Optimize memory usage and performance by using ByteArray when possible and improve logging

14 files changed, 168 insertions, 201 deletions

diff --git a/ebics/src/main/kotlin/Ebics.kt b/ebics/src/main/kotlin/Ebics.kt
index 406da44c..91a41022 100644
--- a/ebics/src/main/kotlin/Ebics.kt
+++ b/ebics/src/main/kotlin/Ebics.kt
@@ -310,7 +310,7 @@ class HpbResponseData(
 
 fun parseEbicsHpbOrder(orderDataRaw: ByteArray): HpbResponseData {
     val resp = try {
-        XMLUtil.convertStringToJaxb<HPBResponseOrderData>(orderDataRaw.toString(Charsets.UTF_8))
+        XMLUtil.convertBytesToJaxb<HPBResponseOrderData>(orderDataRaw)
     } catch (e: Exception) {
         throw EbicsProtocolError(HttpStatusCode.InternalServerError, "Invalid XML (as HPB response) received from bank")
     }
@@ -331,10 +331,10 @@ fun parseEbicsHpbOrder(orderDataRaw: ByteArray): HpbResponseData {
     )
 }
 
-fun ebics3toInternalRepr(response: String): EbicsResponseContent {
+fun ebics3toInternalRepr(response: ByteArray): EbicsResponseContent {
     // logger.debug("Converting bank resp to internal repr.: $response")
     val resp: JAXBElement<Ebics3Response> = try {
-        XMLUtil.convertStringToJaxb(response)
+        XMLUtil.convertBytesToJaxb(response)
     } catch (e: Exception) {
         throw EbicsProtocolError(
             HttpStatusCode.InternalServerError,
@@ -368,9 +368,9 @@ fun ebics3toInternalRepr(response: String): EbicsResponseContent {
     )
 }
 
-fun ebics25toInternalRepr(response: String): EbicsResponseContent {
+fun ebics25toInternalRepr(response: ByteArray): EbicsResponseContent {
     val resp: JAXBElement<EbicsResponse> = try {
-        XMLUtil.convertStringToJaxb(response)
+        XMLUtil.convertBytesToJaxb(response)
     } catch (e: Exception) {
         throw EbicsProtocolError(
             HttpStatusCode.InternalServerError,
diff --git a/ebics/src/main/kotlin/EbicsOrderUtil.kt b/ebics/src/main/kotlin/EbicsOrderUtil.kt
index ef7ed1f7..c056ddde 100644
--- a/ebics/src/main/kotlin/EbicsOrderUtil.kt
+++ b/ebics/src/main/kotlin/EbicsOrderUtil.kt
@@ -39,12 +39,12 @@ object EbicsOrderUtil {
     inline fun <reified T> decodeOrderDataXml(encodedOrderData: ByteArray): T {
         return InflaterInputStream(encodedOrderData.inputStream()).use {
             val bytes = it.readAllBytes()
-            XMLUtil.convertStringToJaxb<T>(bytes.toString(Charsets.UTF_8)).value
+            XMLUtil.convertBytesToJaxb<T>(bytes).value
         }
     }
 
     inline fun <reified T> encodeOrderDataXml(obj: T): ByteArray {
-        val bytes = XMLUtil.convertJaxbToString(obj).toByteArray()
+        val bytes = XMLUtil.convertJaxbToBytes(obj)
         return DeflaterInputStream(bytes.inputStream()).use {
             it.readAllBytes()
         }
diff --git a/ebics/src/main/kotlin/XMLUtil.kt b/ebics/src/main/kotlin/XMLUtil.kt
index 63dbf35b..5947341a 100644
--- a/ebics/src/main/kotlin/XMLUtil.kt
+++ b/ebics/src/main/kotlin/XMLUtil.kt
@@ -287,17 +287,17 @@ class XMLUtil private constructor() {
          * @param xmlString XML body, as read from the POST body.
          * @return InputStream object, as wanted by the validator.
          */
-        fun validateFromString(xmlString: String): Boolean {
-            val xmlInputStream: InputStream = ByteArrayInputStream(xmlString.toByteArray())
+        fun validateFromBytes(xml: ByteArray): Boolean {
+            val xmlInputStream: InputStream = ByteArrayInputStream(xml)
             val xmlSource = StreamSource(xmlInputStream)
             return validate(xmlSource)
         }
 
-        inline fun <reified T> convertJaxbToString(
+        inline fun <reified T> convertJaxbToBytes(
             obj: T,
             withSchemaLocation: String? = null
-            ): String {
-            val sw = StringWriter()
+            ): ByteArray {
+            val w = ByteArrayOutputStream()
             val jc = JAXBContext.newInstance(T::class.java)
             val m = jc.createMarshaller()
             m.setProperty(Marshaller.JAXB_FORMATTED_OUTPUT, true)
@@ -305,8 +305,8 @@ class XMLUtil private constructor() {
                 m.setProperty(Marshaller.JAXB_SCHEMA_LOCATION, withSchemaLocation)
             }
             m.setProperty("com.sun.xml.bind.namespacePrefixMapper", DefaultNamespaces())
-            m.marshal(obj, sw)
-            return sw.toString()
+            m.marshal(obj, w)
+            return w.toByteArray()
         }
 
         inline fun <reified T> convertJaxbToDocument(
@@ -328,37 +328,31 @@ class XMLUtil private constructor() {
         }
 
         /**
-         * Convert a XML string to the JAXB representation.
+         * Convert XML bytes to the JAXB representation.
          *
-         * @param documentString the string to convert into JAXB.
+         * @param documentBytes the bytes to convert into JAXB.
          * @return the JAXB object reflecting the original XML document.
          */
-        inline fun <reified T> convertStringToJaxb(documentString: String): JAXBElement<T> {
+        inline fun <reified T> convertBytesToJaxb(documentBytes: ByteArray): JAXBElement<T> {
             val jc = JAXBContext.newInstance(T::class.java)
             val u = jc.createUnmarshaller()
             return u.unmarshal(            /* Marshalling the object into the document.  */
-                StreamSource(StringReader(documentString)),
+                StreamSource(ByteArrayInputStream(documentBytes)),
                 T::class.java
             )
         }
 
