rawTCP2HTTP never was a perfect solution, but things have become really bad:
- While the passthru/passthru trick with FSH timeout of 1sec works for clients not sending a FIN with rawTCP2HTTP running on <18.104.22.168 firmwares (there DataPower did not send a FIN to client when FSH timeout occured), networking behavior changed starting with 22.214.171.124 firmware. Now connection is terminated completely on frontside timeout, resulting in an Internal error response to client.
- What remains is that sending rawTCP binary message from client terminated with FIN (like netcat command "nc" does) still works even with 7.0.0.x firmware.
- There were Requests For Enhancement, but I cannot find any of them anymore in RFE tool :-(
See the details on this slide (packet capture screenshot on the following slide):
The status of DataPower rawTCP data processing is:
DataPower does support rawTCP processing (XML and Non-XML) to the backend (tcp:///, tcpssl:///, ...),
see slide http://www-01.ibm.com/support/docview.wss?uid=swg27019118&aid=1#page=14 for an example
DataPower does provide rawTCP Front Side Handlers for XML processing
Configuring a stateless raw XML handler
Configuring a stateful raw XML handler
- since quite some time there exists an Enhancement request for a rawTCP Non-XML Front Side Handler
1.5 years ago I developed a prototype of a rawTCP2HTTP converter in DataPower Firmware which allows to convert
rawTCP Non-XML data to HTTP chunked data which can then be processed by any (DataPower) HTTP service
(see IBM publication Bridging raw TCP binary data to HTTP, http://priorartdatabase.com/IPCOM/000197959)
So it seems that processing rawTCP binary data is not possible with DataPower appliances.
Even one week ago I would have said "it is impossible to process Non-XML rawTCP data on DataPower appliances".
But that is not true, and this posting is just another one in the series of "does not work out-of-the-box on DataPower but can be made working"
- Non-XML data processing on DataPower XS40?
- Adding latency during service development for backend simulation
- Sending zip archives to DataPower
- Processing UTF-8 URL-encoded URIs with WebSphere DataPower
- Enhancing “near” SOAP With Attachment data
- Processing embedded stylesheets
So now that we know that it can be done the question is how.
It turns out to be really easy to create a rawTCP2HTTP service as MPGW service on DataPower.
Even though XA35 and XS40 do not allow for binary data processing they at least allow for Non-XML UTF-8 data processing by the first link of above list.
We make use of the fact that binary input of Non-XML transformations needs to be "consumed", otherwise the default behavior is that it will be copied to the output (see 3rd and 1st link above).
In addition we use a rawTCP XML Front Side Handler as that is the only one not complaining about protocol violations.
And then we make sure that INPUT is guaranteed to not being consumed -- thats all.
So this is rawTCP2HTTP MPGW service:
- Front Side Protocol: Stateless Raw XML Handler listening on port1
- Request Type: Non-XML
- Type: static backend
- Backend URL: http://127.0.0.1:port2
- Response Type: Pass-Thru
And this is rawTCP2HTTP policy:
- match all
- Results action from NULL to OUTPUT
- curl --data-binary @file ... http://dpbox:port1
- ab -p file ... http://dpbox:port1
Sending rawTCP data can be done by Netcat tool (nc), this statement sends file to service listening on port at host:
- nc host port < file
To have a basis for measurements I chose a very simple Non-XML example service (toHexb.xsl).
It just returns the (Non-XML) input as hexadecimal string, see posting DataPower "binary" node type (binaryNode) for details:
$ cat toHexb.xsl <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns:dp="http://www.datapower.com/extensions" extension-element-prefixes="dp" > <dp:input-mapping href="store:///pkcs7-convert-input.ffd" type="ffd"/> <xsl:output omit-xml-declaration="yes" /> <xsl:template match="/"> <xsl:copy-of select="substring( dp:radix-convert( dp:concat-base64( 'IA==', dp:binary-encode(/object/message) ), 64, 16 ), 3)"/> </xsl:template> </xsl:stylesheet> $
Now sending a request is not that spectacular -- we get the same hexadecimal output for file te3t we can also get by octal dump (od) tool:
[stammw@bl3d2027@de ~]$ nc 192.168.10.1 2091 <te3t ; echo 74650374 [stammw@bl3d2027@de ~]$ od -Ax -tcx1 te3t 000000 t e 003 t 74 65 03 74 000004 [stammw@bl3d2027@de ~]$
But this is really over rawTCP!
