Command Endpoint

The Automation HTTP / REST Service

The Nuxeo Automation Server module provides a REST API to execute operations on a Nuxeo server.

To use the Automation REST service you need to know the URL where the service is exposed, and the different formats used by the service to exchange information. All the other URLs that appear in the content exchanged between the client and server are relative paths to the Automation service URL.

You can discover the Command Endpoint by playing live on the Nuxeo Platform API Playground, in the Command section.

Operations context and parameters as well as response objects (documents) are formatted as JSON objects. To transport blobs, HTTP multipart requests should be used to attach blob binary data along with the JSON objects describing the operation request.

The REST service is bound to the http://<host>/nuxeo/site/automation path. To get the service description you should do a GET on the service URL using an Accept type of application/json+nxautomation. You will get in response the service description as a JSON document. This document will contain the list of available operations and chains, as well as the URLs for other optional services provided (like login or document type service).

By default all the chains and operations that are not UI related are accessible through REST. Anyway you can filter the set of exposed operations and chains or protect them using security rules. For more details on this see Filtering Exposed Operations.

Example - Getting the Automation Service.

Let say the service is bound to http://NUXEO_SERVER/nuxeo/site/automation. Then to get the service description you should do:

GET http://localhost:8080/nuxeo/site/automation
Accept: application/json+nxautomation

You will get response a JSON document like:

HTTP/1.1 200 OK
Content-Type: application/json+nxautomation

{
  "paths": {"login" : "login"},
  "operations": [
      "id" : "Blob.Attach",
      "label": "Attach File",
      "category": "Files",
      "description": "Attach the input file to the document given as a parameter. If the xpath points to a blob list then the blob is appended to the list, otherwise the xpath should point to a blob property. If the save parameter is set the document modification will be automatically saved. Return the blob.",
      "url": "Blob.Attach",
      "signature": [ "blob", "blob" ],
      "params": [
         {
           "name": "document",
            "type": "document",
            "required": true,
            "values": []
         },
         {
           "name": "save",
           "type": "boolean",
           "required": false,
           "values": ["true"]
         },
         {
           "name": "xpath",
           "type": "string",
           "required": false,
           "values": ["file:content"]
         }
      ]
  // ... other operations follow here
  ],
  "chains" : [
    // a list of operation chains (definition is identical to regular operations)
  ]
}

You can see the automation service is returning the registry of operations and chains available on the server.

Each operation and chain signature is fully described to be able to do operation validation on client side, for instance. Also some additional information that can be used in an UI is provided (operation label, full description, operation category etc.).

The url property of an operation (or automation chain) is the relative path to use to execute the operation. For example if the service URL is http://NUXEO_SERVER/nuxeo/site/automation and the Blob.Attach operation has the url Blob.Attach then the full URL to that operation will be: http://NUXEO_SERVER/nuxeo/site/automation/Blob.Attach.

The paths property is used to specify various relative paths (relative to the automation service) of services exposed by the automation server. In the above example you can see that the "login" service is using the relative path "login".

This service can be used to sign-in and check if the username/password is valid. To use this service you should do a POST to the login URL (e.g. http://NUXEO_SERVER/nuxeo/site/automation/login) using basic authentication. If authentication fails you will receive a 401 HTTP response. Otherwise the 200 code is returned.

The login service can be used to do (and check) a user login. Note that WWW-Authenticate server response is not yet implemented so you need to send the basic authentication header in each call if you are not using cookies (in that case you only need once to authenticate - for example using the login service).

Executing Operations

The operations registry (loaded doing a GET on the Automation service URL) contains the entire information you need to execute operations.

To execute an operation you should build an operation request descriptor and post it on the operation URL. When sending an operation request you must use the application/json+nxrequest content type (application/json since 5.9.5 is allowed as well). Also you need to authenticate your request (using basic authentication) since most of the operations are accessing the Nuxeo repository.

