Wave 3 of Business Network changes. (#193)

* R3NET-546: Re-arrange independent flows into separate packages. Functionally this is a NOP change.

* R3NET-546: Start BNO as a separate Corda node and improve GUI experience for IOU.

* R3NET-546: Move all the membership checks to the Business Network Owner node side, creating "InitiatedBy" flows as necessary.

* R3NET-546: Make MembershipViolationException AMQP serializable.

* R3NET-546: Improve GUI error reporting in case of membership violation.

* R3NET-546: Code changes following review by: @shamsasari

* R3NET-546: Code changes following review by: @shamsasari

* R3NET-546: Added a dedicated InvalidMembershipListNameException.

samples/business-network-demo/src/main/kotlin/net/corda/sample/businessnetwork/iou/IOUContract.kt

@@ -1,4 +1,4 @@
-package net.corda.sample.businessnetwork
+package net.corda.sample.businessnetwork.iou
 
 import net.corda.core.contracts.CommandData
 import net.corda.core.contracts.Contract

samples/business-network-demo/src/main/kotlin/net/corda/sample/businessnetwork/iou/IOUFlow.kt

@@ -1,4 +1,4 @@
-package net.corda.sample.businessnetwork
+package net.corda.sample.businessnetwork.iou
 
 import co.paralleluniverse.fibers.Suspendable
 import net.corda.core.contracts.Command
@@ -9,19 +9,19 @@ import net.corda.core.identity.Party
 import net.corda.core.transactions.SignedTransaction
 import net.corda.core.transactions.TransactionBuilder
 import net.corda.core.utilities.ProgressTracker
-import net.corda.sample.businessnetwork.membership.MembershipAware
-import net.corda.sample.businessnetwork.membership.CheckMembershipFlow
-import net.corda.sample.businessnetwork.membership.CheckMembershipResult
+import net.corda.sample.businessnetwork.membership.flow.CheckMembershipFlow
+import net.corda.sample.businessnetwork.membership.flow.CheckMembershipResult
 import kotlin.reflect.jvm.jvmName
 
 @InitiatingFlow
 @StartableByRPC
 class IOUFlow(val iouValue: Int,
-              val otherParty: Party) : FlowLogic<SignedTransaction>(), MembershipAware {
+              val otherParty: Party) : FlowLogic<SignedTransaction>() {
 
     companion object {
+        // TODO: Derive membership name from CorDapp config.
         val allowedMembershipName =
-                CordaX500Name("AliceBobMembershipList", "AliceBob", "Washington", "US")
+                CordaX500Name("AliceBobMembershipList", "Oslo", "NO")
     }
 
     /** The progress tracker provides checkpoints indicating the progress of the flow to observers. */

samples/business-network-demo/src/main/kotlin/net/corda/sample/businessnetwork/iou/IOUFlowResponder.kt

@@ -1,4 +1,4 @@
-package net.corda.sample.businessnetwork
+package net.corda.sample.businessnetwork.iou
 
 import co.paralleluniverse.fibers.Suspendable
 import net.corda.core.contracts.requireThat
@@ -7,14 +7,14 @@ import net.corda.core.flows.FlowSession
 import net.corda.core.flows.InitiatedBy
 import net.corda.core.flows.SignTransactionFlow
 import net.corda.core.transactions.SignedTransaction
-import net.corda.sample.businessnetwork.membership.MembershipAware
+import net.corda.sample.businessnetwork.membership.flow.CheckMembershipFlow
+import net.corda.sample.businessnetwork.membership.flow.CheckMembershipResult
 
 @InitiatedBy(IOUFlow::class)
-class IOUFlowResponder(val otherPartySession: FlowSession) : FlowLogic<Unit>(), MembershipAware {
+class IOUFlowResponder(val otherPartySession: FlowSession) : FlowLogic<Unit>() {
     @Suspendable
     override fun call() {
-
-        otherPartySession.counterparty.checkMembership(IOUFlow.allowedMembershipName, this)
+        check(subFlow(CheckMembershipFlow(otherPartySession.counterparty, IOUFlow.allowedMembershipName)) == CheckMembershipResult.PASS)
 
         subFlow(object : SignTransactionFlow(otherPartySession, SignTransactionFlow.tracker()) {
             override fun checkTransaction(stx: SignedTransaction) = requireThat {

samples/business-network-demo/src/main/kotlin/net/corda/sample/businessnetwork/iou/IOUState.kt

