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The APIs are simply a contract about the directory structure of the marketplace. All APIs are relative to a base path. For example, cask.co/marketplace/v1. The structure is expected to be:
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GET <base>/<cdap-version>v1/packages.json <base>/<cdap-version>v1/packages/<package-name>/<version>/icon.jpgpng <base>/<cdap-version>v1/packages/<package-name>/<version>/license.txt <base>/<cdap-version>v1/packages/<package-name>/<version>/spec.json <base>/<cdap-version>v1/packages/<package-name>/<version>/spec.json.asc <base>/<cdap-version>v1/packages/<package-name>/<version>/archive.zip <base>/<cdap-version>v1/packages/<package-name>/<version>/archive.zip.asc |
...
List all Packages
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GET /v1/<cdap-version>/packages.json ex: GET /4.0.0v1/packages.json [ { "name": "PurchaseExample", "label": "Purchase History", "description": "Example Application demonstrating usage of flows, workflows, mapreduce, and services.", "author": "Cask", "org": "Cask Data Inc.", "version": "4.0.1", "categories": [ "examples" ], "cdapVersion": "[4.0.0,4.1.0) }, { "name": "HelloWorld", "label": "Hello World", "description": "Simple application demonstrating usage of flows and services.", "author": "Cask", "org": "Cask Data Inc.", "version": "4.0.0", "categories": [ "examples" ], }, "cdapVersion": "[4.0.0,4.1.0)" }, ... ] |
This list is not expected to change often. It can be cached by the UI if needed. The 'cdapVersion' specifies which versions of cdap the package is compatible with. If none is given, it is compatible with all versions.
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This leaves grouping by category up to the UI. If needed, we could perhaps add packages-<category>.json files that only list the packages in a specific category. This also leaves display of multiple versions of the same package up to the UI. Though it seems like most of the time we would only have one version of the package per cdap version so maybe it's not a big problem. This also leaves filtering of packages incompatible with the cdap instance up to the UI. |
Get Package Archive
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GET /<cdap-version>v1/packages/<package-name>/<version>/archive.zip ex: GET /4.0.0v1/packages/PurchaseExample/4.0.1/archive.zip [ binary archive contents] |
Get Package Archive Signature
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GET /<cdap-version>v1/packages/<package-name>/<version>/archive.zip.asc ex: GET /4.0.0//v1/packages/PurchaseExample/4.0.1/archive.zip.asc [ archive signature ] |
Get Package Spec
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GET /<cdap-version>v1/packages/<package-name>/<version>/spec.json ex: GET /4.0.0v1/packages/PurchaseExample/4.0.0/spec.json { "spec-versionspecVersion": "1.0", "name": "PurchaseExample", "label": "Purchase History", "description": "Example Application demonstrating usage of flows, workflows, mapreduce, and services.", "author": "Cask", "org": "Cask Data Inc.", "version": "4.0.0", "created": 1234567899, "cdapVersion": "[4.0.0,4.1.0)", "changelog": "fixed a small parsing bug", "categories": [ "examples" ], "dependencies": { }, "actions": [ { "type": "create_artifact", "arguments": [ { "name": "name", "value": "PurchaseHistoryExample" }, { "name": "version", "value": "4.0.1" }, { "name": "scope", "value": "user" }, { "name": "jar", "value": "PurchaseHistoryExample-4.0.1.jar" } ] }, { "type": "create_app", "arguments": [ { "name": "name", "default": "PurchaseHistory" } ] } ] } |
Get Package Spec Signature
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GET /<cdap-version>v1/packages/<package-name>/<version>/spec.asc ex: GET /4.0.0v1/packages/PurchaseExample/4.0.0/spec.asc [ spec signature ] |
Get Package Icon
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GET /<cdap-version>v1/packages/<package-name>/<version>/icon.jpgpng ex: GET /4.0.0v1/packages/PurchaseExample/4.0.0/icon.jpgpng [ icon bytes ] |
Get Package License
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GET /<cdap-version>v1/packages/<package-name>/<version>/license.txt ex: GET /4.0.0v1/packages/PurchaseExample/4.0.0/license.txt Copyright © 2014-2016 Cask Data, Inc. Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. ... |
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Since people will be able to download code from the marketplace, it is especially important that there is protection against malicious code. We can make use of PGP in order to sign both the package archive and the package spec that are downloadable from the marketplace. The Market UI will have to be configured to use a GPG key (for the public CDAP marketplace, we could re-use the GPG key used for CDAP rpms and debians or create another one). It can then use that public key along with the signature APIs to verify that the spec and archive were signed by the owner of the package. There will also be a setting that lets people turn off signature checking in case its not needed for internally hosted repositories.
