Recipes

In the recipes documentation, we aim to describe some patterns to organize your API calls to maximize performance.

If you can give the equivalent example in your own language-of-preference, please submit a pull request!

Creating a Zaak, a Document and relating them

Python (Django)

Javascript

Using Django with zgw-consumers

import base64
from datetime import date

from zgw_consumers.constants import APITypes
from zgw_consumers.models import Service

zrc_client = Service.objects.filter(api_type=APITypes.zrc).get().build_client()
drc_client = Service.objects.filter(api_type=APITypes.drc).get().build_client()

# zaak creation
today = date.today().strftime("%Y-%m-%d")
zaak_body = {
    "zaaktype": "https://test.openzaak.nl/catalogi/api/v1/zaaktypen/4acb5ab8-f189-4559-b18a-8a54553a74ff",
    "bronorganisatie": "123456782",
    "verantwoordelijkeOrganisatie": "123456782",
    "registratiedatum": today,
    "startdatum": today,
}
zaak: dict = zrc_client.create("zaak", zaak_body)

# document creation
with open("/tmp/some_file.txt", "rb") as some_file:
    document_body = {
        "bronorganisatie": "123456782",
        "creatiedatum": today,
        "titel": "Example document",
        "auteur": "Open Zaak",
        "inhoud": base64.b64encode(some_file.read()).decode("utf-8"),
        "bestandsomvang": some_file.size,
        "bestandsnaam": some_file.name,
        "taal": "nld",
        "informatieobjecttype": (
            "https://test.openzaak.nl/catalogi/api/v1/"
            "informatieobjecttypen/abb89dae-238e-4e6a-aacd-0ba9724350a9"
        )
    }
document: dict = drc_client.create("enkelvoudiginformatieobject", document_body)

# relate them
zio_body = {
    "zaak": zaak["url"],
    "informatieobject": document["url"],
}
zio: dict = zrc_client.create("zaakinformatieobject", zio_body)

import jwt from 'jsonwebtoken';

const CLIENT_ID = 'example';
const SECRET = 'secret';

// helpers
const getJWT = () => {
  return jwt.sign(
    {client_id: CLIENT_ID},
    SECRET,
    {
      algorithm: 'HS256',
      issuer: CLIENT_ID,
    }
  );
};

const apiCall = (url, method='get', body) => {
  const fetchBody = body ? JSON.stringify(body) : null;
  const token = getJWT();
  const response = await fetch(
    url,
    {
      method: method,
      headers: {
        'Authorization': `Bearer ${token}`,
        'Accept': 'application/json',
      },
      body: _body
    }
  );
  const responseData = await response.json();
  return responseData;
};

const toBase64 = file => new Promise((resolve, reject) => {
    const reader = new FileReader();
    reader.readAsDataURL(file);
    reader.onload = () => resolve(reader.result);
    reader.onerror = error => reject(error);
});

// zaak creation
const today = '2020-10-16';
const zaakBody = {
    'zaaktype': 'https://test.openzaak.nl/catalogi/api/v1/zaaktypen/4acb5ab8-f189-4559-b18a-8a54553a74ff',
    'bronorganisatie': '123456782',
    'verantwoordelijkeOrganisatie': '123456782',
    'registratiedatum': today,
    'startdatum': today,
}
const zaak = await apiCall(
  'https://test.openzaak.nl/zaken/api/v1/zaken',
  'POST',
  zaakBody
);

// document creation
const someFile = document.querySelector('#myfile').files[0];
const documentBody = {
  'bronorganisatie': '123456782',
  'creatiedatum': today,
  'titel': 'Example document',
  'auteur': 'Open Zaak',
  'inhoud': toBase64(someFile),
  'bestandsomvang': someFile.size,
  'bestandsnaam': someFile.name,
  'taal': 'nld',
  'informatieobjecttype': `https://test.openzaak.nl/catalogi/api/v1/
informatieobjecttypen/abb89dae-238e-4e6a-aacd-0ba9724350a9`
};

const doc = await apiCall(
  'https://test.openzaak.nl/documenten/api/v1/enkelvoudiginformatieobjecten',
  'POST',
  documentBody
);

// relate them
const zioBody = {
  'zaak': zaak.url,
  'informatieobject': doc.url
};
const zio = await apiCall(
  'https://test.openzaak.nl/zaken/api/v1/zaakinformatieobjecten',
  'POST',
  zioBody,
);

Retrieving the documents related to a Zaak

Key problem here is that one Zaak has (probably) multiple documents related to it, and retrieving them sequentially is a performance hit that gets worse with the amount of documents.

The solution is to use some form of threading/concurrency offered by your language.

Python (Django)

Javascript

Using Django with zgw-consumers, we can use the concurrent.fututures.ThreadPoolExecutor, where each job will run in its own thread. This gets close to retrieving all the documents in parallel instead of sequentially, resulting in a constant-time determined by the slowest API call.

from typing import List

from zgw_consumers.constants import APITypes
from zgw_consumers.models import Service
from zgw_consumers.concurrent import parallel

zrc_client = Service.objects.filter(api_type=APITypes.zrc).get().build_client()
drc_client = Service.objects.filter(api_type=APITypes.drc).get().build_client()

zaak_url = "https://test.openzaak.nl/zaken/api/v1/zaken/b604ea56-f01c-432e-8d61-fd4ab02893dc"
zios: List[dict] = zrc_client.list("zaakinformatieobject", {"zaak": zaak_url})
document_urls = [zio["informatieobject"] for zio in zios]
with parallel() as executor:
    _documents = executor.map(
        lambda url: drc_client.retrieve("enkelvoudiginformatieobject", url=url),
        document_urls
    )
documents: List[dict] = list(_documents)

Similarly to the Python case, we leverage the Javacsript async/await event loop. Once we’ve collected all the URLs of documents to retrieve, we create promises and by using Promise.all, all API calls are being performed in parallel (at least for the network IO part).

import jwt from 'jsonwebtoken';

const CLIENT_ID = 'example';
const SECRET = 'secret';

// helpers
const getJWT = () => {
  return jwt.sign(
    {client_id: CLIENT_ID},
    SECRET,
    {
      algorithm: 'HS256',
      issuer: CLIENT_ID,
    }
  );
};

const get = (url) => {
  const token = getJWT();
  const response = await fetch(
    url,
    {
      method: 'get',
      headers: {
        'Authorization': `Bearer ${token}`,
        'Accept': 'application/json',
      },
    }
  );
  const responseData = await response.json();
  return responseData;
};

const zaakUrl = 'https://test.openzaak.nl/zaken/api/v1/zaken/b604ea56-f01c-432e-8d61-fd4ab02893dc';
const zios = await get(`https://test.openzaak.nl/zaken/api/v1/zaakinformatieobjecten?zaak=${zaakUrl}`);
const promises = zios.map(zio => get(zio.informatieobject));
const documents = await Promise.all(promises);