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Editorial Team
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Asked: 2026-05-13T05:38:40+00:00

I’ve run into reoccuring problem for which I haven’t found any good examples or

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I’ve run into reoccuring problem for which I haven’t found any good examples or patterns.

I have one core service that performs all heavy datasbase operations and that sends results to different front ends (html, silverlight/flash, web services etc).
One of the service operation is “GetDocuments”, which provides a list of documents based on different filter criterias. If I only had one front-end, I would like to package the result in a list of Document DTOs (Data transfer objects) that just contains the data. However, different front-ends needs different amounts of “metadata”. The simples client just needs the document headline and a link reference. Other clients wants a short text snippet of the document, another one also wants a thumbnail and a third wants the name of the author. Its basically all up to the implementation of the GUI what needs to be displayed.

Whats the best way to model this:

  1. As a lot of different DTOs (Document, DocumentWithThumbnail, DocumentWithTextSnippet)
    • tends to become a lot of classes
  2. As one DTO containing all the data, where the client choose what to display
    • Lots of unnecessary data sent
  3. As one DTO where certain fields are populated based on what the client requested
    • Tends to become a very large class that needs to be extended over time
  4. One DTO but with some kind of generic “Metadata” field containing requested metadata.

Or are there other options?

Since I want a high performance service, I need to think about both network load and caching strategies.

Does anyone have any good patterns or practices that might help me?

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1 Answer

  1. Editorial Team

    What I would do is give the front end the ability to request the presence of the wanted metadata ( say getDocument( WITH_THUMBNAILS | WITH_TEXT_SNIPPET ) )

    Then this DTO is built with only this requested information.
    Adding all the possible metadata is as you said, unacceptable.

    I will surely stay with one class defining all the possible methods (getTitle(), getThumbnail()) and if possible it will return a placeholder when the thumbnail was not requested. Something like “Image not available”.

    If you want to model this like a pattern, take a look at the factory patterns.

    Hope this helps you.

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