Package Spec
The package spec contains some metadata about the spec itself, and a list of steps to perform on the CDAP instance. It is a JSON file of the following structure:
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{ "spec-versionspecVersion": "1.0" "actionsname": ["<name>", actionspec1"version": "<version>", actionspec2"label": "<label>", "description": ..."<description>", ] "org": "<org>", "categories": [ <categories> ], "cdapVersion": "<compatible-versions>", "changelog": "<changes>", "actions": [ actionspec1, actionspec2, ... ] } |
The actions in the spec will correspond to steps in the UI wizard for installing the package.
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{ "type": "create_artifact" | "create_app" | "create_stream" | "create_dataset" | "load_datapack" | "install_package" "arguments": [ { "name": [argument name], "value": [argument value], "canModify": true | false (defaults to false) } ] } |
...
name | description | required? | default |
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name | artifact name | yes | |
jar | name of jar file in package archive | no (if using externalArchive) | |
externalJar | link to download 3rd party jar | no | none |
externalArchive | link to download 3rd party archive | no | none |
externalArchiveSignature | link to get 3rd party archive signature | no | none |
externalArchiveJar | path of the jar file in the external archive | no | none |
scope | artifact scope (implies API to add system artifacts is added in 4.0) | no | user |
version | artifact version to pass as Artifact-Version header | no | none |
config | config file contains artifact parents, plugins, and properties | no | none |
...
name | description | required? | default | |||
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name | stream name | yes | ||||
description | stream description, results in call to set stream properties | no | empty | |||
format | stream format as json object, results in call to set stream properties | no | empty | |||
schema | stream schema, results in call to set stream properties | no | empty | |||
ttl | stream ttl, results in call to set stream properties | no | empty | |||
notification.threshold.mb | mb threshold for sending notifications, results in call to set stream properties | no | empty loadfiles | files in the package archive to write to the stream. results in a call to write to the stream in batch | no | empty |
create_dataset
Results in a call to http://docs.cdap.io/cdap/current/en/reference-manual/http-restful-api/dataset.html#creating-a-dataset
name | description | required? | default |
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name | dataset name | yes | |
type | dataset type | yes | |
description | dataset description | no | empty |
properties | json map of dataset properties | no | empty |
Dependencies
Packages will be able to specify dependencies on other packages.
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{
...
"dependencies": [
{
"name": "spark-plugins",
"version": "1.5.0"
}
]
} |
If other packages are listed as a dependency, the actions for the dependent package must be executed before the actions of the current package
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load_datapack
Loads a datapack into some dataset or stream.
name | description | required? | default |
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name | dataset/stream name | yes | |
files | files to load into the dataset/stream | yes |
install_package
Installs another package from the marketplace.
name | description | required? | default |
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name | package name | yes | |
version | package version | yes |
Failures
Since a package spec can contain multiple actions, what happens if some actions succeed and then one action fails? Since the CDAP APIs backing these actions are idempotent, we can ask the user if they want to retryWe will not attempt rollback or anything like that. Instead, all the wizards that execute the actions must be idempotent. For example, if told to add an artifact and the artifact already exists, the step can simply be skipped.
