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http-service-clients/output/01-registry-and-crud.txt

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+# groups the HttpServiceProxyRegistry knows about
+group apikey  -> [ApiKeyClient]
+group bearer  -> [SecureClient]
+group flaky   -> [FlakyClient]
+group github  -> [GitHubClient]
+group oauth   -> [OAuthClient]
+group posts   -> [ParamsClient, PostClient]
+group resilient -> [ResilientClient]
+PostClient bean is a JDK proxy: true
+registry.getClient("posts", PostClient.class) is the injected bean: true
+
+# CRUD against the stub (every call is a real HTTP request)
+findAll() -> 3 posts
+findById(1) -> Post[id=1, userId=1, title=First post, body=Body of the first post]
+findByUser(2) -> [3]
+findEntity(2) -> status 200 OK, Content-Type application/json
+create(...) -> id 101
+update(1, ...) -> title 'Updated Title'
+delete(1) -> void, no exception
+
+# argument kinds (ParamsClient)
+@RequestHeader        -> upstream saw X-Correlation-Id=abc-123
+@RequestParam(required=false), null -> 3 posts
+@RequestParam(defaultValue="2")   -> posts [3]
+URI argument          -> Second post
+
+# what the stub actually received
+GET /posts
+GET /posts/1
+GET /posts?userId=2
+GET /posts/2
+POST /posts
+PUT /posts/1
+DELETE /posts/1
+GET /echo/headers
+GET /posts
+GET /posts?userId=2
+GET /posts/2

http-service-clients/output/02-properties-and-pitfalls.txt

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+# A. the keys the article's first version used (spring.http.client.service.group.<g>.base-url)
+findAll() -> java.lang.IllegalArgumentException: URI with undefined scheme
+
+# B. the keys Spring Boot 4.1.2 binds (spring.http.serviceclient.<g>.base-url)
+findAll() -> OK -> 3
+
+# C. no base URL at all
+findAll() -> java.lang.IllegalArgumentException: URI with undefined scheme
+
+# D. a return type that does not match the JSON (array decoded as a single Post)
+list() -> org.springframework.web.client.RestClientException: Error while extracting response for type [com.ankurm.hsc.model.Post] and content type [application/json]
+root cause class: tools.jackson.databind.exc.MismatchedInputException
+
+# E. @GetMapping on a client interface instead of @GetExchange
+createClient(UsesRequestMapping.class).list() -> java.lang.IllegalStateException: Unexpected method invocation: public abstract java.lang.String com.ankurm.hsc.Step02PropertiesAndPitfallsTest$UsesRequestMapping.list()

http-service-clients/output/03-error-handling.txt

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+# 1. framework defaults (a plain RestClient, no status handler)
+findById(99) -> HttpClientErrorException$NotFound
+  status      : 404 NOT_FOUND
+  message     : 404 Not Found: "{"type":"https://stub.example/problems/post-not-found","title":"Post not found","status":404,"detail":"No post with id 99","instance":"/posts/99"}"
+  content-type: application/problem+json
+  getResponseBodyAs(ProblemDetail): title='Post not found' detail='No post with id 99' type=https://stub.example/problems/post-not-found
+alwaysDown() -> HttpServerErrorException.ServiceUnavailable, status 503 SERVICE_UNAVAILABLE
+
+# 2. a response that never comes: read timeout is 1500ms on the flaky group, /slow takes 3000ms
+slow() -> ResourceAccessException, cause java.net.http.HttpTimeoutException
+  message: I/O error on GET request for "http://127.0.0.1:<port>/slow": Request cancelled
+
+# 3. nobody listening
+findAll() -> ResourceAccessException, cause java.net.ConnectException
+
+# 4. Optional<Post> and ResponseEntity<Post> on a 404 with the default handler
+findOptional(99) -> NotFound
+findEntity(99)   -> NotFound
+
+# 5. NotFoundRestClientAdapterDecorator (spring-web 7.0.10) turns a 404 into an empty result
+findById(99)     -> null
+findOptional(99) -> Optional.empty
+findEntity(99)   -> status 404 NOT_FOUND, body null
+
+# 6. our own defaultStatusHandler on the "posts" group (UpstreamProblemStatusHandler)
+findById(99) -> UpstreamNotFoundException: Upstream says not found: No post with id 99
+  problem.type=https://stub.example/problems/post-not-found instance=/posts/99
+create(blank title) -> UpstreamValidationException: Upstream rejected the request: Validation failed
+  extension 'errors' = [{field=title, message=must not be blank}]
+alwaysDown() -> UpstreamUnavailableException: Upstream unavailable (503): Upstream is down for maintenance

http-service-clients/output/04-controller-advice.txt

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+# our service (MockMvc, real HTTP to the stub behind it)
+GET /api/posts/1       -> 200 {"id":1,"userId":1,"title":"First post","body":"Body of the first post"}
+GET /api/posts/99      -> 404 {"detail":"No post with id 99","instance":"/api/posts/99","status":404,"title":"Not Found"}
+POST blank title       -> 400 {"detail":"Upstream rejected the request","instance":"/api/posts","status":400,"title":"Bad Request","errors":[{"field":"title","message":"must not be blank"}]}
+GET /api/down          -> 502 {"detail":"Upstream service error","instance":"/api/down","status":502,"title":"Bad Gateway"}
+GET /api/slow          -> 504 {"detail":"Upstream service timed out","instance":"/api/slow","status":504,"title":"Gateway Timeout"}

