Lost some bytes sending with websockets

jars · 2016-10-24 13:16:57

Hi,
Modifying the Project31ChatServer example, I compress some json records with Zlib for compatibility and then call "NotifyBlaBla(pseudo,msg)" where msg is the compressed json.
Once compressed I take volume size to compare with the size received.
What happens is that the client receive fewer bytes than the server sends.
I have no idea how to solve it or because it happens.
Thanks in advance for any help.

ab · 2016-10-24 13:24:28

I guess that the chat server expect text, not binary content.

jars · 2016-10-24 13:32:14

Hi ab,
Then, how can I send this?

ab · 2016-10-24 13:43:19

If you use text transmission, the only possibility is to base-64 encode the compressed content.

You need to use a binary transmission with your WebSockets, like for the TWebSocketProtocolBinary, instead of the TWebSocketProtocolChat protocol, which is text-based.
BTW, TWebSocketProtocolBinary has already built-in compression and encryption available.

Why do you want to reinvent the wheel?

jars · 2016-10-24 13:58:55

Why do you want to reinvent the wheel?

Because I don't know which programming language will use on client-side

ab · 2016-10-24 14:20:27

So, keep with JSON and text protocol, without compression.
It will be safe and easy enough to work with, for any client-side client.

Cross-platform compression is very difficult to implement.
The only possible way may be to implement https://tools.ietf.org/html/rfc7692 but even this is a proposed standard, not widely adopted I'm afraid...

jars · 2016-10-24 14:46:36

I can't keep it without compression because the json size is about 150k.
Is there another way to send this binary data?
I only need to send this data from server to clients.

Last edited by jars (2016-10-24 14:59:09)

ab · 2016-10-24 15:27:28

Long polling may be easier to implement.
But it will depend also on the clients possibilities/technologies used.

But of course, WebSockets binary could be used for that.
Just create your own server side protocol class, taking inspiration from TWebSocketProtocolBinary and TWebSocketProtocolChat.

mORMot Open Source

#1 2016-10-24 13:16:57

Lost some bytes sending with websockets

#2 2016-10-24 13:24:28

Re: Lost some bytes sending with websockets

#3 2016-10-24 13:32:14

Re: Lost some bytes sending with websockets

#4 2016-10-24 13:43:19

Re: Lost some bytes sending with websockets

#5 2016-10-24 13:58:55

Re: Lost some bytes sending with websockets

#6 2016-10-24 14:20:27

Re: Lost some bytes sending with websockets

#7 2016-10-24 14:46:36

Re: Lost some bytes sending with websockets

#8 2016-10-24 15:27:28

Re: Lost some bytes sending with websockets

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