Microservices Introduction

Microservices Conventions

In this API, client refers to an external application that is calling CDAP using the HTTP interface. application refers to a user application that has been deployed into CDAP.

Base URL

All URLs referenced in these APIs have this base URL:

http://<host>:<port>

where:

Parameter	Description

Parameter	Description
`host`	Host name of the CDAP server.
`port`	Port set as the `router.bind.port` in `cdap-site.xml` (default: 11015).

Note: If SSL is enabled for CDAP, then the base URL uses https instead and port becomes the port that is set as the router.ssl.server.port in cdap-site.xml (default: 10443).

In this API, each endpoint is documented with the HTTP method for the request and a resource identifier. The base URL is assumed to precede each API's resource identifier. For example, the endpoint documentation for creating an application is:

PUT /v3/namespaces/<namespace-id>/apps/<app-id>

This means you would use:

PUT http://<host>:<port>/v3/namespaces/<namespace-id>/apps/<app-id>

If you are using the CDAP Sandbox, running on your local machine, you might make a curl call such as:

Linux:

Windows:

Variable Replacement

Text that are variables that you are to replace is indicated by a series of angle brackets (< >). For example:

indicates that text such as <namespace-id> and <app-id> are variables and that you are to replace them with your values, perhaps in this case the namespace default and the application myapp:

Reserved and Unsafe Characters

In path parameters, reserved and unsafe characters must be replaced with their equivalent percent-encoded format, using the "%hh" syntax, as described in RFC3986: Uniform Resource Identifier (URI): Generic Syntax.

In general, any character that is not a letter, a digit, or one of $-_.+!*'() should be encoded.

See the section on Path Parameters for suggested approaches to encoding parameters.

Additionally, there are further restrictions on the characters used in certain parameters such as namespaces.

Names and Characters for Namespace Identifiers

Namespaces have a limited set of characters allowed in their identifier; they are restricted to letters (a-z, A-Z), digits (0-9), hyphens (-), and underscores (_). There is no size limit on the length of a namespace identifier nor on the number of namespaces.

The three namespaces cdap, default, and system are reserved. The cdap and system namespaces cannot be used by users directly. The default namespace, however, can be used by anyone.

All reserved namespaces cannot be deleted.

Microservices Status Codes

Common status codes returned for all HTTP calls:

Code	Description	Explanation

Code	Description	Explanation
`200`	`OK`	The request returned successfully.
`400`	`Bad Request`	The request had a combination of parameters that is not recognized.
`401`	`Unauthorized`	The request did not contain an authentication token; see the section below on Working with CDAP Security.
`403`	`Forbidden`	The request was authenticated but the client does not have permission; requests can fail due to a lack of privilege, as described in the section below on “Working with CDAP Security”.
`404`	`Not Found`	The request did not address any of the known URIs.
`405`	`Method Not Allowed`	A request was received with a method not supported for the URI.
`409`	`Conflict`	A request could not be completed due to a conflict with the current resource state.
`500`	`Internal Server Error`	An internal error occurred while processing the request.
`501`	`Not Implemented`	A request contained a query that is not supported by this API.

Note: These returned status codes are not necessarily included in the descriptions of the APIs, but a request may return any of these.

Working with CDAP Security

When working with a CDAP cluster with security enabled (security.enabled=true in cdap-site.xml), all calls to the HTTP RESTful APIs must be authenticated. Clients must first obtain an access token from the authentication server (see Client Authentication). In order to authenticate, all client requests must supply this access token in the Authorization header of the request:
For CDAP-issued access tokens, the authentication scheme must always be Bearer.
When working with a CDAP cluster with authorization enabled (security.authorization.enabled=true in cdap-site.xml), all calls to the HTTP RESTful APIs must be authorized. Clients must be privileged, following the polices described in Authorization Policies.