Community resourceWorksheet

OCR H446 1.3.4 Client-side and server-side processing

Part 6 of 8 · H446 1.3.4 · Web technologies

Deciding whether work happens in the browser or on the service's own infrastructure is the reasoning H446 1.3.4 rewards, and the language a task is written in is not the answer to it. This worksheet classifies tasks by data location, trust, responsiveness and shared state, then applies the split to a service running on weak devices over an unreliable connection.

Students will:

  • classify tasks by where they run and say why that location is required
  • explain why a check made in the browser cannot be trusted on its own
  • identify the points where data crosses between browser and server
  • recommend a processing split for a service limited by device power and connection quality

Inside: 5 explanation cells, 1 multiple-choice question, 2 fill-in-the-blanks cells and 2 written answers. 27 marks, about 40 to 50 minutes.

Series: H446 1.3.4 · Web technologies, part 6 of 8.

Shared by Coding PathwayVerified teacher

  • 10 cells
  • About 45 minutes
  • CC BY-SA 4.0
  • Shared 31 Aug 2026
  • Updated 3 Sept 2026

Preview

The whole resource, exactly as a class sees it. Answers and marking are held back.

Client-side and server-side processing

Client-side processing runs on the user's device, commonly in the browser. Server-side processing runs on infrastructure controlled by the service. Classify the task, location, responsibility and data need, not only the language name.

One journey, two locations

Client-side and server-side processing split an end-to-end request client side: user's browser/device• load/render HTML and apply CSS• immediate interface behaviour• preliminary JavaScript validation request/dataresponse server side: controlled service• authoritative validation and rules• protected data access• database query and result generation• shared processing independent of client power Client checks improve experience; they do not make submitted data trusted.Classify the task and location, not the language name alone.

HTML loading, CSS application and immediate browser interaction are client-side examples in OCR's model. A server can enforce authoritative business rules and query protected shared data. Both sides may validate: the client improves responsiveness; the server must not trust a client-controlled check.

Worked service: equipment booking

The browser shows the form, applies styles and immediately warns when an end time is earlier than a start time. It then submits the requested slot. The server checks the rule again, verifies identity, queries the shared booking database and accepts or rejects the request.

The first check reduces avoidable requests and provides quick feedback. The repeated server check is still needed because browser code and submitted data can be changed.

Multiple choice1 mark

Which task most clearly belongs on the server side for a shared booking service?

  • AApply the page's CSS colours
  • BQuery the protected central database for current availability
  • CDisplay a character counter while the user types
  • DExpand a menu immediately after a click
Fill in the blanks4 marks
Applying CSS is usually gap 1 side. Browser JavaScript that gives an immediate empty-field warning is gap 2 side. An authoritative stock query is gap 3 side. The server should gap 4 important submitted data even after a browser check.
  • client
  • server
  • validate
  • trust
Written answer8 marks

For a library reservation, classify and justify: render HTML; apply CSS; update an on-page character count; check the member's borrowing limit; query whether the copy is available; return a confirmation page. State where data crosses between sides.

Treat confirmation generation as server-side when it depends on authoritative results; the browser renders the returned page.

Students type their answer here.

Apply the model independently

The remaining tasks change the context or reduce the support. Complete them without copying the worked model, then check that each explanation connects a mechanism to its consequence.

Written answer10 marks

A field survey app serves old low-power tablets over an unreliable connection but stores sensitive shared records centrally. Compare moving more processing to the client with keeping more on the server. Recommend a split for form feedback, calculations that use only current input, identity/permission checks and database updates.

Use responsiveness, connection/traffic, client capability, central updates and protected data. Qualify every benefit.

Students type their answer here.

Fill in the blanks4 marks
Client-side code runs on the user's checkpoint gap 1. Server-side code runs on the service's checkpoint gap 2. Browser validation can improve checkpoint gap 3, but authoritative checks still belong on the checkpoint gap 4.

Review your understanding

Before submitting, check that you can explain the main distinction in your own words, apply it in an unfamiliar context and justify each consequence rather than only naming a feature.