├── .github └── PULL_REQUEST_TEMPLATE.md ├── COPYING ├── HACKING.org ├── Makefile ├── README-elpa ├── README.org ├── crdt-pkg.el └── crdt.el /.github/PULL_REQUEST_TEMPLATE.md: -------------------------------------------------------------------------------- 1 | :warning: This repo is a read-only mirror. Please submit changes upstream instead :warning: 2 | -------------------------------------------------------------------------------- /COPYING: -------------------------------------------------------------------------------- 1 | GNU GENERAL PUBLIC LICENSE 2 | Version 3, 29 June 2007 3 | 4 | Copyright (C) 2007 Free Software Foundation, Inc. 5 | Everyone is permitted to copy and distribute verbatim copies 6 | of this license document, but changing it is not allowed. 7 | 8 | Preamble 9 | 10 | The GNU General Public License is a free, copyleft license for 11 | software and other kinds of works. 12 | 13 | The licenses for most software and other practical works are designed 14 | to take away your freedom to share and change the works. By contrast, 15 | the GNU General Public License is intended to guarantee your freedom to 16 | share and change all versions of a program--to make sure it remains free 17 | software for all its users. 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It is safest 630 | to attach them to the start of each source file to most effectively 631 | state the exclusion of warranty; and each file should have at least 632 | the "copyright" line and a pointer to where the full notice is found. 633 | 634 | 635 | Copyright (C) 636 | 637 | This program is free software: you can redistribute it and/or modify 638 | it under the terms of the GNU General Public License as published by 639 | the Free Software Foundation, either version 3 of the License, or 640 | (at your option) any later version. 641 | 642 | This program is distributed in the hope that it will be useful, 643 | but WITHOUT ANY WARRANTY; without even the implied warranty of 644 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 645 | GNU General Public License for more details. 646 | 647 | You should have received a copy of the GNU General Public License 648 | along with this program. If not, see . 649 | 650 | Also add information on how to contact you by electronic and paper mail. 651 | 652 | If the program does terminal interaction, make it output a short 653 | notice like this when it starts in an interactive mode: 654 | 655 | Copyright (C) 656 | This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'. 657 | This is free software, and you are welcome to redistribute it 658 | under certain conditions; type `show c' for details. 659 | 660 | The hypothetical commands `show w' and `show c' should show the appropriate 661 | parts of the General Public License. Of course, your program's commands 662 | might be different; for a GUI interface, you would use an "about box". 663 | 664 | You should also get your employer (if you work as a programmer) or school, 665 | if any, to sign a "copyright disclaimer" for the program, if necessary. 666 | For more information on this, and how to apply and follow the GNU GPL, see 667 | . 668 | 669 | The GNU General Public License does not permit incorporating your program 670 | into proprietary programs. If your program is a subroutine library, you 671 | may consider it more useful to permit linking proprietary applications with 672 | the library. If this is what you want to do, use the GNU Lesser General 673 | Public License instead of this License. But first, please read 674 | . 675 | -------------------------------------------------------------------------------- /HACKING.org: -------------------------------------------------------------------------------- 1 | * Algorithm 2 | 3 | Background reading: [[https://en.wikipedia.org/wiki/Conflict-free_replicated_data_type][CRDT]] 4 | 5 | This packages implements the Logoot split algorithm 6 | ~André, Luc, et al. "Supporting adaptable granularity of changes for massive-scale collaborative editing." 9th IEEE International Conference on Collaborative Computing: Networking, Applications and Worksharing. IEEE, 2013.~ 7 | 8 | The CRDT-ID blocks are implemented by text property ='crdt-id=. 9 | A continous range of text with the same ='crdt-id= property represent a CRDT-ID block. 10 | The ='crdt-id= is a a cons of =(ID-STRING . END-OF-BLOCK-P)=, 11 | where =ID-STRING= represent the CRDT-ID of the leftmost character in the block. 12 | If =END-OF-BLOCK-P= is =NIL=, the block is a non-rightmost segment splitted from a larger block, 13 | so insertion at the right of this block shouldn't be merged into the block by sharing the base CRDT-ID and increasing offset. 