@@ -1,4 +1,4 @@
-package net.corda.sample.businessnetwork
+package net.corda.sample.businessnetwork.iou
 
 import net.corda.core.contracts.ContractState
 import net.corda.core.identity.Party

samples/business-network-demo/src/main/kotlin/net/corda/sample/businessnetwork/membership/CheckMembershipFlow.kt

@@ -1,38 +0,0 @@
-package net.corda.sample.businessnetwork.membership
-
-import co.paralleluniverse.fibers.Suspendable
-import net.corda.core.flows.FlowLogic
-import net.corda.core.flows.FlowSession
-import net.corda.core.flows.InitiatedBy
-import net.corda.core.flows.InitiatingFlow
-import net.corda.core.identity.CordaX500Name
-import net.corda.core.identity.Party
-import net.corda.core.serialization.CordaSerializable
-import net.corda.core.utilities.unwrap
-
-@CordaSerializable
-enum class CheckMembershipResult {
-    PASS,
-    FAIL
-}
-
-@InitiatingFlow
-class CheckMembershipFlow(private val otherParty: Party, private val membershipName: CordaX500Name) : FlowLogic<CheckMembershipResult>(), MembershipAware {
-    @Suspendable
-    override fun call(): CheckMembershipResult {
-        otherParty.checkMembership(membershipName, this)
-        // This will trigger CounterpartyCheckMembershipFlow
-        val untrustworthyData = initiateFlow(otherParty).sendAndReceive<CheckMembershipResult>(membershipName)
-        return untrustworthyData.unwrap { it }
-    }
-}
-
-@InitiatedBy(CheckMembershipFlow::class)
-class CounterpartyCheckMembershipFlow(private val otherPartySession: FlowSession) : FlowLogic<Unit>(), MembershipAware {
-    @Suspendable
-    override fun call() {
-        val membershipName = otherPartySession.receive<CordaX500Name>().unwrap { it }
-        otherPartySession.counterparty.checkMembership(membershipName, this)
-        otherPartySession.send(CheckMembershipResult.PASS)
-    }
-}

samples/business-network-demo/src/main/kotlin/net/corda/sample/businessnetwork/membership/MembershipAware.kt

@@ -1,26 +0,0 @@
-package net.corda.sample.businessnetwork.membership
-
-import net.corda.core.flows.FlowException
-import net.corda.core.flows.FlowLogic
-import net.corda.core.identity.AbstractParty
-import net.corda.core.identity.CordaX500Name
-import net.corda.core.node.ServiceHub
-import net.corda.sample.businessnetwork.membership.internal.MembershipListProvider
-
-interface MembershipAware {
-    /**
-     * Checks that party has at least one common membership list with current node.
-     * TODO: This functionality ought to be moved into a dedicated CordaService.
-     */
-    fun <T> AbstractParty.checkMembership(membershipName: CordaX500Name, initiatorFlow: FlowLogic<T>) {
-        val membershipList = getMembershipList(membershipName, initiatorFlow.serviceHub)
-        if (this !in membershipList) {
-            val msg = "'$this' doesn't belong to membership list: ${membershipName.commonName}"
-            throw MembershipViolationException(msg)
-        }
-    }
-
-    fun getMembershipList(listName: CordaX500Name, serviceHub: ServiceHub): MembershipList = MembershipListProvider.obtainMembershipList(listName, serviceHub.networkMapCache)
-}
-
-class MembershipViolationException(msg: String) : FlowException(msg)

samples/business-network-demo/src/main/kotlin/net/corda/sample/businessnetwork/membership/ObtainMembershipListContentFlow.kt

@@ -1,16 +0,0 @@
-package net.corda.sample.businessnetwork.membership
-
-import co.paralleluniverse.fibers.Suspendable
-import net.corda.core.flows.FlowLogic
-import net.corda.core.flows.StartableByRPC
-import net.corda.core.identity.AbstractParty
-import net.corda.core.identity.CordaX500Name
-
-/**
- * Flow to obtain content of the membership lists this node belongs to.
- */
-@StartableByRPC
-class ObtainMembershipListContentFlow(private val membershipListName: CordaX500Name) : FlowLogic<Set<AbstractParty>>(), MembershipAware {
-    @Suspendable
-    override fun call(): Set<AbstractParty> = getMembershipList(membershipListName, serviceHub).content()
-}

samples/business-network-demo/src/main/kotlin/net/corda/sample/businessnetwork/membership/flow/CheckMembershipFlow.kt

