Mocks

These mocks (not final) give an idea of the flow users will go through in order to install a package from the Cask Market.

Terminology

package - A collection of entities (artifacts, applications, datasets, streams) to add to CDAP. A package is identified by a name and version, and can be tagged with one or more categories. A package consists of an archive of resources (tarball) and a package spec.

package spec - A json file containing a list of actions to perform against CDAP. For example, a spec for the Purchase History example will include an action to add the Purchase History artifact, then an action to create an application from that artifact.

package archive - A tarball containing any resources needed to perform the actions in the package spec. For example, if the spec contains an action to add an artifact, the archive must contain the jar file to add.

category - A package can be tagged with one or more categories. A category corresponds to one of the tabs on the left bar of the mocks.

APIs

All APIs are relative to a base path. For example, cask.co/marketplace/v1. In the initial version, there will only be GET APIs.

List Groups

GET /groups
ex: GET /groups
[
  {
    "name": "examples",
    "label": "Examples",
    "description": "Example applications to get started with CDAP."
  },
  {
    "name": "hydrator-plugins",
    "label": "Hydrator Plugins",
    "description": "Collections of plugins to extend Hydrator functionality."
  },
  ...
]

Get Group Icon

GET /groups/<group>/icon
ex: GET /groups/examples/icon 
[binary image contents]

List Packages in a Group

GET /groups/<group>/packages
ex: GET /groups/examples/packages
[
  {
    "name": "PurchaseExample",
    "label": "Purchase History",
    "description": "Example Application demonstrating usage of flows, workflows, mapreduce, and services.",
    "author": "Cask",
    "org": "Cask Data Inc."
  },
  {
    "name": "HelloWorld",
    "label": "Hello World",
    "description": "Simple application demonstrating usage of flows and services.",
    "author": "Cask",
    "org": "Cask Data Inc."
  },
  ...
]

Get Package Icon

GET /groups/<group>/packages/<package>/icon
ex: GET /groups/examples/packages/PurchaseExample/icon
[binary image contents]

List Package Versions

GET /groups/<group>/packages/<package>/versions
ex: GET /groups/examples/packages/PurchaseExample/versions
[
  {    
    "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",
    "created": 1234567899,
    "changelog": [
      "fixed a small parsing bug"
    ]
  },
  {    
    "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": 1234567890,
    "changelog": [
      "updated APIs to work with CDAP 4.0.0"
    ]
  },
  ...
]

Get Package Archive

GET /groups/<group>/packages/<package>/versions/<version>/archive.tgz
ex: GET /groups/examples/packages/PurchaseExample/versions/4.0.1/archive.tgz
[ binary archive contents]

Get Package Archive Signature

GET /groups/<group>/packages/<package>/versions/<version>/archive.tgz.asc
ex: GET /groups/examples/packages/PurchaseExample/versions/4.0.1/archive.tgz.asc
[ archive signature ]

Get Package Spec

GET /groups/<group>/packages/<package>/versions/<version>/spec
ex: GET /groups/examples/packages/PurchaseExample/versions/4.0.1/spec
{
  "metadata": {
    "spec-version": "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": "4.0.1",
  "created": 1234567899,
  "changelog": [
    "fixed a small parsing bug"
  ],
  "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"
        }
      ]
    }
  ],
  "dependencies": {
    "cdap": {
      "minVersion": "4.0.0",
      "maxVersion": "4.1.0"
    }
  }
}

Get Package Spec Signature

GET /groups/<group>/packages/<package>/versions/<version>/spec.asc
ex: GET /groups/examples/packages/PurchaseExample/versions/4.0.1/spec.asc
[ spec signature ]

Security

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.

Package Spec

The package spec contains some metadata about the spec itself, and a list of actions to perform on the CDAP instance. It is a JSON file of the following structure:

{
  "metadata": {
    "spec-version": "1.0"
  },
  "actions": [
    actionspec1,
    actionspec2,
    ...
  ]
}

The actions in the spec will correspond to steps in the UI wizard for installing the package.

