[Twisted-Python] Serial interface for software program

[anatoly techtonik]

Hi Laurens,

Well, Manhole looks way more advanced than my idea. I just need to
be able to tap into one way application event stream - there is no input
from the other side, so application doesn't need to prepare for that.

So, serial != terminal. There might be in future, but now I am more
interested in accessibility of tap interface rather than its features.

On Mon, May 5, 2014 at 6:42 PM, Laurens Van Houtven <_ at lvh.io> wrote:
> Hi Anatoly,
>
>
> Do you know about manhole? I made a video that also demos axiom, but it
> should show you what manhole does :)
>
> https://www.youtube.com/watch?v=3-UZiO-AnLc
>
> Essentially it's "repl in a running process".
>
>
> hth
> lvh
>
>
> On Mon, May 5, 2014 at 4:43 AM, anatoly techtonik <techtonik at gmail.com>
> wrote:
>>
>> Hello, network hackers,
>>
>> Recently I've got a Raspberry Pi and a friend showed me its serial
>> interface and helped to setup it. I was stunned. What I saw - you open
>> serial terminal, and you jump in into the middle of boot section. Just
>> open a terminal and you see what's going on inside of R.Pi. Any time.
>> That's was an intro. =)
>>
>> For a long time I wanted the same interface for debugging software
>> programs. When I was hacking on Spyder I found that my human brain is
>> too limited to squeeze details of dynamic of interaction of objects at
>> run-time. Spyder is written in Python with Qt, and it is a parallel
>> application much like any Twisted app is. But I wanted to push the
>> progress, I have to deal with complexity, so I badly needed to be able
>> to draw a video of interaction at run-time. That was the problem I
>> tried to solve.
>>
>> And for the first step I needed a way to connect to Spyder at run-time
>> and see what's going on. I didn't know how to call that way before,
>> but now I have a rather accurate wording - "a serial interface for an
>> application". That is the background for the question I am trying to
>> ask.
>>
>> What is the best way to implement such interface considering the
>> following properties:
>> 1. it needs to be simple (so that you can quickly create python script
>> that reads the info)
>> 2. it needs to be universal (so that script for one app worked for other)
>> 3. it should be asynchronous (connected terminal should not degrade
>> performance)
>> 4. it needs to be reliable (at least detecting missing packets)
>> 5. and cross-platform (and pure python)
>>
>> Why Twisted? For the first I think that this problem is actual for
>> people who are dealing with complexity of dynamic and interconnected
>> systems built with the help of Twisted. For the second I believe it
>> can only be solved or analyzed by people skilled in interprocess and
>> internetwork communications.
>>
>> One button test:
>> 1. program behaves weird
>> 2. user hits the button
>> 3. terminal pops up
>> 4. shows a lot of data for a running program
>>
>> I am interested to know.
>> 1. how the button should discover the program
>> network port seems cool, but what about two parallel programs? what
>> about different programs that provide this interface?
>>
>> 2. how terminal receives the data
>> i see it as line based - one line - one event, everything is text
>>
>> 3. how to make it fast
>> TCP clearly won't here
>>
>> 4. how to send the data
>> what if two threads (or parallel code) produce serial data? who should
>> run the server that serves connected terminals, and how other thread
>> will send message to this server? you can not run two TCP servers on
>> the same port on the app side, so is there an alternative? how to
>> detect missing data in a stream? how to avoid dealing with incomplete
>> packets and low level network details?
>>
>> Thanks. I'd like to get back to hacking on Spyder one day, but this is
>> a stumbling block for me every time I think about it or any program of
>> compared complexity.
>> --
>> anatoly t.
>>
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>
>
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-- 
anatoly t.