How does blockchain.info get other's txid and details?

[gpmn]

I know bitcoin network will broadcast/share each trading data;

But I can not find such API interface in bitcoin's wiki page ,such as : https://en.bitcoin.it/wiki/Original_Bitcoin_client/API_calls_list#See_Also

So I'm wondering, where does blockchain get such infomation from? Is there any other APIs that I do not know?

[Danglebee]

i confused
blockchain site tell peer which forward tx to blockchain site.
here api list ? https://en.bitcoin.it/wiki/Original_Bitcoin_client/API_calls_list

[dave111223]

They basically have to loop through every transaction and put it into their own indexable database (such as mysql).  Where transactions can be looked up on the based on the the transaction ID, address etc...

Or could try something like this, which appears to parse the blockchain on the fly to lookup info:
https://github.com/mcdee/blockparser