@@ -0,0 +1,42 @@
+package net.corda.sample.businessnetwork.membership.flow
+
+import co.paralleluniverse.fibers.Suspendable
+import net.corda.core.flows.FlowLogic
+import net.corda.core.flows.FlowSession
+import net.corda.core.flows.InitiatedBy
+import net.corda.core.flows.InitiatingFlow
+import net.corda.core.identity.CordaX500Name
+import net.corda.core.identity.Party
+import net.corda.core.serialization.CordaSerializable
+import net.corda.core.utilities.unwrap
+
+@CordaSerializable
+enum class CheckMembershipResult {
+    PASS,
+    FAIL
+}
+
+@InitiatingFlow
+class CheckMembershipFlow(private val otherParty: Party, private val membershipName: CordaX500Name) : FlowLogic<CheckMembershipResult>() {
+    @Suspendable
+    override fun call(): CheckMembershipResult {
+        val bnoParty = serviceHub.networkMapCache.getPeerByLegalName(membershipName)
+        return if (bnoParty != null) {
+            // This will trigger CounterpartyCheckMembershipFlow
+            val untrustworthyData = initiateFlow(bnoParty).sendAndReceive<CheckMembershipResult>(otherParty)
+            untrustworthyData.unwrap { it }
+        } else {
+            throw InvalidMembershipListNameException(membershipName)
+        }
+    }
+}
+
+@InitiatedBy(CheckMembershipFlow::class)
+class OwnerSideCheckMembershipFlow(private val initiatingPartySession: FlowSession) : FlowLogic<Unit>(), MembershipAware {
+    @Suspendable
+    override fun call() {
+        val partyToCheck = initiatingPartySession.receive<Party>().unwrap { it }
+        partyToCheck.checkMembership(ourIdentity.name, this)
+        initiatingPartySession.send(CheckMembershipResult.PASS)
+    }
+}

samples/business-network-demo/src/main/kotlin/net/corda/sample/businessnetwork/membership/flow/MembershipAware.kt

@@ -0,0 +1,32 @@
+package net.corda.sample.businessnetwork.membership.flow
+
+import net.corda.core.flows.FlowException
+import net.corda.core.flows.FlowLogic
+import net.corda.core.identity.AbstractParty
+import net.corda.core.identity.CordaX500Name
+import net.corda.core.node.ServiceHub
+import net.corda.sample.businessnetwork.membership.internal.MembershipListProvider
+import org.slf4j.LoggerFactory
+
+interface MembershipAware {
+    /**
+     * Checks that party is included into the specified membership list.
+     */
+    fun <T> AbstractParty.checkMembership(membershipName: CordaX500Name, initiatorFlow: FlowLogic<T>) {
+        LoggerFactory.getLogger(javaClass).debug("Checking membership of party '${this.nameOrNull()}' in membership list '$membershipName'")
+        val membershipList = getMembershipList(membershipName, initiatorFlow.serviceHub)
+        if (this !in membershipList) {
+            val msg = "'$this' doesn't belong to membership list: ${membershipName.organisation}"
+            throw MembershipViolationException(msg)
+        }
+    }
+
+    fun getMembershipList(listName: CordaX500Name, serviceHub: ServiceHub): MembershipList {
+        LoggerFactory.getLogger(javaClass).debug("Obtaining membership list for name '$listName'")
+        return MembershipListProvider.obtainMembershipList(listName, serviceHub.networkMapCache)
+    }
+}
+
+class MembershipViolationException(val msg: String) : FlowException(msg)
+
+class InvalidMembershipListNameException(val membershipListName: CordaX500Name) : FlowException("Business Network owner node not found for: $membershipListName")

samples/business-network-demo/src/main/kotlin/net/corda/sample/businessnetwork/membership/flow/MembershipList.kt

@@ -1,4 +1,4 @@
-package net.corda.sample.businessnetwork.membership
+package net.corda.sample.businessnetwork.membership.flow
 
 import net.corda.core.identity.AbstractParty
 

samples/business-network-demo/src/main/kotlin/net/corda/sample/businessnetwork/membership/flow/ObtainMembershipListContentFlow.kt

