Introduction to FTP Adapters
While working on integration projects particularly involving legacy systems, many times there is requirement to get a flat-file or a CSV (Comma Separated Values) from a remote server and then process it as XML or file using some delimiters and use this file or write the XML data into another file. This can be achieved by Java code.
Oracle BPEL provides “FTP Adapters” to achieve these functionalities. FTP adapter can be treated as a service which provides following operations from a remote server.
1.Get a file from a remote server
2.Put a file to a remote server
3.Synchronous Get or Get a current file.
“Get” operation can be used when requirement is to poll on a particular location or directory at particular intervals and once file with name specified as available process it. This operation also provides an option to delete or to achieve a processed file.
“Put” operation can be used to write the data into a file at a particular location. The same operation provides option to append data to an existing file and once a particular size is exceeded create another file.
If requirement is to read data from a file at a location which can be dynamically specified, then “Synchronous Get” operation can be used. Following section gives the difference between “Get” operation and “Synchronous Get” operation.
Difference between Get Adapter and Synchronous Get Adapter
1.“Get” operation in FTP Adapter polls the given input file periodically according to the frequency given, that is, it tries if the file is available at given location after a specified interval waits until the given file doesn't exist. Once file is available it starts processing it by creating an instance of the BPEL process. Whereas “ Synchronous Get” operation in FTP Adapter reads the file only when the instance is triggered and it does not create the instance on its own, Neither it polls on particular directory
2.FTP Adapter with “Get Operation” can be invoked only using “Receive Activity” whereas for “Synchronous Get” Operation of the FTP adapter has to be invoked using “Invoke Activity”
How to create a BPEL process using an FTP Adapter service
1.Create a new application using the Application navigator.
2.Right click on this new application and select “New project“.
3.Then select BPEL process and select “Empty BPEL” template for this newly created BPEL project Name the BPEL process accordingly and then click 'Finish' to create an empty BPEL process.
4.Navigate to the “Component Palette” and select “Services” option. Services palette enlists all the services options available which can be used to invoke another service or system using either partner links or Adapters.
5.Now drag the “FTP Adapter” and drop it in the services portion of the BPEL process, an Adapter Configuration Wizard appears. Click next to go the next window. In step 1, specify a desired name to the adapter and then click next to go the next window.
6.In Step 2, specify the JNDI name of the FTP Server.
The JNDI name of a resource and the name of the resource reference are not the same. This approach to naming requires mapping of the two names before deployment, but it also decouples components from resources. Because of this decoupling, if at a later time the component needs to access a different resource, you don't have to change the name in the code.
(Read “How to configure the JNDI in Application server console” at the end of
the section)
After specifying all the required information, click next to go to the next window.
7.In the next step, select the operation as per requirement to create FTP adapter for. Select the radio button “Get” to create an adapter to read a file and click next to go to the next window. In FTP Adapter, an additional operation is also supported where the user can select if the file is of ascii type or binary type. The user can select the radio button”Ascii” if the file is of ascii type, else select the radio button “Binary” as per the requirement.
8. In the next step, specify the path of the incoming file.
Location of the path can be specified in two ways 1) Physical path and 2) Logical path.
Physical path is the absolute location of the file where it is located. This specified directory should be accessible to the server.
Logical path is the location of the file relative to the current location of the file adapter on server.
Default option is “Physical path”
Options either to archive processed files or delete files after successful processing of file can be specified using options Available.
There might be requirement to save the files after processing the data from it. In such conditions, these files can be achieved to by checking the box “Archive processed files” in this window. The path of the directory where the processed files have to be saved (or archived) after processing can be specified. Again this path can be either absolute or logical based on the option selected earlier.
Instead, at times the files after retrieving the data from the file need to be deleted. This can be achieved by checking the box “Delete files after successful retrieval” in this window.
After specifying all the required information, click next to go to the next window.
8. In the next Step, specify the name of the file from where the data need to be retrieved.
File names can be specified using two options, 1) File Wildcards and 2) Regular Expressions.
“File Wildcards” allows user to specify file having a similar naming pattern like po*.txt where * can be replaced by any character or digit or symbol.; whereas “Regular Expressions” can be used for normal search where in it searches for the file having similar string pattern.
User can also specify the naming pattern of the files which needs to be excluded (if any) from the reading operation.
