Support for custom headers in the download http requests and use ETags for upload

engine/src/main/java/com/google/android/fhir/impl/FhirEngineImpl.kt

@@ -161,7 +161,7 @@ internal class FhirEngineImpl(private val database: Database, private val contex
         database.updateVersionIdAndLastUpdated(
           id,
           type,
-          response.etag,
+          getVersionFromETag(response.etag),
           response.lastModified.toInstant()
         )
       }
@@ -179,6 +179,17 @@ internal class FhirEngineImpl(private val database: Database, private val contex
     }
   }
 
+  /**
+   * FHIR uses weak ETag that look something like W/"MTY4NDMyODE2OTg3NDUyNTAwMA", so we need to
+   * extract version from it. See https://hl7.org/fhir/http.html#Http-Headers.
+   */
+  private fun getVersionFromETag(eTag: String) =
+    if (eTag.startsWith("W/")) {
+      eTag.split("\"")[1]
+    } else {
+      eTag
+    }
+
   /**
    * May return a Pair of versionId and resource type extracted from the
    * [Bundle.BundleEntryResponseComponent.location].

engine/src/main/java/com/google/android/fhir/sync/DataSource.kt

@@ -26,23 +26,13 @@ import org.hl7.fhir.r4.model.Resource
  * operations are [Bundle] based to optimize network traffic.
  */
 internal interface DataSource {
-  /**
-   * @return [Bundle] of type [BundleType.SEARCHSET] for a successful operation, [OperationOutcome]
-   * otherwise. Call this api with the relative path of the resource search url to be downloaded.
-   */
-  suspend fun download(path: String): Resource
-
-  /**
-   * @return [Bundle] on a successful operation, [OperationOutcome] otherwise. Call this api with
-   * the [Bundle] that contains individual requests bundled together to be downloaded from the
-   * server. (e.g. https://www.hl7.org/fhir/bundle-request-medsallergies.json.html)
-   */
-  suspend fun download(bundle: Bundle): Resource
+  /** @return [Bundle] on a successful operation, [OperationOutcome] otherwise. */
+  suspend fun download(request: Request): Resource
 
   /**
    * @return [Bundle] of type [BundleType.TRANSACTIONRESPONSE] for a successful operation,
    * [OperationOutcome] otherwise. Call this api with the [Bundle] that needs to be uploaded to the
    * server.
    */
-  suspend fun upload(bundle: Bundle): Resource
+  suspend fun upload(request: BundleRequest): Resource
 }

engine/src/main/java/com/google/android/fhir/sync/DownloadWorkManager.kt

@@ -45,25 +45,30 @@ interface DownloadWorkManager {
   suspend fun processResponse(response: Resource): Collection<Resource>
 }
 
-sealed class Request {
+sealed class Request(open val headers: Map<String, String>) {
   companion object {
     /** @return [UrlRequest] for a FHIR search [url]. */
-    fun of(url: String) = UrlRequest(url)
+    fun of(url: String, headers: Map<String, String> = emptyMap()) = UrlRequest(url, headers)
 
     /** @return [BundleRequest] for a FHIR search [bundle]. */
-    fun of(bundle: Bundle) = BundleRequest(bundle)
+    fun of(bundle: Bundle, headers: Map<String, String> = emptyMap()) =
+      BundleRequest(bundle, headers)
   }
 }
 
 /**
  * A [url] based FHIR request to download resources from the server. e.g.
  * `Patient?given=valueGiven&family=valueFamily`
  */
-data class UrlRequest(val url: String) : Request()
+data class UrlRequest(val url: String, override val headers: Map<String, String> = emptyMap()) :
+  Request(headers)
 
 /**
  * A [bundle] based FHIR request to download resources from the server. For an example, see
  * [bundle-request-medsallergies.json](https://www.hl7.org/fhir/bundle-request-medsallergies.json.html)
  * .
  */
-data class BundleRequest(val bundle: Bundle) : Request()
+data class BundleRequest(
+  val bundle: Bundle,
+  override val headers: Map<String, String> = emptyMap()
+) : Request(headers)

engine/src/main/java/com/google/android/fhir/sync/download/DownloaderImpl.kt

@@ -52,7 +52,7 @@ internal class DownloaderImpl(
     while (request != null) {
       try {
         resourceTypeToDownload = request.toResourceType()
-        downloadWorkManager.processResponse(download(request)).toList().let {
+        downloadWorkManager.processResponse(dataSource.download(request)).toList().let {
           downloadedResourcesCount += it.size
           emit(DownloadState.Success(it, totalResourcesToDownloadCount, downloadedResourcesCount))
         }
@@ -64,12 +64,6 @@ internal class DownloaderImpl(
     }
   }
 
