Retrieving info from various services

[dsable]

I see numerous applications that retrieve information from various services. For example, applications tracking the progress of delivery of packages from a whole bunch of services, such as DHL, UPS, and many more. So far, I have been unable to find open protocols for retrieving this sort of information. So, how do they do it? Do they have "connections"? Do they simply parse the HTML pages that report this kind of information to users? Any ideas? Also interested in retrieving (and making changes to) information on mobile phone accounts.

Thank you.

[smasher]

Originally Posted by dsable

I see numerous applications that retrieve information from various services. For example, applications tracking the progress of delivery of packages from a whole bunch of services, such as DHL, UPS, and many more. So far, I have been unable to find open protocols for retrieving this sort of information. So, how do they do it? Do they have "connections"? Do they simply parse the HTML pages that report this kind of information to users? Any ideas? Also interested in retrieving (and making changes to) information on mobile phone accounts.

Thank you.

Many large web sites such as Amazon and Ebay provide "API"s of their own that allow you to query their data - usually by sending a http request and getting XML in return, which you can read with NSXMLParser. Others (usually news/info sites) provide daily RSS feeds that informy you of new content.

It's dangerous to parse the HTML directly - any change to the site's design could break your program.