4 replies to this topic

[mladen8]

Hello,
i am new to PHP but i have basic understanding of how things work.
I want to build a script that will check for changes on websites that are entered and then email users when something change.

I found this script: Wizecho spider class
That let you fetch source code of remote website, i just need to make it compare results with first checking of site and then email users.
Please help me in any way you can.

I searched forums but i didn't find anything similar like this.
Thanks

[matrob]

What type of changes? When users enter content or when the site admin makes a change?

[mladen8]

It really doesn't matter now, i will try to distinguish "comments" from "content" later, i just want to loop comparing source code until its different.

[Orjan]

The easiest thing would probably be to store a hash of the page in the DB and then compare it to the new version's hash, if it's the same, the content is also the same.

[Alexander]

Orjan is correct, storing hashes to check for recency would be the normal. Two hashing recommendations are CRC32B (see hash_file()), a faster checksum hashing algorithm is ADLER32.

Another somewhat faster approach would be to send an HTTP "HEAD" command to the server and check for something such as an ETAG, although some don't set it.