-        /**
-         * Extract String from DOM.
-         *
-         * @param document the DOM to extract the string from.
-         * @return the final String, or null if errors occur.
-         */
-        fun convertDomToString(document: Document): String {
+        fun convertDomToBytes(document: Document): ByteArray {
             /* Make Transformer.  */
             val tf = TransformerFactory.newInstance()
             val t = tf.newTransformer()
 
-            /* Make string writer.  */
-            val sw = StringWriter()
+            /* Make bytes writer.  */
+            val w = ByteArrayOutputStream()
 
             /* Extract string.  */
-            t.transform(DOMSource(document), StreamResult(sw))
-            return sw.toString()
+            t.transform(DOMSource(document), StreamResult(w))
+            return w.toByteArray()
         }
 
         /**
@@ -391,20 +385,6 @@ class XMLUtil private constructor() {
             return m.unmarshal(document, finalType) // document "went" into Jaxb
         }
 
-        /**
-         * Parse string into XML DOM.
-         * @param xmlString the string to parse.
-         * @return the DOM representing @a xmlString
-         */
-        fun parseStringIntoDom(xmlString: String): Document {
-            val factory = DocumentBuilderFactory.newInstance().apply {
-                isNamespaceAware = true
-            }
-            val xmlInputStream = ByteArrayInputStream(xmlString.toByteArray())
-            val builder = factory.newDocumentBuilder()
-            return builder.parse(InputSource(xmlInputStream))
-        }
-
         /** Parse [xml] into a XML DOM */
         fun parseBytesIntoDom(xml: ByteArray): Document {
             val factory = DocumentBuilderFactory.newInstance().apply {
@@ -415,10 +395,10 @@ class XMLUtil private constructor() {
             return builder.parse(InputSource(xmlInputStream))
         }
 
-        fun signEbicsResponse(ebicsResponse: EbicsResponse, privateKey: RSAPrivateCrtKey): String {
+        fun signEbicsResponse(ebicsResponse: EbicsResponse, privateKey: RSAPrivateCrtKey): ByteArray {
             val doc = convertJaxbToDocument(ebicsResponse)
             signEbicsDocument(doc, privateKey)
-            val signedDoc = XMLUtil.convertDomToString(doc)
+            val signedDoc = XMLUtil.convertDomToBytes(doc)
             // logger.debug("response: $signedDoc")
             return signedDoc
         }
diff --git a/ebics/src/main/kotlin/ebics_h004/EbicsRequest.kt b/ebics/src/main/kotlin/ebics_h004/EbicsRequest.kt
index 263fb71a..2b89e963 100644
--- a/ebics/src/main/kotlin/ebics_h004/EbicsRequest.kt
+++ b/ebics/src/main/kotlin/ebics_h004/EbicsRequest.kt
@@ -286,11 +286,10 @@ class EbicsRequest {
     }
 
     companion object {
-
         fun createForDownloadReceiptPhase(
-            transactionId: String?,
-            hostId: String
-
+            transactionId: String,
+            hostId: String,
+            success: Boolean
         ): EbicsRequest {
             return EbicsRequest().apply {
                 header = Header().apply {
@@ -310,7 +309,7 @@ class EbicsRequest {
                 body = Body().apply {
                     transferReceipt = TransferReceipt().apply {
                         authenticate = true
-                        receiptCode = 0 // always true at this point.
+                        receiptCode = if (success) 1 else 0
                     }
                 }
             }
diff --git a/ebics/src/main/kotlin/ebics_h005/Ebics3Request.kt b/ebics/src/main/kotlin/ebics_h005/Ebics3Request.kt
index 54987c8b..ab710690 100644
--- a/ebics/src/main/kotlin/ebics_h005/Ebics3Request.kt
+++ b/ebics/src/main/kotlin/ebics_h005/Ebics3Request.kt
@@ -368,8 +368,9 @@ class Ebics3Request {
     companion object {
 
         fun createForDownloadReceiptPhase(
-            transactionId: String?,
-            hostId: String
+            transactionId: String,
+            hostId: String,
+            success: Boolean
         ): Ebics3Request {
             return Ebics3Request().apply {
                 header = Header().apply {
@@ -389,7 +390,7 @@ class Ebics3Request {
                 body = Body().apply {
                     transferReceipt = TransferReceipt().apply {
                         authenticate = true
-                        receiptCode = 0 // always true at this point.
+                        receiptCode = if (success) 1 else 0
                     }
                 }
             }
diff --git a/ebics/src/test/kotlin/EbicsMessagesTest.kt b/ebics/src/test/kotlin/EbicsMessagesTest.kt
index 5d0f8f5d..2b8d63ca 100644
--- a/ebics/src/test/kotlin/EbicsMessagesTest.kt
+++ b/ebics/src/test/kotlin/EbicsMessagesTest.kt
@@ -17,8 +17,6 @@
  * <http://www.gnu.org/licenses/>
  */
 
-package tech.libeufin.sandbox
-
 import junit.framework.TestCase.assertEquals
 import org.apache.xml.security.binding.xmldsig.SignatureType
 import org.junit.Test
@@ -43,7 +41,7 @@ class EbicsMessagesTest {
     fun testImportNonRoot() {
         val classLoader = ClassLoader.getSystemClassLoader()
         val ini = classLoader.getResource("ebics_ini_inner_key.xml")
-        val jaxb = XMLUtil.convertStringToJaxb<SignatureTypes.SignaturePubKeyOrderData>(ini.readText())
+        val jaxb = XMLUtil.convertBytesToJaxb<SignatureTypes.SignaturePubKeyOrderData>(ini.readBytes())
         assertEquals("A006", jaxb.value.signaturePubKeyInfo.signatureVersion)
     }
 
