File Adapter BPEL Trigger

Question

Hi,
This should be a really easy thing to do but I'm obviously missing something simple and fundamental.
I want to set up a BPEL process that is initiated by the receipt of a file. All I initially want to get from that trigger is the name of the file and pass that value on to the next step in the chain.
So, I created a new BPEL Process project and added a File Adapter service, filling in all the details for picking up the file from the place that it'll arrive. Reading the "Adapter" manual, I should be able to get the file details (name, directory) by adding UseHeaders="true" into the JCA definition in the File Adapter's WSDL file. I have done this. Doing this creates another WSDL file called fileAdapterInboundHeader.wsdl Now, this is where I get lost. How do I use this?
By default, a new BPEL Process diagram shows a "Client" Partner Link, a receiveInput activity and a replyOutput activity. The receiveInput activity links from the Client Partner Link and the replyOutput activity links back to the Client.
So I'm guessing that I need to replace the Client partner link with my new File Adapter service so that the detection of the file starts my BPEL process, rather than some triggered activity from a client.
This is basically what I've done but it's really not working. How do I get at the filename that's gathered by the File Adapter service? Do I need an XML schema definition to work from?
Perhaps there's a nice simple example of this somewhere that somebody could point me at? I've been searching but not found anything yet.
Thanks,
Andy

