iServe - turning iPhones into a web servers

Service structure

user sitting in front of a browser <---> web server <---> zeromq broker <---> iOS app

• iOS app https://github.com/fumin/rubymotion-zeromq
• zeromq majordomo broker https://github.com/fumin/mdbroker
• web server https://github.com/fumin/world

Available routes

• / redirects to photo_album
• /photo_album displays thumbnails of photos in device
• /number_of_images returns the number of photos
• /images/:id returns the full resolution image of photo number id
• /thumbnails/:id returns the thumbnail of photo number id

Differences from the official majordomo protocol

This protocol has been slightly modified to enable streaming. The interaction between a client and a worker in the official protocol is a simple request-reply one:

    client  ---------- request -----------> worker
    client <--- reply [msg1, msg2, ...] --- worker

However, when the reply consists of several hundren thousand bytes, for example, a 1024x768 image, and is sent over a slow 3G wireless network, the whole system becomes vulnerable to timeouts in both the client and worker side. This modified protocol attempts to solve this problem by streaming the large payload of the reply:

    client  -------------- request -----------> worker
    client <---- reply [a1, a2, ... 'more'] --- worker
    client <---- reply [b1, b2, ... 'more'] --- worker
                             ...
    client <---- reply [n1, n2, ... nn] ------- worker

Note that trailing 4 byte 'more' string is the signal for more coming bytes.

Dependencies

• rubymotion http://www.rubymotion.com/
• zeromq 3.2.0 http://www.zeromq.org/
• zlib 1.2.7 http://zlib.net/

References

• official zeromq majordomo documentation http://rfc.zeromq.org/spec:7