@@ -54,7 +52,7 @@ class EbicsMessagesTest {
     fun testStringToJaxb() {
         val classLoader = ClassLoader.getSystemClassLoader()
         val ini = classLoader.getResource("ebics_ini_request_sample.xml")
-        val jaxb = XMLUtil.convertStringToJaxb<EbicsUnsecuredRequest>(ini.readText())
+        val jaxb = XMLUtil.convertBytesToJaxb<EbicsUnsecuredRequest>(ini.readBytes())
         println("jaxb loaded")
         assertEquals(
             "INI",
@@ -74,7 +72,7 @@ class EbicsMessagesTest {
             }
             this.versionNumber = listOf(HEVResponse.VersionNumber.create("H004", "02.50"))
         }
-        XMLUtil.convertJaxbToString(hevResponseJaxb)
+        XMLUtil.convertJaxbToBytes(hevResponseJaxb)
     }
 
     /**
@@ -84,7 +82,7 @@ class EbicsMessagesTest {
     fun testDomToJaxb() {
         val classLoader = ClassLoader.getSystemClassLoader()
         val ini = classLoader.getResource("ebics_ini_request_sample.xml")!!
-        val iniDom = XMLUtil.parseStringIntoDom(ini.readText())
+        val iniDom = XMLUtil.parseBytesIntoDom(ini.readBytes())
         XMLUtil.convertDomToJaxb<EbicsUnsecuredRequest>(
             EbicsUnsecuredRequest::class.java,
             iniDom
@@ -109,22 +107,22 @@ class EbicsMessagesTest {
                 }
             }
         }
-        val text = XMLUtil.convertJaxbToString(responseXml)
-        assertTrue(text.isNotEmpty())
+        val bytes = XMLUtil.convertJaxbToBytes(responseXml)
+        assertTrue(bytes.isNotEmpty())
     }
 
     @Test
     fun testParseHiaRequestOrderData() {
         val classLoader = ClassLoader.getSystemClassLoader()
-        val hia = classLoader.getResource("hia_request_order_data.xml")!!.readText()
-        XMLUtil.convertStringToJaxb<HIARequestOrderData>(hia)
+        val hia = classLoader.getResource("hia_request_order_data.xml")!!.readBytes()
+        XMLUtil.convertBytesToJaxb<HIARequestOrderData>(hia)
     }
 
     @Test
     fun testHiaLoad() {
         val classLoader = ClassLoader.getSystemClassLoader()
         val hia = classLoader.getResource("hia_request.xml")!!
-        val hiaDom = XMLUtil.parseStringIntoDom(hia.readText())
+        val hiaDom = XMLUtil.parseBytesIntoDom(hia.readBytes())
         val x: Element = hiaDom.getElementsByTagNameNS(
             "urn:org:ebics:H004",
             "OrderDetails"
@@ -150,7 +148,7 @@ class EbicsMessagesTest {
                 "ebics_ini_inner_key.xml"
             )
             assertNotNull(file)
-            XMLUtil.convertStringToJaxb<SignatureTypes.SignaturePubKeyOrderData>(file.readText())
+            XMLUtil.convertBytesToJaxb<SignatureTypes.SignaturePubKeyOrderData>(file.readBytes())
         }
 
         val modulus = jaxbKey.value.signaturePubKeyInfo.pubKeyValue.rsaKeyValue.modulus
@@ -161,8 +159,8 @@ class EbicsMessagesTest {
     @Test
     fun testLoadIniMessage() {
         val classLoader = ClassLoader.getSystemClassLoader()
-        val text = classLoader.getResource("ebics_ini_request_sample.xml")!!.readText()
-        XMLUtil.convertStringToJaxb<EbicsUnsecuredRequest>(text)
+        val text = classLoader.getResource("ebics_ini_request_sample.xml")!!.readBytes()
+        XMLUtil.convertBytesToJaxb<EbicsUnsecuredRequest>(text)
     }
 
     @Test
@@ -185,14 +183,14 @@ class EbicsMessagesTest {
                 }
             }
         }
-        print(XMLUtil.convertJaxbToString(response))
+        print(XMLUtil.convertJaxbToBytes(response).toString())
     }
 
     @Test
     fun testLoadHpb() {
         val classLoader = ClassLoader.getSystemClassLoader()
-        val text = classLoader.getResource("hpb_request.xml")!!.readText()
-        XMLUtil.convertStringToJaxb<EbicsNpkdRequest>(text)
+        val text = classLoader.getResource("hpb_request.xml")!!.readBytes()
+        XMLUtil.convertBytesToJaxb<EbicsNpkdRequest>(text)
     }
 
     @Test
@@ -248,9 +246,8 @@ class EbicsMessagesTest {
             }
         }
 
-        val str = XMLUtil.convertJaxbToString(htd)
-        println(str)
-        assert(XMLUtil.validateFromString(str))
+        val bytes = XMLUtil.convertJaxbToBytes(htd)
+        assert(XMLUtil.validateFromBytes(bytes))
     }
 
 
@@ -308,9 +305,8 @@ class EbicsMessagesTest {
                 })
         }
 
-        val str = XMLUtil.convertJaxbToString(hkd)
-        println(str)
-        assert(XMLUtil.validateFromString(str))
+        val bytes = XMLUtil.convertJaxbToBytes(hkd)
+        assert(XMLUtil.validateFromBytes(bytes))
     }
 