Action Spec

Each action will contain a type, a list of arguments, and dependencies. Each type of action will require different arguments. In the first version, the following types will be supported: create_artifact, create_app, create_stream, create_dataset, create_hydrator_draft.

{
  "type": "create_artifact" | "create_app" | "create_stream" | "create_dataset" | "create_hydrator_draft",
  "arguments": [
    {
      "name": [argument name],
      "value": [argument value],
      "canModify": true | false
    }
  ]
}

Some arguments can be modified by users in the resulting wizard. For example, the name of an application may be a field that the user should be able to edit.

create_artifact

Results in a call to http://docs.cdap.io/cdap/current/en/reference-manual/http-restful-api/artifact.html#add-an-artifact

name	description	required?	default
name	artifact name	yes
jar	name of jar file in package archive	yes
archivelink	link to download 3rd party archive	no	none
archivesig	link to get 3rd party archive signature	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
parents	artifact parents to pass as Artifact-Extends header	no	none
plugins	artifact plugins to pass as Artifact-Plugins header	no	none

create_app

Results in a call to http://docs.cdap.io/cdap/current/en/reference-manual/http-restful-api/lifecycle.html#create-an-application

name	description	required?	default
name	app name	yes
artifact	scope, name, version of the artifact to create the app with	yes
config	app config (file in the package archive)	no	empty

create_stream

Results in a call to http://docs.cdap.io/cdap/current/en/reference-manual/http-restful-api/stream.html#creating-a-stream

Depending on the arguments, subsequent calls to http://docs.cdap.io/cdap/current/en/reference-manual/http-restful-api/stream.html#getting-and-setting-stream-properties (to set format, schema, ttl)

and http://docs.cdap.io/cdap/current/en/reference-manual/http-restful-api/stream.html#sending-events-to-a-stream-in-batch (load data into a stream) may be made.

name	description	required?	default
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
name	dataset name	yes
type	dataset type	yes
description	dataset description	no	empty
properties	json map of dataset properties	no	empty

create_hydrator_draft

Results in whatever the UI does to create a draft

name	description	required?
name	pipeline name	yes
artifact	scope, name, version of the artifact to create the app with	yes
config	pipeline config (file in the package archive)	yes

Dependencies

Packages will only be able to specify dependencies on the CDAP version, as well as dependencies on the existence of specific CDAP entities. For example, the core-plugins-1.5.0 package requires that there exist system artifacts cdap-data-pipeline-4.0.0 and cdap-data-streams-4.0.0 in the CDAP instance.

{
  ...
  "dependencies": {
    "cdap": {
      "minVersion": "4.0.0",
      "maxVersion": "4.1.0"
    },
    "artifacts": [
      { 
        "scope": "system",
        "name": "spark-plugins",
        "minVersion": "1.5.0",
        "maxVersion": "1.6.0"
      },
      ...
    ],
    "streams": [
      { "name": "smsTexts" }
    ],
    "datasets": [
      { "name": "spamTexts" }
    ]
  }
}

Min versions are inclusive and max versions are exclusive.

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 retry.

Architecture

There will be a set of marketplace APIs that the UI will use to get groups, packages, package versions, icons, and package tarballs. There will be a market server that powers these APIs. The server will use a set of internal storage interfaces that define how to read the information required by the APIs. We can start with a storage implementation that simply reads from local files, and perhaps another storage implementation that reads from cloud storage like S3.

The market server will be stateless, so a load balancer can be placed in front of it to ensure that it is highly available and to ensure that it can handle a high volume of requests

File Store

The first implementation of the storage layer can simply be a store that looks at a filesystem for files containing the relevant information. The File Store will expect a specific directory structure:

<base dir>/<group>/icon.jpg
<base dir>/<group>/meta.json
<base dir>/<group>/<package>/<version>/spec.json
<base dir>/<group>/<package>/<version>/icon.jpg
<base dir>/<group>/<package>/<version>/archive.tgz
 
ex:
/opt/cdap/marketplace/examples/icon.jpg
/opt/cdap/marketplace/examples/meta.json
/opt/cdap/marketplace/examples/PurchaseExample/4.0.1/archive.tgz
/opt/cdap/marketplace/examples/PurchaseExample/4.0.1/spec.json
/opt/cdap/marketplace/examples/PurchaseExample/4.0.1/icon.jpg
/opt/cdap/marketplace/examples/PurchaseExample/4.0.0/archive.tgz
/opt/cdap/marketplace/examples/PurchaseExample/4.0.0/spec.json
/opt/cdap/marketplace/examples/PurchaseExample/4.0.0/icon.jpg

On start up, the server will scan the base directory, load relevant information into memory, and simply serve data based on the contents of the files. This would also let ops teams manage the marketplace through use of 'group' packages and 'cask package' packages.

