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ql
Posted on Wednesday, June 18, 2003 - 05:11 am:   

Hi BN,

I have decoded SM of m-notification-ind. But I ask you for three questions. Plz tell me their key.

SM PDU :
udh : 0605040B8423F0
body : 36 06 226170706C69636174696F6E2F766E642E7761702E6D6D732D6D65737361676500 AF84......

1. What do 0x36 means?

2. If 06 22 ....00 is content-ID: application/vnd.wap.mms-message, Then, Is 0x06 field name of content-ID?

3. What do 0xAF84 means?
Bryce Norwood - NowSMS Support
Posted on Wednesday, June 18, 2003 - 06:46 pm:   

QL,

You're looking at a WSP push header. So all the questions kind of tie together. Take a look at the WAP connection less push PDU format in the WSP specification.

0x22 specifies the length of the content type field and headers.

"application/vnd.wap.mms-message" is the content type.

AF84 is part of the headers (X-Wap-Application-ID).

-bn
ql
Posted on Thursday, June 19, 2003 - 05:12 am:   

I see. ThanX.

What do the first data (0x36) of body means?

QL
Bryce Norwood - NowSMS Support
Posted on Thursday, June 19, 2003 - 05:22 am:   

QL,

I have to make you read the specs a little bit. Actually, I always find it helpful when I can look at the spec and finally say ... "Aha!" It helps me understand it better.

Take a look at the WAP WSP specification. Chapter 8, WSP Data Unit Structure and Encoding. Section 8.2 Protocol Data Unit Structure ... with a particular emphasis on 8.2.1 (PDU Common FieldS) and 8.2.4.1 (Push and Confirmed Push).

You're looking at connection-less push, so also refer to section 7.2 on Connectionless WSP.

I think this will help complete the understanding.

-bn
ql
Posted on Friday, June 20, 2003 - 04:51 am:   

ThanX. I have known.

QL
Murali Mohan.K
Posted on Tuesday, June 24, 2003 - 05:37 am:   

Hi Bryce,

Can you tell me from where exactly the WDP headers start in the PDu given above ?

SM PDU :
udh : 0605040B8423F0 -- is it WDP headers?? OR SMS headers ??

WSP headers : 36 06 22 6170706C69636174696F6E2F766E642E7761702E6D6D732D6D65737361676500 AF84......


Thanx in advance..
Murali
Bryce Norwood - NowSMS Support
Posted on Tuesday, June 24, 2003 - 01:32 pm:   

Murali,

Logically WDP has port mappings to allow different protocols to send and receive packets on well-defined ports (similar to UDP or TCP in the IP world).

SMS doesn't have that concept. So WDP defines a mapping of WDP to GSM SMS where the ports are defined in the user data header (UDH) of the SMS message. This is defined in the same way as Nokia Smart Messaging.

UDH is also used for segmentation and the ability to send multiple messages that can be reassembled into a single message at the receiver.

The WDP spec defines this mapping of the WDP protocol to GSM SMS and defines how the UDH is used.

So technically, I'd say that the UDH is SMS headers required to implement WDP over GSM SMS.

-bn
Murali Mohan.K
Posted on Wednesday, June 25, 2003 - 07:54 am:   

So this means there will not be any WDP headers as such (usually all protocol layers will have headers which will be stripped off in its peer).
But the SMS implementation (WDP bearer here) should parse UDH headers and get the destination port and server ports.

Let me know if this is correct..

murali
Bryce Norwood - NowSMS Support
Posted on Wednesday, June 25, 2003 - 06:22 pm:   

Murali,

That is correct.

-bn
Jack
Posted on Sunday, September 21, 2003 - 01:49 pm:   

Hello everybody,

I love this message board.

Has anybody figured out why the From-value (in MMSEncapsulation) has a Value-length prefix?

It seems redundant?

Best wishes

Jack
Bryce Norwood - NowSMS Support
Posted on Wednesday, September 24, 2003 - 11:00 pm:   

Jack,

There are a lot of cases where things seem redundant like this, but the reason is so that they can follow general WSP decoding rules, where a decoder can skip over items that it does not understand (for example encodings defined in a future version). See section 8.4.1.2 of the Wireless Session Protocol (WSP) specification. I think the following statement from that spec sums up the reasoning very nicely:


quote:


The WSP field values are encoded so that the length of the field value can always be determined, even if the detailed format of a specific field value is not known.




-bn