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> $`\textcolor{#890000}{\text{THIS SDK IS IN DEVELOPMENT AND NOT READY FOR PRODUCTION USE YET!!!}}`$

## About the FIT-Connect Java SDK

The Java SDK for FIT-Connect enables to build clients for senders and subscribers without directly interacting with any REST-Endpoints.
It provides a simple fluent API that guides through the creation and sending of a submission, as well as receiving submissions as a subscriber.

For further information, check out the official docs: [FIT-Connect Documentation](https://docs.fitko.de/fit-connect/docs/) as well as the:

* [Self-Service-Portal (Testing Environment)](https://portal.auth-testing.fit-connect.fitko.dev/)
* [FITKO project website](https://www.fitko.de/projektmanagement/fit-connect)

## **Outline**
[[_TOC_]]

## Getting Started

How to set up the SDK project locally.

### Build Dependencies

This section lists major frameworks/libraries used in the SDK.

* Java 11 (LTS)
* Maven 3.x
* Junit 5

FIT-Connect dependencies:
* [JWKValidator 1.4.0](https://git.fitko.de/fit-connect/jwk-validator)

Further 3rd party dependencies:

* Nimbus-Jose JWT
* Spring Web/HTTP
* Jackson FasterXMl
* JCommander
* Snakeyaml
* OpenCSV 

### Prerequisites

* Java Runtime >= 11, check your current setup in your commandline
  ```sh
  java --version 
  ```
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### Add FIT-Connect SDK to your build

To add a dependency on FIT-Connect using Maven, use the following:

```xml
<dependency>
  <groupId>dev.fitko.fitconnect.sdk</groupId>
  <artifactId>client</artifactId>
  <version>[Latest Version]</version>
</dependency>
```
With `[Latest Version]` of the last stable build or snapshot.

If you use a snapshot version, please add the maven snapshot repo to your pom.
```xml
<distributionManagement>
  <snapshotRepository>
  <id>ossrh</id>
  <url>https://s01.oss.sonatype.org/content/repositories/snapshots</url>
  </snapshotRepository>
</distributionManagement>
```

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## Modules

See the projects' module documentation for more specific information:

* [API Module ](api/README.md)
* [Core Module ](core/README.md)
* [Client Module ](client/README.md)

## Setup

_The following steps show how to get the SDK running_

1. Create and [account](https://docs.fitko.de/fit-connect/docs/getting-started/account) on the self-service portal
2. Get your sender/subscriber API-key credentials
3. Clone the sdk repo
   ```sh
   git clone https://git.fitko.de/fit-connect/sdk-java
   ```
4. Build the project with the included maven wrapper (no separate maven installation needed)
   ```sh
   ./mvnw clean install -DskipTests
   ```
5. Configure your `config.yml` (see [template](/config.yml))
    - add Sender OAuth credentials from the self-service portal to *SENDER* section 
    - add Subscriber OAuth credentials from the self-service portal to *SUBSCRIBER* section 
    - add reference to private decryption key (JWK) to *SUBSCRIBER* section
    - add reference to private signature key (JWK) to *SUBSCRIBER* section


6. Provide config via environment variable ``FIT_CONNECT_CONFIG`` or load the config with
    ````java
      final var config = ApplicationConfigLoader.loadConfig("absolute/path/to/config.yml");
      final var senderClient = ClientFactory.senderClient(config);
      ````

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## API Usage for Routing
The Routing-Client allows to retrieve data about areas and services as well as their service destination.
A typical workflow using the `RoutingClient` and `SenderClient` would be:

1) Find the `areaId` for an area via routing
2) Find the destination for a `leikaKey` and an `areaId` via routing
3) Submit a new submission to the destination using the `SenderClient`

### Finding Areas
Areas can be searched with one or more search criteria:

```java
final RoutingClient routingClient = ClientFactory.routingClient(config);

final var citySearchCriterion = "Leip*";
final var zipCodeSearchCriterion = "04229";

// get first 5 area results
final List<Area> areas = routingClient.findAreas(List.of(citySearchCriterion, zipCodeSearchCriterion), 0, 5);

LOGGER.info("Found {} areas", areas.size());
for (final Area area : areas){
    LOGGER.info("Area {} with id {} found", area.getName(), area.getId());
}
```

### Finding Destinations by service identifier and region

For searching a destination the `DestinationSearch.Builder` is used pass a search request to the routing client. 
The leikaKey is mandatory, as well as (max.) one other search criterion for the area/region, like one of:
- ars amtlicher regionalschlüssel
- ags amtlicher gemeindeschlüssel
- areaId identifier of an area that can be retrieved via [finding areas](#finding-areas)

```java
final RoutingClient routingClient = ClientFactory.routingClient(config);

final DestinationSearch search = DestinationSearch.Builder()
        .withLeikaKey("99123456760610")
        .withArs("064350014014")
        .withLimit(5)
        .build();

// get first 5 route results
final List<Route> routes = routingClient.findDestinations(search);

LOGGER.info("Found {} routes for service identifier {}", routes.size(), leikaKey);
for (final Route route : routes){
    LOGGER.info("Route {} with destinationId {} found", route.getName(), route.getDestinationId());
}
```


## API Usage for Sender

For sending submission and already encrypted submissions builder are provided to construct the necessary payload to be sent. 
Builders allow method chaining and guide through all necessary steps.