14 | 15 | =ID-STRING= is a unibyte string representing a CRDT-ID (for efficient comparison). 16 | Every two bytes represent a big endian encoded integer. 17 | For base IDs, last two bytes are always representing Site ID. 18 | Stored strings are BASE-ID:OFFSETs. So the last two bytes represent offset, 19 | and second last two bytes represent Site ID. 20 | 21 | * Protocol 22 | 23 | Text-based version 24 | (it should be easy to migrate to a binary version. Using text for better debugging for now) 25 | 26 | Note: Starting from =v0.3.0=, we separate /User IDs/ and /Site IDs/. 27 | Site IDs are /buffer local/ and temporarily assigned to users with writable access. 28 | 29 | Every message takes the form =(type . body)= 30 | 31 | - Text Editing 32 | A peer must obtain a =site-id= before performing the following operations, 33 | by remote calling =crdt-get-write-access=. See [[Remote Function]]. 34 | + insert :: 35 | body takes the form =(buffer-name user-id crdt-id position-hint content)= 36 | - =position-hint= is the buffer position where the operation happens at the site 37 | which generates the operation. Then we can play the trick that start search 38 | near this position at other sites to speedup CRDT ID search 39 | - =content= is the string to be inserted 40 | 41 | + delete :: 42 | body takes the form =(buffer-name user-id position-hint . crdt-id-list)= 43 | - =crdt-id-list= is generated from =CRDT--DUMP-IDS= from the deleted text 44 | 45 | + cursor :: 46 | body takes the form 47 | =(buffer-name user-id point-position-hint point-crdt-id mark-position-hint mark-crdt-id)= 48 | =*-crdt-id= can be either a CRDT ID, or 49 | - =nil=, which means clear the point/mark 50 | - =""=, which means =(point-max)= 51 | 52 | - Contact information 53 | 54 | + contact :: 55 | body takes the form =(user-id slot value)= 56 | - =slot= can be one of 57 | #+BEGIN_SRC emacs-lisp 58 | name host service focus 59 | #+END_SRC 60 | 61 | + leave :: 62 | body takes the form =(user-id)= 63 | 64 | This message is sometime sent from client to server to indicate disconnection, 65 | if the underlying proxy doesn't indicate disconnection properly. 66 | 67 | - Login 68 | + hello :: 69 | This message is sent from client to server, when a client connect to the server. 70 | body takes the form =(protocol-version &optional response)= 71 | 72 | + challenge :: 73 | body takes the form =(salt)= 74 | 75 | + login :: 76 | It's always sent after server receives a hello message. 77 | Assigns a User ID to the client 78 | body takes the form =(user-id)=. 79 | 80 | - Initial Synchronization 81 | + sync :: 82 | This message is sent from server to client to get it sync to the state on the server. 83 | Might be used for other optimization in the future. 84 | One optimization I have in mind is let server try to merge all CRDT item into a single 85 | one and try to synchronize this state to clients at best effort. 86 | body takes the form =(buffer-name . crdt-id-list)= 87 | - =crdt-id-list= is generated from =CRDT--DUMP-IDS= 88 | 89 | + ready :: 90 | body takes the form =(buffer-name major-mode-symbol)= 91 | Indicates the end of a batch of synchronization messages 92 | (which usually contains some =cursor= messages, a =sync= message, 93 | and some =overlay-*= messages). 94 | The client should now try to enable =major-mode-symbol= in the 95 | synchronized buffer. 96 | 97 | - Error Recovery 98 | Note: when a client side error happens, it just sends a =get= message and 99 | follow initial synchronization procedure to reinitialize the buffer. 100 | 101 | + error :: 102 | body takes the form =(buffer-name error-symbol . error-datum)=. 103 | This message is sent from server to client to notice that some messages from the 104 | client is not processed due to error =(error-symbol . error-datum)=. 105 | Normally client should follow initial synchronization procedure to reinitialize the buffer. 106 | - =buffer-name= can also be =nil=, which signifies that it's a session error. 107 | The only reasonable thing to do is to disconnect in this scenario. 108 | Currently, this happens when client/server protocol version doesn't match. 109 | 110 | - Buffer Service 111 | + add :: 112 | Indicates that the server has started sharing some buffers. 113 | body takes the form =buffer-name-list= 114 | 115 | + remove :: 116 | Indicates that the server has stopped sharing some buffers. 117 | body takes the form =buffer-name-list= 118 | 119 | + get :: 120 | Request the server to resend =sync= message for a buffer. 