Definitions
Data Types
Varint
To understand IOTMP, you first need to understand varints. Varints are a method of serializing integers using one or more bytes. Smaller numbers take a smaller number of bytes.
Each byte in a varint, except the last byte, has the most significant bit (msb) set – this indicates that there are further bytes to come. The lower 7 bits of each byte are used to store the two's complement representation of the number in groups of 7 bits, least significant group first.
So, for example, here is the number 1 – it's a single byte, so the msb is not set:
And here is 300 – this is a bit more complicated:
How do you figure out that this is 300? First you drop the msb from each byte, as this is just there to tell us whether we've reached the end of the number (as you can see, it's set in the first byte as there is more than one byte in the varint):
You reverse the two groups of 7 bits because, as you remember, varints store numbers with the least significant group first. Then you concatenate them to get your final value:
Any
Stream
A "stream" is an independent, bidirectional sequence of messages exchanged between the client and server within an IOTMP connection. Streams have several important characteristics:
A single IOTMP connection can contain multiple concurrently open streams, with either endpoint interleaving frames from multiple streams.
Streams can be established and used unilaterally or shared by either the client or server.
Streams can be closed by either endpoint, or closed automatically depending on the message type.
The order in which frames are sent on a stream is significant. Recipients process frames in the order they are received.
Streams are identified by an integer. Stream identifiers are assigned to streams by the endpoint initiating the stream.
Stream Identifier
Resources
Recurs
Field Identifier
Resource Parameters
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