http-service-clients/output/05-retries.txt

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+# 1. RetryTemplate around the call (org.springframework.core.retry, spring-core 7.0.10)
+get("tpl", failures=2) -> 'Recovered on call 3'
+stub saw 3 calls; listener events: [beforeRetry, onRetryFailure(ServiceUnavailable), beforeRetry, onRetrySuccess]
+maxRetries(2) against a dead upstream -> HttpServerErrorException$ServiceUnavailable / 503 Service Unavailable: "{"type":"https://stub.example/problems/service-unavailable","title":"Service Unavailable","status":503,"detail":"Flaky upstream, call 3","instance":"/flaky/exhaust"}"
+stub saw 3 calls
+execute() instead of invoke() -> RetryException, retryCount=2, exceptions=3, last=ServiceUnavailable
+
+# 2. @Retryable on the @HttpExchange interface method (bean from the "flaky" group)
+get("ann", failures=2) -> 'Recovered on call 3'; stub saw 3 calls
+get("ann-dead", failures=10) -> HttpServerErrorException$ServiceUnavailable / 503 Service Unavailable: "{"type":"https://stub.example/problems/service-unavailable","title":"Service Unavailable","status":503,"detail":"Flaky upstream, call 4","instance":"/flaky/ann-dead"}"
+stub saw 4 calls (maxRetries = 3)
+
+# 3. the same retry as a ClientHttpRequestInterceptor on the "resilient" group (idempotent methods only)
+get("icpt", failures=2) -> 'Recovered on call 3'; stub saw 3 calls; interceptor attempts so far: 3
+POST createUnstable -> HttpServerErrorException$ServiceUnavailable / 503 Service Unavailable: "{"type":"https://stub.example/problems/service-unavailable","title":"Service Unavailable","status":503,"detail":"Created, but the response was lost","instance":"/posts/unstable"}"
+stub created the resource 1 time(s): the interceptor did not retry a POST
+
+# 4. the trap: @Retryable on a POST whose response was lost after the server did the work
+createUnstable() -> id 102, body 'created 2 times so far'
+stub created the resource 2 times for ONE logical call
+
+# 5. Resilience4j 2.4.0 around the same plain client
+maxAttempts(3), failures=2 -> 'Recovered on call 3'; stub saw 3 calls
+maxAttempts(3) against a dead upstream -> ServiceUnavailable; stub saw 3 calls

http-service-clients/output/06-auth-bearer-and-api-key.txt

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+# 1. no credentials (a plain RestClient)
+whoAmI() -> 401 Unauthorized, WWW-Authenticate: Bearer realm="stub"
+
+# 2. bearer token added by a ClientHttpRequestInterceptor on the "bearer" group
+whoAmI() -> {caller=demo-user, tokenKind=static}
+headers the upstream saw: Authorization=Bearer <redacted>, X-Correlation-Id present=true (8 chars)
+
+# 3. API key from spring.http.serviceclient.apikey.default-header.X-Api-Key (no Java at all)
+whoAmI() -> {caller=demo-service, auth=api-key}
+headers the upstream saw: X-Api-Key=demo-key-123, X-Correlation-Id present=true
+
+# 4. the interceptor is per group: the "apikey" group never sends Authorization
+Authorization header on the apikey group: null

http-service-clients/output/07-oauth2-client-credentials.txt

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+# @ClientRegistrationId("stub") on the interface + OAuth2RestClientHttpServiceGroupConfigurer
+call 1: whoAmI() -> {caller=demo-user, tokenKind=oauth2}
+call 2: whoAmI() -> {caller=demo-user, tokenKind=oauth2}
+call 3: whoAmI() -> {caller=demo-user, tokenKind=oauth2}
+
+# what the stub saw, in order
+POST /oauth/token
+GET /secure/bearer
+GET /secure/bearer
+GET /secure/bearer
+token requests: 1
+
+# the same interface WITHOUT the group configurer: the annotation is silently ignored
+whoAmI() -> 401 UNAUTHORIZED

http-service-clients/output/08-mock-rest-service-server.txt

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+# 1. GET: URL, method and the decoded record
+findById(1) -> Post[id=1, userId=1, title=Test Title, body=Test body]
+
+# 2. POST: the request body the interface sent
+create(...) -> id 101 (request matched: path, method, Content-Type, JSON body)
+
+# 3. a ProblemDetail 404 goes through the real status handler
+findById(9) -> UpstreamNotFoundException (handler decoded the body: 'No post with id 9')
+
+# 4. a 500 with no body: the handler falls back instead of crashing
+findAll() -> UpstreamUnavailableException: Upstream unavailable (500): (no problem+json body)
+
+# 5. what MockRestServiceServer cannot tell you
+timeouts, connection resets, TLS and real serialisation quirks never happen here; see 03 and 05 for the real server.

http-service-clients/output/09-rest-client-test-slice.txt

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+# a proxy built from the slice's own RestClient.Builder, which the mock server IS bound to
+findById(1) -> Post[id=1, userId=1, title=From the mock, body=b]

http-service-clients/output/09b-rest-client-test-old-claim.txt

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+@RestClientTest(PostClient.class), then @Autowired PostClient -> no such bean (null)
+MockRestServiceServer bean present -> true

http-service-clients/output/09c-rest-client-test-group-client.txt

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+PostClient from the @ImportHttpServices group is injected: true
+server.expect(...) -> IllegalStateException: Unable to use auto-configured MockRestServiceServer since a mock server customizer has not been bound to a RestTemplate or RestClient