to transport messages at minimal cost. However, it was necessary to limit the length of the messages to 128 bytes (later improved to 140 bytes, or 160 seven-bit characters) so that the messages could fit into the existing signaling formats."

Using the Groovy code that I did the other day to send a text message via a twitter Direct Message, if the message length is greater than 140 characters, twitter complains with this error:

403:The request is understood, but it has been refused.  An accompanying error message will explain why.
{"request":"\/1\/direct_messages\/new.json","error":"The text of your direct message is over 140 characters."}
TwitterException{exceptionCode=[6bcd7469-01bff100], statusCode=403, retryAfter=0, rateLimitStatus=null, version=2.1.7}

That kinda says that I can send 140 characters, so what's this nonsense about a 90 character limit?

Well, true, you can send 140 characters but if you're hacking the system for the purposes of having Twitter forward your message as a text message to a phone then different rules apply.

Take a look at what happens when you send a Direct Message of 140 characters to an account that is set up to send a txt:
String message = "12345678911234567892123456789312345678941234567895" +
                 "12345678961234567897123456789812345678991234567891" +

DirectMessage directMessage = twitter.sendDirectMessage(screenName, message)
Twitter breaks the message into 2 separate texts (and my phone occasionally gets the 2nd text first).

For the app that I'm working on, I need my data in a single text message, I don't want the mess of re-assembling.

I think the message split is because a header of:

"Direct from" screen name:

and a footer of

"Reply with 'd" screen name "hi.'"

is added to each message.

I've found that the amount of data that you can actually send depends on the screen name.  Since screen names can be up to 15 chars, you lose:

Direct from screenname:
= up to 28 characters (12 + screen name)

Reply with 'd screenname hi.'
= up to 34 characters (19 + screen name)

140 - 28 - 34 = 78

Uh, 78 is not 90.  What the heck? I guess my math has errors.

But check this out.  By adjusting my direct message, I find that a 90 character message is the sweet spot for a 15 character screen name and the message is sent as a single text.  91 characters will cause the message to be split over 2 texts.

Maybe that header and footer isn't as big as I think it is.

140 - 90 = 50 characters for header/footer?

If a screen name is used twice (2 * 15 = 30), then maybe the bloat is only 20 characters?

What happens if I send messages to a different screen name, one that is smaller than 15 characters?

What is I use a screen name of 8 characters?  Should I be able to send a message of

140 - 20 (bloat) - (2 * 8) = 104 characters?

After a quick reassignment of my phone to a different twitter account, I tried a test with a screen name that is 8 characters.  Could I send 104?  Durn right I could!  And I could also send 109.  But 110 would cause a message split.  So I have an extra 5 characters unaccounted  for.

What happens if I send to a ...  No, this is going on too long. 

The max screen name is 15 characters and that limits the max amount of data that can be sent in one message to 90 characters.

If the screen name is less than 15 characters, then you get 90 plus some extra.  YMMV

What do you think? Leave a comment.