     @Test
@@ -361,11 +357,11 @@ class EbicsMessagesTest {
             }
         }
 
-        val str = XMLUtil.convertJaxbToString(ebicsRequestObj)
-        val doc = XMLUtil.parseStringIntoDom(str)
+        val str = XMLUtil.convertJaxbToBytes(ebicsRequestObj)
+        val doc = XMLUtil.parseBytesIntoDom(str)
         val pair = CryptoUtil.generateRsaKeyPair(1024)
         XMLUtil.signEbicsDocument(doc, pair.private)
-        val finalStr = XMLUtil.convertDomToString(doc)
-        assert(XMLUtil.validateFromString(finalStr))
+        val bytes = XMLUtil.convertDomToBytes(doc)
+        assert(XMLUtil.validateFromBytes(bytes))
     }
 }
\ No newline at end of file
diff --git a/ebics/src/test/kotlin/EbicsOrderUtilTest.kt b/ebics/src/test/kotlin/EbicsOrderUtilTest.kt
index 05f7f72d..c78da738 100644
--- a/ebics/src/test/kotlin/EbicsOrderUtilTest.kt
+++ b/ebics/src/test/kotlin/EbicsOrderUtilTest.kt
@@ -302,7 +302,7 @@ class EbicsOrderUtilTest {
                     </Permission>
                 </UserInfo>
             </HTDResponseOrderData>
-        """.trimIndent()
-        XMLUtil.convertStringToJaxb<HTDResponseOrderData>(orderDataXml);
+        """.trimIndent().toByteArray()
+        XMLUtil.convertBytesToJaxb<HTDResponseOrderData>(orderDataXml);
     }
 }
\ No newline at end of file
diff --git a/ebics/src/test/kotlin/XmlUtilTest.kt b/ebics/src/test/kotlin/XmlUtilTest.kt
index b8639d7a..93ca8bf2 100644
--- a/ebics/src/test/kotlin/XmlUtilTest.kt
+++ b/ebics/src/test/kotlin/XmlUtilTest.kt
@@ -37,8 +37,7 @@ class XmlUtilTest {
 
     @Test
     fun deserializeConsecutiveLists() {
-
-        val tmp = XMLUtil.convertStringToJaxb<HTDResponseOrderData>("""
+        val tmp = XMLUtil.convertBytesToJaxb<HTDResponseOrderData>("""
             <?xml version="1.0" encoding="UTF-8" standalone="yes"?>
             <HTDResponseOrderData xmlns="urn:org:ebics:H004">
               <PartnerInfo>
@@ -81,7 +80,7 @@ class XmlUtilTest {
                   <OrderTypes>C54 C53 C52 CCC</OrderTypes>
                 </Permission>
               </UserInfo>
-            </HTDResponseOrderData>""".trimIndent()
+            </HTDResponseOrderData>""".trimIndent().toByteArray()
         )
 
         println(tmp.value.partnerInfo.orderInfoList[0].description)
@@ -90,7 +89,7 @@ class XmlUtilTest {
     @Test
     fun exceptionOnConversion() {
         try {
-            XMLUtil.convertStringToJaxb<EbicsKeyManagementResponse>("<malformed xml>")
+            XMLUtil.convertBytesToJaxb<EbicsKeyManagementResponse>("<malformed xml>".toByteArray())
         } catch (e: javax.xml.bind.UnmarshalException) {
             // just ensuring this is the exception
             println("caught")
@@ -115,12 +114,12 @@ class XmlUtilTest {
 
     @Test
     fun basicSigningTest() {
-        val doc = XMLUtil.parseStringIntoDom("""
+        val doc = XMLUtil.parseBytesIntoDom("""
             <myMessage xmlns:ebics="urn:org:ebics:H004">
                 <ebics:AuthSignature />
                 <foo authenticate="true">Hello World</foo>
             </myMessage>
-        """.trimIndent())
+        """.trimIndent().toByteArray())
         val kpg = KeyPairGenerator.getInstance("RSA")
         kpg.initialize(2048)
         val pair = kpg.genKeyPair()
@@ -155,10 +154,9 @@ class XmlUtilTest {
         }
 
         val signature = signEbicsResponse(response, pair.private)
-        val signatureJaxb = XMLUtil.convertStringToJaxb<EbicsResponse>(signature)
+        val signatureJaxb = XMLUtil.convertBytesToJaxb<EbicsResponse>(signature)
 
         assertTrue(
-
             XMLUtil.verifyEbicsDocument(
                 XMLUtil.convertJaxbToDocument(signatureJaxb.value),
                 pair.public
@@ -168,13 +166,13 @@ class XmlUtilTest {
 
     @Test
     fun multiAuthSigningTest() {
-        val doc = XMLUtil.parseStringIntoDom("""
+        val doc = XMLUtil.parseBytesIntoDom("""
             <myMessage xmlns:ebics="urn:org:ebics:H004">
                 <ebics:AuthSignature />
                 <foo authenticate="true">Hello World</foo>
                 <bar authenticate="true">Another one!</bar>
             </myMessage>
-        """.trimIndent())
+        """.trimIndent().toByteArray())
         val kpg = KeyPairGenerator.getInstance("RSA")
         kpg.initialize(2048)
         val pair = kpg.genKeyPair()
@@ -185,8 +183,8 @@ class XmlUtilTest {
     @Test
     fun testRefSignature() {
         val classLoader = ClassLoader.getSystemClassLoader()
-        val docText = classLoader.getResourceAsStream("signature1/doc.xml")!!.readAllBytes().toString(Charsets.UTF_8)
-        val doc = XMLUtil.parseStringIntoDom(docText)
+        val docText = classLoader.getResourceAsStream("signature1/doc.xml")!!.readAllBytes()
+        val doc = XMLUtil.parseBytesIntoDom(docText)
         val keyText = classLoader.getResourceAsStream("signature1/public_key.txt")!!.readAllBytes()
         val keyBytes = Base64.getDecoder().decode(keyText)
         val key = CryptoUtil.loadRsaPublicKey(keyBytes)
diff --git a/nexus/src/main/kotlin/tech/libeufin/nexus/EbicsFetch.kt b/nexus/src/main/kotlin/tech/libeufin/nexus/EbicsFetch.kt
index 407e2818..0bca13c5 100644
--- a/nexus/src/main/kotlin/tech/libeufin/nexus/EbicsFetch.kt
+++ b/nexus/src/main/kotlin/tech/libeufin/nexus/EbicsFetch.kt
@@ -101,26 +101,15 @@ private suspend inline fun downloadHelper(
             ebics2Req.orderParams
         )
     }
-    logger.trace(initXml)
-    try {
-        return doEbicsDownload(
-            ctx.httpClient,
-            ctx.cfg,
-            ctx.clientKeys,
-            ctx.bankKeys,
-            initXml,
-            isEbics3,
-            tolerateEmptyResult = true
-        )
-    } catch (e: EbicsSideException) {
-        logger.error(e.message)
-        /**
-         * Failing regardless of the error being at the client or at the
-         * bank side.  A client with an unreliable bank is not useful, hence
-         * failing here.
-         */
-        throw e
-    }
+    return doEbicsDownload(
+        ctx.httpClient,
+        ctx.cfg,
+        ctx.clientKeys,
+        ctx.bankKeys,
+        initXml,
+        isEbics3,
+        tolerateEmptyResult = true
+    )
 }
 