“Files contain multiple Messages” can be checked if the incoming file is expected to have more than one message. Number of messages needs to be retrieved in batches if the incoming file having multiple messages can also be specified. Default number is “1”
9. Select polling frequency and minimum file age accordingly.
“Polling frequency” is the interval after which the adapter needs to poll the file periodically to receive the data.
“Minimum File age” is the minimum time adapter should wait, after the file is created. In other words,”Minimum file age” refers to the time elapsed between the file creation and next run of the polling frequency.
Click next to go to the next window.
10.The next window prompts to select a schema format for the data to be retrieved.
Select a schema which already exists in the project (if any) or create a new schema format using a sample data file. Click next to go to the next window.
11.Click “Finish”. Click “Apply” and “OK” on the “Create partner link” window to end the process of creating an adapter.
Please note that at this point a wsdl with file adapter name is created. This can be viewed in Application Navigator. This file can be used to edit the options selected in configuration wizard.
12.Now navigate the component palette to the “Process Activities”.
13.Drag a “Receive” activity and drop it in the process. Connect it with the Adapter created in the previous step. An “Edit receive” wizard appears.
14.Create a variable to receive the data from the file adapter, by clicking the icon highlighted in the figure below.
15.To create a “Global variable” check radio button and click “OK” to create a variable.
16.Check create instance and click “Apply” and “OK” to complete the receive activity. The BPEL process looks as shown below.
17.Deploy the process to the server and the process itself creates an instance. Check the “Flow” and “Audit” of the instance. The input file is read and transformed to XML format. For example, if the input file contains the data “Hello,BPEL,Process”, it will be transformed as shown below.
-
-
hello
BPEL
Process
Hence the input data from a flat file is transformed to desired XML format.
How to Create FTP Adapter to Put or Sync Get
If FTP adapter with “Put” operation is created, while creation, wizard prompts for
I.Directory of the outgoing file
II.Naming convention for the outgoing files
III.Schema format which defines the data in the outgoing file.
If FTP adapter with “Synchronous Get” operation is created, wizard prompts for
I.Directory of the incoming file
II.Name of the incoming file.
III.Schema format of the data in the incoming file.
(Note that wizard doesn't prompt for the polling frequency and minimum file age as in get FTP adapter.)
While working on integration projects particularly involving legacy systems, many times there is requirement to get a flat-file or a CSV (Comma Separated Values) from a remote server and then process it as XML or file using some delimiters and use this file or write the XML data into another file. This can be achieved by Java code.
Oracle BPEL provides “FTP Adapters” to achieve these functionalities. FTP adapter can be treated as a service which provides following operations from a remote server.
1.Get a file from a remote server
2.Put a file to a remote server
3.Synchronous Get or Get a current file.
“Get” operation can be used when requirement is to poll on a particular location or directory at particular intervals and once file with name specified as available process it. This operation also provides an option to delete or to achieve a processed file.
“Put” operation can be used to write the data into a file at a particular location. The same operation provides option to append data to an existing file and once a particular size is exceeded create another file.
If requirement is to read data from a file at a location which can be dynamically specified, then “Synchronous Get” operation can be used. Following section gives the difference between “Get” operation and “Synchronous Get” operation.
Difference between Get Adapter and Synchronous Get Adapter
1.“Get” operation in FTP Adapter polls the given input file periodically according to the frequency given, that is, it tries if the file is available at given location after a specified interval waits until the given file doesn't exist. Once file is available it starts processing it by creating an instance of the BPEL process. Whereas “ Synchronous Get” operation in FTP Adapter reads the file only when the instance is triggered and it does not create the instance on its own, Neither it polls on particular directory
2.FTP Adapter with “Get Operation” can be invoked only using “Receive Activity” whereas for “Synchronous Get” Operation of the FTP adapter has to be invoked using “Invoke Activity”
How to create a BPEL process using an FTP Adapter service
1.Create a new application using the Application navigator.
2.Right click on this new application and select “New project“.
3.Then select BPEL process and select “Empty BPEL” template for this newly created BPEL project Name the BPEL process accordingly and then click 'Finish' to create an empty BPEL process.
4.Navigate to the “Component Palette” and select “Services” option. Services palette enlists all the services options available which can be used to invoke another service or system using either partner links or Adapters.
5.Now drag the “FTP Adapter” and drop it in the services portion of the BPEL process, an Adapter Configuration Wizard appears. Click next to go the next window. In step 1, specify a desired name to the adapter and then click next to go the next window.
