Your sentence has two elements in question: a relative clause and a prepositional phrase.
when opening a
typeOfObject in this view
form a relative clause. It is introduced by the relative adverb "when" and contains the verb "opening."
An introductory relative clause should be separated from the main clause by a comma when it is not essential to the meaning of the sentence. In this case,
Send in an object like this
can be understood completely; the introductory relative clause just adds additional background information. (Grammar Bytes!)
In contrast, the words
By strong convention
form a prepositional phrase. It is introduced by the preposition "by" and contains the object of the preposition "convention."
Purdue OWL suggests that introductory prepositional phrases should only be followed by a comma if they are long (more than five words) or part of a series of prepositional phrases (e.g. "On the windowsill in my bedroom, I placed a terrarium.").
Therefore, you should retain the comma after "view" but do not need another comma after "convention."
Since this answer is long enough as-is, I will leave it to another user to advise you on the "like this" and colon question.