@@ -0,0 +1,34 @@
+package net.corda.sample.businessnetwork.membership.flow
+
+import co.paralleluniverse.fibers.Suspendable
+import net.corda.core.flows.*
+import net.corda.core.identity.AbstractParty
+import net.corda.core.identity.CordaX500Name
+import net.corda.core.utilities.unwrap
+
+/**
+ * Flow to obtain content of the membership lists this node belongs to.
+ */
+@StartableByRPC
+@InitiatingFlow
+class ObtainMembershipListContentFlow(private val membershipListName: CordaX500Name) : FlowLogic<Set<AbstractParty>>() {
+    @Suspendable
+    override fun call(): Set<AbstractParty> {
+        val bnoParty = serviceHub.networkMapCache.getPeerByLegalName(membershipListName) ?:
+                throw InvalidMembershipListNameException(membershipListName)
+        val untrustworthyData = initiateFlow(bnoParty).receive<Set<AbstractParty>>()
+        return untrustworthyData.unwrap { it }
+    }
+}
+
+@InitiatedBy(ObtainMembershipListContentFlow::class)
+class OwnerSideObtainMembershipListContentFlow(private val initiatingPartySession: FlowSession) : FlowLogic<Unit>(), MembershipAware {
+    @Suspendable
+    override fun call() {
+        // Checking whether the calling party is a member. If not it is not even in position to enquire about membership list content.
+        initiatingPartySession.counterparty.checkMembership(ourIdentity.name, this)
+
+        val membershipListContent: Set<AbstractParty> = getMembershipList(ourIdentity.name, serviceHub).content()
+        initiatingPartySession.send(membershipListContent)
+    }
+}

samples/business-network-demo/src/main/kotlin/net/corda/sample/businessnetwork/membership/internal/CsvMembershipList.kt

@@ -4,7 +4,7 @@ import com.opencsv.CSVReaderBuilder
 import net.corda.core.identity.AbstractParty
 import net.corda.core.identity.CordaX500Name
 import net.corda.core.node.services.NetworkMapCache
-import net.corda.sample.businessnetwork.membership.MembershipList
+import net.corda.sample.businessnetwork.membership.flow.MembershipList
 import java.io.InputStream
 
 /**

samples/business-network-demo/src/main/kotlin/net/corda/sample/businessnetwork/membership/internal/MembershipListProvider.kt

@@ -2,9 +2,9 @@ package net.corda.sample.businessnetwork.membership.internal
 
 import net.corda.core.identity.CordaX500Name
 import net.corda.core.node.services.NetworkMapCache
-import net.corda.sample.businessnetwork.membership.MembershipList
+import net.corda.sample.businessnetwork.membership.flow.MembershipList
 
 object MembershipListProvider {
     fun obtainMembershipList(listName: CordaX500Name, networkMapCache: NetworkMapCache): MembershipList =
-            CsvMembershipList(MembershipListProvider::class.java.getResourceAsStream("${listName.commonName}.csv"), networkMapCache)
+            CsvMembershipList(MembershipListProvider::class.java.getResourceAsStream("${listName.organisation}.csv"), networkMapCache)
 }

tools/explorer/src/main/kotlin/net/corda/explorer/ExplorerSimulation.kt

@@ -14,8 +14,8 @@ import net.corda.core.messaging.FlowHandle
 import net.corda.core.messaging.startFlow
 import net.corda.core.utilities.OpaqueBytes
 import net.corda.core.utilities.getOrThrow
-import net.corda.sample.businessnetwork.IOUFlow
-import net.corda.sample.businessnetwork.membership.ObtainMembershipListContentFlow
+import net.corda.sample.businessnetwork.iou.IOUFlow
+import net.corda.sample.businessnetwork.membership.flow.ObtainMembershipListContentFlow
 import net.corda.finance.GBP
 import net.corda.finance.USD
 import net.corda.finance.contracts.asset.Cash
@@ -32,8 +32,14 @@ import net.corda.testing.driver.PortAllocation
 import net.corda.testing.driver.driver
 import java.time.Instant
 import java.util.*
+import kotlin.reflect.KClass
 
 class ExplorerSimulation(private val options: OptionSet) {
+
+    private companion object {
+        fun packagesOfClasses(vararg classes: KClass<*>): List<String> = classes.map { it.java.`package`.name }
+    }
+
     private val user = User("user1", "test", permissions = setOf(
             startFlow<CashPaymentFlow>(),
             startFlow<CashConfigDataFlow>(),
@@ -52,6 +58,7 @@ class ExplorerSimulation(private val options: OptionSet) {
     private lateinit var bobNode: NodeHandle
     private lateinit var issuerNodeGBP: NodeHandle
     private lateinit var issuerNodeUSD: NodeHandle
+    private lateinit var bnoNode: NodeHandle
     private lateinit var notary: Party
 
