Monday, October 9, 2017

Getting Started with Logic Apps - Enterprise Application Integration


In last post we saw, how to do file routing using LogicApps. But in real world, Enterprise Application Integration have more than just routing – Messaging Solution or some kind of Business Process Automation(It can be simple or complex in nature).


Messaging solution basically revolves around VETER, it can be either combination of all or few of them. In Logic Apps we have XML Validation to validate, Transform XML to do transformation, xpath can be used to extract xml and to Enrich(compose new message) and route  we have connectors available.

VETER
In this post we will see with an example, how to validate, transform and route using Logic App.


Scenario:


Requirement is to route the Trip related details which is received in csv format from sales department in a folder to destination folder but in XML format which is expected by downstream system.

In order to implement this solution In logic app, we need to have schemas related to csv and xml , and a map doing a transformation from csv to xml.

Unlike BizTalk which provides us platform to create the artifacts needed (schemas, maps, pipelines etc) which can be orchestrated or used in work flow, logic app is platform for only designing/orchestrating  workflow around the services available (using Trigger, Connectors, Azure functions etc.).

Although we can design Logic app using browser, we don’t have provision to create schema or map using browser but they can be used in workflow if available to it. To make this availability possible– Integration Account is introduced which is part of Enterprise Integration Pack, which acts as a container having capability to store Schemas, Map, Certificates, Trading Partners, and Agreements. And to deal with the creation of Schemas and Maps there is SDK provided, It can be downloaded from below link

Microsoft Azure Logic Apps Enterprise Integration Tools for Visual Studio 2015 2.0

              

Note: If you already have BizTalk env, then you don’t need to download the SDK, the schemas and maps created in BizTalk application are absolutely compatible.

Once you have schemas and maps created, using either of the above ways – those can be uploaded to the Integration account. Later this Integration account has to be linked to Logic App, in order to use the artifacts.

Steps in creating solution


For demonstration, I have used folder as source and destination which is on-premises. In real world scenario it can be anything - source/destination can be on prem or in cloud. 


Creating schemas and map

As am using BizTalk for creating schemas and map, I create BizTalk project whereas if you are using SDK, you would be creating Integration project(this template gets added to visual studio when SDk is installed.

BizTalk New Project

Create one flat file schema-Trip.xsd .Its extension is xsd as the representation of flat file is in xml but with the help of FlatFileExtension class all properties related to flat file are made available.
flat file schema

and one xml based schema - Trip_Xml.xsd

xml schema




Now create a Map with Flat file schema as source and Xml schema as destination, mapping is one to one, expect have concatenated the address.


flat file to xml schema

One more step, before we move ahead is to save the xslt generated from above map. Right click Map-->Validate Map. In output pane, you will see the path of stored XSLT, copy the file and save it in your current project folder.


Creating Integration Account, Uploading schemas and maps


Login to Azure portal and click on new button, search for Integration Account. Provide the name, resource group, Pricing , Location and click on create.

Create Integration Account


There are two options in Pricing Tier 1. Free and 2. Standard, would recommend to use Free as you are able to create a maximum of one account per region and store up to 10 Agreements and 25 maps. Schemas, certificates, and partners have no limits and you can upload as many as you need.


Now to upload the schemas, select the above created Integration Account-->click on schemas on left pane--> click on Add button --> provide name --> browse to folder having the schema of interest--> click ok
upload schemas in Integration Account



and to upload the map,select the above created Integration Account-->click on Maps on left pane--> click on Add button --> provide name --> browse to folder having the map of interest(choose the xslt file we saved earlier)--> click ok
upload map in Integration Account

Note: Only xslt file is supported as of now, .btm is not supported. Read The provided map definition is not valid

Creating Logic App

Note: Make sure your integration account and logic app are in the same Azure location before you begin.

Now on Azure portal click New and search for Logic App, select the blank Template.Provide the name, region, resource group etc.

First thing to do is after creating and before designing, we need to link the integration Account in order to use schemas and map (you can link it later too but you will get error while you look for schemas or map)

link integration account with Logic apps


The workflow is – Pick flat file from on prem folder, decode it using Flat file decoder, validate it against the flat file schema,  transform the file and save it to another on-prem folder .

Configure the File System connector to trigger the logic app when new file is created in folder after every one minute, followed by action to fetch the content of file. Read Getting Started with Logic Apps - File Routing
file system trigger and action

Add new Action and search for Flat file decoding, use the File content from previous step and select the flat file schema uploaded earlier in Integration Account Trip_FF

Flat file decoding action

Next Action is to add XML Validation, use Body of previous step and select the schema to validate against - Trip_FF
xml validation action
Now we have valid decoded Flat file which needs to be transformed to expected XML, add Transform XML action, select the Body from previous step (here you will see two Body select the one related to Flat File Decoding. Read Required property 'content' expects a value but got null. Path ''.'
Transform xml action

The final step is to save the above transformed file to destination location, add Create File action, provide the out folder, name and use the content from Transform XML
create file action

That's it, final workflow is as below, save it and test.
final eai workflow


Testing


For testing I generated an instance from flat file and update the values in it, and saved it in the IN folder


Input to workflow
 And in Out folder I can see the output
Output of workflow


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