News and views from a software developer's perspective
Tuesday, February 04, 2003Answering my earlier question: Perhaps it's possible to create web-based email that uses primarily stateless HTTP. I don't know enough about the options for authentication to know if the use of HTTP could truly be stateless. Would the server have to maintain state associated with the user authentication? Or, would that "state" be insignificant to the point that it's pretty much transparent to the developer/designer. For example, could each email account have its own directory that is password protected by the usual mechanism provided by the web server (.htaccess).
Which is more scalable, IMAP4 email or a web-based email?
At first one might think it has to be web-based email, because it uses a web-based architecture, which has proven scalability. If you think deeper, though, maybe that's not necessarily true. The web is highly scalable when you think of it in terms of a REST architecture, but that implies a stateless architecture -- HTTP without cookies, if you will. When you must maintain state, then the "web-based" architecture is not as easily scalable as a stateless architecture. Now, consider a connection-based protocol like IMAP4. Is it scalable? Well, a TCP connection requires the host to maintain state, namely, the state of the connection, identified by a quintuple (remote address, remote port, local address, local port, protocol). So, it's really not that different from a stateful HTTP protocol, except that in the case of IMAP4, the state is maintained by the operating system and in the case of stateful HTTP, the state is maintained by the application. When HTTP needs to scale to hundreds of thousands of simulaneous session, a reverse proxy or some other device is required to distribute the load among mulitiple servers. Could one create a reverse proxy for IMAP4? I would think so.
In summary, I don't think developers/designers should be quick to write off connection-oriented protocols like IMAP4 in favor of HTTP-based protocols.
Spam deluge leads to search for silver bullet
"Spam is a huge concern for us because consumers are just erasing everything. They don't know the difference between spam and legitimate marketing," said Christina Duffney, a spokeswoman for the DMA.
Ms. Duffney, you're wrong. Consumers know the difference. It's the marketers who don't know the difference between spam and legitimate marketing.