The examples below expect a loaded configuration via the ApplicationConfigLoader.

### Hand in already encrypted submission (e.g. from frontend)
If all data, metadata and attachments are encrypted outside the SDK the sender client allows to retrieve the public key for encryption as well as sending of already encrypted payloads.

> For further information on how to implement end-2-end encryption please check the [FIT-Connect documentation](https://docs.fitko.de/fit-connect/docs/getting-started/encryption).

#### 1.  Retrieve public encryption key:

```java
final var destinationId = UUID.fromString("d2d43892-9d9c-4630-980a-5af341179b14");
final Optional<String> publicJwk =  ClientFactory.senderClient(config).getPublicKey(destinationId);
```

#### 2. Send encrypted data

To send an encrypted submission the builder `EncryptedSubmissionBuilder` is needed to construct an `EncryptedSubmissionPayload` object.
The payload can be submitted as shown below via the `ClientFactory`.

If optional attachments are added, the UUID needs to be provided for each attachment to be able to announce them before the submission is actually sent. 
This is necessary because the SDK does not have access to the already encrypted metadata that, which contains that information.

```java
// The constructed client can be reused to send multiple submissions
final SenderClient senderClient = ClientFactory.senderClient(config);

final EncryptedSubmissionPayload frontendEncryptedPayload = EncryptedSubmissionBuilder.Builder()
        .withEncryptedAttachment(UUID.fromString("d2d43892-9d9c-4630-980a-5af341179b14"), "$encrpyt€ed @tt@chment")  // optional
        .withEncryptedData("{$encrpyt€ed json}")
        .withEncryptedMetadata("$encrpyt€ed metadata")
        .withDestination(UUID.fromString("d2d43892-9d9c-4630-980a-5af341179b14"))
        .withServiceType("Führerscheinummeldung", "urn:de:fim:leika:leistung:99400048079000")
        .build();

final SentSubmission sentSubmission = senderClient.submit(frontendEncryptedPayload);
```

| **Important** |
| ------------- |
| If destination id (`destinationId`) and service type (`leikaKey`) are provided by a frontend component, they MUST NOT be blindly trusted. Instead, the sender's backend MUST check if sending submissions of this service type to the specified destination is allowed. |


### Hand in a new submission with unencrypted data

If all data, metadata and attachments are encrypted in the sender using the SDK, the client automatically handles the encryption.

Be aware that this example is not end-2-end encrypted, see [FIT-Connect documentation](https://docs.fitko.de/fit-connect/docs/getting-started/encryption) for details.

To send a submission the builder `SubmissionBuilder` is needed to construct a `SubmissionPayload` object.
The payload can be submitted as shown below via the `ClientFactory`.

```java
// The constructed client can be reused to send multiple submissions
final SenderClient senderClient = ClientFactory.senderClient(config);

final SubmissionPayload submissionPayload = SubmissionBuilder.Builder()
        .withAttachment(Path.of("path/to/attachment.txt").toFile()) // optional
        .withJsonData("{ \"foo\" : \"bar\"}")
        .withDestination(UUID.fromString("d2d43892-9d9c-4630-980a-5af341179b14"))
        .withServiceType("Führerscheinummeldung", "urn:de:fim:leika:leistung:99400048079000")
        .build();

final SentSubmission sentSubmission = senderClient.submit(submissionPayload);

```

### Read the Event-Log
To read the event-log, destinationId and caseId are needed. 
```java
final var caseId = UUID.fromString("d2d43892-9d9c-4630-980a-5af341179b14");
final var destinationId = UUID.fromString("d2d43892-9d9c-4630-980a-5af341179b14");

final List<EventLogEntry> eventLog = ClientFactory.senderClient(config).getEventLog(caseId, destinationId);

for(EventLogEntry logEntry: eventLog) {
    LOGGER.info("Event: {}", logEntry.getEvent());
    LOGGER.info("EventId: {}", logEntry.getEventId());
    LOGGER.info("Issued at: {}", logEntry.getIssueTime());
    LOGGER.info("Issuer: {}", logEntry.getIssuer());
    LOGGER.info("CaseId: {}", logEntry.getCaseId());
    LOGGER.info("SubmissionId: {}", logEntry.getSubmissionId());
    LOGGER.info("Problems: {}", logEntry.getProblems());
}
```

