So, what is fallback messaging?
Consider two friends who communicate via various network oriented means (IM, Email, SMS, etc.), we'll call them bluesmoon and mannu (because they are two people who communicated this way for several years before meeting IRL). Now, said friends are extremely tech savvy, and have accounts on virtually every server that offers free accounts, and then some.
So, you've got them on MSN, Yahoo!, AOL, ICQ... um, ok, not ICQ because ICQ started sucking, Jabber, and that's just IM. They prolly have 3 or 4, maybe 5 accounts on each of these services, ok, maybe just one on AOL. Then they have email accounts. The standard POP3 accounts, 3 gmail accounts, a Yahoo! account for every yahoo ID, and likely no hotmail accounts (even though they have MSN passports) because we all know that hotmail is passé.
These guys also have lj accounts and one or two cellular phones on different service providers.
Ok, now that we have our protagonists well defined, let's set up the scene.
Act 1, scene 1Mannu and bluesmoon are chatting over, umm, we'll pick MSN to start with. So mannu and bluesmoon are chatting over MSN, when all of a sudden <insert musical score for suspense here> a message pops up:
The MSN server is going down for maintenance, all conversations will now end
Sweet. So MSN decides that we're not allowed to talk anymore.
What are our options? Oh well, Yahoo!'s still online, so switch to Yahoo!. It's much nicer too because you can chat while invisible too. MSN (officially) doesn't let you do that.
So, they switch to Yahoo!, but... what the heck were they chatting about when the server went down? Context lost. They need to start a new conversation, most likely centred around cursing MSN. What's worse is that the earlier conversation was being archived because they may have needed it as a reference later. The new conversation can also be archived, but it's a pain to merge all these different archives later.
Anyway, they plough ahead. The conversation veers back on topic, ... but now the main net connection goes down. The only things that work are websites and email. What do you do? What do you do? Ok, Dennis Hopper I am not, so let's forget I said that.
The easiest option would be for bluesmoon to send a mail to mannu saying, "Hey dude, my net connection went down, gotta end the convo here.", or he could send the same in an SMS. But to do that he's gotta start yet another program and type out stuff out of context again, or worse, type out an SMS that he has to pay for!
So, here's where fallback messaging comes in.
Act 1, Scene 1, Take 2<jump back to the MSN chat>
Where were we? Oh yeah, the MSN server goes down. Now, what if the chat client we were using was smart enough to figure this out, and do something about it. What's that something you say? Switch to the next available service. So, in this case, the chat program would automatically and seamlessly switch to using Yahoo!
There's several user centric pluses here. The people chatting do not need to know that a server went down, leave alone care about it and figure out what to do. Archives will be maintained across sessions. The context of the conversation will be preserved. Mannu and bluesmoon can go on chatting as if nothing happened.
If all the IM protocols go down, the chat client could switch to Email or SMS. Of course, mannu should have to tell it explicitly to use one of these, because the conversation will no longer be online. There's gonna be delays between sending the message and getting a response, so the chatters need to know about this.
So, how does your chat client know that you have buddies on multiple services, and about their email address and phone number?
Well, the chat client would have to group accounts on various services into a single contact. This kind of grouping also has other benefits.
Two people chatting with each other now don't have to think about user names and different services and what not. Mannu wants to chat with bluesmoon, he just selects bluesmoon from his buddy list. He doesn't have to care whether bluesmoon has an account on MSN, Yahoo!, AOL or whatever. Why should he care? So, I'd be chatting one to one with another person, without caring about what happens behind the scenes. Isn't that what makes for a good play?
Well, at some point mannu would have to care about services and user names, because he'd actually have to manually add and group all these accounts into one. Perhaps he could also set preferences of the order in which to fallback. That's all a one time set up. For the continuous ease of use to follow, I'd say it's worth it.
Is this really possible? Yeah, sure it is. You can thank Torrey Searle for that. Torrey implemented everybuddy to do just this, and threw in loads of sanity checking - thanks for that dude. It's what drew me to use and then work on the project for so long.
So, is this really possible? Probably not until IM companies decide that the network is just a transport, and it's the value a user derives from using that transport that makes them choose one service over another. It's why we choose the Mumbai-Pune expressway over NH4 that runs through the ghats, even though there's a toll.
Update I did a talk on fallback messaging at Linux Bangalore 2004