-  private suspend fun download(request: Request) =
-    when (request) {
-      is UrlRequest -> dataSource.download(request.url)
-      is BundleRequest -> dataSource.download(request.bundle)
-    }
-
   private fun Request.toResourceType() =
     when (this) {
       is UrlRequest ->
@@ -82,7 +76,7 @@ internal class DownloaderImpl(
       .getSummaryRequestUrls()
       .map { summary ->
         summary.key to
-          runCatching { dataSource.download(summary.value) }
+          runCatching { dataSource.download(Request.of(summary.value)) }
             .onFailure { Timber.e(it) }
             .getOrNull()
             .takeIf { it is Bundle }

engine/src/main/java/com/google/android/fhir/sync/remote/FhirHttpDataSource.kt

@@ -16,18 +16,23 @@
 
 package com.google.android.fhir.sync.remote
 
+import com.google.android.fhir.sync.BundleRequest
 import com.google.android.fhir.sync.DataSource
-import org.hl7.fhir.r4.model.Bundle
+import com.google.android.fhir.sync.Request
+import com.google.android.fhir.sync.UrlRequest
 
 /**
  * Implementation of [DataSource] to sync data with the FHIR server using HTTP method calls.
  * @param fhirHttpService Http service to make requests to the server.
  */
 internal class FhirHttpDataSource(private val fhirHttpService: FhirHttpService) : DataSource {
 
-  override suspend fun download(path: String) = fhirHttpService.get(path)
+  override suspend fun download(request: Request) =
+    when (request) {
+      is UrlRequest -> fhirHttpService.get(request.url, request.headers)
+      is BundleRequest -> fhirHttpService.post(request.bundle, request.headers)
+    }
 
-  override suspend fun download(bundle: Bundle) = fhirHttpService.post(bundle)
-
-  override suspend fun upload(bundle: Bundle) = fhirHttpService.post(bundle)
+  override suspend fun upload(request: BundleRequest) =
+    fhirHttpService.post(request.bundle, request.headers)
 }

engine/src/main/java/com/google/android/fhir/sync/remote/FhirHttpService.kt

@@ -28,11 +28,11 @@ internal interface FhirHttpService {
    * @return The server may return a particular [Resource], [Bundle] or [OperationOutcome] based on
    * the request processing.
    */
-  suspend fun get(path: String): Resource
+  suspend fun get(path: String, headers: Map<String, String>): Resource
 
   /**
    * Makes a HTTP-POST method request to the server with the [Bundle] as request-body.
    * @return The server may return [Bundle] or [OperationOutcome] based on the request processing.
    */
-  suspend fun post(bundle: Bundle): Resource
+  suspend fun post(bundle: Bundle, headers: Map<String, String>): Resource
 }

engine/src/main/java/com/google/android/fhir/sync/remote/RetrofitHttpService.kt

@@ -27,15 +27,18 @@ import org.hl7.fhir.r4.model.Resource
 import retrofit2.Retrofit
 import retrofit2.http.Body
 import retrofit2.http.GET
+import retrofit2.http.HeaderMap
 import retrofit2.http.POST
 import retrofit2.http.Url
 
 /** Retrofit service to make http requests to the FHIR server. */
 internal interface RetrofitHttpService : FhirHttpService {
 
-  @GET override suspend fun get(@Url path: String): Resource
+  @GET
+  override suspend fun get(@Url path: String, @HeaderMap headers: Map<String, String>): Resource
 