Answer 1

I've written up this procedure in a bit more detail than RedRocker originally provided so that people like me who are complete noobs to BPEL and JDeveloper can do this more easily. The example I give here takes the filename and writes it to a database table. The table just has a FILE_ID column (automatically populated from a sequence by an ON-INSERT trigger) and a CONTENTS column (where the file name goes):
How-To Get the name of an Input File and store it in a database table column.
1) Assuming that you're using JDeveloper and you have an Application Workspace, right-click on the Application and choose New Project from the context menu.
2) In the New Gallery, select Projects and then choose BPEL Process Project from the Items list:
3) Create an Empty BPEL Process by choosing Empty BPEL Process from the Template dropdown of the BPEL Project Creation Wizard.
4) This will bring up a completely empty BPEL Process in JDeveloer:
5) From the Component Palette (top-right), choose Services and then locate the File Adapter Service in the list.
6) Drag the File Adapter service from the Component panel to one of the Services columns in the main BPEL process designer (centre window). A Wizard will appear.
7) Enter a name for the Service (eg. GetFileName). Fill in the description if you wish.
8) Choose Read from the Operation Type list (adjust the Operation Name if you like):
9) Enter the physical directory (or logical name for one) where the file is to be read from. Decide on whether you want the file to be deleted after it's been read (it won't be re-processed if it's left there since each poll cycle only looks for files that arrived more recently than its previous cycle), and whether to archive the file.
10) Enter appropriate file selection filter criteria (note that for this BPEL example we're not interested in the file's content at all so the "Files contain Multiple Messages" tickbox and "Publish Messages in Batches of" selector are unimportant):
11) Select an appropriate Polling Frequency:
12) Select an Opaque schema (we're not interested in the file's content in this example)
13) Click Finish
14) Click OK to close the Partner Link creation wizard
15) Click Save All.
16) From the Application Navigator, drill down through the newly created BPEL Project, through the Integration Content folder to find your GetFileName Partner link. Expand this and double-click the GetFileName.wsdl file. In the centre panel, click the Source tab (at the bottom):
17) Scroll down to the <jca:operation> tag and add the attribute UseHeaders="true" at the end
18) Click Save All.
19) Return to the main GetFileName BPEL Process designer by clicking the tab name at the top of the centre window. In the Structure panel (bottom-left), expand the Variables folder, followed by the Process folder and click the exposed Variables folder
20) Create a variable by clicking the "Wand +" icon.
21) Give the variable a meaningful name (FileName) and choose Message Type. Click the Browse flashlight:
22) Choose InboundHeader_msg by drilling down as shown:
23) Click OK and OK.
24) In the Component palette (top-right), choose Process Activities from the dropdown list. Locate the Receive activity and drag it to the centre of the middle panel (ie. the BPEL Designer window) into the area marked "Drop Activity Here":
25) Double-click the new Receive activity to bring up the properties dialogue box. On the General tab, give the activity a meaningful name (eg. ReceiveFilename).
Click the Browse flashlight next to the Partner Link field and choose GetFileName from the list. The Operation dropdown will automatically show "Read" which is correct.
26) Click the Auto-Create Variable ("Wand +") icon next to the Variable field. This variable is merely a placeholder for the content of the file being read. Because we've said that the incoming file's schema is Opaque, this variable will not get populated. However, we still need to have a variable. Give the variable a meaningful name (eg. FileContent) and allow the type to be selected automatically and then click OK on the Create Variable dialogue.
27) Given that we'd want the receipt of a file to be individually traceable, ensure that the Create Instance checkbox is ticked on the General tab:
28) Click the Adapters tab. Click the Browse flashlight next to the Header Variable field and select the FileName variable from the list presented and click OK:
29) Click OK on the Receive activity property page to return to the main BPEL Designer screen.
30) At this point, the data is available within the BPEL process but needs to be assigned to something. In this example, the value is going to be written to the FILE_NAME column in a table called ACH_INUPT_FILE. This will be done through an Insert performed by a Database Adapter. The ACH_INUPT_FILE table is configured to have an ON-INTERT trigger which automatically selects a value from a Sequence for its Primary Key value. Therefore simply inserting a row will provide a Unique value in the FILE_ID column.
The next thing we need to do is create the Partner Link that performs the Insert operation. This will create a variable which we can assign the File Name to when this new Service is linked into the process flow.
From the Component panel, choose Services from the dropdown. Locate the Database Adapter service and drag one onto the BPEL Designer page in the Services column.
The Adapter Configuration wizard appears. Enter a meaningful name from the adapter (eg. WriteFileName). Enter a description if you like and click Next.
31) Choose the appropriate Connection from the dropdown list. Click Next.
32) Choose "Perform an Operation on a Table" for the Operation Type and deselect all operations except Insert Only. Click Next.
33) Click the Import Tables button. From the presented table, ensure that the table that's going to hold the data is selected by shuttling the table from the Available panel to the Selected panel. In this case I've selected the ACH_INPUT_FILE table. Click OK.
34) The Select Table panel shows the ACH_INPUT_FILE table. Click Next.
35) In this example there are no further relationships to make, so click Next on the Relationships page:
36) Click Finish. The Database Adapter's Partner Link properties page is displayed. Note that the Partner Link Type and Partner Role are automatically populated from the information gathered in the previous set of dialogue pages. Note that to change any of those values previously entered, click the Define Adapter Service icon. Click OK.
37) In the Components Palette, select Process Activities from the dropdown. Locate the Invoke activity and drag one to the main BPEL process flow and drop it immediately below the ReceiveFilename activity.
38) Double-click the new Invoke activity and the Invoke property panel is shown. On the General tab, give the Invoke activity a meaningful name (eg. InvokeWriteFileName).
Click the Browse flashlight next to the Partner Link field and select WriteFileName from the list of presented services. Click OK.
39) Note that the operation "insert" is automatically populated into the Operation dropdown.
40) Click the Automatically Create Input Variable icon (Wand +) next to the Input Variable field. Accept the default "InvokeWriteFileName_insert_InputVariable". This creates the variable of the right type that's needed by the WriteFileName service.
41) Click OK to close the WriteFileName Invoke activity property sheet. Note that there is a warning flag next to the new Invoke activity. We need to assign the file name to the Invoke activity's Input Variable.
42) From the Component Palette, drag an Assign activity so that it sits between the Receive and the Invoke activities in the BPEL flow.
43) Double-click the new Assign activity and click the General tab. Enter a meaningful name for the activity (eg. AssignFileNameToDBWriteInput).
44) Click the Copy Operation tab. Click the Create button and select Copy Operation from the list of types.
45) In the From panel, choose Expression from the Dropdown list. From the panel, click the XPath Expression Builder icon (highlighted).
46) From the Function list dropdown under the Functions heading, select Conversion Functions. Double-click the "string()" function. This moves the string() function into the Expression panel at the top as shown.
47) In the Expression panel, click inside the ( and ) brackets. Expand the variable FileName in the BPEL Variables panel below and select the fileName element from the InboundFileHeaderType element. Double-click the fileName to move the XPath expression into the Expression panel:
48) Click OK. In the To panel, ensure that the Type dropdown shows Variable. Drill into the InvokeWriteFileName_insert_InputVariable and select the element that the file name is to be assigned to. In the example illustrated, the variable is called "contents" but that's just because the table has that as the field name rather than "filename".
49) Click OK. The Assign property sheet shows the Copy Operation as below:
50) Click OK. The Invoke operation may still show a warning flag. Click the flag to see the errors/warnings. If there are now errors/warnings shown, click OK to dismiss the panel and the flag will disappear. The BPEL Process is complete and can be deployed.
It is long-winded, but it might just help somebody else.
Andy