 /**
@@ -282,7 +271,7 @@ private fun ingestDocument(
             val acks = parseCustomerAck(xml)
             for (ack in acks) {
                 when (ack.actionType) {
-                    HacAction.FILE_DOWNLOAD -> logger.trace("$ack")
+                    HacAction.FILE_DOWNLOAD -> logger.debug("$ack")
                     HacAction.ORDER_HAC_FINAL_POS -> {
                         // TODO update pending transaction status
                         logger.debug("$ack")
diff --git a/nexus/src/main/kotlin/tech/libeufin/nexus/EbicsSetup.kt b/nexus/src/main/kotlin/tech/libeufin/nexus/EbicsSetup.kt
index 75b70c42..bd95543b 100644
--- a/nexus/src/main/kotlin/tech/libeufin/nexus/EbicsSetup.kt
+++ b/nexus/src/main/kotlin/tech/libeufin/nexus/EbicsSetup.kt
@@ -156,9 +156,10 @@ suspend fun doKeysRequestAndUpdateState(
         KeysOrderType.HIA -> generateHiaMessage(cfg, privs)
         KeysOrderType.HPB -> generateHpbMessage(cfg, privs)
     }
-    val xml = client.postToBank(cfg.hostBaseUrl, req)
-    if (xml == null) {
-        throw Exception("Could not POST the ${orderType.name} message to the bank")
+    val xml = try {
+        client.postToBank(cfg.hostBaseUrl, req)
+    } catch (e: Exception) {
+        throw Exception("Could not POST the ${orderType.name} message to the bank at '${cfg.hostBaseUrl}'", e)
     }
     val ebics = parseKeysMgmtResponse(privs.encryption_private_key, xml)
     if (ebics == null) {
diff --git a/nexus/src/main/kotlin/tech/libeufin/nexus/ebics/Ebics2.kt b/nexus/src/main/kotlin/tech/libeufin/nexus/ebics/Ebics2.kt
index cc9da79f..d5ed2795 100644
--- a/nexus/src/main/kotlin/tech/libeufin/nexus/ebics/Ebics2.kt
+++ b/nexus/src/main/kotlin/tech/libeufin/nexus/ebics/Ebics2.kt
@@ -84,10 +84,9 @@ suspend fun fetchBankAccounts(
 ): HTDResponseOrderData? {
     val xmlReq = createEbics25DownloadInit(cfg, clientKeys, bankKeys, "HTD")
     val bytesResp = doEbicsDownload(client, cfg, clientKeys, bankKeys, xmlReq, false)
-    val xmlResp = bytesResp.toString(Charsets.UTF_8)
     return try {
         logger.debug("Fetched accounts: $bytesResp")
-        XMLUtil.convertStringToJaxb<HTDResponseOrderData>(xmlResp).value
+        XMLUtil.convertBytesToJaxb<HTDResponseOrderData>(bytesResp).value
     } catch (e: Exception) {
         logger.error("Could not parse the HTD payload, detail: ${e.message}")
         return null
@@ -104,7 +103,7 @@ fun createEbics25DownloadInit(
     bankKeys: BankPublicKeysFile,
     orderType: String,
     orderParams: EbicsOrderParams = EbicsStandardOrderParams()
-): String {
+): ByteArray {
     val nonce = getNonce(128)
     val req = EbicsRequest.createForDownloadInitializationPhase(
         cfg.ebicsUserId,
@@ -127,7 +126,7 @@ fun createEbics25DownloadInit(
         clientKeys.authentication_private_key,
         withEbics3 = false
     )
-    return XMLUtil.convertDomToString(doc)
+    return XMLUtil.convertDomToBytes(doc)
 }
 
 /**
@@ -137,16 +136,19 @@ fun createEbics25DownloadInit(
  * @param clientKeys user EBICS private keys.
  * @param transactionId transaction ID of the EBICS communication that
  *        should receive this receipt.
+ * @param success was the download sucessfully processed
  * @return receipt request in XML.
  */
 fun createEbics25DownloadReceiptPhase(
     cfg: EbicsSetupConfig,
     clientKeys: ClientPrivateKeysFile,
-    transactionId: String
-): String {
+    transactionId: String,
+    success: Boolean
+): ByteArray {
     val req = EbicsRequest.createForDownloadReceiptPhase(
         transactionId,
-        cfg.ebicsHostId
+        cfg.ebicsHostId,
+        success
     )
     val doc = XMLUtil.convertJaxbToDocument(req)
     XMLUtil.signEbicsDocument(
@@ -154,7 +156,7 @@ fun createEbics25DownloadReceiptPhase(
         clientKeys.authentication_private_key,
         withEbics3 = false
     )
-    return XMLUtil.convertDomToString(doc)
+    return XMLUtil.convertDomToBytes(doc)
 }
 
 /**
@@ -173,7 +175,7 @@ fun createEbics25DownloadTransferPhase(
     segNumber: Int,
     totalSegments: Int,
     transactionId: String
-): String {
+): ByteArray {
     val req = EbicsRequest.createForDownloadTransferPhase(
         hostID = cfg.ebicsHostId,
         segmentNumber = segNumber,
@@ -186,7 +188,7 @@ fun createEbics25DownloadTransferPhase(
         clientKeys.authentication_private_key,
         withEbics3 = false
     )
-    return XMLUtil.convertDomToString(doc)
+    return XMLUtil.convertDomToBytes(doc)
 }
 
