[Ur] Fatal initialization error: Table 'uw_chatroom_room_subscriber' does not exist.

[Stefan Scott Alexander]

Sean -

The application is running fine now - see my response elsewhere in this
thread. (I had to create a Postgres superuser with the same name as my
Linux user.)

Regarding the chatroom application: It is interesting to notice that it
provides much of the same "live" behavior as the Meteor NodeJS framework's
Distributed Data Protocol (DDP), as demonstrated in their tutorial
involving creating a "To Do" list:

https://github.com/meteor/simple-todos/

https://www.meteor.com/try

There is also a more complicated Meteor example involving multiple ToDo
lists, which can be created as follows:

meteor create --example todos

Unfortunately the Meteor framework only works with MongoDB - a NoSQL
database which does not provide ACID transactional guarantees.

One difference between Ur/Web's "Chatroom" example and Meteor's "ToDo"
examples is that items in the ToDo examples can be inserted, updated and
deleted - whereas in the current Chatroom example, items can only be
inserted. Otherwise the Ur/Web Chatroom example is the same as the Meteor
ToDos example (the more complicated one, involving multiple ToDo lists).

It would be interesting to add update and delete functionality to the
Chatroom example. This would generalize it, from allowing only insert
operations, to allowing insert / update / delete operations (ie, it would
be a CRUD app which also pushes changes "live" to each user, just like
Meteor's ToDo examples).

It is interesting to note that many people consider Meteor to be the best
NodeJS framework - probably precisely because of this Distributed Data
Protocol (DDP) pushing changes "live" to all connected users. On the other
hand, many people avoid Meteor because it is tied to the NoSQL, non-ACID
database MongDB.

If a nicely packaged step-by-step online demo tutorial similar to Meteor's
ToDo examples were created for Ur/Web, it would probably attract a lot of
attention among people looking for decent web frameworks.

- Scott
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