An operation request is a JSON document having the following format:

  input: "the_operation_input_object_reference",
  params: {key1: "value1", key: "value2", ...},
  context: {key1: "val1", ... }

All these three request parameters are optional and depend on the executed operation.

• If the operation has no input (a void operation) then the input parameter can be omitted.
• If the operation has no parameters then params can be omitted.
• If the operation does not want to push some specific properties in the operation execution context then context can be omitted. In fact context parameters are useless for now but may be used in future.

The input parameter is a string that acts as a reference to the real object to be used as the input. There are four types of supported inputs: void, document, document list, blob, blob list.

• To specify a "void" input (i.e. no input) you should omit the input parameter.
• To specify a reference to a document you should use the document absolute path or document UID prefixed using the string doc:. Example: doc:/default-domain/workspaces/myworkspace or doc:96bfb9cb-a13d-48a2-9bbd-9341fcf24801
• To specify a reference to a list of documents you should use a comma separated list of absolute document paths, or UID prefixed by the string docs:. Example: docs:/default-domain/workspaces/myworkspace, 96bfb9cb-a13d-48a2-9bbd-9341fcf24801.
• When using blobs (files) as input you cannot refer them using a string locator since the blob is usually a file on the client file system or raw binary data. For example, let say you want to execute the Blob.Attach operation that takes as input a blob and set it on the given document (the document is specified through 'params'). Because the file content you want to set is located on the client computer, you cannot use a string reference. In that case you MUST use a multipart/related request that encapsulate as the root part your JSON request as an application/json+nxrequest content and the blob binary content in a related part.
• In case you want a list of blobs as input then you simply add one additional content part for each blob in the list. The only limitation (in both blob and blob list case) is to put the request content part as the first part in the multipart document. The order of the blob parts will be preserved and blobs will be processed in the same order (the server assumes the request part is the first part of the multipart document - e.g. Content-Ids are not used by the server to identify the request part).

Example 1 - Invoking A Simple Operation

POST /nuxeo/site/automation/Document.Fetch HTTP/1.1
Accept: application/json+nxentity, */*
Content-Type: application/json+nxrequest; charset=UTF-8
Authorization: Basic QWRtaW5pc3RyYXRvcjpBZG1pbmlzdHJhdG9y
Host: localhost:8080

{"params":{"value":"/default-domain/workspaces/myws/file"},"context":{}}

This operation will return the document content specified by the value parameter.

Example 2 - Invoking An Operation Taking a Blob as Input

Here is an example on invoking Blob.Attach operation on a document given by its path (/default-domain/workspaces/myws/file in our example).

POST /nuxeo/site/automation/Blob.Attach HTTP/1.1
Accept: application/json+nxentity, */*
Content-Type: multipart/related;
    boundary="----=_Part_0_130438955.1274713628403"; type="application/json+nxrequest"; start="request"
Authorization: Basic QWRtaW5pc3RyYXRvcjpBZG1pbmlzdHJhdG9y
Host: localhost:8080

------=_Part_0_130438955.1274713628403
Content-Type: application/json+nxrequest; charset=UTF-8
Content-Transfer-Encoding: 8bit
Content-ID: request
Content-Length: 75

{"params":{"document":"/default-domain/workspaces/myws/file"},"context":{}}

------=_Part_0_130438955.1274713628403
Content-Type: image/jpeg
Content-Transfer-Encoding: binary
Content-Disposition: attachment; filename=test.jpg
Content-ID: input

[binary data comes here]

------=_Part_0_130438955.1274713628403--

In both examples you can see that the following Accept header is used: Accept: application/json+nxentity, **/**.

This header is important since is is specifying that the client accept as a response either a JSON encoded entity, either a blob that may have any type (in case of blob download). The application/json+nxentity is the first content type to help the server choose the format of the response when returning an encoded object.

Operation Execution Response

An operation can have one of the following output types:

• document: A repository document;
• documents: A list of documents;
• blob: A blob (binary content usually attached to a document);
• blobs: A list of blobs;
• void: The operation has no output (output is void).