121 | body takes the form =(buffer-name)= 122 | 123 | - Overlay Synchronization 124 | + overlay-add :: 125 | body takes the form 126 | #+BEGIN_SRC 127 | (buffer-name user-id logical-clock species 128 | front-advance rear-advance 129 | start-position-hint start-crdt-id 130 | end-position-hint end-crdt-id) 131 | #+END_SRC 132 | 133 | + overlay-move :: 134 | body takes the form 135 | #+BEGIN_SRC 136 | (buffer-name user-id logical-clock 137 | start-position-hint start-crdt-id 138 | end-position-hint end-crdt-id) 139 | #+END_SRC 140 | 141 | + overlay-put :: 142 | body takes the form =(buffer-name user-id logical-clock prop value)= 143 | 144 | + overlay-remove :: 145 | body takes the form =(buffer-name user-id logical-clock)= 146 | 147 | - <> 148 | + fcap :: 149 | body takes the form =(fcap-symbol nonce in-states out-states . interactive-form)= 150 | This grants a "functional capability" to a peer. 151 | Nonce is a random number to prevent forging capability. 152 | - =in-states= is a list of state symbols that the function depends on. 153 | =out-states= is a list of state symbols that the function modifies and should be synchronized 154 | to the caller. 155 | See [[Allowed state symbols]]. 156 | 157 | + funcall :: 158 | body takes the form 159 | #+BEGIN_SRC 160 | (user-id logical-clock spawn-user-id 161 | state-list nonce fcap-symbol . args) 162 | #+END_SRC 163 | - =spawn-user-id= represents the site where the interactive command is originally invoked 164 | + It can be different from =user-id= because a remote function can call a remote function! 165 | This is especially useful when client makes a remote call, 166 | but the call on the server request some interactive input, 167 | and such interactive call are remote-called back into the client. 168 | - =state-list= is an alist of bindings. 169 | (except that we use 1 element list for the CDRs, to save a dot in the serialized string) 170 | (CDRs can also be 2 element list of the form =(crdt-id pos-hint)=) 171 | <> are 172 | #+BEGIN_SRC 173 | window window-point buffer buffer-content point 174 | mark mark-active transient-mark-mode last-command-event 175 | #+END_SRC 176 | 177 | + return :: 178 | body takes the form =(user-id logical-clock state-list success-p . return-values)= 179 | 180 | - Buffer local variables 181 | + var :: body takes the form =(buffer-name variable-symbol . args)= 182 | =args= is passed to the variable receiver =(get variable-symbol 'crdt-variable-receiver)= 183 | to calculate an updated value. 184 | The actual format of =args= depends on the variable sender and receiver 185 | (which supposed implement some CRDT). 186 | 187 | All peer must make sure they install the same kind of variable sender and receiver 188 | for =variable-symbol=. 189 | 190 | - Remote Buffer Process 191 | + process :: 192 | body takes the form =(buffer-name string)= 193 | Sent from client to server, request sending =string= 194 | to the process buffer associated to =buffer-name=. 195 | 196 | + process-mark :: 197 | body takes the form =(buffer-name crdt-id position-hint)=. 198 | 199 | NOTE: for =overlay-put=, =overlay-move= and =process-mark=, server must also broadcast the message 200 | *back to the client that generated it*, to ensure consistent global history. 201 | 202 | * Emacs as a collaborative operating system 203 | 204 | The goal: With a few annotations, developer should be able to make any Emacs application 205 | collaboration-powered. Emacs should be one of the most powerful collaboration platforms. 206 | 207 | How: There're plenty of Emacs applications centered around the buffer and buffer-local-variables. 208 | By implementing synchronization primitives for all components in a buffer, 209 | pretty much everything can be made collaborative. 210 | Synchronize arbitrary buffer-local-variable reasonably is hard, but user annotations can help. 211 | 212 | ** How to implement collaboration support for a package 213 | 214 | ~crdt.el~ provides two sets of facilities for adding collaboration support, a command-based one and a state-based one. 215 | Package hackers are free to combine them to provide desired behavior. 216 | 217 | *** Command-based collaboration 218 | 219 | This is a simple method to add collaboration support. 220 | After registering a command with =crdt-register-remote-command=, 221 | an =:around= advice is added such that when a client invoke this command, 222 | an request is sent to the server instead of running the command locally. 223 | 224 | Hackers must make sure that they declare what sets of buffer state the command uses 225 | to fully preserve user intent. 226 | 227 | Although relatively simple, collaboration command implemented using this method 228 | must go through a round trip to the server and will incur latency. 229 | 230 | **** Why we need used-state-set annotations 231 | 232 | Suppose Alyssa P. Hacker does =(crdt-register-remote-command 'eval-last-sexp)=, 233 | but didn't declare that =eval-last-sexp= uses content of the buffer. 