Note: with such little logic in the server, why bother having a server at all? Why not just stick an Apache server in front of files or serve directly from S3? The assumption is that we will need to add more complicated functionality in the future, such as APIs to add groups and packages, ability to search for packages by various fields, etc.

Example Use Cases

Scenario 1: Add a draft of a SFDC Lead Dump Hydrator pipeline

When the user clicks on the '+' button, the UI makes a call:

GET /groups
[
  {
    "name": "examples",
    "label": "Examples",
    "description": "Example applications to get started with CDAP."
  },
  {
    "name": "hydrator-pipelines",
    "label": "Hydrator Pipelines",
    "description": "Templates of various Hydrator pipelines."
  },
  ...
]

to display all the different types of things the user can add in the CDAP marketplace. Among that list is 'Hydrator Pipelines', which the user clicks on. The UI makes another call to list the packages in the 'Hydrator Pipelines' group:

GET /groups/hydrator-plugins/packages
[
  ...,
  {
    "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."
  },
  ...
]

Among that list is the 'SFDC Lead Dump' package, which the user clicks on. The UI makes a call to get all versions of that package:

GET /groups/hydrator-plugins/packages/sfdc-lead-dump/versions
[
  {
    "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": [
      "fixed a small parsing bug"
    ],
    "dependencies": {
      "cdap": {
        "minVersion": "4.0.0",
        "maxVersion": "4.1.0"
      }
    }
  },
  ...
]

It defaults to the most recent version that is compatible with the version of CDAP that is running. The user decides to install the package, so the UI makes a call to get the package spec:

GET /groups/hydrator-pipelines/packages/sfdc-lead-dump/versions/1.0.1/spec
{
  "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": [
    "fixed a small parsing bug"
  ],
  "actions": [
    {
      "type": "create_artifact",
      "arguments": [
        {
          "name": "scope",
          "value": "user",
          "canModify": false
        },
        {
          "name": "name",
          "value": "sfdc-plugins",
          "canModify": false
        },
        {
          "name": "version",
          "value": "1.0.0",
          "canModify": false
        },
        {
          "name": "parents",
          "value": "system:cdap-data-pipeline[4.0.0,4.1.0)",
          "canModify": false
        },
        {
          "name": "jar",
          "value": "sfdc-plugins.jar", // file in the archive
          "canModify": false
        }
      ]
    },
    {
      "type": "create_hydrator_draft",
      "arguments": [
        {
          "name": "artifact",
          "value": {
            "scope": "system",
            "name": "cdap-data-pipeline",
            "version": "4.0.0"
          },
          "canModify": false
        },
        {
          "name": "name",
          "value": "SFDC Lead Dump",
          "canModify": true
        },
        {
          "name": "config",
          "value": "sfdc.json", // file in the archive
          "canModify": false
        }
      ]
    }
  ]
}

The UI also fetches the spec signature and uses the public key to validate the spec:

GET /groups/hydrator-pipelines/packages/sfdc-lead-dump/versions/1.0.1/spec.asc

The UI also fetch the package archive and signature. It validates the package, and writes the archive to a local temporary directory so that it can use its resources to create the plugins artifact and create the hydrator draft

GET /groups/hydrator-pipelines/packages/sfdc-lead-dump/versions/1.0.1/archive.tgz
GET /groups/hydrator-pipelines/packages/sfdc-lead-dump/versions/1.0.1/archive.tgz.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 draft.

Scenario 7: Add MySQL jdbc driver as a Hydrator plugin.

