jueves, 17 de septiembre de 2015

JSON Web Services

Legacy:JSON Web Service

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1 Overview

The ability to describe sets of data in JSON format is a natural extension to the JavaScript language. ServiceNow supports a web service interface that operates on the JSON object as the data input and output format.
Note: The JSON Web Service feature is replaced by JSONv2 starting with the Dublin release.

The JSON web service is provided by a platform-level processor similar to the services for SOAPWSDLCSV, Excel, and XML. Like those services, the JSON service is triggered by the standalone JSON URL parameter. For example:
https://<instance name>.service-now.com/mytable.do?JSON
Having the JSON object available as a data format for web services means that you can create (insert), update, and query any data in the ServiceNow platform using the JSON object format, and get results in the JSON object format.

1.1 Security

Like all other HTTP-based web services available on the platform, the JSON web service is required to authenticate using basic authentication by default. The user ID that is used for authentication is subjected to access control in the same way as an interactive user.

2 Activating the Plugin

An administrator must activate the JSON Web Service plugin to configure a JSON web service.

3 JSON Object Format

The JSON object is built in two structures:
  • A collection of name/value pairs. In various languages, this is realized as an object, record, struct, dictionary, hash table, keyed list, or associative array.
  • An ordered list of values. In most languages, this is realized as an array, vector, list, or sequence.

In its simplest form, a JSON object is just a comma delimited set of name/value pairs. For example:
{"name one":"value one","name two":"value two"}
The following is a sample of a single record array of incidents in JSON:
    "__status": "success",
    "sla_due":"2010-03-04 22:51:49",
    "opened_at":"2010-02-23 22:51:49",
    "sys_updated_on":"2010-02-23 22:51:49",
    "sys_meta":"System meta data",
    "sys_created_on":"2010-02-23 22:51:49",
    "approval":"not requested",
    "short_description":"this was inserted with python",
The following is a record array of incident responses with an error.
    "records": [
            "__error": {
                "message": "Invalid Insert into: incident",
                "reason": "Data Policy Exception:  Short description is mandatory "
            "__status": "failure",
            "active": "true",
            "activity_due": "",
            "approval": "not requested",
            "approval_history": "",
            "approval_set": "",
            "assigned_to": "",
            "assignment_group": "d625dccec0a8016700a222a0f7900d06",
            "business_duration": "",
            "business_stc": "",
            "calendar_duration": "",
            "calendar_stc": "",
            "caller_id": "",
            "category": "inquiry",
            "caused_by": "",
            "child_incidents": "0",
            "close_code": "",
            "close_notes": "",
            "closed_at": "",
            "closed_by": "",
            "cmdb_ci": "",
            "comments": "",
            "comments_and_work_notes": "",
            "company": "",
            "contact_type": "phone",
            "correlation_display": "",
            "correlation_id": "",
            "delivery_plan": "",
            "delivery_task": "",
            "description": "",
            "due_date": "",
            "escalation": "0",
            "expected_start": "",
            "follow_up": "",
            "group_list": "",
            "impact": "3",
            "incident_state": "1",
            "knowledge": "false",
            "location": "",
            "made_sla": "true",
            "notify": "1",
            "number": "INC0010001",
            "opened_at": "2013-07-23 18:01:17",
            "opened_by": "6816f79cc0a8016401c5a33be04be441",
            "order": "",
            "parent": "",
            "parent_incident": "",
            "priority": "5",
            "problem_id": "",
            "reassignment_count": "0",
            "reopen_count": "0",
            "resolved_at": "",
            "resolved_by": "",
            "rfc": "",
            "severity": "3",
            "short_description": "",
            "skills": "",
            "sla_due": "",
            "state": "1",
            "subcategory": "",
            "sys_class_name": "incident",
            "sys_created_by": "admin",
            "sys_created_on": "2013-07-23 18:01:17",
            "sys_domain": "global",
            "sys_id": "a96479343cb60100a92ec9a477ba9e45",
            "sys_mod_count": "0",
            "sys_updated_by": "admin",
            "sys_updated_on": "2013-07-23 18:01:17",
            "time_worked": "",
            "upon_approval": "proceed",
            "upon_reject": "cancel",
            "urgency": "3",
            "user_input": "",
            "watch_list": "",
            "work_end": "",
            "work_notes": "",
            "work_notes_list": "",
            "work_start": ""

3.1 Response Status

In both of the code samples, the JSON object returned elements that describe the status of the GlideRecord response and whether the response included an error.

