jpos : how to handle messages with different headers with different length listening to the same endpoint and using different packager - jpos

Question

it is not a duplicate question since the previous question some functionality changed and this as a extension of the below. created a new post so helpful for others too who look for different solutions
jpos : how to handle messages with different headers with different length listening to the same endpoint and using same packager
The scenario is a third party application will send messages to jpos. possibility is that it will send two types of messages with different message header length say one will be length 22 bytes and another will be 44 bytes.the packager will be different.
As advised in the above solution I created a custom channel and it works fine.but now the challenge is how can i use different packager for each different request type
example
header1 -- use x packager
header2 -- use y packager
do I have to create new packager if so how can i link the server and the packager and the header types.
looks very challenging and jpos is getting very interesting.
<property name="packager-config" value="cfg/packager/CISebcdic.xml"="True" />
<server class="org.jpos.q2.iso.QServer" logger="Q2" name="gwmip-server-7003" realm="bnet-server-8000">
<attr name="port" type="java.lang.Integer">7003</attr>
<channel class="org.jpos.iso.channel.NACChannel"
packager="org.jpos.iso.packager.GenericPackager"
type="server"
logger="Q2"
>
<property name="packager-config" value="cfg/packager/CISebcdic.xml" debug="True" />
<property name="timeout" value="180000"/>
</channel>
<request-listener class="org.jpos.iso.IncomingListener" logger="Q2" realm="incoming-request-listener">
<property name="queue" value="GWMIPTXNMGR" />
<property name="ctx.DESTINATION" value="jPOS-AUTORESPONDER" />
</request-listener>
</server>
Please help,
Thank in advance,
totally lost below is the one which I am trying, the issue is with
protected ISOPackager getDynamicPackager(byte[] header, byte[]
message)
I am getting the error as below
<log realm="gwmip-server-5281.server.session/10.157.152.95:26215" at="2020-04-18T00:52:22.018">
<session-error>
<exception name="unexpected exception">
java.io.IOException: unexpected exception
at org.jpos.iso.BaseChannel.receive(BaseChannel.java:787)
at org.jpos.iso.ISOServer$Session.run(ISOServer.java:344)
at org.jpos.util.ThreadPool$PooledThread.run(ThreadPool.java:76)
Caused by: java.lang.NullPointerException
at java.nio.HeapByteBuffer.<init>(HeapByteBuffer.java:70)
at java.nio.ByteBuffer.wrap(ByteBuffer.java:373)
at org.jpos.iso.channel.GWMipChannel.getDynamicPackager(GWMipChannel.java:73)
at org.jpos.iso.BaseChannel.receive(BaseChannel.java:743)
... 2 more
Updated Custom Channel
package org.jpos.iso.channel;
import org.jpos.core.Configuration;
import org.jpos.core.ConfigurationException;
import org.jpos.iso.ISOException;
import org.jpos.iso.ISOMsg;
import org.jpos.iso.ISOPackager;
import org.jpos.iso.packager.GenericPackager;
import org.jpos.iso.packager.MadaPackager;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.Arrays;
public class GWMipChannel extends NACChannel {
byte[] madaHeader = {(byte) 0x00, (byte) 0x18, (byte) 0xd6, (byte) 0xf3, (byte) 0xf6, (byte) 0xf8, (byte) 0xf7};
byte[] nitmxHeader = {(byte) 0x00, (byte) 0x18, (byte) 0xd6, (byte) 0xf3, (byte) 0xf7, (byte) 0xf3, (byte) 0xf2};
byte[] response_mada_header = {(byte) 0x00, (byte) 0x31, (byte) 0xc9, (byte) 0xf3, (byte) 0xf6, (byte) 0xf8, (byte) 0xf7};
#Override
protected byte[] readHeader(int hLen) throws IOException {
byte[] header = new byte[25];
serverIn.readFully(header, 0, 25);
boolean mada_header = ByteBuffer.wrap(header, 0, 7).equals(ByteBuffer.wrap(madaHeader));
boolean nitmx_header = ByteBuffer.wrap(header, 0, 7).equals(ByteBuffer.wrap(nitmxHeader));
boolean rsp_mada_header = ByteBuffer.wrap(header, 0, 7).equals(ByteBuffer.wrap(response_mada_header, 0, 7));
ISOPackager packager;
if (mada_header) {
return header;
} else if (nitmx_header) {
header = Arrays.copyOf(header,47 );
serverIn.readFully(header, 25, 22);
return header;
} else if (rsp_mada_header) {
//serverIn.readFully(header, 0, 50);
header = Arrays.copyOf(header, 48);
serverIn.readFully(header, 0, 48);
return header;
}
return header;
}
#Override
protected void sendMessageHeader(ISOMsg m, int len) throws IOException {
byte[] header = m.getHeader();
//assume header is the one to send, and already has 22 or 44 length
//or you can check
serverOut.write(header);
}
#Override
protected ISOPackager getDynamicPackager(byte[] header, byte[] message) {
boolean mada_header = ByteBuffer.wrap(header, 0, 7).equals(ByteBuffer.wrap(madaHeader,0,7));
boolean nitmx_header = ByteBuffer.wrap(header, 0, 7).equals(ByteBuffer.wrap(nitmxHeader,0,7));
ISOPackager packager = null;
if(mada_header) {
try {
packager = new GenericPackager("cfg/packager/CISebcidic_mada.xml");
} catch (ISOException e) {
e.printStackTrace();
}
}
else if (nitmx_header) {
try {
packager = new GenericPackager("cfg/packager/AS2805_NITMX.xml");
} catch (ISOException e) {
e.printStackTrace();
}
} else {
Exception e = new ISOException();
e.printStackTrace();
//return some default or throw some runtime exception exception
}
return packager;
}
}
the server configuration file is
<server class="org.jpos.q2.iso.QServer" logger="Q2" name="gwmip-server-5281" realm="gwmip-server-5281">
<attr name="port" type="java.lang.Integer">5281</attr>
<channel class="org.jpos.iso.channel.GWMipChannel"
packager="org.jpos.iso.packager.GenericPackager"
type="server"
logger="Q2"
header="0018D6F3F7F3F2000000000000000000000000000000000002"
>
<property name="packager-config" value="cfg/packager/AS2805_NITMX.xml" debug="True" />
<property name="timeout" value="180000"/>
</channel>
<request-listener class="org.jpos.iso.IncomingListener" logger="Q2" realm="incoming-request-listener">
<property name="queue" value="GWMIPTXNMGR" />
<property name="ctx.DESTINATION" value="gwmip-AUTORESPONDER" />
</request-listener>
</server>

Answer 1

In your Channel custom channel implementation you can override the getDynamicPackager(byte[] header, byte[] message)
//instantiate each as required in constructor for instance or you can make them configurable through setConfiguration
protected ISOPackager packager22, packager44;
protected byte[] len22HeaderPrefix, len44HeaderPrefix;
protected int headerPrefixLen = 4; //4 according to your other question
protected getDynamicPackager(byte[] header, byte[] message) {
if (Arrays.equals(header, len22HeaderPrefix, 0, prefixLen)) {
return packager22;
} else if (Arrays.equals(header, len44HeaderPrefix, 0, headerPrefixLen)) {
return packager44;
} else {
//return some default or throw some runtime exception exception
}
}