How can this website call the dynamic content of another website?

How can this website call the dynamic content of another website ~ There are two programs installed in the same space, which are different domain names. how can I call the content displayed by this member on another website ~~ How can this website call the dynamic content of another website ~
There are two programs installed in the same space, which are different domain names. how can I call the content displayed by this member on another website ~~ Share:
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If these programs provide APIs, it is best to call the APIs by yourself, which is also the safest.

If not, you can simulate access to obtain data.

Also, these programs are yours, so the database is yours. you can directly access the database!
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Post .. This is the same as calling web interfaces.
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Your database is ready. if your database can be accessed remotely, you can access the database directly.

Or curl.
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If you do not directly access the database, it will be troublesome. this involves data synchronization, synchronous login registration, member data synchronization, and data synchronization, you have to write a set of api programs by yourself. the api is implemented through socket communication. php uses curl and fsocket to simplify socket communication.
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It's not true to write a webservice.
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1) iframe
2) 3) PHP remote download and retrieval