|Possibilities for the bpm'online integration over the OData protocol|
Glossary Item Box
Open Data (OData) protocol is an open web-protocol for requesting and updating data based on the REST architectural trekking using the Atom/XML and JSON standards .
The access to the bpm'online data and objects over the OData protocol may be received by any third-party application, which supports exchange with HTTP messages and may process XML or JSON data. In this case, data are available in the form of resources addressed over URI .
The access to data and its modification is implemented with the help of standard HTTP – GET, PUT/MERGE, POST and DELETE commands .
Using PUT and DELETE HTTP methods will cause “405 Method not allowed” error until WebDAV HTTP extension is switched off in application Web.Config.
Working over the OData has several features conditioned by the specifics of the REST approach :
- The application server does not store session status. All data required for a request processing is contained in the request itself .
- OData objects have the idempotence property. This means that a repeated action over an object does not modify the latter.
- When the GET request receives the object value, no modification of this or any other object must occur.
Today, a large number of client libraries for work with OData have been developed for popular application and mobile platforms, including:
All client libraries for working with OData may be downlowded using the following link http://www.odata.org/libraries.
Implementation of the OData protocol in bpm'online
The bpm'online application supports the following operations with objects and their collections over the OData protocol:
|Group of operations||Operations|
|Operations with objects||
|Functions of work with strings||
|Functions of work with date and time||
Please note that bpm'online implements the forced paging when returning resultant objects collections. A request returns first 40 objects by default. To modify the default paging implementation, standard structures of OData requests may be used: $top, $skip, $orderby .
Below are the examples of building requests for access to bpm'online objects over the OData protocol .
Work with bpm'online objects over the OData protocol
OData service for access to bpm'online objects
The access to bpm'online entities over the OData protocol is provided by the EntityDataService.svc web-service.
The address of the EntityDataService.svc service is as follows:
The data model of the EntityDataService.svc service is described in its metadata which can be received using the standard OData syntaxes structure — $metadata.
All requests to bpm'online must be authenticated .
The authentication methods supported by bpm'online are described in the article Authenticating external requests to bpm'online services.
Examples of implementing the access to bpm'online objects over the OData protocol
- Working with bpm'online objects over the OData protocol using Http request
- Working with bpm'online objects over the OData protocol WCF-client