Apart from these possible outputs, the operation can abort due to an exception.

All these cases are represented using the following HTTP responses:

• document  -> A JSON object describing the document is returned. The used Content-Type is application/json+nxentity
• documents -> a JSON object describing the document list is returned. The used Content-Type is application/json+nxentity
• blob -> The blob raw content is returned. The used Content-Type will be the same as the blob mime-type.
• blobs -> A Multipart/Mixed content is returned. Each part will be a blob from the list (order is preserved). Each part will use the right Content-Type as given by the blob mime-type.
• void -> HTTP 204 is returned. No content and no Content-Type is returned.
• exception -> A status code > 400 is returned and the content will be the server exception encoded as a JSON object. The used Content-Type is application/json+nxentity.

When an exception occurs, the server tries to return a meaningful status code. If no suitable status code is found, a generic 500 code (server error) is used.

You noticed that each time when returned objects are encoded as JSON objects, the application/json+nxentity Content-Type will be used. We also saw that only document, documents and exception objects are encoded as JSON.

Here we will discuss the JSON format used to encode these objects.

Document

A JSON document entity contains the minimal required information about the document as top level entries.

These entries are always set on any document and are using the following keys:

• uid: The document UID;
• path: The document path (in the repository);
• type: The document type;
• state: The current life cycle state;
• title: The document title;
• lastModifed: The last modified timestamp.

All the other document properties are contained within a "properties" map using the property XPath as the key for the top level entries.

Complex properties are represented as embedded JSON objects and list properties as embedded JSON arrays.

Example of a JSON document entry:

{
  "entity-type": "document",
  "uid": "96bfb9cb-a13d-48a2-9bbd-9341fcf24801",
  "path": "/default-domain/workspaces/myws/file",
  "type": "File",
  "state": "project",
  "title": "file",
  "lastModified": "2010-05-24T15:07:08Z",
  "properties":   {
    "uid:uid": null,
    "uid:minor_version": "0",
    "uid:major_version": "1",
    "dc:creator": "Administrator",
    "dc:contributors": ["Administrator"],
    "dc:source": null,
    "dc:created": "2010-05-22T08:42:56Z",
    "dc:description": "",
    "dc:rights": null,
    "dc:subjects": [],
    "dc:valid": null,
    "dc:format": null,
    "dc:issued": null,
    "dc:modified": "2010-05-24T15:07:08Z",
    "dc:coverage": null,
    "dc:language": null,
    "dc:expired": null,
    "dc:title": "file",
    "files:files": [],
    "common:icon": null,
    "common:icon-expanded": null,
    "common:size": null,
    "file:content":     {
      "name": "test.jpg",
      "mime-type": "image/jpeg",
      "encoding": null,
      "digest": null,
      "length": "290096",
      "data": "files/96bfb9cb-a13d-48a2-9bbd-9341fcf24801?path=%2Fcontent"
    },
    "file:filename": null
  }

The top level properties title and lastModified have the same value as the corresponding embedded properties dc:title and dc:modified.

Documents

The documents JSON entity is a list of JSON document entities and have the entity type documents. The documents in the list are containing only the required top level properties.

Example:

{
  entity-type: "documents"
  entries: [
   {
     "entity-type": "document",
     "uid": "96bfb9cb-a13d-48a2-9bbd-9341fcf24801",
     "path": "/default-domain/workspaces/myws/file",
     "type": "File",
     "state": "project",
     "title": "file",
     "lastModified": "2010-05-24T15:07:08Z",
   },
   ...
   ]
 }

Exception

JSON exception entities have a exception entity type and contain information about the exception, including the server stack trace.

