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This week, we’ll study a Message Transformation pattern known as Content Filter.

When do I use this pattern?

Content Filter pattern, as the name suggests, is used to filter out elements from the content of the message.

There are two main use cases of the Content Filter pattern:

1. Removing out certain elements from a Node
2. Removing out Nodes from a set of repeating Nodes based on a condition

I’ll explore Use Case 1 in this blog. For example, removing out elements from Order payload that are not required by the receiver.

For Use Case 2, I refer you to Alex‘s blog on Content Filter pattern where he shows Use Case 2 in SAP Cloud Platform Integration and SAP Process Orchestration.

Content Filter in CPI

In CPI, we can use the Message Mapping component to remove unnecessary elements.

I’ll get the Orders from Northwind service with Customer data and remove out some elements to demonstrate this pattern.

Integration Flow

Removing Elements from an Order

The integration flow is very simple. It starts immediately using Timer Event, gets the Orders from Northwind by applying the Command Message pattern, and filters out unnecessary elements using Message Mapping component.

Configuration of OData Receiver Adapter

Content Filter

In the Content Filter, we filter out the Id fields from the Order node and the Id and Contact details from the Customer node.

Removed Elements from Order

Removed Elements from Customer

Execution

The result of using the content filter is that we are left with a succinct message.

Message before Content Filter

<Orders>
    <Order>
        <RequiredDate>1996-08-01T00:00:00.000</RequiredDate>
        <ShipName>Vins et alcools Chevalier</ShipName>
        <Customer>
            <Customer>
                <CompanyName>Vins et alcools Chevalier</CompanyName>
                <Address>59 rue de l&apos;Abbaye</Address>
                <Phone>26.47.15.10</Phone>
                <Region/>
                <PostalCode>51100</PostalCode>
                <Country>France</Country>
                <CustomerID>VINET</CustomerID>
                <City>Reims</City>
                <Fax>26.47.15.11</Fax>
                <ContactName>Paul Henriot</ContactName>
                <ContactTitle>Accounting Manager</ContactTitle>
            </Customer>
        </Customer>
        <ShippedDate>1996-07-16T00:00:00.000</ShippedDate>
        <ShipCity>Reims</ShipCity>
        <CustomerID>VINET</CustomerID>
        <ShipVia>3</ShipVia>
        <ShipPostalCode>51100</ShipPostalCode>
        <OrderID>10248</OrderID>
        <OrderDate>1996-07-04T00:00:00.000</OrderDate>
        <ShipRegion/>
        <ShipAddress>59 rue de l&apos;Abbaye</ShipAddress>
        <ShipCountry>France</ShipCountry>
        <EmployeeID>5</EmployeeID>
        <Freight>32.3800</Freight>
    </Order>
    ...
</Orders>

Message after Content Filter

<Orders>
    <Order>
        <OrderID>10248</OrderID>
        <OrderDate>1996-07-04T00:00:00.000</OrderDate>
        <RequiredDate>1996-08-01T00:00:00.000</RequiredDate>
        <ShippedDate>1996-07-16T00:00:00.000</ShippedDate>
        <ShipVia>3</ShipVia>
        <Freight>32.3800</Freight>
        <ShipName>Vins et alcools Chevalier</ShipName>
        <ShipAddress>59 rue de l&apos;Abbaye</ShipAddress>
        <ShipCity>Reims</ShipCity>
        <ShipRegion></ShipRegion>
        <ShipPostalCode>51100</ShipPostalCode>
        <ShipCountry>France</ShipCountry>
        <Customer>
            <Customer>
                <CompanyName>Vins et alcools Chevalier</CompanyName>
                <ContactName>Paul Henriot</ContactName>
                <ContactTitle>Accounting Manager</ContactTitle>
            </Customer>
        </Customer>
    </Order>
    ...
</Orders>

Conclusion

Content Filter pattern can be used to remove elements from a given node or remove certain nodes from a set of repeating nodes based on a condition. For both use cases, CPI has inbuilt components.

References/Further Readings

• Content Filter Pattern in Enterprise Integration Patterns
• Alex‘s blog on Content Filter pattern
• EIPinCPI
  • Command Message
• CPI Components
  • Timer Event
  • Message Mapping

Hope this helps,
Bala

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