The log contains the event, issuer and occurred problems like shown in the example output below:
````plaintext
 Event: https://schema.fitko.de/fit-connect/events/submit-submission
 EventId: 659bcbe7-fd53-4313-a1c3-192bccc95f94
 Issued at: Thu Dec 15 10:23:51 CET 2022
 Issuer: https://submission-api-testing.fit-connect.fitko.dev
 CaseId: cb9a5a78-0ec6-492c-b652-0d7aa5e488b0
 SubmissionId: 7502200b-f12d-4fc5-9669-ad3e3337396b
 Problems: []
````

### Read the latest status of a submission

Instead of the entire log, the latest status for a submission can be retrieved as well.
        
```java
final SentSubmission sentSubmission =  ... // persisted sent submission by sender client
final EventStatus eventStatus = ClientFactory.senderClient(config).getStatusForSubmission(sentSubmission);

LOGGER.info("Current status for submission {} => {}", sentSubmission.getSubmissionId(), eventStatus.getStatus());
```
The example output shows the current state of the submission after being created, following the transitions in the diagram below:

````plaintext
Current status for submission 43cf7163-5163-4bc8-865e-be96e271ecc3 => incomplete
````

<img src="https://docs.fitko.de/fit-connect/assets/images/status-ebe91122f32321e22f094882a66c1139.svg">

### Validating callbacks

When receiving callbacks from the FIT-Connect system, sender (and subscriber) of submissions have to check if the received data is valid to prevent unauthorized calls from messing with the business processes and user data. The values needed for this validation are transmitted  within the received HTTP requests. FIT-Connect uses the HMAC mechanism to proof the validity of its calls.

More details on how this method works can be found here:
- https://docs.fitko.de/fit-connect/docs/details/callbacks/#callback-validation
- https://www.rfc-editor.org/rfc/rfc2104

The Java SDK provides a convenient method for validating callbacks, its usage could look like this:

```java
final SenderClient senderClient = ClientFactory.senderClient(config);

final ValidationResult validationResult = senderClient.validateCallback("hmac", 0L, "body", "secret");

if(validationResult.hasError()){
    LOGGER.error(validationresult.getError().getMessage());
}
```

## API Usage for Subscriber

### Retrieving submissions
Submissions can be fetched by id or as a list of submissions for a specific case.
#### List with pagination
Limit and offset parameters allow to page through the result.
```java
final int offset = 0;
final int limit = 100;
final var destinationId = UUID.fromString("d2d43892-9d9c-4630-980a-5af341179b14");
final Set<SubmissionForPickup> firstOneHundredSubmissions = ClientFactory.subscriberClient(config).getAvailableSubmissions(destinationId), limit, offset);
```

#### List without pagination
Listing available submissions without pagination pulls the first 500 entries.
```java
final var destinationId= UUID.fromString("d2d43892-9d9c-4630-980a-5af341179b14");
final Set<SubmissionForPickup> submissions = ClientFactory.subscriberClient(config).getAvailableSubmissions(destinationId);
```
#### Receive single submission

```java
final submissionId = UUID.fromString("d2d43892-9d9c-4630-980a-5af341179b14");
final ReceivedSubmission receivedSubmission =  ClientFactory.subscriberClient(config).requestSubmission(submissionId);
```
Now, the received submission allows access to the decrypted data, attachments, metadata and ids
```java
 // access data
final String data = receivedData.getData();
final URI dataSchemaUri = receivedData.getDataSchemaUri();
final MimeType mimeType = receivedData.getDataMimeType();

// access metadata
final Metadata  = receivedData.getSubmissionMetdata();

// access attachments
for(final ReceivedAttachment attachment : receivedSubmission.getAttachments()){
    final byte[] attachmentRawData = attachment.getData();
    final String originalFilename = attachment.getFilename();
    final UUID attachmentId = attachment.getAttachmentId();
}

// access further ids of submission
final UUID caseId  = receivedData.getCaseId();
final UUID submissionId  = receivedData.getSubmissionId();
final UUID destinationId  = receivedData.getDestinationId();
```

### Sending events to the event-log

In order to accept or reject a submission, the subscriber client can send events ([security-event-tokens](https://www.rfc-editor.org/rfc/rfc8417.html)) to the event-log.
For more details please see the documentation on [events](https://docs.fitko.de/fit-connect/docs/getting-started/event-log/overview) and the creation of [set-events](https://docs.fitko.de/fit-connect/docs/getting-started/event-log/set-creation).