-  @POST(".") override suspend fun post(@Body bundle: Bundle): Resource
+  @POST(".")
+  override suspend fun post(@Body bundle: Bundle, @HeaderMap headers: Map<String, String>): Resource
 
   class Builder(
     private val baseUrl: String,

engine/src/main/java/com/google/android/fhir/sync/upload/BundleUploader.kt

@@ -19,6 +19,7 @@ package com.google.android.fhir.sync.upload
 import com.google.android.fhir.LocalChange
 import com.google.android.fhir.db.impl.dao.LocalChangeToken
 import com.google.android.fhir.sync.DataSource
+import com.google.android.fhir.sync.Request
 import com.google.android.fhir.sync.ResourceSyncException
 import com.google.android.fhir.sync.UploadResult
 import com.google.android.fhir.sync.Uploader
@@ -47,7 +48,7 @@ internal class BundleUploader(
     bundleGenerator.generate(localChangesPaginator.page(localChanges)).forEach {
       (bundle, localChangeTokens) ->
       try {
-        val response = dataSource.upload(bundle)
+        val response = dataSource.upload(Request.of(bundle))
 
         completed += bundle.entry.size
         emit(getUploadResult(response, localChangeTokens, total, completed))

engine/src/main/java/com/google/android/fhir/sync/upload/HttpVerbBasedBundleEntryComponentGenerator.kt

@@ -56,7 +56,15 @@ internal abstract class HttpVerbBasedBundleEntryComponentGenerator(
 
   private fun getEntryRequest(localChange: LocalChange) =
     Bundle.BundleEntryRequestComponent(
-      Enumeration(Bundle.HTTPVerbEnumFactory()).apply { value = httpVerb },
-      UriType("${localChange.resourceType}/${localChange.resourceId}")
-    )
+        Enumeration(Bundle.HTTPVerbEnumFactory()).apply { value = httpVerb },
+        UriType("${localChange.resourceType}/${localChange.resourceId}")
+      )
+      .apply {
+        // FHIR supports weak Etag, See ETag section https://hl7.org/fhir/http.html#Http-Headers
+        when (localChange.type) {
+          LocalChange.Type.UPDATE,
+          LocalChange.Type.DELETE -> ifMatch = "W/\"${localChange.versionId}\""
+          LocalChange.Type.INSERT -> {}
+        }
+      }
 }

engine/src/main/java/com/google/android/fhir/testing/Utilities.kt

@@ -24,10 +24,12 @@ import com.google.android.fhir.FhirEngine
 import com.google.android.fhir.LocalChange
 import com.google.android.fhir.db.impl.dao.LocalChangeToken
 import com.google.android.fhir.search.Search
+import com.google.android.fhir.sync.BundleRequest
 import com.google.android.fhir.sync.ConflictResolver
 import com.google.android.fhir.sync.DataSource
 import com.google.android.fhir.sync.DownloadWorkManager
 import com.google.android.fhir.sync.Request
+import com.google.android.fhir.sync.UrlRequest
 import com.google.common.truth.Truth.assertThat
 import java.net.SocketTimeoutException
 import java.time.OffsetDateTime
@@ -93,15 +95,13 @@ fun readJsonArrayFromFile(filename: String): JSONArray {
 
 object TestDataSourceImpl : DataSource {
 
-  override suspend fun download(path: String): Resource {
-    return Bundle().apply { type = Bundle.BundleType.SEARCHSET }
-  }
-
-  override suspend fun download(bundle: Bundle): Resource {
-    return Bundle().apply { type = Bundle.BundleType.BATCHRESPONSE }
-  }
+  override suspend fun download(request: Request) =
+    when (request) {
+      is UrlRequest -> Bundle().apply { type = Bundle.BundleType.SEARCHSET }
+      is BundleRequest -> Bundle().apply { type = Bundle.BundleType.BATCHRESPONSE }
+    }
 
-  override suspend fun upload(bundle: Bundle): Resource {
+  override suspend fun upload(request: BundleRequest): Resource {
     return Bundle().apply { type = Bundle.BundleType.TRANSACTIONRESPONSE }
   }
 }
@@ -177,32 +177,28 @@ object TestFhirEngineImpl : FhirEngine {
 