See the following screenshot of a "All Interfaces" (3.8.2 firmware) packet capture.
The Filter for ports 2091 and 2092 just selects the "interesting" part of packect capture.
At the bottom left you see the command execution and output.
On the bottom right you see Follow TCP Stream for services on port 2091 (rawTCP) and 2092 (HTTP).
Hexadecimally displayed content of packet 116 is just the HTTP post of 2091 service to 2092 service after FIN ACK has been received.
This is the first restriction of rawTCP2HTTP service -- it cannot deal with HTTP persistent connections.
Time stamps for packets 110 and 128 show that the transaction took 2.003ms.
But that is not the value which is important.
Important is the average transaction overhead of rawTCP service on 2091 over HTTP service on 2092.
There are quite some tools like ApacheBench (ab) mentioned above for getting performance information of HTTP services.
I was not able to find a similar tool for benchmarking rawTCP performance.
Therefore I wrote one myself based on TCPClient.c (
It was able to benchamrk rawTCP as well as HTTP data (by sending the necessary HTTP Post data).
For persistent and non-persistent connection HTTP benchmarking my numbers were similar to ApacheBench results (-k option for "keepalive").
These are the average results for sending 20000 requests with a concurrency of 20 to a 9004 DataPower from a directly connected Laptop:
- 0.1985ms per request for rawTCP service on 2091
- 0.0809ms per request for HTTP service on 2092 (without persistent connections)
- 0.0647ms per request for HTTP service on 2092 (with persistent connections)
So the overhead of rawTCP2HTTP service is 0.1985ms - 0.0647ms = 0.1338ms.
While for this very simple example service the overhead time dominates the total transaction time, 0.14ms overhead for rawTCP processing enablement is a good price for many real world Non-XML processing scenarios -- until now this is the only way to process rawTCP Non-XML data on DataPower appliances.
These are reasons why the "real" Non-XML rawTCP Front Side Handler of above mentioned Enhancement Request is still needed:
- enabling persistent connections
- reducing/eliminating 0.1338ms overhead of adding/removing of HTTP headers
- having to use "XML rawTCP Front Side Handler" for dealing with "Non-XML data" sounds "interesting" at least :-)
Last, but not least, see that NonXML rawTCP processing on a XA35 or XS40 DataPower appliance is possible by above technique and
the technique from 1st link posting above (by "prepend=" trick with convert-http action):
$ od -Ax -tcx1 test
000000 t e s t 1 2 3 t e s t 1 2 3 t e 74 65 73 74 31 32 33 74 65 73 74 31 32 33 74 65 000010 s t \n 73 74 0a 000013 $ $ nc cosmopolitan 2091 < test | tidy -q -xml <?xml version="1.0" encoding="utf-8"?> <request> <url>/basic.xml?transaction=1</url> <base-url>/basic.xml</base-url> <args src="url"> <arg name="transaction">1</arg> </args> <args src="body"> <arg name="prepend">test123test123test</arg> </args> </request> $ soma/doSoma admin soma/version.xml cosmopolitan:5550 | xpath++ "//Version/text()" - Enter host password for user 'admin': ------------------------------------------------------------------------------- XS126.96.36.199.1 $
I tested rawTCP2HTTP on all supported release branches.
Finally I just tested it on a box with 188.8.131.52 firmware without problems.
184.108.40.206 DataPower Firmware was released in 1H2009 -- since then rawTCP2HTTP service waited to be discovered ... ;-)