234 | Now the hackers are conspiring in an ~crdt.el~ session. 235 | Ben Bitdiddle places cursor after =(+ 1 1)= and run =eval-last-sexp=. 236 | However, the moment Ben Bitdiddle's request arrives at the server, 237 | Cy D. Fect has changed =(+ 1 1)= to =(+ 1 2)= (their message arrives first!). 238 | Now the server does what it sees and return =3=, instead of =2=. 239 | 240 | The correct solution is to let the server roll-back to the state when Ben Bitdiddle invoked the command. 241 | It is relatively expensive thus we don't want to do this for every command, 242 | thus we require package hackers to annotate explicitly. 243 | 244 | /The above mechanism haven't been implemented yet!/ 245 | But adding annotations now will help adding it in the future. 246 | To implement this mechanism we need to add lamport timestamp to every messages 247 | (which may corresponds to mutation of interesting states), 248 | and send a vector clock in =command= messages which depend on buffer content. 249 | 250 | *** State-based collaboration 251 | 252 | We can also synchronize the underlying state of the packages 253 | rather than proxying user-level commands. 254 | If there're good CRDT candidates to be used for the state 255 | (hackers need to understand what concurrency semantics their state need to have!), 256 | then the commands can have real-time effect without needing to be acknowledged from the server. 257 | 258 | =crdt-org-sync-overlay-mode= is an example of this approach. 259 | 260 | Overall, this method is much more complicated than command-base method. 261 | Development of the facility is still on-going. 262 | 263 | ** TODO Task list for ~crdt.el~ facility 264 | - [X] synchronize buffer text (insert/delete) 265 | - [X] synchronize overlays 266 | - [-] synchronize major/minor modes 267 | + [X] initial synchronization of major modes 268 | + [ ] toggle minor modes on the fly 269 | + [X] change major modes on the fly 270 | - [-] set of synchronization primitives for buffer local variables 271 | + [-] server dictated 272 | + [ ] non incremental 273 | + [X] naive incremental 274 | + [ ] state-of-the-art level tree diff 275 | + [ ] a library of CRDTs 276 | - [X] synchronize text properties (any use case for this?) 277 | + [X] synchronize when new text is inserted 278 | + [X] synchronize when changed 279 | - [ ] synchronize markers (any use case for this?) 280 | - [-] remote command 281 | + [X] basic remote command (only possibly use =(point)=) 282 | + [X] command that uses region 283 | + [ ] correctly handle command that uses buffer content 284 | + [ ] handle arbitrary =interactive= form (firstly, what's the right thing to do?) 285 | - [-] remote buffer process 286 | + [X] process mark 287 | + [X] send to process 288 | + [ ] make sure "pseudo process" really looks like process 289 | (define complete set of advices) 290 | 291 | ** Notes and examples of CRDTize built-in packages 292 | 293 | Search for =;;; Built-in package integrations= in ~crdt.el~ 294 | 295 | * TODO Cross-editor support 296 | 297 | The current plan is to reuse the Emacs implementation as a local server for any other editor, aka Emacs as a service. 298 | The benefit is that we don't need to reimplement the sophiscated CRDT algorithm in other +uncivilized+ environments. 299 | We then just need to design a thin protocol that communicate between local Emacs and the other editor. 300 | Since this protocol communicate only locally, the latency should be negligible, 301 | therefore we use a blocking reader/writer lock based synchronization scheme. 302 | 303 | ** Lock: modes of operations 304 | 305 | It turns out that I vastly over-estimated the extensibility of /The Other Editors/. 306 | For example, lots of them (including M$ vScoDe and cult 666) doesn't seem to have anything like =pre-command-hook=, 307 | making it impossible to implement a usual bidirectional locking mechanism 308 | (because we can't tell those editors to acquire lock from Emacs before running commands that potentially modify the buffer). 309 | 310 | Currently I implemneted a hack that by default let /The Other Editors/ hold the lock, but upon receiving 311 | an =acquire= from Emacs, let /The Other Editors/ dead loops to hopefully halt command execution until Emacs gives back the lock. 312 | Emacs thus must give back lock as soon as possible to un-hang /The Other Editors/. 313 | 314 | Q: What if Emacs GCs? 315 | /Q got thrown out of the window./ 316 | 317 | ** Bridge protocol 318 | 319 | - Reader/writer lock 320 | + aquire :: body takes the form =()= 321 | + release :: body takes the form =()= 322 | 323 | The rest is mostly analogue to the primary protocol for Emacsen, 324 | except that CRDT IDs are replaced by explicit integer position (start from 1, as in Emacs). 