     private val RPCConnections = ArrayList<CordaRPCConnection>()
@@ -65,7 +72,8 @@ class ExplorerSimulation(private val options: OptionSet) {
 
     fun startDemoNodes() {
         val portAllocation = PortAllocation.Incremental(20000)
-        driver(portAllocation = portAllocation, extraCordappPackagesToScan = listOf("net.corda.finance", IOUFlow::class.java.`package`.name),
+        driver(portAllocation = portAllocation,
+                extraCordappPackagesToScan = packagesOfClasses(CashPaymentFlow::class, IOUFlow::class, ObtainMembershipListContentFlow::class),
                 isDebug = true, waitForAllNodesToFinish = true, jmxPolicy = JmxPolicy(true)) {
             // TODO : Supported flow should be exposed somehow from the node instead of set of ServiceInfo.
             val alice = startNode(providedName = ALICE_NAME, rpcUsers = listOf(user))
@@ -76,14 +84,16 @@ class ExplorerSimulation(private val options: OptionSet) {
                     customOverrides = mapOf("issuableCurrencies" to listOf("GBP")))
             val issuerUSD = startNode(providedName = usaBankName, rpcUsers = listOf(manager),
                     customOverrides = mapOf("issuableCurrencies" to listOf("USD")))
+            val bno = startNode(providedName = IOUFlow.allowedMembershipName, rpcUsers = listOf(user))
 
             notaryNode = defaultNotaryNode.get()
             aliceNode = alice.get()
             bobNode = bob.get()
             issuerNodeGBP = issuerGBP.get()
             issuerNodeUSD = issuerUSD.get()
+            bnoNode = bno.get()
 
-            arrayOf(notaryNode, aliceNode, bobNode, issuerNodeGBP, issuerNodeUSD).forEach {
+            arrayOf(notaryNode, aliceNode, bobNode, issuerNodeGBP, issuerNodeUSD, bnoNode).forEach {
                 println("${it.nodeInfo.legalIdentities.first()} started on ${it.configuration.rpcAddress}")
             }
 

tools/explorer/src/main/kotlin/net/corda/explorer/model/MembershipListModel.kt

@@ -9,8 +9,8 @@ import net.corda.client.jfx.utils.map
 import net.corda.core.identity.AbstractParty
 import net.corda.core.messaging.startFlow
 import net.corda.core.utilities.getOrThrow
-import net.corda.sample.businessnetwork.IOUFlow
-import net.corda.sample.businessnetwork.membership.ObtainMembershipListContentFlow
+import net.corda.sample.businessnetwork.iou.IOUFlow
+import net.corda.sample.businessnetwork.membership.flow.ObtainMembershipListContentFlow
 
 class MembershipListModel {
     private val proxy by observableValue(NodeMonitorModel::proxyObservable)

tools/explorer/src/main/kotlin/net/corda/explorer/views/Network.kt

@@ -83,9 +83,10 @@ class Network : CordaView() {
                     .map { it.stateAndRef.state.data }.getParties()
             val outputParties = it.transaction.tx.outputStates.observable().getParties()
             val signingParties = it.transaction.sigs.map { it.by.toKnownParty() }
-            // Input parties fire a bullets to all output parties, and to the signing parties. !! This is a rough guess of how the message moves in the network.
+            // Input parties fire a bullets to all output parties, then to the signing parties and then signing parties to output parties.
+            // !! This is a rough guess of how the message moves in the network.
             // TODO : Expose artemis queue to get real message information.
-            inputParties.cross(outputParties) + inputParties.cross(signingParties)
+            inputParties.cross(outputParties) + inputParties.cross(signingParties) + signingParties.cross(outputParties)
         }
     }
 

tools/explorer/src/main/kotlin/net/corda/explorer/views/TransactionViewer.kt

@@ -28,7 +28,7 @@ import net.corda.core.identity.AbstractParty
 import net.corda.core.identity.CordaX500Name
 import net.corda.core.identity.Party
 import net.corda.core.utilities.toBase58String
-import net.corda.sample.businessnetwork.IOUState
+import net.corda.sample.businessnetwork.iou.IOUState
 import net.corda.explorer.AmountDiff
 import net.corda.explorer.formatters.AmountFormatter
 import net.corda.explorer.formatters.Formatter

tools/explorer/src/main/kotlin/net/corda/explorer/views/cordapps/iou/IOUViewer.kt