Hosting a Custom Marketplace
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When the user clicks on the '+' button, the UI makes a call to get all the packages it can install:
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GET /4.0.0v1/packages.json [ ..., { "name": "sfdc-lead-dump", "label": "SFDC Lead Dump", "description": "Reads SFDC data from a CDAP Stream, filters invalid records, and dumps the data to a CDAP Table.", "author": "Cask", "org": "Cask Data Inc.", "version": "1.0.0", "categories": [ "hydrator-pipelines" ] }, ... ] |
Among that list is version 1.0.1 of the 'SFDC Lead Dump' package, which the user clicks on. The UI makes a call to get the license for that package:
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GET /4.0.0v1/packages/sfdc-lead-dump/1.0.0/license.txt [ apache2 license ] |
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The user accepts the conditions, and the UI makes a call to get the spec for that package:
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GET /4.0.0v1/packages/sfdc-lead-dump/1.0.0/spec.json { "name": "sfdc-lead-dump", "label": "SFDC Lead Dump", "description": "Reads SFDC data from a CDAP Stream, filters invalid records, and dumps the data to a CDAP Table.", "author": "Cask", "org": "Cask Data Inc.", "version": "1.0.1", "created": 1234567899, "changelog": "", "actions": [ { "type": "create_artifact", "arguments": [ { "name": "scope", "value": "user" }, { "name": "name", "value": "sfdc-plugins" }, { "name": "version", "value": "1.0.0" }, { "name": "config", "value": "sfdc-plugins.json" // file in the archive }, { "name": "jar", "value": "sfdc-plugins.jar" // file in the archive } ] }, { "type": "create_app", "arguments": [ { "name": "artifact", "value": { "scope": "system", "name": "cdap-data-pipeline", "version": "4.0.0" } }, { "name": "name", "value": "SFDC Lead Dump", "canModify": true }, { "name": "config", "value": "sfdc.json" // file in the archive } ] } ] } |
The UI also gets the spec signature to validate the spec:
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GET /4.0.0v1/packages/sfdc-lead-dump/1.0.1/spec.json.asc |
The UI also fetches the package archive and signature. It validates the package, and unzips the archive to a local temporary directory so that it can use its resources to create the plugins artifact and create the hydrator draft
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GET /4.0.0v1/packages/sfdc-lead-dump/1.0.1/archive.tgzzip GET /4.0.0v1/packages/sfdc-lead-dump/1.0.1/archive.tgzzip.asc |
Based on the package spec, the UI can setup the relevant wizards and make the relevant CDAP calls to first create the plugin artifact, and next create the Hydrator pipeline.
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When the user clicks on the '+' button, the UI makes a call to list all packages that can be added to CDAP:
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GET /4.0.0/v1/packages.json [ ..., { "name": "mysql-jdbc-driver", "label": "MySQL JDBC Driver", "description": "JDBC Driver for MySQL databases.", "author": "MySQL", "org": "Oracle", "version": "5.1.39", "categories": [ "hydrator-plugins" ] }, ... ] |
Among the list is the MySQL JDBC Driver, which the user clicks on. The UI makes a call to get the license for that package:
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GET /4.0.0v1/packages/mysql-jdbc-driver/5.1.39/license.txt [ gpl license ] |
The user accepts the conditions, and the UI makes a call to get the spec for that package:
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GET /4.0.0v1/packages/mysql-jdbc-driver/5.1.39/spec.json { "name": "mysql-jdbc-driver", "label": "MySQL JDBC Driver", "description": "JDBC Driver for MySQL databases.", "author": "MySQL", "org": "Oracle", "version": "5.1.39", "categories": [ "hydrator-plugins" ] "created": 1234567899, "actions": [ { "type": "create_artifact", "arguments": [ { "name": "scope", "value": "user" }, { "name": "name", "value": "mysql-connector-java" }, { "name": "version", "value": "5.1.39java" }, { "name": "parentsversion", "value": "system:cdap-data-pipeline[3.0.0,10.0.0]/system:cdap-data-streams[3.0.0,10.0.0]5.1.39" }, { "name": "externalArchive" "value": "https://dev.mysql.com/downloads/file/?id=462849" }, { "name": "externalArchiveSignature", "value": "https://dev.mysql.com/downloads/gpg/?file=mysql-connector-java-5.1.39.zip.gz" }, { "name": "externalArchiveJar", "value": "mysql-connector-java-5.1.39-bin.zip.gzjar" }, { "name": "config", "value": "mysql-connector-java-5.1.39.json" // file in the archive containing parents and plugins } ] } ] } |
The UI also makes a call to get the spec signature to make sure it is valid:
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GET /groups/hydrator-pluginsv1/packages/mysql-jdbc-driver/versions/5.1.39/spec.asc |
The UI then makes calls to get the archive and its signature to validate the archive, and unzip it in a local directory. It uses the jar and json config file contained in the archive to make a request to add the artifact to cdap.
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GET /4.0.0v1/packages/mysql-jdbc-driver/5.1.39/archive.zip.asc GET /4.0.0v1/packages/mysql-jdbc-driver/5.1.39/archive.zip |