Plan and compare interfaces reliably
A connection is useful when the right information arrives at the right time. API development therefore covers more than a successful technical request. Data meaning, failures and responsibilities matter.
Describe the exchange objective
State source and target systems and the intended business result: transferring orders, updating products, providing documents or sending measurements. Clarify sending, receiving or synchronizing in both directions.
A new API for future partners differs from connecting existing programs. A faulty interface first needs a bounded investigation before the solution and scope are settled.
| Task | First clarification |
|---|---|
| Connect systems | Source, target and required operations |
| Provide a new API | Future users, permitted operations and description |
| Change an interface | Version, workflows and preserved behaviour |
| Investigate a fault | Bounded example and responsible systems |
Check existing capabilities and versions
Known programs and versions help the provider examine APIs, file exports or other access. Systems do not all permit the same objects or writes. Access conditions, licences and vendor support can affect scope.
Ask for documented operations, fields and responses. Machine-readable descriptions can support tests and documentation without proving that the required capabilities are actually implemented.
Define data and authoritative sources
Assign an authoritative source to each important data type. Identifiers, required fields, units, states and change rules must align. Technically successful transfer can still produce the wrong business result.
Two-way exchange needs rules for simultaneous changes and duplicates. Agree deletion and incomplete-record handling. Initial enquiries can describe data categories without real customer data.
Clarify frequency, failures and limits
Individual requests, events and periodic batches have different requirements. State known volumes and peaks in the common brief; unknown scale can be clarified initially.
Test repeated events, partial success, timeouts and interrupted services. Retries must be bounded without silently creating duplicate orders or extra charges. Define when a person should intervene.
Define permissions and operation
Valid credentials do not automatically permit every action or record. Check who may read or change each type of data. Personal-data exchange also needs clear responsibilities and appropriate scope.
Agree operation, version changes, error records and incidents with the system owners. Logs should contain only necessary information. Passwords, keys, production data and full error logs do not belong in a public initial enquiry.
Separate development and ongoing costs
The quote should distinguish analysis, data mapping, implementation, testing and documentation. Existing connectors may be reusable, but need checking against the particular scope.
Include API licences, usage-based services, operation and later changes. Bounded requests and clear cost assumptions matter with third-party services. A successful test does not guarantee a monetary cap for future operation.
| Cost component | Check the quotation |
|---|---|
| Analysis | Available access, data and open questions |
| Implementation | Mapping, transfer and failure handling |
| Acceptance | Examples, permission tests and documentation |
| Operation | Licences, usage, support and version changes |
Prepare the enquiry and acceptance tests
Goal, systems, direction, data types, frequency and operating responsibilities support an initial assessment. Describe versions, approximate volumes and special cases in one common brief without credentials or confidential files.
Then agree harmless examples: normal exchange, invalid data, denied access, repetition and interruption. Check the business outcome in both systems and record responsibilities and handover.
Frequently asked questions
Is an API the same as a file export?
No. Both can transfer data, but operations, frequency, responses and permissions differ.
Must we specify a protocol such as REST?
Not initially. Known systems and the intended exchange are enough; state existing constraints in the brief.
Does a successful request prove correct data?
Not automatically. Check mapping, states and target-system results as well as the technical response.
Why test repeated events?
An event can arrive again after an interruption. Duplicate and partial-success handling should be defined.
Does initial assessment need our passwords?
No. Describe systems and data categories. Any later test access belongs in a separately agreed secure process.
Which costs follow development?
Depending on the solution: licences, API usage, operation, support and version changes. Have these itemized separately.