325 | 326 | - Text Editing 327 | + insert :: body takes the form =(buffer-name position content)= 328 | + delete :: body takes the form =(buffer-name position length)= 329 | 330 | - Peer State 331 | + cursor :: body takes the form =(buffer-name user-id point-position mark-position)= 332 | =*-position= can be either an integer, or 333 | - =nil=, which means clear the point/mark 334 | 335 | + contact :: same as primary protocol. 336 | + leave :: same as primary protocol. 337 | 338 | - Login 339 | Note that we don't include challenge/response authentication mecahnism. 340 | 341 | + hello :: same as primary protocol. 342 | + login :: same as primary protocol. 343 | 344 | - Initial Synchronization 345 | + sync :: body takes the form =(buffer-name content-string)= 346 | + ready :: same as primary protocol. 347 | 348 | - Buffer Service 349 | + add :: same as primary protocol. 350 | + remove :: same as primary protocol. 351 | + get :: same as primary protocol. 352 | -------------------------------------------------------------------------------- /Makefile: -------------------------------------------------------------------------------- 1 | EMACS=emacs 2 | 3 | .PHONY: package elpa clean compile 4 | 5 | package: *.el 6 | @ver=`grep -o "Version: .*" crdt.el | cut -c 10-`; \ 7 | tar czvf crdt-$$ver.tar.gz --mode 644 $$(find . -name \*.el) 8 | 9 | elpa: *.el 10 | @version=`grep -o "Version: .*" crdt.el | cut -c 10-`; \ 11 | dir=crdt-$$version; \ 12 | mkdir -p "$$dir"; \ 13 | cp $$(find . -name \*.el) crdt-$$version; \ 14 | echo "(define-package \"crdt\" \"$$version\" \ 15 | \"Simultaneous text editing over network\")" \ 16 | > "$$dir"/crdt-pkg.el; \ 17 | tar cvf crdt-$$version.tar --mode 644 "$$dir" 18 | 19 | clean: 20 | @rm -rf crdt-*/ crdt-*.tar crdt-*.tar.gz *.elc 21 | 22 | compile: 23 | ${EMACS} -Q --batch -L . -f batch-byte-compile crdt.el 24 | -------------------------------------------------------------------------------- /README-elpa: -------------------------------------------------------------------------------- 1 | 1 Introduction 2 | ══════════════ 3 | 4 | `crdt.el' is a real-time collaborative editing environment for Emacs 5 | using Conflict-free Replicated Data Types. 6 | 7 | Highlights: 8 | • [CRDT], darling child of collaborative editing researches… 9 | • Share multiple buffer in one session 10 | • See other users' cursor and region 11 | • Synchronize Org mode folding status 12 | • Org mode integration 13 | • Comint derivatives integration (experimental) 14 | 15 | 16 | [CRDT] 17 | 18 | 19 | 20 | 2 Usage 21 | ═══════ 22 | 23 | 2.1 Installation 24 | ──────────────── 25 | 26 | `crdt.el' is now on GNU ELPA! Just `M-x package-install crdt'. 27 | 28 | *Caution!!!* Please make sure that you and your peers are on the same 29 | `crdt.el' version! It turns out to be one of the most common causes 30 | of `crdt.el' not working. Because currently the network protocol is 31 | not stablized, behavior when using mismatched versions is 32 | unexpectable. 33 | • Strictly speaking, it should work when `crdt-protocol-version' are 34 | defined (added after version `0.2.5') and the same on all peers. 35 | But why not save some hassle and keep everyone on the latest 36 | version. 37 | • To upgrade, just `M-x package-reinstall crdt', then preferably 38 | restart Emacs. To check your `crdt.el' version, `M-x crdt-version'. 39 | 40 | 41 | 2.2 Start a shared session 42 | ────────────────────────── 43 | 44 | A shared session is a place that can contains multiple buffers (or 45 | files), and multiple users can join to collaboratively edit those 46 | buffers (or files). Think about a meeting room with some people 47 | working together on some papers. 48 | 49 | In some buffer, `M-x crdt-share-buffer'. Then enter session name. 50 | This add the current buffer to the existing session with that name. 51 | If no such exists, it creates a new session with the provided session 52 | name, and initially contains the current buffer as a shared buffer. 53 | 54 | If a new session is to be created, you need to enter port (default to 55 | 6530), optional password and your display name (default to your 56 | current `(user-full-name)'). 57 | 58 | Experimental settings: "Secure Port" specifies TLS port, and "Command 59 | Functions" specifies user permissions. It's ok to just use the default 60 | values. 61 | 62 | 63 | 2.3 Join a session 64 | ────────────────── 65 | 66 | `M-x crdt-connect', then enter address, port, and your display name. 67 | 68 | If the server has provided the permission (this is the default case), 69 | connected user may also add their buffers to the session via `M-x 70 | crdt-share-buffer'. 