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# Combine XML Files via Poll Enrich
Learn how to enrich the payload with data retrieved from a file on the SFTP server using ‘Combine XML’ Aggregation Algorithm.
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## Implementation
To showcase the poll enrich capability, we use a simple scenario.
The example integration flow **File Transfer - Combine XML Files via Poll Enrich** is designed the following way:
Add the following files on your SFTP server whereas the name of the file should be the **product ID with suffix xml**:
`HT-1000.xml`
> ### Sample Code:
> ```
> <root>
> <Product>
> <ProductId>HT-1000</ProductId>
> <ProductName>Notebook Basic 15</ProductName>
> <Category>Notebooks</Category>
> <CurrencyCode>EUR</CurrencyCode>
> <Price>956.00</Price>
> </Product>
> </root>
>
> ```
`HT-1001.xml`
> ### Sample Code:
> ```
> <root>
> <Product>
> <ProductId>HT-1001</ProductId>
> <ProductName>Notebook Basic 17</ProductName>
> <Category>Notebooks</Category>
> <CurrencyCode>EUR</CurrencyCode>
> <Price>1249.00</Price>
> </Product>
> </root>
>
> ```
`HT-1002.xml`
> ### Sample Code:
> ```
> <root>
> <Product>
> <ProductId>HT-1002</ProductId>
> <ProductName>Notebook Basic 18</ProductName>
> <Category>Notebooks</Category>
> <CurrencyCode>EUR</CurrencyCode>
> <Price>1570.00</Price>
> </Product>
> </root>
>
> ```
In the first step **Content Modifier** ‘Define file name’, the exchange property ‘file’ is defined using the following XPath:
`concat(//PurchaseOrder/Item/ProductId , ".xml")`.
See [Access Header and Properties in XPath](access-header-and-properties-in-xpath-996ce78.md).
In the *Source* tab of the *SFTP* sender adapter, enter the *Directory*, *Address* of the SFTP server \(`host:port`\), *Proxy Type* \(On-Premise/Internet\), *Location ID* \(if On-Premise\) and *Credential Name* to access the SFTP server. Those parameters are externalized so that you can use your own SFTP server.
See [Configure Externalized Parameters of an Integration Flow](configure-externalized-parameters-of-an-integration-flow-462a478.md).
*Directory* and *File Name* are set dynamically via the header and the beforehand created message property.
If you switch to the *Processing* tab, you will notice that the file is kept on the SFTP server after the message has been processed:
In the *Processing* tab of *Poll Enrich* set the *Aggregation Algorithm* to *Combine XML*.
In this case the message polled from the SFTP server will be combined with the source message. After the **Poll Enrich step** the message has the following structure:
> ### Sample Code:
> ```
> <?xml version='1.0' encoding='UTF-8'?>
> <multimap:Messages xmlns:multimap="http://sap.com/xi/XI/SplitAndMerge">
> <multimap:Message1>
> <PurchaseOrder PurchaseOrderNumber="99401" OrderDate="2019-05-06">
> <Item ItemNumber="10">
> <ProductId>HT-1000</ProductId>
> <Quantity>2</Quantity>
> </Item>
> </PurchaseOrder>
> </multimap:Message1>
> <multimap:Message2>
> <root>
> <Product>
> <ProductId>HT-1000</ProductId>
> <ProductName>Notebook Basic 15</ProductName>
> <Category>Notebooks</Category>
> <CurrencyCode>EUR</CurrencyCode>
> <Price>956.00</Price>
> </Product>
> </root>
> </multimap:Message2>
> </multimap:Messages>
>
> ```
The subsequent Message Mapping step maps from this multimap message to a multimap order and the overall **Price** is calculated based on the **Quantity** and **Price** per item of the product.
The subsequent Filter step removes the multimapping from the message. It uses the following XPath expression:
`//PurchaseOrder`
To execute the scenario, expand the Postman collection *Modeling Basics* and the folder*FileTransfer* in the Postman client. There you can find the POST request **CombineXMLFiles** including the following body:
> ### Sample Code:
> ```
> <PurchaseOrder PurchaseOrderNumber="99401" OrderDate="2019-05-06">
> <Item ItemNumber="10">
> <ProductId>HT-1002</ProductId>
> <Quantity>10</Quantity>
> </Item>
> </PurchaseOrder>
>
> ```
Before running the scenario, maintain the **value of the header directory** of the Postman request corresponding to the **folder** on your sftp server where you put the file, see above. Once the scenario is executed, it creates a new entry in the Data Store *FileTransfer-Combine* with the content of the combined files:
> ### Sample Code:
> ```
> <PurchaseOrder PurchaseOrderNumber="99401" OrderDate="2019-05-06">
> <Item ItemNumber="10">
> <ProductId>HT-1002</ProductId>
> <ProductName>Notebook Basic 18</ProductName>
> <Category>Notebooks</Category>
> <Quantity>10</Quantity>
> <CurrencyCode>EUR</CurrencyCode>
> <Price>15700.00</Price>
> </Item>
> </PurchaseOrder>
>
> ```