 /**
@@ -202,10 +204,10 @@ fun createEbics25DownloadTransferPhase(
  */
 fun parseKeysMgmtResponse(
     clientEncryptionKey: RSAPrivateCrtKey,
-    xml: String
+    xml: ByteArray
 ): EbicsKeyManagementResponseContent? {
     val jaxb = try {
-        XMLUtil.convertStringToJaxb<EbicsKeyManagementResponse>(xml)
+        XMLUtil.convertBytesToJaxb<EbicsKeyManagementResponse>(xml)
     } catch (e: Exception) {
         tech.libeufin.nexus.logger.error("Could not parse the raw response from bank into JAXB.")
         return null
@@ -238,7 +240,7 @@ fun parseKeysMgmtResponse(
  * @param clientKeys set of all the client keys.
  * @return the raw EBICS INI message.
  */
-fun generateIniMessage(cfg: EbicsSetupConfig, clientKeys: ClientPrivateKeysFile): String {
+fun generateIniMessage(cfg: EbicsSetupConfig, clientKeys: ClientPrivateKeysFile): ByteArray {
     val iniRequest = EbicsUnsecuredRequest.createIni(
         cfg.ebicsHostId,
         cfg.ebicsUserId,
@@ -246,7 +248,7 @@ fun generateIniMessage(cfg: EbicsSetupConfig, clientKeys: ClientPrivateKeysFile)
         clientKeys.signature_private_key
     )
     val doc = XMLUtil.convertJaxbToDocument(iniRequest)
-    return XMLUtil.convertDomToString(doc)
+    return XMLUtil.convertDomToBytes(doc)
 }
 
 /**
@@ -257,7 +259,7 @@ fun generateIniMessage(cfg: EbicsSetupConfig, clientKeys: ClientPrivateKeysFile)
  * @param clientKeys set of all the client keys.
  * @return the raw EBICS HIA message.
  */
-fun generateHiaMessage(cfg: EbicsSetupConfig, clientKeys: ClientPrivateKeysFile): String {
+fun generateHiaMessage(cfg: EbicsSetupConfig, clientKeys: ClientPrivateKeysFile): ByteArray {
     val hiaRequest = EbicsUnsecuredRequest.createHia(
         cfg.ebicsHostId,
         cfg.ebicsUserId,
@@ -266,7 +268,7 @@ fun generateHiaMessage(cfg: EbicsSetupConfig, clientKeys: ClientPrivateKeysFile)
         clientKeys.encryption_private_key
     )
     val doc = XMLUtil.convertJaxbToDocument(hiaRequest)
-    return XMLUtil.convertDomToString(doc)
+    return XMLUtil.convertDomToBytes(doc)
 }
 
 /**
@@ -276,7 +278,7 @@ fun generateHiaMessage(cfg: EbicsSetupConfig, clientKeys: ClientPrivateKeysFile)
  * @param clientKeys set of all the client keys.
  * @return the raw EBICS HPB message.
  */
-fun generateHpbMessage(cfg: EbicsSetupConfig, clientKeys: ClientPrivateKeysFile): String {
+fun generateHpbMessage(cfg: EbicsSetupConfig, clientKeys: ClientPrivateKeysFile): ByteArray {
     val hpbRequest = EbicsNpkdRequest.createRequest(
         cfg.ebicsHostId,
         cfg.ebicsPartnerId,
@@ -286,7 +288,7 @@ fun generateHpbMessage(cfg: EbicsSetupConfig, clientKeys: ClientPrivateKeysFile)
     )
     val doc = XMLUtil.convertJaxbToDocument(hpbRequest)
     XMLUtil.signEbicsDocument(doc, clientKeys.authentication_private_key)
-    return XMLUtil.convertDomToString(doc)
+    return XMLUtil.convertDomToBytes(doc)
 }
 
 /**
diff --git a/nexus/src/main/kotlin/tech/libeufin/nexus/ebics/Ebics3.kt b/nexus/src/main/kotlin/tech/libeufin/nexus/ebics/Ebics3.kt
index 16e5daba..796e7809 100644
--- a/nexus/src/main/kotlin/tech/libeufin/nexus/ebics/Ebics3.kt
+++ b/nexus/src/main/kotlin/tech/libeufin/nexus/ebics/Ebics3.kt
@@ -41,16 +41,19 @@ import javax.xml.datatype.DatatypeFactory
  * @param clientKeys subscriber private keys.
  * @param transactionId EBICS transaction ID as assigned by the
  *        bank to any successful transaction.
+ * @param success was the download sucessfully processed
  * @return the raw XML of the EBICS request.
  */
 fun createEbics3DownloadReceiptPhase(
     cfg: EbicsSetupConfig,
     clientKeys: ClientPrivateKeysFile,
-    transactionId: String
-): String {
+    transactionId: String,
+    success: Boolean
+): ByteArray {
     val req = Ebics3Request.createForDownloadReceiptPhase(
         transactionId,
-        cfg.ebicsHostId
+        cfg.ebicsHostId,
+        success
     )
     val doc = XMLUtil.convertJaxbToDocument(req)
     XMLUtil.signEbicsDocument(
@@ -58,7 +61,7 @@ fun createEbics3DownloadReceiptPhase(
         clientKeys.authentication_private_key,
         withEbics3 = true
     )
-    return XMLUtil.convertDomToString(doc)
+    return XMLUtil.convertDomToBytes(doc)
 }
 
 /**
@@ -78,7 +81,7 @@ fun createEbics3DownloadTransferPhase(
     howManySegments: Int,
     segmentNumber: Int,
     transactionId: String
-): String {
+): ByteArray {
     val req = Ebics3Request.createForDownloadTransferPhase(
         cfg.ebicsHostId,
         transactionId,
@@ -91,7 +94,7 @@ fun createEbics3DownloadTransferPhase(
         clientKeys.authentication_private_key,
         withEbics3 = true
     )
-    return XMLUtil.convertDomToString(doc)
+    return XMLUtil.convertDomToBytes(doc)
 }
 
 /**
@@ -108,7 +111,7 @@ fun createEbics3DownloadInitialization(
     bankkeys: BankPublicKeysFile,
     clientKeys: ClientPrivateKeysFile,
     orderParams: Ebics3Request.OrderDetails.BTDOrderParams
-): String {
+): ByteArray {
     val nonce = getNonce(128)
     val req = Ebics3Request.createForDownloadInitializationPhase(
         cfg.ebicsUserId,
@@ -129,7 +132,7 @@ fun createEbics3DownloadInitialization(
         clientKeys.authentication_private_key,
         withEbics3 = true
     )
-    return XMLUtil.convertDomToString(doc)
+    return XMLUtil.convertDomToBytes(doc)
 }
 
