DAP4 Chunking - Revision history

Ndp: /* Error response */

2012-02-21T23:24:11Z

Error response

← Older revision		Revision as of 23:24, 21 February 2012
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	=== Error response ===		=== Error response ===

	~~Built in to the BES currently~~ is the ~~error message response to~~ a ~~BES client~~ request~~. Specifically, if the BES client issues a command and the BES server has a problem with it~~ (either with the ~~command~~ itself, the processing of the response to the ~~command~~, or sending of the response) then the ~~BES~~ server will send an extension chunk to the ~~BES~~ client with the name/value pair "status=error;", and, following that chunk, data chunks will contain the error information followed by the last chunk. The extension chunk with the error status could come following a series of data chunks containing the partial response.		If an error is encountered during the processing of a request (either with the request itself, the processing of the response to the request, or sending of the response) then the server will send an extension chunk to the client with the name/value pair "status=error;", and, following that chunk, data chunks will contain the error information followed by the last chunk. The extension chunk with the error status could come following a series of data chunks containing the partial response.

Ndp: /* Client/server exit */

2012-02-21T23:21:47Z

Client/server exit

← Older revision		Revision as of 23:21, 21 February 2012
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	Read/receive should be called until the last chunk in the transmission is received. The last chunk is represented by chunk size of 0.		Read/receive should be called until the last chunk in the transmission is received. The last chunk is represented by chunk size of 0.

	~~=== Client/server exit ===~~

	~~The exit handshake used to take place with an exit token. Now, instead, it is done with an exit extension. The chunk will look like this:~~

	~~0000014xstatus=PPT_EXIT_NOW;~~

	~~followed by the last chunk signifying the end of the transmission.~~

	~~0000000d~~

	=== Chunking State Diagram ===		=== Chunking State Diagram ===

Ndp: /* Graphical representation of chunking scheme */

2012-02-21T23:21:40Z

Graphical representation of chunking scheme

← Older revision		Revision as of 23:21, 21 February 2012
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	It is possible that the chunk may not come across in one read call to the underlying socket layer. The first 8 bytes represent information about the chunk, the first seven bytes being the size of the chunk and the eighth byte being the type of data the chunk contains. Read should be called until the entire chunk has been received.		It is possible that the chunk may not come across in one read call to the underlying socket layer. The first 8 bytes represent information about the chunk, the first seven bytes being the size of the chunk and the eighth byte being the type of data the chunk contains. Read should be called until the entire chunk has been received.

	Read/receive should be called until the last chunk is received. The last chunk is represented by chunk size of 0.		Read/receive should be called until the last chunk in the transmission is received. The last chunk is represented by chunk size of 0.

	=== Client/server exit ===		=== Client/server exit ===

Ndp: Created page with "== Overview == === Chunking Scheme ===

        chunked-body     =  *chunked-section last-chunk         chunked-section  = chunk | chunk-extension               chunk-exten..."

2012-02-21T23:20:09Z

Created page with "== Overview == === Chunking Scheme === <pre> chunked-body = *chunked-section last-chunk chunked-section = chunk | chunk-extension chunk-exten..."

New page

== Overview ==

=== Chunking Scheme ===

<pre>
chunked-body = *chunked-section last-chunk

chunked-section = chunk | chunk-extension

chunk-extension = chunk-size "x" 1*(chunk-ext-name [ "=" chunk-ext-val ] ";")

chunk = chunk-size "d" chunk-data

chunk-size = 7HEXDIG
last-chunk = 7("0") "d"

chunk-ext-name = token
; sequence of 7-bit ASCII printable chars

chunk-ext-val = token | quoted-string
; quoted-string is DQUOTE token DQUOTE

chunk-data = chunk-size(OCTET)
; exactly chunk-size bytes
</pre>

=== Graphical representation of chunking scheme ===

[[Image:BES chunking 7 1.jpg]]

size - Stored in the first seven bytes are the size of the chunk (in bytes). The size does not include the first 8 bytes which are the chunk size and the chunk type (x or d). The size is a 16 bit integer encoded in 7 bytes as 7 ASCII characters that represent the size as a 7 hexadecimal (base 16) digits. If the size is 0, this signifies the end of the transmission, no more chunks follow.

type - The eighth byte is the type of chunk that follows. The type can be one of
* x - extension, one or more name=value; pairs
* d - data, actual data

data - The data part of the chunk, meaning either extensions or data, not both

Extensions are a name/value pair and can represent information needed by the underlying communication layer. For example: status=error; would mean that an error has occurred. This chunk would not contain the error/exception information itself. Following chunks would hold that information and would be of type d (for data).

It is possible that the chunk may not come across in one read call to the underlying socket layer. The first 8 bytes represent information about the chunk, the first seven bytes being the size of the chunk and the eighth byte being the type of data the chunk contains. Read should be called until the entire chunk has been received.

Read/receive should be called until the last chunk is received. The last chunk is represented by chunk size of 0.

=== Client/server exit ===

The exit handshake used to take place with an exit token. Now, instead, it is done with an exit extension. The chunk will look like this:

0000014xstatus=PPT_EXIT_NOW;

followed by the last chunk signifying the end of the transmission.

0000000d

=== Chunking State Diagram ===

[[Image:ChunkedStreamReaderStateDiagram.png|1000px]]

=== Error response ===

Built in to the BES currently is the error message response to a BES client request. Specifically, if the BES client issues a command and the BES server has a problem with it (either with the command itself, the processing of the response to the command, or sending of the response) then the BES server will send an extension chunk to the BES client with the name/value pair "status=error;", and, following that chunk, data chunks will contain the error information followed by the last chunk. The extension chunk with the error status could come following a series of data chunks containing the partial response.