6.In Step 2, specify the JNDI name of the FTP Server.
The JNDI name of a resource and the name of the resource reference are not the same. This approach to naming requires mapping of the two names before deployment, but it also decouples components from resources. Because of this decoupling, if at a later time the component needs to access a different resource, you don't have to change the name in the code.
(Read “How to configure the JNDI in Application server console” at the end of
the section)
After specifying all the required information, click next to go to the next window.
7.In the next step, select the operation as per requirement to create FTP adapter for. Select the radio button “Get” to create an adapter to read a file and click next to go to the next window. In FTP Adapter, an additional operation is also supported where the user can select if the file is of ascii type or binary type. The user can select the radio button”Ascii” if the file is of ascii type, else select the radio button “Binary” as per the requirement.
8. In the next step, specify the path of the incoming file.
Location of the path can be specified in two ways 1) Physical path and 2) Logical path.
Physical path is the absolute location of the file where it is located. This specified directory should be accessible to the server.
Logical path is the location of the file relative to the current location of the file adapter on server.
Default option is “Physical path”
Options either to archive processed files or delete files after successful processing of file can be specified using options Available.
There might be requirement to save the files after processing the data from it. In such conditions, these files can be achieved to by checking the box “Archive processed files” in this window. The path of the directory where the processed files have to be saved (or archived) after processing can be specified. Again this path can be either absolute or logical based on the option selected earlier.
Instead, at times the files after retrieving the data from the file need to be deleted. This can be achieved by checking the box “Delete files after successful retrieval” in this window.
After specifying all the required information, click next to go to the next window.
8. In the next Step, specify the name of the file from where the data need to be retrieved.
File names can be specified using two options, 1) File Wildcards and 2) Regular Expressions.
“File Wildcards” allows user to specify file having a similar naming pattern like po*.txt where * can be replaced by any character or digit or symbol.; whereas “Regular Expressions” can be used for normal search where in it searches for the file having similar string pattern.
User can also specify the naming pattern of the files which needs to be excluded (if any) from the reading operation.
“Files contain multiple Messages” can be checked if the incoming file is expected to have more than one message. Number of messages needs to be retrieved in batches if the incoming file having multiple messages can also be specified. Default number is “1”
9. Select polling frequency and minimum file age accordingly.
“Polling frequency” is the interval after which the adapter needs to poll the file periodically to receive the data.
“Minimum File age” is the minimum time adapter should wait, after the file is created. In other words,”Minimum file age” refers to the time elapsed between the file creation and next run of the polling frequency.
Click next to go to the next window.
10.The next window prompts to select a schema format for the data to be retrieved.
Select a schema which already exists in the project (if any) or create a new schema format using a sample data file. Click next to go to the next window.
11.Click “Finish”. Click “Apply” and “OK” on the “Create partner link” window to end the process of creating an adapter.
Please note that at this point a wsdl with file adapter name is created. This can be viewed in Application Navigator. This file can be used to edit the options selected in configuration wizard.
12.Now navigate the component palette to the “Process Activities”.
13.Drag a “Receive” activity and drop it in the process. Connect it with the Adapter created in the previous step. An “Edit receive” wizard appears.
14.Create a variable to receive the data from the file adapter, by clicking the icon highlighted in the figure below.
15.To create a “Global variable” check radio button and click “OK” to create a variable.
16.Check create instance and click “Apply” and “OK” to complete the receive activity. The BPEL process looks as shown below.
17.Deploy the process to the server and the process itself creates an instance. Check the “Flow” and “Audit” of the instance. The input file is read and transformed to XML format. For example, if the input file contains the data “Hello,BPEL,Process”, it will be transformed as shown below.
-
-
Hence the input data from a flat file is transformed to desired XML format.
How to Create FTP Adapter to Put or Sync Get
If FTP adapter with “Put” operation is created, while creation, wizard prompts for
I.Directory of the outgoing file
II.Naming convention for the outgoing files
III.Schema format which defines the data in the outgoing file.
If FTP adapter with “Synchronous Get” operation is created, wizard prompts for
I.Directory of the incoming file
II.Name of the incoming file.
III.Schema format of the data in the incoming file.
(Note that wizard doesn't prompt for the polling frequency and minimum file age as in get FTP adapter.)
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