71 | 72 | Connection URLs look like `ein://ipaddress:6530' 73 | 74 | 75 | 2.4 Navigate through sessions 76 | ───────────────────────────── 77 | 78 | Sessions 79 | `M-x crdt-list-sessions' lists all sessions. 80 | 81 | Buffers 82 | `M-x crdt-list-buffers' lists all buffers in current session. 83 | In the displayed buffer list, press `RET' in the session list to 84 | see buffers in the selected session. 85 | 86 | You can also use `M-x crdt-switch-to-buffer' to interactively 87 | switch to another buffer in the current session. 88 | 89 | Users 90 | In a CRDT shared buffer (either server or client), `M-x 91 | crdt-list-users' to list active users. In the displayed user 92 | list, press `RET' on an entry to goto that user's cursor 93 | position. Press `f' to follow that user, and press `f' again or 94 | `M-x crdt-stop-follow' to stop following. 95 | 96 | You can also use `M-x crdt-goto-next-user' and `M-x 97 | crdt-goto-prev-user' to cycle through users' cursor positions 98 | from any CRDT shared buffer (don't need to be in the user list 99 | buffer). 100 | 101 | 102 | 2.5 Stop sharing 103 | ──────────────── 104 | 105 | `M-x crdt-stop-session' stops a session you've started and disconnect 106 | all other users from it. This will ask for your confirmation, 107 | customize `crdt-confirm-stop-session' if you want to disable it. 108 | 109 | You can also press `k' or `d' in the session list (show it by `M-x 110 | crdt-list-sessions'). 111 | 112 | `M-x crdt-stop-share-buffer' removes current buffer from its CRDT 113 | session (this operation is only allowed at server side). You can also 114 | press `k' or `d' in the buffer list. 115 | 116 | 117 | 2.6 Disconnect from a session 118 | ───────────────────────────── 119 | 120 | `M-x crdt-disconnect', then choose a session to disconnect from. 121 | 122 | You can also press `k' or `d' in the session list (show it by `M-x 123 | crdt-list-sessions'). 124 | 125 | The server Emacs has the privilege to disconnect a user from a 126 | session. To do so, press `k' or `d' on an entry in the user list 127 | (show it by `M-x crdt-list-users'). 128 | 129 | 130 | 2.7 Fancy stuff 131 | ─────────────── 132 | 133 | Visualizing author of parts of the document 134 | Turn on `crdt-visualize-author-mode' to color text based on 135 | which user authored it. 136 | 137 | Synchronizing Org folding status 138 | Turn on `crdt-org-sync-overlay-mode'. All peers that have this 139 | enabled have their folding status synchronized. Peers without 140 | enabling this minor mode are unaffected. 141 | 142 | Comint integration 143 | Just go ahead and share you comint REPL buffer! Tested: `shell' 144 | and `cmuscheme'. By default, when sharing a comint buffer, 145 | `crdt.el' temporarily reset input history (as in `M-n' `M-p') so 146 | others don't spy into your `.bash_history' and alike. You can 147 | customize this behavior using variable 148 | `crdt-comint-share-input-history'. 149 | 150 | 151 | 2.8 What if we don't have a public IP? 152 | ────────────────────────────────────── 153 | 154 | There're various workaround. 155 | 156 | • You can use [tuntox] to proxy your connection over the [Tox] 157 | protocol. `crdt.el' has experimental built-in integration for 158 | `tuntox'. To enable it, you need to install `tuntox', set up the 159 | custom variable `crdt-tuntox-executable' accordingly (the path to 160 | your `tuntox' binary), and set the custom variable 161 | `crdt-use-tuntox'. Setting it to `t' make `crdt.el' always create 162 | `tuntox' proxy for new server sessions, and setting it to `'confirm' 163 | make `crdt.el' ask you every time when creating new sessions. After 164 | starting a session with `tuntox' proxy, you can `M-x crdt-copy-url' 165 | to copy a URL recognizable by `M-x crdt-connect' and share it to 166 | your friends. Be aware that according to my experience, `tuntox' 167 | takes significant time to establish a connection (sometimes up to 168 | half a minute), however it gets much faster after the connection is 169 | established. 170 | 171 | 172 | • You can use SSH port forwarding if you have a VPS with public IP. 173 | Example usage: 174 | ┌──── 175 | │ $ ssh -R EXAMPLE.COM:6530:127.0.0.1:6530 EXAMPLE.COM 176 | └──── 177 | This make your `crdt.el' session on local port `6530' accessible 178 | from `EXAMPLE.COM:6530'. 179 | 180 | Note that you need to set the following `/etc/ssh/sshd_config' 181 | option on your VPS 182 | ┌──── 183 | │ GatewayPorts yes 184 | └──── 185 | 186 | • For other tunneling solutions, see 187 | 188 | 189 | 190 | [tuntox] 191 | 192 | [Tox] 193 | 194 | 195 | 3 Service 196 | ═════════ 197 | 198 | `crdt.el' uses emacs' built in `(make-network-process)' to exchange 199 | elisp messages between clients, see `crdt--format-message'. 