Imixs Micro-Service-Architecture

The Imixs Workflow project provides a REST API to access all resources concerning a process management system. This Interface was designed to access the Imixs Workflow from any external client. It provides methods to create, update and read workitems

In various projects there is a requirement to integrate external master data which is not part of the process management system. An example there for is the customer or address data located in a remote system.

To access such external data from the workflow application in a general and easy way we think about a generic  kind of micro-service-architecture to be used to access any external data.

Imixs Micro-Service-Architecture

The Imixs Micro-Service-Architecture is an idea to provide a concept to access any remote data based on a RESTfull service architecture. The idea is to split the problem into a generic data-value object and a generic API to access these objects. Both concepts should be based on RESTfull Services

A data object can be treated as a generic value-object like the imixs workflow business-data. This object can store any kind of data. See the following JSON example:

{"item":[
   {"name":"$uniqueid","value":{"@type":"xs:string","$":"141cb98aecc-18544f1b"}},
   {"name":"$modelversion","value":{"@type":"xs:string","$":"bestandspflege-de-0.0.2"}},
   {"name":"$processid","value":{"@type":"xs:int","$":"2000"}},
   {"name":"namcreator","value":{"@type":"xs:string","$":"admin"}}, 
   {"name":"$isauthor","value":{"@type":"xs:boolean","$":"true"}},
   {"name":"_subject","value":{"@type":"xs:string","$":"JUnit Test-6476"}}, 
   {"name":"txtworkflowstatus","value":{"@type":"xs:string","$":"Vorlauf"}}, 
   {"name":"txtworkflowresultmessage","value":{"@type":"xs:string","$":""}}
  ]}

As this concept is still part of the Imixs Workflow project this formats are described in the Imixs project:

To identify a external master data the standard attribute ‘$uniqueid’ can be used which should contain the primary key of the object. In addition the following default attributes can be provided. This attributes define a kind of minimum set to describe the data object:

Core Properties Type read/
write
Description
$Created Date no Date of creation
$Modified Date no Date of last modification
$uniqueId String no The unique ID of this data
$uniqueIdRef String yes A reference to a connected workItem
txtname String no A short name of the data used for lookups
txtdescription String no A long description of the data

 

The REST API

REST is an architectural style that can be used to guide the construction of web services in a more easy kind as a service which uses the SOAP specification. REST is based on URIs. An URI is a unique resource identifier. In REST an URI represents a resource and is used to get or modify a resource. In the meaning of this micro-service-architecture the URIs represent master data provided by a remote system. Each kind of master data source should be identified by a unique resource name, e.g.:

  • /customer/xxxxx-xxxxx
  • /car/xxxxx-xxxxx
  • /part/xxxxx-xxxxx

The last part of the URI identifies a data object by its primary key ($uniqueid) to create, update or delete. These crud operations are mapped to the corresponding http method:

  • POST/PUT  – creates or updates a data object
  • GET – reads a data object
  • DELETE – removes the data object

Posting a data object means to update the object. The method should accept any set or subset of attributes. This means if a POST request sends only a few attributes only these attributes should be updated.

Access data collections

To get a collection of data object the main URI can be used together with the GET method , e.g.

GET:   /customer/

To restrict, filter or sort the collection the following query params should be provided:

  •  /customer?count=10   – returns 10 elements
  • /customer?start=10 – returns elements from position 10
  • /customer?txtname=xxx – returns elements matching the attribute ‘txtname=xxx’
  • /customer?sort=1  – defines the sortorder of the returned collection (0=creation date descending ,1=creation date ascending ,2=modified date descending ,3=modified date ascending)

 

This is just a draft version of a concept to provide a generic interface to external data from a remote system.

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