Backender’s Spellbook : my response to your request

How should the backend respond to a request?

This question has no objectively right answer. It really depends on the situation. But I’m going to try to pitch my philosophy in give them everything and maintain structure.

caveat : if you have sensitive information, then of course redact that information; this data should never be given to the client to begin with.

Example : Pet Shelter

In this fictitious example, I work as a volunteer software developer at an dog animal shelter. I need to keep track of every dog that comes into the shelter for legal and bookkeeping purposes. We have a website that shows the names and pictures of our pets.

On the backend, we collect a lot of information about each pet. This includes :

• name
• breed
• location-found
• start-date
• leave-date
• isAdopted
• s3ImageId (this could go on for quite a while …)

As mentioned earlier, the website needs to render a picture of the pet along with their name.

In an attempt to give them everything, the UI will fetch all the pets in the database (footnote 1), and the backend will respond with a list of pets. This list of pets will include ALL the information for each pet in the database. My point is that I don’t need or want to conform to the requirements of the frontend; even though the name and picture are the only requirements, I still give them info about the location-found, start-date, etc… It is realistic and responsible to expect changes in your application. The front end could decide that want to list the breed and list when the pet first arrived. If I did not return all the information to begin with, then I would need to change the contract. Changing the contract is a hassle and can be avoided.

To my second point in maintain structure, there was no custom ListDogResponse response class. I just returned all the information the Dog class had to begin with. I’ve seen a lot of people implement this idea of an opaqueClass or transparentClass which hides or shows data about your class. This confuses me because often the data I care about is missing.

in summary

• I believe it is necessary and important for the frontend to shape the data they deal with.
• I don’t believe in the backend needing to bend and make compromises and conveniences for the front end.
• I believe transport opaque and transparent classes to be confusing and dishonest.

With a broad and accurate transfer of data, the backend and frontend can treat the alike. This will make code paths and execution behave more similarly across network requests.

(1) I’m ignoring any paging requirements for simplicity. Were a small animal shelter.