3.1.1 status

The status element uses this syntax:
"__status": "<value>",
where <value> is success or failure.
When the status element returns failure, the error element is added to identify the error and reason.

3.1.2 error

The error element uses this syntax:
"__error": {
:"message": "<error value>",
:"reason": "<reason value> "
where <error value> is the error message text and <reason value> is the reason the error was triggered.

4 Setting the Number of Rows Returned

The following system property controls how many rows JSON returns with each query.
glide.processor.json.row_limitSpecify the maximum number of rows a JSON query returns.
  • Type: integer
  • Default value: 250
  • Location: Add to the System Properties [sys_properties] table

5 Action Parameters

Action parameters are separate and different from data parameters because they specify the action to take when the JSON object parameter is POSTed or when it is part of an HTTP GET. The parameters can also be specified as a field in the supplied JSON object. They have the effect of triggering an action in the case of sysparm_action, or filtering the results of an update or query in the case of sysparm_query.

5.1 sysparm_action

Following are the valid values for sysparm_action and the corresponding actions triggered by the API.
Data Retrieval
Method SummaryDescription
getKeysQuery the targeted table using an encoded query string and return a comma delimited list of sys_id values.
getRecordsQuery the targeted table using an encoded query string and return all matching records and their fields.
getQuery a single record from the targeted table by specifying the sys_id in the sysparm_sys_id URL parameter, and return the record and its fields.

Data Modification
Method SummaryDescription
insertCreate one or more new records for the table targeted in the URL.
insertMultipleCreate multiple new records for the table targeted in the URL.
updateUpdate existing records for the table targeted in the URL, filtered by an encoded query string.
deleteRecordDelete one record from the table targeted in the URL by specifying the sys_id in the sysparm_sys_id URL parameter.
deleteMultipleDelete multiple records from the table targeted in the URL, filtered by an encoded query string.

5.2 sysparm_query

Specify an encoded query string to be used in getgetRecordsupdate or deleteMultiple sysparm_action values.

5.3 sysparm_view

Specify a form view to customize the return values for get and getRecords function calls. When a view is specified, the query returns only the fields defined in this view, including referenced values. If there is no view name, or if the view name is not valid, then the query returns all field names that are marked active in the dictionary.

5.4 sysparm_sys_id

Specify a target sys_id during a get or delete function call (sysparm_action value).

5.5 displayvariables

Set this boolean value to true during a get or getRecords function call to retrieve all variables attached to this record.

6 Data Retrieval API

You can query for data by issuing an HTTPS GET request to the platform. By default, a GET request is interpreted as a get function if a sysparm_sys_id parameter is present. Otherwise, it is interpreted as agetRecords function. You can also specify a URL parameter sysparm_action=get. Query responses are always encapsulated by a records hash of records, where each individual record's values are themselves hashed by field name.

6.1 Return Display Value for Reference Variables

When you are getting a record from a get or getRecords function, all the fields associated with that record are returned. The fields are often reference fields that contain a sys_id for another table. The base system behavior is to return the sys_id value for those fields. To have the display value for the field returned, use one of these options:
  • Add the property glide.json.return_displayValue to the system properties, and every JSON request will return a display value for a reference field.
  • Add the parameter displayvalue=true to the JSON request URL and JSON requests with that parameter will return a display value instead of the sys_id for a reference field. The JSON request URL would look like this:
https://<instance name>.service-now.com/incident.do?JSON&sysparm_action=getRecords&sysparm_query=active=true^category=hardware&displayvalue=true
  • Add the parameter displayvalue=all to the JSON request URL, and JSON requests with that parameter will return a display value and the sys_id for a reference field. The response element name for the display value field will be prefixed with dv_, for example, dv_caller_id.

6.2 Return Display Variables

Use the displayvariables parameter to return an array of variables associated with a service catalog item record when using a get or getRecords function. The variables are expressed hierarchically. A variable container has the container's variables in its children field.
To get display variables, add the parameter displayvariables=true to the JSON request URL. The JSON request URL would look like this:
https://<instance name>.service-now.com/sc_req_item.do?JSON&sysparm_action=getRecords&
White space has been added to the following example for clarity:
"variables":[{"children":null,"name":"asset_tag","order":1300,"question_text":"Asset Tag","type":6,"value":""},
"name":"Test one","order":-1,"question_text":"Testing","type":0,"value":null},
{"children":null,"name":"","order":200,"question_text":"Please specify an operating system","type":3,"value":"Windows XP"},
{"children":[{"children":null,"name":"create_item","order":1000,"question_text":"Create an Inventory Item?","type":7,"value":""}],
{"children":null,"name":"serial_number","order":1100,"question_text":"Serial Number","type":6,"value":""},
{"children":null,"name":"hard_drive","order":100,"question_text":"What size hard drive do you want?","type":3,"value":"60 GB"},
{"children":null,"name":"name","order":1200,"question_text":"Name of new inventory item","type":6,"value":""},