@@ -2,10 +2,17 @@ package net.corda.explorer.views.cordapps.iou
 
 import de.jensd.fx.glyphs.fontawesome.FontAwesomeIcon
 import de.jensd.fx.glyphs.fontawesome.FontAwesomeIconView
+import javafx.beans.binding.Bindings
+import javafx.geometry.Pos
 import javafx.scene.input.MouseButton
 import javafx.scene.layout.BorderPane
+import net.corda.client.jfx.model.TransactionDataModel
+import net.corda.client.jfx.model.observableList
+import net.corda.client.jfx.utils.map
 import net.corda.core.utilities.Try
 import net.corda.explorer.model.CordaView
+import net.corda.explorer.model.CordaWidget
+import net.corda.sample.businessnetwork.iou.IOUState
 import net.corda.explorer.model.MembershipListModel
 import tornadofx.*
 
@@ -13,6 +20,7 @@ class IOUViewer : CordaView("IOU") {
     // Inject UI elements.
     override val root: BorderPane by fxml()
     override val icon: FontAwesomeIcon = FontAwesomeIcon.CHEVRON_CIRCLE_RIGHT
+    override val widgets = listOf(CordaWidget(title, IOUWidget(), icon)).observable()
 
     // Wire up UI
     init {
@@ -28,8 +36,22 @@ class IOUViewer : CordaView("IOU") {
     }
 
     fun isEnabledForNode(): Boolean = Try.on {
-                // Assuming if the model can be initialized - the CorDapp is installed
-                val allParties = MembershipListModel().allParties
-                allParties[0]
-            }.isSuccess
+        // Assuming if the model can be initialized - the CorDapp is installed
+        val allParties = MembershipListModel().allParties
+        allParties[0]
+    }.isSuccess
+
+    private class IOUWidget : BorderPane() {
+        private val partiallyResolvedTransactions by observableList(TransactionDataModel::partiallyResolvedTransactions)
+        private val iouTransactions = partiallyResolvedTransactions.filtered { t -> t.transaction.tx.outputs.any({ ts -> ts.data is IOUState }) }
+
+        init {
+            right {
+                label {
+                    textProperty().bind(Bindings.size(iouTransactions).map(Number::toString))
+                    BorderPane.setAlignment(this, Pos.BOTTOM_RIGHT)
+                }
+            }
+        }
+    }
 }

tools/explorer/src/main/kotlin/net/corda/explorer/views/cordapps/iou/NewTransaction.kt

@@ -1,6 +1,7 @@
 package net.corda.explorer.views.cordapps.iou
 
 import com.google.common.base.Splitter
+import com.sun.javafx.collections.ImmutableObservableList
 import javafx.beans.binding.Bindings
 import javafx.beans.binding.BooleanBinding
 import javafx.collections.FXCollections
@@ -15,13 +16,15 @@ import net.corda.client.jfx.model.*
 import net.corda.client.jfx.utils.isNotNull
 import net.corda.client.jfx.utils.map
 import net.corda.core.flows.FlowException
+import net.corda.core.identity.AbstractParty
 import net.corda.core.identity.Party
 import net.corda.core.identity.PartyAndCertificate
 import net.corda.core.messaging.FlowHandle
 import net.corda.core.messaging.startFlow
 import net.corda.core.transactions.SignedTransaction
 import net.corda.core.utilities.getOrThrow
-import net.corda.sample.businessnetwork.IOUFlow
+import net.corda.core.utilities.loggerFor
+import net.corda.sample.businessnetwork.iou.IOUFlow
 import net.corda.explorer.formatters.PartyNameFormatter
 import net.corda.explorer.model.MembershipListModel
 import net.corda.explorer.views.bigDecimalFormatter
@@ -46,7 +49,12 @@ class NewTransaction : Fragment() {
     fun show(window: Window) {
 
         // Every time re-query from the server side
-        val elementsFromServer = MembershipListModel().allParties
+        val elementsFromServer = try {
+            MembershipListModel().allParties
+        } catch (ex: Exception) {
+            loggerFor<NewTransaction>().error("Unexpected error fetching membership list content", ex)
+            ImmutableObservableList<AbstractParty>()
+        }
 
         partyBChoiceBox.apply {
             items = FXCollections.observableList(parties.map { it.chooseIdentityAndCert() }).filtered { elementsFromServer.contains(it.party) }.sorted()