<div dir="ltr"><div><div class="gmail_extra"><div><div>Quick browsed the doc this morning.<br></div><div><br>Very happy to see this. Some novelty here I think. The Pub/Sub vs. say strict Actor Peer-To-Peer seems more flexible. Typed Endpoints and Handlers. Yea!! <br> <br>Looks like I can throw out some really half-baked code that addresses similar functionality as Marketplace and does a poor job of doing so and use Marketplace.<br> <br></div>What is the general assumption, if any, regarding message delivery guarantees? Guaranteed, Once-And-Only-Once, At-Most-Once. And Message Ordering. Say between 2 physical node Ground-VMs across a network?<br> </div><div>Node 1 - Process A - sends M1 - sends M2 ----> Node 2 - Process B always consumes M1 before M2?<br><br></div><div>Also rather curious on details of Marketplaces' approach to "Let-It-Fail" semantics and Nanny monitoring / restarting of processes.<br> </div><div><br></div><div>And it's in Typed Racket too. Double plus good.<br></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Wed, May 29, 2013 at 5:47 PM, Sam Tobin-Hochstadt <span dir="ltr"><<a href="mailto:samth@ccs.neu.edu" target="_blank">samth@ccs.neu.edu</a>></span> wrote:<br> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">We are happy to announce the release of Marketplace, a new programming<br> language for building functional network programs. Marketplace combines<br> two fundamental ideas in a new way: nested virtual machines and<br> publish/subscribe messaging. Nesting allows programs to isolate<br> processes and to delimit conversations. While publish/subscribe generalizes<br> point-to-point and broadcast messaging, it smoothly turns the appearance<br> and disappearance of participants and resources into _presence_ and<br> _absence_ messages. Such messages make it particularly easy to start and<br> stop services and to manage resources based on demand.<br> <br> Here is a simple TCP echo server written in Marketplace:<br> <br> #lang marketplace<br> <br> (endpoint #:subscriber (tcp-channel ? (tcp-listener 5999) ?)<br> #:conversation (tcp-channel from to _)<br> #:on-presence (spawn #:child (echoer from to)))<br> <br> ;; echoer: TcpAddress TcpAddress -> Transition<br> (define (echoer from to)<br> (transition stateless<br> (endpoint #:subscriber (tcp-channel from to ?)<br> #:on-absence (quit)<br> [(tcp-channel _ _ data)<br> (send-message (tcp-channel to from data))])))<br> <br> The initial `endpoint` subscribes to TCP messages on port 5999. When a<br> conversational partner appears, the endpoint spawns a new process that runs an<br> `echoer` process. The latter is stateless and subscribes to TCP<br> messages. When it gets messages with payload `data`, it sends them back<br> out with the opposite addressing; when the TCP conversation disappears, it<br> quits.<br> <br> Thus far, we have built several real systems using Marketplace: a<br> DNS server, a DNS proxy, and an SSH server. The DNS proxy has handled<br> DNS traffic for ourselves and other members of our lab for the last<br> several months.<br> <br> You can read an overview along with detailed documentation for<br> Marketplace at <a href="http://tonyg.github.io/marketplace/" target="_blank">http://tonyg.github.io/marketplace/</a> .<br> <br> To get the sources for Marketplace as well as the applications<br> point your browser to <a href="https://github.com/tonyg/marketplace" target="_blank">https://github.com/tonyg/marketplace</a> .<br> <br> Enjoy!<br> <br> Tony Garnock-Jones<br> <span><font color="#888888">Sam Tobin-Hochstadt<br> Matthias Felleisen<br> ____________________<br> Racket Users list:<br> <a href="http://lists.racket-lang.org/users" target="_blank">http://lists.racket-lang.org/users</a><br> </font></span></blockquote></div><br></div></div></div>