Document updated on Jul 12, 2020
Supported backend encodings
Setting the encoding is an important part of the backend definition, as it informs KrakenD how to parse the responses of your services.
Each backend can reply with a different encoding and KrakenD does not have any problem working with mixed encodings at the same time. You can use the following encoding in each backend section:
jsonsafejsonxmlrssstringno-op
Notice that all values are in lower case. Unknown values for encoding or no value at all, is treated as json.
Each backend declaration can set a different encoder to process the responses, and still, KrakenD can transparently work with the mixed content returning a unified encoding in the endpoint.
How to choose the backend encoding?
Follow this table to determine how to treat your backend content:
| The backend returns… | Then use encoding… |
|---|---|
JSON inside an object ({}) | json |
JSON inside an array/collection ([]) | json with "is_collection": true |
| JSON with variable types | safejson |
| XML | xml |
| RSS | rss |
| Not an object, but a string | string |
| Nevermind, just proxy | no-op (read how) |
If you want to return to the client a JSON array instead of an object, consider using the following combinations: output_encoding: json-collection in your endpoint, and is_collection: true in your backend. See response content types.
When hesitating whether to use safejson or json and the is_collection=true, the json encoder is faster and more performant but less resilient: it will fail when the content doesn’t have the expected type.
The following example demonstrates how an endpoint /abc is feeding on three different services and urls /a, /b, and /c and aggregates their responses:
{
"endpoints": [
{
"endpoint": "/abc",
"backend": [
{
"url_pattern": "/a",
"encoding": "json",
"host": [
"http://service-a.company.com"
]
},
{
"url_pattern": "/b",
"encoding": "xml",
"host": [
"http://service-b.company.com"
]
},
{
"url_pattern": "/c",
"encoding": "rss",
"host": [
"http://service-c.company.com"
]
}
]
}
]
}As you can see, having the encoding declaration inside every backend allows you to consume services with different content types. The endpoint /abc instead uses the encoding of your choice (e.g., JSON), but is feeding and merging from XML, RSS and JSON content simultaneously.