Example:

{
  "entity-type": "exception",
  "type": "org.nuxeo.ecm.automation.OperationException",
  "status": 500,
  "message": "Failed to execute operation: Blob.Attach",
  "stack": "org.nuxeo.ecm.automation.OperationException: Failed to invoke operation Blob.Attach\n\tat org.nuxeo.ecm.automation.core.impl.InvokableMethod.invoke(InvokableMethod.java:143)\n\t ..."
}

Document Property Types

Here you can find more details on the JSON document entity format.

• A document entity is using a string value for any scalar property value.
• Dates are encoded as W3C dates (in UTC timezone)
• Apart from strings, you may have null values for properties that are not set (but are defined by the schema), JSON objects (maps) for complex properties, and JSON arrays for array or list properties.
• Blob data is encoded as a relative URL (relative to Automation service URL) from where you can download the raw data of the blob (using a GET request on that URL).

Property values can be of one of these types:

• string
• long: Encoded as a string representation of the number (in Java: Long.toString());
• double: Encoded as a string representation of the number (in Java: Double.toString());
• date: Encoded as a W3C format (UTC timezone preferred);
• boolean: "true" or "false"; For null values the JSON null keyword is used.

Operation Request Parameters

Here you can find more details about the request format.

Request input

As we seen a request may have as input:

• A document,
• A list of documents,
• A blob,
• A list of blobs.

To refer to a document you should use either the absolute path of the document (starting with '/' !) or the document UID. Examples:

• input: "/" -> to refer to the repository root
• input: "/default-domain/workspaces/ws" -> to refer to the 'ws' workspace
• input: "96bfb9cb-a13d-48a2-9bbd-9341fcf24801" -> to refer to a document havin this UID.

To refer to a list of documents, you must use a comma separated list of document identifiers. Example: input: "/default-domain/workspaces/ws, 96bfb9cb-a13d-48a2-9bbd-9341fcf24801"

When using a blob as the input of an operation, you cannot use the "input" request property since the blob may contain binary data. In that case you must use a Multipart/Related request as described above and put the blob raw data in the second body part of the request.

To use a list of blobs as the input, you should use the same method as for a single blob, and put each blob in the list in a separate body part. Note that the order of the body parts is important: blobs will be processed in the same order that they appear in the Multipart document.

Also, when using Multipart/Related requests you must always put the JSON encoded request in the first body part.

Request parameter types

The operation parameters specified inside the params property of the request are all strings. Operation parameters are typed, so on the server side the operation will know how to decode parameters in real Java classes. The supported parameter types are: string, long (integer number), double (floating point number), date, properties, document, documents, EL expression, EL template.

Here are some rules on how to encode operation parameters:

• string: Let it as is.
• long: Just use a string representation of the number (in Java Long.toString()).
• double: Just use a string representation of the number (in Java Double.toString()).
• date: Use the W3C format (UTC timezone preferred).
• boolean: "true" or "false".
• document: Use the document UID or the absolute document path.
• documents: Use a comma separated list of document references.
• EL expression: put the expr: string before your EL expression. (E.g. expr: Document.path).
• EL template: put the expr: string before your template. (E.g. expr: SELECT * FROM Document WHERE dc:title=@{my_var})

Note that expressions also you specify relative paths (relative to the context document) using expr: ./my/doc.

In fact all these encoding rules are the same as the one you can use when defining operation chains in Nuxeo XML extensions.

Operation vs. Transactions

The server runs an operation or operation chain in a single transaction. A rollback is done if the operation execution caused an exception.

The transaction is committed when the operation (or operation chain) successfully terminated.

Operations can be executed in two different contexts: either in the context of a stateful repository session, either one session per operation.

By default operations are reusing the same session if your client supports cookies (even in basic authentication).

To enable stateless sessions, you need to modify some Nuxeo configuration. This will not be explained here (TODO: add link). In stateless mode the session is closed at the end of the request.

Note that Automation service is using Nuxeo WebEngine for HTTP request management.

Operation Security

Some operations are allowed to be executed only by some users or groups. This is defined on the server side through Nuxeo XML extensions.

See Filtering Exposed Operations for more details.