Add pubsub module

.gitignore

@@ -7,7 +7,7 @@
 !/.idea/codeStyleSettings.xml
 
 # Gradle interim configs
-.gradle/*
+*/.gradle/*
 
 # Generated source code
 */generated/*

README.md

@@ -1,34 +1,41 @@
 # gcloud-java
 
-[![codecov](https://codecov.io/gh/SpineEventEngine/gcloud-java/branch/master/graph/badge.svg)](https://codecov.io/gh/SpineEventEngine/gcloud-java)
-[![Build Status](https://travis-ci.com/SpineEventEngine/gcloud-java.svg?branch=master)](https://travis-ci.com/SpineEventEngine/gcloud-java)
+[![codecov][codecov-badge]][codecov] [![Build Status][travis-badge]][travis]
 
+[codecov]: https://codecov.io/gh/SpineEventEngine/gcloud-java
+[codecov-badge]: https://codecov.io/gh/SpineEventEngine/gcloud-java/branch/master/graph/badge.svg
+[travis]: https://travis-ci.com/SpineEventEngine/gcloud-java
+[travis-badge]: https://travis-ci.com/SpineEventEngine/gcloud-java.svg?branch=master
+
 Support for Spine-based Java apps running at Google Cloud.
 
 ### Artifacts
 
 Gradle:
 
-```groovy
+```kotlin
 dependencies {
-    implementation (
-
-        // Datastore Storage support library.
-        "io.spine.gcloud:spine-datastore:1.5.0",
-        
-        // Stackdriver Trace support library.
-        "io.spine.gcloud:spine-stackdriver-trace:1.5.0",
-
-        // Datastore-related test utilities (if needed).
-        "io.spine.gcloud:testutil-gcloud:1.5.0"
-    )
+    // Datastore Storage support library.
+    implementation("io.spine.gcloud:spine-datastore:1.5.22")
+
+    // Pub/Sub messaging support library.
+    implementation("io.spine.gcloud:spine-pubsub:1.5.22")
+
+    // Stackdriver Trace support library.
+    implementation("io.spine.gcloud:spine-stackdriver-trace:1.5.22")
+
+    // Datastore-related test utilities (if needed).
+    implementation("io.spine.gcloud:testutil-gcloud:1.5.22")
 }
 ```
 
 These artifacts should be used as a part of the Spine server application.
 
-For the details on setting up the server environment please refer to [Spine Bootstrap Gradle plugin](https://github.com/SpineEventEngine/bootstrap/) 
-and [Spine `core` modules](https://github.com/SpineEventEngine/core-java/) documentation. 
+For the details on setting up the server environment please refer to
+[Spine Bootstrap Gradle plugin][bootstrap] and [Spine `core` modules][core-java] documentation. 
+
+[bootstrap]: https://github.com/SpineEventEngine/bootstrap/
+[core-java]: https://github.com/SpineEventEngine/core-java/
 
 ### Configuring Datastore
 
@@ -40,8 +47,9 @@ be set. Please notice a special index configuration for your custom `Aggregate`
 
 The configuration file is located at `./datastore/config/index.yaml`. 
 
-Please see the [Google Cloud Platform documentation](https://cloud.google.com/datastore/docs/tools/indexconfig)
-for the details.
+Please see the [Google Cloud Platform documentation][datastore-index] for the details.
+
+[datastore-index]: https://cloud.google.com/datastore/docs/tools/indexconfig
 
 ##### Custom indexes
 
@@ -51,9 +59,10 @@ Such an approach is useful to optimize read-side querying. In this case more Dat
 
 __Example:__
 Assuming you have a Projection type called `CustomerProjection`. Its state is declared in 
-the Protobuf type `my.company.Customer`. It has Entity Columns `country` and
-`companySize`. Once you try to make a query in those Columns, the Datastore will fail with 
+the Protobuf type `my.company.Customer`. It has Entity Columns `country` and `companySize`. 
+Once you try to make a query in those Columns, the Datastore will fail with 
 an internal Exception. To prevent this, you should create an index for your `CustomerProjection`:
+
 ```yaml
 - kind: my.company.Customer
     ancestor: no
@@ -69,11 +78,12 @@ This section describes testing the `gcloud-java` library itself.
 ##### Preconditions
 
 To run the task successfully, you must have `gcloud` tool properly installed and configured: 
- - install gcloud of the last version;
+ - [install][gcloud-install] `gcloud` of the last version;
  - login under a Google account when initializing the `gcloud`;
  - to run tests you should select `spine-dev` Google Cloud Console project;
  - skip Google App Engine setup if not required.
 