#### Accepting a submission
If the functional review by the subscriber was positive, the submission can be accepted with an `accept-submission` event.
```java
final var submissionId = UUID.fromString("d2d43892-9d9c-4630-980a-5af341179b14");

ClientFactory.subscriberClient(config)
        .requestSubmission(submissionId)
        .acceptSubmission();
```
After the accept event was sent the submission transitions into the state `deleted` and is removed.
#### Rejecting a submission
If the functional or technical review by the subscriber was negative, e.g. there is a discrepancy within the semantics of the data, the submission can be rejected with an `reject-submission` event.
The rejection takes a list of `dev.fitko.fitconnect.api.domain.model.event.problems.*` as parameter to specify the problem. 
See the Fit-Connect documentation for more details on [available (technical) problems](https://docs.fitko.de/fit-connect/docs/receiving/verification).
```java
final var submissionId = UUID.fromString("d2d43892-9d9c-4630-980a-5af341179b14");

final var rejectionProblems = List.of(new DataSchemaViolation());

ClientFactory.subscriberClient(config)
        .requestSubmission(submissionId)
        .rejectSubmission(rejectionProblems);
```
After the rejection event was sent the submission transitions into the state `deleted` and is removed.

### Read the Event-Log
To read the event-log, destinationId and caseId are needed.
```java
final var caseId = UUID.fromString("d2d43892-9d9c-4630-980a-5af341179b14");
final var destinationId = UUID.fromString("d2d43892-9d9c-4630-980a-5af341179b14");

final List<EventLogEntry> eventLog = ClientFactory.subscriberClient(config).getEventLog(caseId, destinationId);

for(EventLogEntry logEntry: eventLog) {
    LOGGER.info("Event: {}", logEntry.getEvent());
    LOGGER.info("EventId: {}", logEntry.getEventId());
    LOGGER.info("Issued at: {}", logEntry.getIssueTime());
    LOGGER.info("Issuer: {}", logEntry.getIssuer());
    LOGGER.info("CaseId: {}", logEntry.getCaseId());
    LOGGER.info("SubmissionId: {}", logEntry.getSubmissionId());
    LOGGER.info("Problems: {}", logEntry.getProblems());
}
```

The log contains the event, issuer and occurred problems like shown in the example output below:
````plaintext
 Event: https://schema.fitko.de/fit-connect/events/create-submission
 EventId: 659bcbe7-fd53-4313-a1c3-192bccc95f94
 Issued at: Thu Dec 15 10:23:51 CET 2022
 Issuer: https://submission-api-testing.fit-connect.fitko.dev
 CaseId: cb9a5a78-0ec6-492c-b652-0d7aa5e488b0
 SubmissionId: 7502200b-f12d-4fc5-9669-ad3e3337396b
 Problems: []
````
For more details please see the [event-log documentation](https://docs.fitko.de/fit-connect/docs/getting-started/event-log/overview). 
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### Validating callbacks

The validation of callbacks works similar to the sender side (see [Sender Callback Validation](#validating-callbacks)), but instead of the `SenderClient`, we use the `SubscriberClient`:

```java
final SubscriberClient subscriberClient = ClientFactory.subscriberClient(config);

final ValidationResult validationResult = subscriberClient.validateCallback("hmac", 0L, "body", "secret");

if(validationResult.hasError()){
    LOGGER.error(validationresult.getError().getMessage());
}
```

## Roadmap

- [ ] Add auto-reject on technical errors
- [ ] Maven central release of 1.0.0

See the [open issues](https://git.fitko.de/fit-connect/planning/-/boards/44?search=SDK) for a full list of proposed features (and known issues).

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<!-- CONTACT -->

## Contact

[FIT-Connect Contact Page](https://docs.fitko.de/fit-connect/contact/) for further information

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## License
Source code is licensed under the [EUPL](https://joinup.ec.europa.eu/page/eupl-text-11-12).

*Rechtlicher Hinweis: Dieses Software Development Kit (SDK) ist dazu bestimmt, die Anbindung einer Software an die FIT-Connect-Infrastruktur zu ermöglichen.
Hierfür kann das SDK in die anzubindenden Software integriert werden.
Erfolgt die Integration des SDK in unveränderter Form, liegt keine Bearbeitung im Sinne der EUPL bzw. des deutschen Urheberrechts vor.
Die Art und Weise der Verlinkung des SDK führt insbesondere nicht zur Schaffung eines abgeleiteten Werkes.
Die unveränderte Übernahme des SDK in eine anzubindende Software führt damit nicht dazu, dass die anzubindende Software unter den Bedingungen der EUPL zu lizenzieren ist.
Für die Weitergabe des SDK selbst - in unveränderter oder bearbeiteter Form, als Quellcode oder ausführbares Programm - gelten die Lizenzbedingungen der EUPL in unverände*rter Weise.

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