 /**
@@ -149,7 +152,7 @@ fun createEbics3RequestForUploadInitialization(
     bankkeys: BankPublicKeysFile,
     clientKeys: ClientPrivateKeysFile,
     orderService: Ebics3Request.OrderDetails.Service
-): String {
+): ByteArray {
     val nonce = getNonce(128)
     val req = Ebics3Request.createForUploadInitializationPhase(
         preparedUploadData.transactionKey,
@@ -174,7 +177,7 @@ fun createEbics3RequestForUploadInitialization(
         clientKeys.authentication_private_key,
         withEbics3 = true
     )
-    return XMLUtil.convertDomToString(doc)
+    return XMLUtil.convertDomToBytes(doc)
 }
 
 /**
@@ -193,7 +196,7 @@ fun createEbics3RequestForUploadTransferPhase(
     clientKeys: ClientPrivateKeysFile,
     transactionId: String,
     uploadData: PreparedUploadData
-): String {
+): ByteArray {
     val chunkIndex = 1 // only 1-chunk communication currently supported.
     val req = Ebics3Request.createForUploadTransferPhase(
         cfg.ebicsHostId,
@@ -207,7 +210,7 @@ fun createEbics3RequestForUploadTransferPhase(
         clientKeys.authentication_private_key,
         withEbics3 = true
     )
-    return XMLUtil.convertDomToString(doc)
+    return XMLUtil.convertDomToBytes(doc)
 }
 
 /**
@@ -230,8 +233,7 @@ suspend fun submitPain001(
     cfg: EbicsSetupConfig,
     clientKeys: ClientPrivateKeysFile,
     bankkeys: BankPublicKeysFile,
-    httpClient: HttpClient,
-    ebicsExtraLog: Boolean = false
+    httpClient: HttpClient
 ) {
     val orderService: Ebics3Request.OrderDetails.Service = Ebics3Request.OrderDetails.Service().apply {
         serviceName = "MCT"
@@ -248,7 +250,6 @@ suspend fun submitPain001(
         bankkeys,
         orderService,
         pain001xml.toByteArray(Charsets.UTF_8),
-        ebicsExtraLog
     )
     logger.debug("Payment submitted, report text is: ${maybeUploaded.reportText}," +
             " EBICS technical code is: ${maybeUploaded.technicalReturnCode}," +
diff --git a/nexus/src/main/kotlin/tech/libeufin/nexus/ebics/EbicsCommon.kt b/nexus/src/main/kotlin/tech/libeufin/nexus/ebics/EbicsCommon.kt
index 6e7eff28..9c07aadb 100644
--- a/nexus/src/main/kotlin/tech/libeufin/nexus/ebics/EbicsCommon.kt
+++ b/nexus/src/main/kotlin/tech/libeufin/nexus/ebics/EbicsCommon.kt
@@ -126,33 +126,19 @@ fun decryptAndDecompressPayload(
  * POSTs the EBICS message to the bank.
  *
  * @param URL where the bank serves EBICS requests.
- * @param msg EBICS message as raw string.
- * @return the raw bank response, if the request made it to the
- *         EBICS handler, or null otherwise.
+ * @param msg EBICS message as raw bytes.
+ * @return the raw bank response.
  */
-suspend fun HttpClient.postToBank(bankUrl: String, msg: String): String? {
-    logger.debug("POSTing EBICS to: $bankUrl")
-    val resp: HttpResponse = try {
-        this.post(urlString = bankUrl) {
-            expectSuccess = false // avoids exceptions on non-2xx statuses.
-            contentType(ContentType.Text.Xml)
-            setBody(msg)
-        }
-    }
-    catch (e: Exception) {
-        // hard error (network issue, invalid URL, ..)
-        logger.error("Could not POST to bank at: $bankUrl, detail: ${e.message}")
-        return null
+suspend fun HttpClient.postToBank(bankUrl: String, msg: ByteArray): ByteArray {
+    logger.debug("POSTing EBICS to '$bankUrl'")
+    val res = post(urlString = bankUrl) {
+        contentType(ContentType.Text.Xml)
+        setBody(msg)
     }
-    // Bank was found, but the EBICS request wasn't served.
-    // Note: EBICS errors get _still_ 200 OK, so here the error
-    // _should_ not be related to EBICS.  404 for a wrong URL
-    // is one example.
-    if (resp.status != HttpStatusCode.OK) {
-        logger.error("Bank was found at $bankUrl, but EBICS wasn't served.  Response status: ${resp.status}, body: ${resp.bodyAsText()}")
-        return null
+    if (res.status != HttpStatusCode.OK) {
+        throw Exception("Invalid response status: ${res.status}")
     }
-    return resp.bodyAsText()
+    return res.readBytes() // TODO input stream
 }
 
 /**
@@ -258,14 +244,18 @@ suspend fun postEbics(
     client: HttpClient,
     cfg: EbicsSetupConfig,
     bankKeys: BankPublicKeysFile,
-    xmlReq: String,
+    xmlReq: ByteArray,
     isEbics3: Boolean
 ): EbicsResponseContent {
-    val respXml = client.postToBank(cfg.hostBaseUrl, xmlReq)
-        ?: throw EbicsSideException(
+    val respXml = try {
+        client.postToBank(cfg.hostBaseUrl, xmlReq)
+    } catch (e: Exception) {
+        throw EbicsSideException(
             "POSTing to ${cfg.hostBaseUrl} failed",
-            sideEc = EbicsSideError.HTTP_POST_FAILED
+            sideEc = EbicsSideError.HTTP_POST_FAILED,
+            e
         )
+    }
     return parseAndValidateEbicsResponse(
         bankKeys,
         respXml,
@@ -307,7 +297,7 @@ suspend fun doEbicsDownload(
     cfg: EbicsSetupConfig,
     clientKeys: ClientPrivateKeysFile,
     bankKeys: BankPublicKeysFile,
-    reqXml: String,
+    reqXml: ByteArray,
     isEbics3: Boolean,
     tolerateEmptyResult: Boolean = false
 ): ByteArray {
@@ -374,9 +364,10 @@ suspend fun doEbicsDownload(
         ebicsChunks
     )
     // payload reconstructed, receipt to the bank.
+    val success = true
     val receiptXml = if (isEbics3)
-        createEbics3DownloadReceiptPhase(cfg, clientKeys, tId)
-    else createEbics25DownloadReceiptPhase(cfg, clientKeys, tId)
+        createEbics3DownloadReceiptPhase(cfg, clientKeys, tId, success)
+    else createEbics25DownloadReceiptPhase(cfg, clientKeys, tId, success)
 