6.3 Controlling the Order of Records

You can control the order that records appear in the JSON response. To set an order, use the ORDERBY or ORDERBYDESC clauses in the URL encoded query. For example,sysparm_query=active=true^ORDERBYnumber^ORDERBYDESCcategory filters all active records and orders the results in ascending order by number first, and then in descending order by category. For more information, see Listing Values in Order.

6.4 getKeys

Get the sys_id of multiple records by specifying an encoded query string in the sysparm_query parameter.
https://<instance name>.service-now.com/incident.do?JSON&sysparm_action=getKeys&sysparm_query=active=true^category=hardware

6.5 get

Get a record directly by specifying the sys_id in a sysparm_sys_id parameter.
https://<instance name>.service-now.com/incident.do?JSON&sysparm_sys_id=9d385017c611228701d22104cc95c371
Optionally, you may also specify the sysparm_action parameter:
https://<instance name>.service-now.com/incident.do?JSON&sysparm_action=get&sysparm_sys_id=9d385017c611228701d22104cc95c371

6.6 getRecords

Get all records by specifying an encoded query string in the sysparm_query parameter.
https://<instance name>.service-now.com/incident.do?JSON&sysparm_action=getRecords&sysparm_query=active=true^category=hardware

7 Data Modification API

To modify the JSON web service, issue an HTTPS POST request to the platform. The HTTP POST must contain a sysparm_action parameter indicating the type of action to be performed, with the incoming JSON object post in the body.
Note: The content-type of the POST should be application/json. It cannot be application/x-www-form-urlencoded or <tt?multipart/form-data</tt>.

7.1 insert

Create a new record in ServiceNow. The JSON object has to be POSTed as the body (content-type is usually application/json, although not enforced). The response from the record creation is a JSON object of the incident that was created.
For example, posting the following JSON object:
{"short_description":"this is a test","priority":"1"}
to the following URL:
https://<instance name>.service-now.com/incident.do?JSON&sysparm_action=insert
creates an incident.
Optionally, you may also specify the sysparm_action in the JSON object. The parameter inside the JSON object takes precedence over the URL parameter. For example:
{"sysparm_action":"insert","short_description":"this is a test","priority":"1"}

7.1.1 Inserting Multiple Records

To create multiple new records in ServiceNow, the input JSON object for the insert function must be an array. The response from the record creation is a JSON object of the incidents that were created. For example, the following JSON object posted to one the following URLs creates two incidents. Note the fields described as an array value for the records field.
{"records":[{"short_description":"this was inserted with python using JSON 1", "priority": "1 - Critical", "impact":"1", "caller_id":"Fred Luddy"},
            {"short_description":"this was inserted with python using JSON 2", "priority": "1 - Critical", "impact":"1", "caller_id":"Fred Luddy"}]}
https://<instance name>.service-now.com/incident.do?JSON&sysparm_action=insert
https://<instance name>.service-now.com/incident.do?JSON&sysparm_action=insertMultiple

7.2 update

Update a record or a list of records filtered by an encoded query string specified by the sysparm_query URL parameter. The JSON object has to be posted as the body (content-type is usually application/json, although not enforced). The response from the record creation is an array of JSON objects representing the records that were updated.
For example, posting the following JSON object:
{"short_description":"this was updated with python", "priority": "3", "impact":"1"}
to the following URL:
updates all incidents with priority 3, and sets the values specified by the JSON object.

7.3 deleteRecord

Delete a single record, identified by a sysparm_sys_id parameter, from the targeted table. The parameter may be encoded in the input JSON object or given as a URL parameter.
to the following URL:
deletes the incident record identified by the sys_id fd4001f80a0a0b380032ffa2b749927b.

7.4 deleteMultiple

Delete multiple records from the targeted table, filtered by an encoded query string specified in the sysparm_query URL parameter. The filter may also be encoded in the input JSON object.
{"sysparm_query":"short_description=this was updated with python"}
to the following URL:
deletes all incident records where the short_description field contains the value this was updated with python.
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