uf:totam
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uf:totam [2010/10/20 16:26] – adding elisag | uf:totam [2021/09/24 10:49] (current) – [Creating a tuplespace and tuples] elisag | ||
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- | ===== Tuples | + | ====== Scoped |
- | TOTAM is an extension to the TOTA tuple space model which introduces | + | TOTAM is tuple space model geared towards mobile ad hoc networks |
+ | TOTAM adopts features of both federated tuple spaces and replication-based approaches: it combines replication of tuples for read operations while guaranteeing atomicity for remove operations. | ||
+ | In TOTAM, tuple spaces are annotated with tuple space descriptors used to determine the scope of a tuple. | ||
+ | The novelty of our approach lies in the use of these tuple space descriptors to determine that a tuple should be propagated before it is transmitted. This enhances privacy and decreases the burden on the network traffic in a wide range of applications. | ||
- | ==== Design | + | ===== Motivation ===== |
- | The original idea was to build a framework similar to [[http:// | + | [[http:// |
+ | These propagation rules are crucial to provide programmers with a flexible mechanism to achieve context-awareness based not only on connectivity but also on semantic information. | ||
- | However, in TOTA tuples are sent to all communication partners in range. Upon arrival at the receiver side, the tuple itself decides whether it has to be stored in that tuple space. By transmitting tuples potential malicious or non-intended users are provided with sensitive information. Not only does sending all tuples blindly to all communication partners in range raise privacy issues, it also creates a network traffic overhead. | + | However, in TOTA tuples are sent to all communication partners in range. Upon arrival at the receiver side, the tuple itself decides whether it has to be stored in that tuple space. As all devices can potentially access all information, |
- | To solve this issues, we extended TOTA with dynamically scoped tuples resulting in the TOTAM ("Tuples | + | ===== Scoped |
- | Another goal was to implement TOTAM as a general framework so that we can then instantiate our TOTAM with guanote objects for the [[: | + | TOTAM provides the programmer |
- | ==== API ==== | + | {{: |
- | Here comes the public interface | + | Figure above illustrates how a scoped tuple is propagated through |
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | ===== API ===== | ||
+ | |||
+ | TOTAM has been implemented in AmbientTalk. The system library shipped with AmbientTalk contains the TOTAM implementation under at/ | ||
+ | |||
+ | ==== Creating a Tuplespace and Tuples ==== | ||
+ | |||
+ | In order to use TOTAM, you need to load the library and create a TOTAM tuple space as follows: | ||
< | < | ||
- | makeTupleSpace() | + | import / |
- | makeTuple(tupleID) | + | def myTupleSpace := makeTupleSpace(); |
- | extendTuple: | + | </ |
+ | |||
+ | A description can be passed in the '' | ||
+ | |||
+ | To create a tuple or a template (i.e. a tuple with wildcards or " | ||
+ | < | ||
+ | // a “hallo” message tuple from wolf. | ||
+ | def halloTuple := tuple: [" | ||
+ | // a template for message tuples from wolf. | ||
+ | def wolfTuples := tuple: [" | ||
+ | // a template for any message tuples. | ||
+ | def msgTuples := tuple: [" | ||
</ | </ | ||
- | A tuple space (ts) in AmbientTota basically consists of a local ts, an ambient ts (to inject | + | |
+ | ==== Adding and Reading Tuples ==== | ||
+ | |||
+ | TOTAM provides operations | ||
< | < | ||
- | // tota operations | + | // add tuple to tuple space |
- | def add(tuple) | + | myTupleSpace.out(halloTuple); |
- | def delete(template) -> vector with the deleted | + | // get a Message tuple |
- | matching the template | + | def aMessageTuple := myTupleSpace.rdp(msgTuples); |
- | def read(template) -> vector with the matching tuples | + | // get all Message |
+ | def messageTuples := myTupleSpace.rdg(msgTuples); | ||
+ | </code> | ||
- | // | + | The '' |
- | def inject(tuple) | + | |
- | // places a listener on to the local TS ( ~ subscribe | + | In the original Linda model, read and in operations were provided |