+[gcloud-install]: https://cloud.google.com/sdk/docs/downloads-interactive
 
 ##### Running the tests
 
@@ -83,16 +93,20 @@ To start a local emulator and run test against it, run `./gradlew check`.
 
 To start an emulator without running tests `./gradlew startDatastore`.
 
-To stop the Datastore emulator, just terminate the emulator process (e.g. `kill -9 $(lsof -i:8080)` or just close the terminal window on Windows).
+To stop the Datastore emulator, just terminate the emulator process (e.g. `kill -9 $(lsof -i:8080)` 
+or just close the terminal window on Windows).
 
 The launched emulator will run at `localhost:8080` and will not have any persistence.
 To change the configuration see `./scripts/start-datastore.*` scripts.
 
 The datastore is cleaned up after each test.
-See test classes under `./datastore/src/test/java/...` and `io.spine.server.storage.datastore.TestDatastoreStorageFactory#clear`.
+See test classes under `./datastore/src/test/java/...` and 
+`io.spine.server.storage.datastore.TestDatastoreStorageFactory#clear`.
 
 *Stackdriver-Trace*
 
-The test are launched in a scope of Gradle `test` phase. However, they rely upon an Google Cloud credentials file located at `<project root>/stackdriver-trace/src/test/resources/spine-dev.json`.
+The test are launched in a scope of Gradle `test` phase. However, they rely on a Google Cloud 
+credentials file located at `<project root>/stackdriver-trace/src/test/resources/spine-dev.json`.
 
-To run the tests, obtain the service account file for your environment and make it available to the test code in the specified location.
+To run the tests, obtain the service account file for your environment and make it available 
+to the test code in the specified location.

build.gradle.kts

@@ -63,7 +63,7 @@ allprojects {
 }
 
 extra["credentialsPropertyFile"] = PublishingRepos.cloudRepo.credentials
-extra["projectsToPublish"] = listOf("datastore", "stackdriver-trace", "testutil-gcloud")
+extra["projectsToPublish"] = listOf("datastore", "stackdriver-trace", "testutil-gcloud", "pubsub")
 
 subprojects {
     apply {

buildSrc/src/main/kotlin/io/spine/gradle/internal/CheckVersionIncrement.kt

@@ -27,6 +27,7 @@ import org.gradle.api.GradleException
 import org.gradle.api.Project
 import org.gradle.api.tasks.Input
 import org.gradle.api.tasks.TaskAction
+import java.io.FileNotFoundException
 import java.net.URL
 
 /**
@@ -52,21 +53,21 @@ open class CheckVersionIncrement : DefaultTask() {
         val artifact = "${project.artifactPath()}/${MavenMetadata.FILE_NAME}"
         val repoUrl = repository.releases
         val metadata = fetch(repoUrl, artifact)
-        val versions = metadata.versioning.versions
-        val versionExists = versions.contains(version)
+        val versions = metadata?.versioning?.versions
+        val versionExists = versions?.contains(version) ?: false
         if (versionExists) {
             throw GradleException("""
                     Version `$version` is already published to maven repository `$repoUrl`.
                     Try incrementing the library version.
-                    All available versions are: ${versions.joinToString(separator = ", ")}. 
+                    All available versions are: ${versions?.joinToString(separator = ", ")}. 
 
                     To disable this check, run Gradle with `-x $name`. 
                     """.trimIndent()
             )
         }
     }
 
-    private fun fetch(repository: String, artifact: String): MavenMetadata {
+    private fun fetch(repository: String, artifact: String): MavenMetadata? {
         val url = URL("$repository/$artifact")
         return MavenMetadata.fetchAndParse(url)
     }
@@ -94,9 +95,19 @@ private data class MavenMetadata(var versioning: Versioning = Versioning()) {
             mapper.configure(FAIL_ON_UNKNOWN_PROPERTIES, false)
         }
 
-        fun fetchAndParse(url: URL): MavenMetadata {
-            val metadata = mapper.readValue(url, MavenMetadata::class.java)
-            return metadata
+        /**
+         * Fetches the metadata for the repository and parses the document.
+         *
+         * <p>If the document could not be found, assumes that the module was never
+         * released and thus has no metadata.
+         */
+        fun fetchAndParse(url: URL): MavenMetadata? {
+            return try {
+                val metadata = mapper.readValue(url, MavenMetadata::class.java)
+                metadata
+            } catch (e: FileNotFoundException) {
+                null
+            }
         }
     }
 }