uf:totam
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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/ | ||
+ | |||
+ | |||
+ | 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: tuple with: closure | + | </ |
+ | |||
+ | A description can be passed in the '' | ||
+ | < | ||
+ | // a “hallo” message tuple from wolf. | ||
+ | def halloTuple | ||
+ | // a template for message tuples from wolf. | ||
+ | def wolfTuples := tuple: [Message, “wolf”, var: `content]; | ||
+ | // a template for any message tuples. | ||
+ | def msgTuples := tuple: [Message, var: `from, var: `content]; | ||
</ | </ | ||
- | A tuple space (ts) in AmbientTota basically consists of a local ts, an ambient ts (to inject | + | 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) | + | Note that these operations are non-blocking. The'' |
- | // places a listener on to the local TS ( ~ subscribe in TOTA) | + | < |
- | // it returns a publication object to be able to unsusbscribe | + | myTupleSpace.goOnline(); |
- | when: template matches:{ | tuple | | + | myTupleSpace.inject: halloTuple; |
- | // code | + | </code> |
- | } | + | |
- | //Templates are currently boolean expressions on tuples. | + | |
- | Example of template applied to guanotes: | + | |
- | { |guanote| | + | |
- | //methods belonging to the propagation protocol | + | Note that the network facilities are disabled by default, so before injecting something in the network, the '' |
- | // notifies | + | A tuple injected to the network carries |
- | // and starts | + | |
- | def notifyTSDiscovered(ts) | + | < |
- | // notifies the arrival of tuples from a ts | + | def defaultPropagationProtocol(){ |
- | // receive | + | isolate: { |
- | def receiveTyples(tuples) | + | //receiver-side protocol |
+ | def decideEnter(ts) { true }; | ||
+ | def doAction(ts){}; | ||
+ | def changeTupleContent(ts){self}; | ||
+ | def decideStore(ts) {true}; | ||
+ | //sender-side protocol | ||
+ | def inScope(descriptor){ true }; | ||
+ | def decideDie(ts){false}; | ||
+ | }; | ||
+ | }; | ||
</ | </ | ||
- | A tuple in our system is just the object contained in a local TS offering the following API to propagate itself: | + | However, other propagation protocols can be created and attached to a tuple before being injected |
< | < | ||
- | // called in every tuple at pass() | + | //define a new propagation protocol |
- | def decidePropagation() -> boolean | + | def blueProtocol := propagationProtocol: |
- | // specifies operations on the local TS | + | def inScope(descriptor) { descriptor.team == " |
- | def doAction | + | }; |
- | // specifies operations on the tuple itself | + | // attach |
- | def changeTupleContent() -> tuple | + | def aBlueTuple := tuple: [Message, " |
- | // if true -> note gets added to local TS | + | withPropagationProtocol: |
- | def decideStore () -> boolean | + | // inject the tuple to the network |
- | // if true -> tuple gets unexported and deleted from local TS. | + | def publication := inject: aBlueTuple; |
- | //new operation not in TOTA | + | |
- | def decideSleep() -> boolean | + | |
</ | </ | ||
- | Ideas: | + | The '' |
+ | |||
+ | < | ||
+ | // sends an antituple to notify the removal of this tuple. | ||
+ | publication.retract(); | ||
+ | </ | ||
+ | |||
+ | In order to notify the removal of a tuple, TOTAM sends an antituple for the removed tuple. For every tuple there is (conceptually) a unique antituple with the same format and content, but with a different sign. All tuples injected by an application have positive sign while their antituples have a negative sign. Whenever a tuple and its antituple are stored in the same tuple space, they immediately annihilate one another, i.e. they both get removed from the tuple space. By means of antituples, TOTAM can “unsend” tuples injected to the network. | ||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
+ | |||
- | TOTA could be combined with the RETE engine we built for the characteristic functions, in the future to reason about multiple tuples. | + | ===== Further Reading ===== |
- | decideSleep() is there for discontinuous decidePropagation functions. for example, tuples that should be only propagated every Tuesday could not implemented with TOTA because | + | **TOTAM: Scoped Tuples |
+ | ([[ http:// |
uf/totam.txt · Last modified: 2021/09/24 10:49 by elisag