- | // it returns a publication object | + | |
- | when: template matches:{ | tuple | | + | |
- | // code | + | |
- | } | + | |
- | //Templates are currently boolean expressions on tuples. | + | |
- | Example | + | |
- | { |guanote| | + | |
- | //methods belonging to the propagation protocol | + | < |
+ | def msgTuples := tuple: [Message, var: `from, var: `content]; | ||
+ | myTupleSpace.whenever: | ||
+ | system.println(“Got message: “ + content + “ from: ” + from); | ||
+ | }; | ||
- | // notifies the discovery of a remote ts | + | myTupleSpace.whenever: |
- | // and starts the propagation protocol | + | |
- | def notifyTSDiscovered(ts) | + | }; |
- | // notifies the arrival of tuples from a ts | + | |
- | // receive side of the propagation protocol | + | |
- | def receiveTyples(tuples) | + | |
</ | </ | ||
- | A tuple in our system | + | The '' |
+ | |||
+ | The '' | ||
< | < | ||
- | // called in every tuple at pass() | + | myTupleSpace.goOnline(); |
- | def decidePropagation() -> boolean | + | myTupleSpace.inject: halloTuple; |
- | // specifies operations on the local TS | + | |
- | def doAction | + | |
- | // specifies operations on the tuple itself | + | |
- | def changeTupleContent() -> tuple | + | |
- | // if true -> note gets added to local TS | + | |
- | def decideStore () -> boolean | + | |
- | // if true -> tuple gets unexported and deleted from local TS. | + | |
- | //new operation not in TOTA | + | |
- | def decideSleep() -> boolean | + | |
</ | </ | ||
- | Ideas: | + | Note that the network facilities are disabled by default, so before injecting something in the network, the '' |
+ | |||
+ | ==== Tuple' | ||
+ | |||
+ | Similar to TOTA, public tuples are replicated and shared amongst devices when devices come into communication range. We thus say that tuple are propagated into the //TOTAM network//, i.e. a logical network formed by all devices which host a TOTAM tuple space. The spread of tuples into the TOTAM network can be controlled by means of a propagation protocol. Each tuple injected into the network carries a propagation protocol that can be customized by developers. What follows shows the default propagation protocol: | ||
+ | |||
+ | < | ||
+ | def defaultPropagationProtocol(){ | ||
+ | isolate: { | ||
+ | // | ||
+ | def decideEnter(ts) { true }; | ||
+ | def doAction(ts){}; | ||
+ | def changeTupleContent(ts){self}; | ||
+ | def decideStore(ts) {true}; | ||
+ | // | ||
+ | def inScope(senderDescriptor, | ||
+ | def decideDie(ts){false}; | ||
+ | }; | ||
+ | }; | ||
+ | </ | ||
+ | |||
+ | Custom propagation protocols can be created and attached to a tuple before being injected in the network as follows: | ||
+ | |||
+ | < | ||
+ | //define a new propagation protocol | ||
+ | def blueProtocol := propagationProtocol: | ||
+ | def inScope(senderDescriptor, | ||
+ | receiverDescriptor.team == " | ||
+ | }; | ||
+ | // attach the protocol to a tuple | ||
+ | def aBlueTuple := tuple: [" | ||
+ | withPropagationProtocol: | ||
+ | // inject the tuple to the network | ||
+ | def publication := inject: aBlueTuple; | ||
+ | </ | ||
+ | |||
+ | The '' | ||
+ | |||
+ | |||
+ | < | ||
+ | // cancels the propagation of the tuple to new devices in the TOTAM network. | ||
+ | publication.cancel(); | ||
+ | // sends an antituple to notify the removal of this tuple in devices which carry a copy. | ||
+ | publication.retract(); | ||
+ | </ | ||
+ | |||
+ | Upon a '' | ||
+ | Upon a '' | ||
+ | |||
+ | |||
+ | < | ||
+ | Note that '' | ||
+ | </ | ||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | ===== Further Reading ===== | ||
- | TOTA could be combined with the RETE engine we built for the characteristic functions, in the future to reason about multiple tuples. | + | **TOTAM: Scoped Tuples |
+ | ([[ http:// | ||
- | decideSleep() is there for discontinuous decidePropagation functions. for example, tuples that should be only propagated every Tuesday could not implemented with TOTA because the propagation protocol only gets called once. We change | + | < |
+ | </ |
uf/totam.1287584787.txt.gz · Last modified: 2010/10/20 16:28 (external edit)