ASAPStorage

Each ASAP application keeps its data in an ASAPStorage.

There is not need for ASAP application to access those storages at all. On the contrary, it is a really good idea to build an ASAP application that uses this library only as it was planned to be: a message routing protocol.

Nevertheless, messages are stored. And sometimes it might be easier or requires less resource to just access those messages instead of keeping a copy in an application specific database. We cannot make that decision but provide a documentation. The general concept of ASAP message storing is explained. Some specifics and deeper insights into the API come later.

Application can send and receive messages with the ASAPPeer interface. A message is sent with a specific format.

There is an ASAPStorage for each format. An ASAPStorage keeps all messages of an ASAP application. It can be seen as an in- and outbox in an e-mail system.

Each ASAPStorage has got an ASAPChunkStorage which holds a number of ASAPChunks. A chunk is a collection of ASAP message with the same uri. There are at least as many different chunks different uris in our application. This code snippet is from was used to explain [how to send a message(./Implement-an-ASAP-application#send-a-message).

public static final String FORMAT = "application/x-YOUR_APP_FORMAT";
public static final String MESSAGE_URI = "YOUR_APP://message";
...
ASAPPeer yourPeer = ..;
...
byte[] yourMessageContent = ..; // create it

// send message
yourPeer.sendASAPMessage(FORMAT , MESSAGE_URI , yourMessageContent);

This message is stored for later or immediate (usally both) delivery. The following code illustrates how to get access to the ChunkStorage where this message is stored:

public static final String FORMAT = "application/x-YOUR_APP_FORMAT";
...
ASAPPeer asapPeer = ..; // got an object reference from somewhere else
ASAPStorage  asapStorage = asapPeer.getASAPStorage(FORMAT);
ASAPChunkStorage chunkStorage = asapStorage.getChunkStorage();

There is one other thing to understand before we get access to our message again: It is the era.

Each ASAPStorage has got an era. It is initialized with zero. The era can be changed whenever a) the peer encounters another one or loses a connection. The era is changed if b) also at least one new message was added to this storage by calling yourPeer.sendASAPMessage().

We have anything we need to find our message in the storage:

int era = asapStorage.getEra(); // current era
ASAPChunk asapChunk = chunkStorage.getChunk(MESSAGE_URI, era);