     // Sending the receipt to the bank.
     postEbics(
@@ -419,8 +410,9 @@ enum class EbicsSideError {
  */
 class EbicsSideException(
     msg: String,
-    val sideEc: EbicsSideError
-) : Exception(msg)
+    val sideEc: EbicsSideError,
+    cause: Exception? = null
+) : Exception(msg, cause)
 
 /**
  * Parses the bank response from the raw XML and verifies
@@ -433,11 +425,11 @@ class EbicsSideException(
  */
 fun parseAndValidateEbicsResponse(
     bankKeys: BankPublicKeysFile,
-    responseStr: String,
+    resp: ByteArray,
     withEbics3: Boolean
 ): EbicsResponseContent {
     val responseDocument = try {
-        XMLUtil.parseStringIntoDom(responseStr)
+        XMLUtil.parseBytesIntoDom(resp)
     } catch (e: Exception) {
         throw EbicsSideException(
             "Bank response apparently invalid",
@@ -455,8 +447,8 @@ fun parseAndValidateEbicsResponse(
         )
     }
     if (withEbics3)
-        return ebics3toInternalRepr(responseStr)
-    return ebics25toInternalRepr(responseStr)
+        return ebics3toInternalRepr(resp)
+    return ebics25toInternalRepr(resp)
 }
 
 /**
@@ -567,7 +559,6 @@ suspend fun doEbicsUpload(
     bankKeys: BankPublicKeysFile,
     orderService: Ebics3Request.OrderDetails.Service,
     payload: ByteArray,
-    extraLog: Boolean = false
 ): EbicsResponseContent {
     val preparedPayload = prepareUploadPayload(cfg, clientKeys, bankKeys, payload, isEbics3 = true)
     val initXml = createEbics3RequestForUploadInitialization(
@@ -577,13 +568,12 @@ suspend fun doEbicsUpload(
         clientKeys,
         orderService
     )
-    if (extraLog) logger.debug(initXml)
     val initResp = postEbics( // may throw EbicsEarlyException
-            client,
-            cfg,
-            bankKeys,
-            initXml,
-            isEbics3 = true
+        client,
+        cfg,
+        bankKeys,
+        initXml,
+        isEbics3 = true
     )
     if (!areCodesOk(initResp)) throw EbicsUploadException(
         "EBICS upload init failed",
diff --git a/nexus/src/test/kotlin/Ebics.kt b/nexus/src/test/kotlin/Ebics.kt
index 9c95b118..507820ce 100644
--- a/nexus/src/test/kotlin/Ebics.kt
+++ b/nexus/src/test/kotlin/Ebics.kt
@@ -35,7 +35,7 @@ class Ebics {
     @Test
     fun iniMessage() = conf { config -> 
         val msg = generateIniMessage(config, clientKeys)
-        val ini = XMLUtil.convertStringToJaxb<EbicsUnsecuredRequest>(msg) // ensures is valid
+        val ini = XMLUtil.convertBytesToJaxb<EbicsUnsecuredRequest>(msg) // ensures is valid
         assertEquals(ini.value.header.static.orderDetails.orderType, "INI") // ensures is INI
     }
 
@@ -43,7 +43,7 @@ class Ebics {
     @Test
     fun hiaMessage() = conf { config -> 
         val msg = generateHiaMessage(config, clientKeys)
-        val ini = XMLUtil.convertStringToJaxb<EbicsUnsecuredRequest>(msg) // ensures is valid
+        val ini = XMLUtil.convertBytesToJaxb<EbicsUnsecuredRequest>(msg) // ensures is valid
         assertEquals(ini.value.header.static.orderDetails.orderType, "HIA") // ensures is HIA
     }
 
@@ -51,7 +51,7 @@ class Ebics {
     @Test
     fun hpbMessage() = conf { config -> 
         val msg = generateHpbMessage(config, clientKeys)
-        val ini = XMLUtil.convertStringToJaxb<EbicsUnsecuredRequest>(msg) // ensures is valid
+        val ini = XMLUtil.convertBytesToJaxb<EbicsUnsecuredRequest>(msg) // ensures is valid
         assertEquals(ini.value.header.static.orderDetails.orderType, "HPB") // ensures is HPB
     }
     // POSTs an EBICS message to the mock bank.  Tests
@@ -68,9 +68,19 @@ class Ebics {
         val clientOk = getMockedClient {
             respondOk("Not EBICS anyway.")
         }
-        assertNull(client404.postToBank("http://ignored.example.com/", "ignored"))
-        assertNull(clientNoResponse.postToBank("http://ignored.example.com/", "ignored"))
-        assertNotNull(clientOk.postToBank("http://ignored.example.com/", "ignored"))
+        runCatching {
+            client404.postToBank("http://ignored.example.com/", "ignored".toByteArray())
+        }.run {
+            val exp = exceptionOrNull()!!
+            assertEquals(exp.message, "Invalid response status: 404 Not Found")
+        }
+        runCatching {
+            clientNoResponse.postToBank("http://ignored.example.com/", "ignored".toByteArray())
+        }.run {
+            val exp = exceptionOrNull()!!
+            assertEquals(exp.message, "Network issue.")
+        }
+        clientOk.postToBank("http://ignored.example.com/", "ignored".toByteArray())
     }
 
     // Tests that internal repr. of keys lead to valid PDF.