General provisions

The DataService web service of bpm'online is a RESTful (Representational State Transfer, REST) service. RESTful data management interface does not require converting data to an external format, such as XML. In a simple RESTful service, each information unit is determined by a global Identifier such as URL. Each URL, in its turn, has a strictly specified format. This is not an optimal way to transfer large arrays of data.

With the use of the DataService, the data can be automatically configured in various data formats such as XML, JSON, HTML, CSV, and JSV. The data structure is determined by data contracts. A complete list of data contracts used by the DataService, can be found in the "DataService web service" article.

SelectQuery data contract

The SelectQuery data contract is used for reading section records. The query data is transferred to DataService via HTTP, with the help of POST by the following URL:

// URL format of the POST query to read data from DataService.
http(s)://[Bpm'online application address]/[Configuration number]/dataservice/[Data fromat]/reply/SelectQuery
// URL example of the POST query to read data from DataService.
http(s)://example.bpmonline.com/0/dataservice/json/reply/SelectQuery

The SelectQuery data contract has a complex hierarchical structure with a number of nesting levels. In the bpm'online server core, it is represented by a SelectQuery class of theTerrasoft.Nui.ServiceModel.DataContract namespace of the Terrasoft.Nui.ServiceModel.dll library of classes. The hierarchical data structure of the SelectQuery data contract can be conveniently viewed in JSON format:

{
    "RootSchemaName":"[Object root schema name]",
    "OperationType":[Type of record operation],
    "Columns":{
        "Items":{
            "Name":{
                "OrderDirection":[Sorting order],
                "OrderPosition":[Column position],
                "Caption":"[Title]",
                "Expression":{
                    "ExpressionType":[Expression type],
                    "ColumnPath":"[Path to column]",
                    "Parameter":[Parameter],
                    "FunctionType":[Function type],
                    "MacrosType":[Macro type],
                    "FunctionArgument":[Function argument],
                    "DatePartType":[Type of date part],
                    "AggregationType":[Aggregation type],
                    "AggregationEvalType":[Aggregation scope],
                    "SubFilters":[Buit-in filters]
                }
            }
        }
    },
    "AllColumns":[Indicates that all columns are selected],
    "ServerESQCacheParameters":{
        "CacheLevel":[Caching level],
        "CacheGroup":[Caching group],
        "CacheItemName":[Record key in repository]
    },
    "IsPageable":[Indicates page-by-page],
    "IsDistinct":[Indicates uniqueness],
    "RowCount":[Number of selected records],
    "ConditionalValues":[Conditions for building a pageable query],
    "IsHierarchical":[Indicates hierarchical data selection],
    "HierarchicalMaxDepth":[Maximum nesting level of the hierarchical query],
    "HierarchicalColumnName":[Column name used to create hierarchical query],
    "HierarchicalColumnValue":[Initial value of hierarchical column],
    "Filters":[Filters]
    }
}

Primary properties of the SelectQuery class and their possible values are available in table 1.

Table 1. SelectQuery class properties

The SelectQueryColumns class has a single Items property, defined as a collection of keys and values Dictionary<string, SelectQueryColumn>. The key is the string with the name of the added column. The value is an instance of the SelectQueryColumn class, defined in the Terrasoft.Nui.ServiceModel.DataContract name space. The properties of the SelectQueryColumn are available in the table 2.

Table 2. SelectQueryColumn class properties

The ColumnExpression class defines expression that sets the type of the schema column. The class is defined in the Terrasoft.Nui.ServiceModel.DataContract name space of the Terrasoft.Nui.ServiceModel library. The properties of an instance of this class are filled in depending on the ExpressionType property, which sets the expression type. The full list of the ColumnExpression class properties is available in table 3.

Table 3. Primary properties of the ColumnExpression class

The Parameter class is defined in the Terrasoft.Nui.ServiceModel.DataContract name space. Its properties are available in table 4.

Table 4. Parameter class properties

The ServerESQCacheParameters class is defined in the Terrasoft.Nui.ServiceModel.DataContract name space. Its properties are available in table 5.

Table 5. ServerESQCacheParameters class properties

The Filters class is defined in the Terrasoft.Nui.ServiceModel.DataContract name space. For details on the properties of this class and its use, please see the "DataService. Data filtering" article.

See Also