 object TestFailingDatasource : DataSource {
 
-  override suspend fun download(path: String): Resource {
-    val allowedChars = ('A'..'Z') + ('a'..'z') + ('0'..'9')
-    // data size exceeding the bytes acceptable by WorkManager serializer
-    val dataSize = Data.MAX_DATA_BYTES + 1
-    val hugeStackTraceMessage = (1..dataSize).map { allowedChars.random() }.joinToString("")
-    throw Exception(hugeStackTraceMessage)
-  }
-
-  override suspend fun download(bundle: Bundle): Resource {
-    throw SocketTimeoutException("Posting Download Bundle failed...")
-  }
-
-  override suspend fun upload(bundle: Bundle): Resource {
+  override suspend fun download(request: Request) =
+    when (request) {
+      is UrlRequest -> {
+        val allowedChars = ('A'..'Z') + ('a'..'z') + ('0'..'9')
+        // data size exceeding the bytes acceptable by WorkManager serializer
+        val dataSize = Data.MAX_DATA_BYTES + 1
+        val hugeStackTraceMessage = (1..dataSize).map { allowedChars.random() }.joinToString("")
+        throw Exception(hugeStackTraceMessage)
+      }
+      is BundleRequest -> throw SocketTimeoutException("Posting Download Bundle failed...")
+    }
+
+  override suspend fun upload(request: BundleRequest): Resource {
     throw SocketTimeoutException("Posting Upload Bundle failed...")
   }
 }
 
 class BundleDataSource(val onPostBundle: suspend (Bundle) -> Resource) : DataSource {
 
-  override suspend fun download(path: String): Resource {
-    TODO("Not yet implemented")
-  }
-
-  override suspend fun download(bundle: Bundle): Resource {
+  override suspend fun download(request: Request): Resource {
     TODO("Not yet implemented")
   }
 
-  override suspend fun upload(bundle: Bundle) = onPostBundle(bundle)
+  override suspend fun upload(request: BundleRequest) = onPostBundle(request.bundle)
 }

engine/src/test/java/com/google/android/fhir/sync/download/DownloaderImplTest.kt

@@ -17,10 +17,12 @@
 package com.google.android.fhir.sync.download
 
 import com.google.android.fhir.logicalId
+import com.google.android.fhir.sync.BundleRequest
 import com.google.android.fhir.sync.DataSource
 import com.google.android.fhir.sync.DownloadState
 import com.google.android.fhir.sync.DownloadWorkManager
 import com.google.android.fhir.sync.Request
+import com.google.android.fhir.sync.UrlRequest
 import com.google.common.truth.Truth.assertThat
 import java.util.LinkedList
 import java.util.Queue
@@ -55,7 +57,7 @@ class DownloaderImplTest {
 
     val testDataSource: DataSource =
       object : DataSource {
-        override suspend fun download(path: String): Resource {
+        private fun download(path: String): Resource {
           return when (path) {
             "Patient" ->
               Bundle().apply {
@@ -92,7 +94,7 @@ class DownloaderImplTest {
           }
         }
 
-        override suspend fun download(bundle: Bundle): Resource {
+        private fun download(bundle: Bundle): Resource {
           return Bundle().apply {
             type = Bundle.BundleType.BATCHRESPONSE
             addEntry(
@@ -116,7 +118,13 @@ class DownloaderImplTest {
           }
         }
 
-        override suspend fun upload(bundle: Bundle): Resource {
+        override suspend fun download(request: Request) =
+          when (request) {
+            is UrlRequest -> download(request.url)
+            is BundleRequest -> download(request.bundle)
+          }
+
+        override suspend fun upload(request: BundleRequest): Resource {
           throw UnsupportedOperationException()
         }
       }
@@ -148,7 +156,7 @@ class DownloaderImplTest {
 
       val testDataSource: DataSource =
         object : DataSource {
-          override suspend fun download(path: String): Resource {
+          private fun download(path: String): Resource {
             return when (path) {
               "Patient" ->
                 Bundle().apply {
@@ -185,7 +193,7 @@ class DownloaderImplTest {
             }
           }
 
-          override suspend fun download(bundle: Bundle): Resource {
+          private fun download(bundle: Bundle): Resource {
             return Bundle().apply {
               type = Bundle.BundleType.BATCHRESPONSE
               addEntry(
@@ -209,7 +217,13 @@ class DownloaderImplTest {
             }
           }
 
-          override suspend fun upload(bundle: Bundle): Resource {
+          override suspend fun download(request: Request) =
+            when (request) {
+              is UrlRequest -> download(request.url)
+              is BundleRequest -> download(request.bundle)
+            }
+
+          override suspend fun upload(request: BundleRequest): Resource {
             throw UnsupportedOperationException()
           }
         }