Take GMail for example.
in the Inbox, you have a list of received emails,
in addition to the mail Subject, there is a sentence from the opening
of the email.
in other words we have Subject + MAIL_BODY.substring(0, LENGTH)
what is the best way to implement this feature ?
if we were dealing with non-String objects, it made sense to just
fetch the fields that are necessary,
like a summary view, and provide detail as user required. making it two
+ step process.
but in this particular case, we have a list of paragraphs, and want to
provide a one line summary of each.
to prepare this one-line summary, we need to retrieve the entire text,
and then call substring, to get the one line summary.
I have 3 solutions, but appreciate if you weigh in on how you would
implement this particular usecase.
Solution #1
1- get the text from the DB
2- extract the first X characters (one-line summary) [do this on the
server]
3- send this one-line summary to the client
4-when client decides to see full text, sends a request
5-this time send the full text
Pros: - less data over the wire (instead of pargraphs after
paragraphs, only one line is sent)
Cons: - subsequent client requests would result in additional network
roundtrip
- string manipulation/extraction to produce the one line
summary results in delay
Solution #2
1-get the text from DB
2-send the entire text to the client
3-when displaying, show only the first sentence,
do this by extracting first X characters, doing this on the client
Cons: transfering so much data can cause delay
Pros: - after initial load, fewer network roundtrip to fetch more data
- text manipulation on the client,
means no delay as a result of waiting for the server to do
the manipulation
Solution #3
having a bit of redundancy,
add an additional field/column to hold the one-line summary.
in other words instead of making one-line summary derivative attribute
(which can be extracted by processing the entire text), we do it once
and store it in the Datastore.
upon user request, we grab this one-line summary column/field.
if user required complete paragraph, we get the column/field
containing the full text.
Cons: redundancy might result in inconsistency, additional work to
keep data consistent
- when user requests for full paragraph, this results in a
server call, which
is not going to happen with Solution #2
Pros: - no repeated processing overhead (text extraction/manipulation)
- best use of bandwith, never sending anything thats going to
waste.
I am thinking of chosing Solution#3,
based on an advice by Google,
that basically stated Storage is cheap, but Bandwith is not,
and user attention span is short therefore no delay ! : )
have you implemented this functionality ?
whats your thought on this,
what would you do ?
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