200 | 201 | You can see these messages in within emacs with `(setq 202 | crdt--log-network-traffic t)' and outside emacs with `nc' or `telnet'. 203 | ┌──── 204 | │ nc localhost 6530 <<< '(hello "0.3.0")' 205 | └──── 206 | 207 | Demonstrating `(hello)', `(get)', and `(leave)' 208 | ┌──── 209 | │ telnet localhost 6530 210 | │ ... 211 | │ (hello "0.3.0") 212 | │ 213 | │ (login 2)(add "testfile.org") .... 214 | │ 215 | │ (get "testfile.org") 216 | │ (sync "testfile.org" (#("FILE CONTENTS .... 217 | │ 218 | │ (leave 2) 219 | └──── 220 | 221 | 222 | 3.1 Messages 223 | ──────────── 224 | 225 | hello, leave, get, cursor, overlay-move, overlay-remove, overlay-put, 226 | return, var, ready 227 | -------------------------------------------------------------------------------- /README.org: -------------------------------------------------------------------------------- 1 | * Introduction 2 | 3 | ~crdt.el~ is a real-time collaborative editing environment for Emacs 4 | using Conflict-free Replicated Data Types. 5 | 6 | Highlights: 7 | - [[https://en.wikipedia.org/wiki/Conflict-free_replicated_data_type][CRDT]], 8 | darling child of collaborative editing researches... 9 | - Share multiple buffer in one session 10 | - See other users' cursor and region 11 | - Synchronize Org mode folding status 12 | - Org mode integration 13 | - Comint derivatives integration (experimental) 14 | 15 | * Usage 16 | 17 | ** Installation 18 | 19 | ~crdt.el~ is now on GNU ELPA! Just =M-x package-install crdt=. 20 | 21 | *Caution!!!* Please make sure that you and your peers are on the same 22 | ~crdt.el~ version! It turns out to be one of the most common causes 23 | of ~crdt.el~ not working. Because currently the network protocol is 24 | not stablized, behavior when using mismatched versions is 25 | unexpectable. 26 | - Strictly speaking, it should work when =crdt-protocol-version= are 27 | defined (added after version =0.2.5=) and the same on all peers. 28 | But why not save some hassle and keep everyone on the latest 29 | version. 30 | - To upgrade, just =M-x package-reinstall crdt=, then preferably 31 | restart Emacs. To check your ~crdt.el~ version, =M-x crdt-version=. 32 | 33 | ** Start a shared session 34 | 35 | A shared session is a place that can contains multiple buffers (or 36 | files), and multiple users can join to collaboratively edit those 37 | buffers (or files). Think about a meeting room with some people 38 | working together on some papers. 39 | 40 | In some buffer, =M-x crdt-share-buffer=. Then enter session name. 41 | This add the current buffer to the existing session with that name. 42 | If no such exists, it creates a new session with the provided session 43 | name, and initially contains the current buffer as a shared buffer. 44 | 45 | If a new session is to be created, you need to enter port (default to 46 | 6530), optional password and your display name (default to your 47 | current =(user-full-name)=). 48 | 49 | Experimental settings: "Secure Port" specifies TLS port, and "Command 50 | Functions" specifies user permissions. It's ok to just use the default 51 | values. 52 | 53 | ** Join a session 54 | 55 | =M-x crdt-connect=, then enter address, port, and your display name. 56 | 57 | If the server has provided the permission (this is the default case), 58 | connected user may also add their buffers to the session via 59 | =M-x crdt-share-buffer=. 60 | 61 | Connection URLs look like =ein://ipaddress:6530= 62 | 63 | ** Navigate through sessions 64 | 65 | - Sessions :: =M-x crdt-list-sessions= lists all sessions. 66 | 67 | - Buffers :: =M-x crdt-list-buffers= lists all buffers in current 68 | session. In the displayed buffer list, press ~RET~ in the session 69 | list to see buffers in the selected session. 70 | 71 | You can also use =M-x crdt-switch-to-buffer= to interactively switch 72 | to another buffer in the current session. 73 | 74 | - Users :: In a CRDT shared buffer (either server or client), =M-x crdt-list-users= 75 | to list active users. In the displayed user list, press ~RET~ on an 76 | entry to goto that user's cursor position. Press ~f~ to follow that 77 | user, and press ~f~ again or =M-x crdt-stop-follow= to stop following. 78 | 79 | You can also use =M-x crdt-goto-next-user= and =M-x crdt-goto-prev-user= 80 | to cycle through users' cursor positions from any CRDT shared buffer 81 | (don't need to be in the user list buffer). 82 | 83 | ** Stop sharing 84 | 85 | =M-x crdt-stop-session= stops a session you've started and disconnect 86 | all other users from it. This will ask for your confirmation, 87 | customize =crdt-confirm-stop-session= if you want to disable it. 88 | 89 | You can also press ~k~ or ~d~ in the session list (show it by =M-x crdt-list-sessions=). 