When the user clicks on the '+' button, the UI makes a call:

GET /groups
[
  {
    "name": "examples",
    "label": "Examples",
    "description": "Example applications to get started with CDAP."
  },
  {
    "name": "hydrator-plugins",
    "label": "Hydrator Plugins",
    "description": "Plugins for Hydrator Pipelines."
  },
  ...
]

to display all the different types of things the user can add in the CDAP marketplace. Among that list is 'Hydrator Plugins', which the user clicks on. The UI makes another call to list the packages in the 'Hydrator Plugins' group:

GET /groups/hydrator-plugins/packages
[
  ...,
  {
    "name": "mysql-jdbc-driver",
    "label": "MySQL JDBC Driver",
    "description": "JDBC Driver for MySQL databases.",
    "author": "MySQL",
    "org": "Oracle"
  },
  ...
]

Among the list is the MySQL JDBC Driver, which the user clicks on. The UI makes a call to get all versions of that package:

GET /groups/hydrator-plugins/packages/mysql-jdbc-driver/versions
[
  {
    "name": "mysql-jdbc-driver",
    "label": "MySQL JDBC Driver",
    "description": "JDBC Driver for MySQL databases.",
    "author": "MySQL",
    "org": "Oracle",
    "version": "5.1.39",
    "created": 1234567899,
    "changelog": [ ],
    "dependencies": { }
  },
  ...
]

The user decides to install the 5.1.38 version of the driver. The UI makes a call to get the spec, and to get the spec signature to make sure it is valid:

GET /groups/hydrator-plugins/packages/mysql-jdbc-driver/versions/5.1.39/spec.asc
GET /groups/hydrator-plugins/packages/mysql-jdbc-driver/versions/5.1.39/spec
{    
  "name": "mysql-jdbc-driver",
  "label": "MySQL JDBC Driver",
  "description": "JDBC Driver for MySQL databases.",
  "author": "MySQL",
  "org": "Oracle",
  "version": "5.1.39",
  "created": 1234567899,
  "actions": [
    {
      "type": "create_artifact",
      "arguments": [
        {
          "name": "scope",
          "value": "user",
          "canModify": false
        },
        {
          "name": "name",
          "value": "mysql-connector-java",
          "canModify": false
        },
        {
          "name": "version",
          "value": "5.1.39",
          "canModify": false
        },
        {
          "name": "parents",
          "value": "system:cdap-data-pipeline[3.0.0,10.0.0]/system:cdap-data-streams[3.0.0,10.0.0]",
          "canModify": false
        },
        {
          "name": "jar",
          "value": "mysql-connector-java-5.1.39-bin.jar", // file in the archive
          "canModify": false
        },
        {
          "name": "archivelink"
          "value": "https://dev.mysql.com/downloads/file/?id=462849",
          "canModify": false
        },
        {
          "name": "archivesig",
          "value": "https://dev.mysql.com/downloads/gpg/?file=mysql-connector-java-5.1.39.tar.gz"
        }
        {
          "name": "plugins",
          "value": {
            "parents": [ "cdap-data-pipeline[3.0.0,10.0.0]" ],
            "plugins": [
              {
                "name" : "mysql",
                "type" : "jdbc",
                "className" : "com.mysql.jdbc.Driver",
                "description" : "Plugin for MySQL JDBC driver"
              }
            ]
          },
          "canModify": false
        }
      ]
    }
  ]
}

The UI then makes calls to get the archive and its signature to validate the archive, and unpack 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.

GET /groups/hydrator-plugins/packages/mysql-jdbc-driver/versions/5.1.38/archive.tgz.asc
GET /groups/hydrator-plugins/packages/mysql-jdbc-driver/versions/5.1.38/archive.tgz

Cask Market Design

Mocks

Terminology

APIs

List Groups

Get Group Icon

List Packages in a Group

Get Package Icon

List Package Versions

Get Package Archive

Get Package Archive Signature

Get Package Spec

Get Package Spec Signature

Security

Package Spec

Action Spec

create_artifact

create_app

create_stream

create_dataset

create_hydrator_draft

Dependencies

Failures

Architecture

File Store

Example Use Cases