90 | 91 | =M-x crdt-stop-share-buffer= removes current buffer from its CRDT 92 | session (this operation is only allowed at server side). You can also 93 | press ~k~ or ~d~ in the buffer list. 94 | 95 | ** Disconnect from a session 96 | 97 | =M-x crdt-disconnect=, then choose a session to disconnect from. 98 | 99 | You can also press ~k~ or ~d~ in the session list (show it by =M-x crdt-list-sessions=). 100 | 101 | The server Emacs has the privilege to disconnect a user from a 102 | session. To do so, press ~k~ or ~d~ on an entry in the user list 103 | (show it by =M-x crdt-list-users=). 104 | 105 | ** Fancy stuff 106 | 107 | - Visualizing author of parts of the document :: 108 | Turn on =crdt-visualize-author-mode= to color text based on which 109 | user authored it. 110 | 111 | - Synchronizing Org folding status :: Turn on 112 | =crdt-org-sync-overlay-mode=. All peers that have this enabled have 113 | their folding status synchronized. Peers without enabling this minor 114 | mode are unaffected. 115 | 116 | - Comint integration :: 117 | Just go ahead and share you comint REPL buffer! Tested: ~shell~ and 118 | ~cmuscheme~. By default, when sharing a comint buffer, ~crdt.el~ 119 | temporarily reset input history (as in =M-n= =M-p=) so others don't 120 | spy into your =.bash_history= and alike. You can customize this 121 | behavior using variable =crdt-comint-share-input-history=. 122 | 123 | ** What if we don't have a public IP? 124 | 125 | There're various workaround. 126 | 127 | - You can use [[https://gitlab.com/gjedeer/tuntox][tuntox]] to proxy 128 | your connection over the [[https://tox.chat][Tox]] protocol. 129 | =crdt.el= has experimental built-in integration for =tuntox=. To 130 | enable it, you need to install =tuntox=, set up the custom variable 131 | =crdt-tuntox-executable= accordingly (the path to your =tuntox= 132 | binary), and set the custom variable =crdt-use-tuntox=. Setting it 133 | to =t= make =crdt.el= always create =tuntox= proxy for new server 134 | sessions, and setting it to ='confirm= make =crdt.el= ask you every 135 | time when creating new sessions. After starting a session with 136 | =tuntox= proxy, you can =M-x crdt-copy-url= to copy a URL 137 | recognizable by =M-x crdt-connect= and share it to your friends. Be 138 | aware that according to my experience, =tuntox= takes significant 139 | time to establish a connection (sometimes up to half a minute), 140 | however it gets much faster after the connection is established. 141 | 142 | 143 | - You can use SSH port forwarding if you have a VPS with public IP. 144 | Example usage: 145 | #+BEGIN_SRC 146 | $ ssh -R EXAMPLE.COM:6530:127.0.0.1:6530 EXAMPLE.COM 147 | #+END_SRC 148 | This make your =crdt.el= session on local port =6530= accessible 149 | from =EXAMPLE.COM:6530=. 150 | 151 | Note that you need to set the following =/etc/ssh/sshd_config= 152 | option on your VPS 153 | #+BEGIN_SRC 154 | GatewayPorts yes 155 | #+END_SRC 156 | 157 | - For other tunneling solutions, see https://github.com/anderspitman/awesome-tunneling 158 | 159 | * Service 160 | =crdt.el= uses emacs' built in =(make-network-process)= to exchange elisp messages between clients, see =crdt--format-message=. 161 | 162 | You can see these messages in within emacs with =(setq crdt--log-network-traffic t)= and outside emacs with =nc= or =telnet=. 163 | #+begin_src bash 164 | nc localhost 6530 <<< '(hello "0.3.0")' 165 | #+end_src 166 | 167 | Demonstrating =(hello)=, =(get)=, and =(leave)= 168 | #+begin_src bash 169 | telnet localhost 6530 170 | ... 171 | (hello "0.3.0") 172 | 173 | (login 2)(add "testfile.org") .... 174 | 175 | (get "testfile.org") 176 | (sync "testfile.org" (#("FILE CONTENTS .... 177 | 178 | (leave 2) 179 | #+end_src 180 | 181 | ** Messages 182 | 183 | hello, leave, get, cursor, overlay-move, overlay-remove, overlay-put, return, var, ready 184 | -------------------------------------------------------------------------------- /crdt-pkg.el: -------------------------------------------------------------------------------- 1 | ;; Generated package description from crdt.el -*- no-byte-compile: t -*- 2 | (define-package "crdt" "0.3.5.0.20241129.104719" "Collaborative editing using Conflict-free Replicated Data Types" 'nil :commit "d9ea57d41db2aa25773bfdd1c12ee8b51b92e61f" :authors '(("Qiantan Hong" . "qhong@alum.mit.edu")) :maintainer '("Qiantan Hong" . "qhong@alum.mit.edu") :keywords '("collaboration" "crdt") :url "https://code.librehq.com/qhong/crdt.el") 3 | --------------------------------------------------------------------------------