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1 : /*
2 : * Copyright (c) 2024 Project CHIP Authors
3 : * All rights reserved.
4 : *
5 : * Licensed under the Apache License, Version 2.0 (the "License");
6 : * you may not use this file except in compliance with the License.
7 : * You may obtain a copy of the License at
8 : *
9 : * http://www.apache.org/licenses/LICENSE-2.0
10 : *
11 : * Unless required by applicable law or agreed to in writing, software
12 : * distributed under the License is distributed on an "AS IS" BASIS,
13 : * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 : * See the License for the specific language governing permissions and
15 : * limitations under the License.
16 : */
17 : #pragma once
18 :
19 : #include <lib/core/CHIPError.h>
20 : #include <lib/core/TLVReader.h>
21 : #include <lib/core/TLVWriter.h>
22 :
23 : #include <app/AttributeValueDecoder.h>
24 : #include <app/AttributeValueEncoder.h>
25 : #include <app/CommandHandler.h>
26 :
27 : #include <app/data-model-provider/ActionReturnStatus.h>
28 : #include <app/data-model-provider/Context.h>
29 : #include <app/data-model-provider/OperationTypes.h>
30 : #include <app/data-model-provider/ProviderMetadataTree.h>
31 :
32 : namespace chip {
33 : namespace app {
34 : namespace DataModel {
35 :
36 : /// Represents operations against a matter-defined data model.
37 : ///
38 : /// Class is SINGLE-THREADED:
39 : /// - operations are assumed to only be ever run in a single event-loop
40 : /// thread or equivalent
41 : /// - class is allowed to attempt to cache indexes/locations for faster
42 : /// lookups of things (e.g during iterations)
43 : class Provider : public ProviderMetadataTree
44 : {
45 : public:
46 192 : ~Provider() override = default;
47 :
48 : // `context` references will be guaranteed valid until Shutdown is called()
49 152 : virtual CHIP_ERROR Startup(InteractionModelContext context) { return CHIP_NO_ERROR; }
50 164 : virtual CHIP_ERROR Shutdown() { return CHIP_NO_ERROR; }
51 :
52 : /// NOTE: this code is NOT required to handle `List` global attributes:
53 : /// AcceptedCommandsList, GeneratedCommandsList OR AttributeList
54 : ///
55 : /// Users of DataModel::Provider are expected to get these lists
56 : /// from ProviderMetadataTree (in particular IM Reads of these
57 : /// attributes will be automatically filled from metadata).
58 : ///
59 : /// When this is invoked, caller is expected to have already done some validations:
60 : /// - `request.path` is a valid path inside the ProviderMetadataTree (an AttributeEntry exists)
61 : /// - Attribute is readable according to the ProviderMetadataTree/AttributeEntry data
62 : /// - Appropriate ACL checks done according to the attribute's AttributeEntry
63 : ///
64 : /// Return value notes:
65 : /// ActionReturnStatus::IsOutOfSpaceEncodingResponse
66 : /// - Indicates that list encoding had insufficient buffer space to encode elements.
67 : /// - encoder::GetState().AllowPartialData() determines if these errors are permanent (no partial
68 : /// data allowed) or further encoding can be retried (AllowPartialData true for list encoding)
69 : virtual ActionReturnStatus ReadAttribute(const ReadAttributeRequest & request, AttributeValueEncoder & encoder) = 0;
70 :
71 : /// Requests a write of an attribute.
72 : ///
73 : /// When this is invoked, caller is expected to have already done some validations:
74 : /// - cluster `data version` has been checked for the incoming request if applicable
75 : /// - validation of ACL/timed interaction flags/writability, if those checks are desired.
76 : /// - `request.path` is a valid path inside the ProviderMetadataTree (an AttributeEntry exists)
77 : /// - Attribute is writable according to the ProviderMetadataTree/AttributeEntry data
78 : /// - Appropriate ACL checks done according to the attribute's AttributeEntry
79 : virtual ActionReturnStatus WriteAttribute(const WriteAttributeRequest & request, AttributeValueDecoder & decoder) = 0;
80 :
81 : /// Indicates the start/end of a series of list operations. This function will be called either before the first
82 : /// Write operation or after the last one of a series of consecutive attribute data of the same attribute.
83 : ///
84 : /// 1) This function will be called if the client tries to set a nullable list attribute to null.
85 : /// 2) This function will only be called at the beginning and end of a series of consecutive attribute data
86 : /// blocks for the same attribute, no matter what list operations those data blocks represent.
87 : /// 3) The opType argument indicates the type of notification (Start, Failure, Success).
88 : virtual void ListAttributeWriteNotification(const ConcreteAttributePath & aPath, ListWriteOperation opType) = 0;
89 :
90 : /// `handler` is used to send back the reply.
91 : /// - returning `std::nullopt` means that return value was placed in handler directly.
92 : /// This includes cases where command handling and value return will be done asynchronously.
93 : /// - returning a value other than Success implies an error reply (error and data are mutually exclusive)
94 : ///
95 : /// Preconditions:
96 : /// - `request.path` MUST refer to a command that actually exists. This is because in practice
97 : /// callers must do ACL and flag checks (e.g. for timed invoke) before calling this function.
98 : ///
99 : /// Callers that do not care about those checks should use `ProviderMetadataTree::AcceptedCommands`
100 : /// to check for command existence.
101 : ///
102 : /// - TODO: as interfaces are updated, we may want to make the above requirement more
103 : /// relaxed, as it seems desirable for users of this interface to have guaranteed
104 : /// behavior (like error on invalid paths) whereas today this seems unclear as some
105 : /// command intercepts do not validate that the command is in fact accepted on the
106 : /// endpoint provided.
107 : ///
108 : /// Return value expectations:
109 : /// - if a response has been placed into `handler` then std::nullopt MUST be returned. In particular
110 : /// note that CHIP_NO_ERROR is NOT the same as std::nullopt:
111 : /// > CHIP_NO_ERROR means handler had no status set and we expect the caller to AddStatus(success)
112 : /// > std::nullopt means that handler has added an appropriate data/status response
113 : /// - if a value is returned (not nullopt) then the handler response MUST NOT be filled. The caller
114 : /// will then issue `handler->AddStatus(request.path, <return_value>->GetStatusCode())`. This is a
115 : /// convenience to make writing Invoke calls easier.
116 : virtual std::optional<ActionReturnStatus> InvokeCommand(const InvokeRequest & request, chip::TLV::TLVReader & input_arguments,
117 : CommandHandler * handler) = 0;
118 : };
119 :
120 : } // namespace DataModel
121 : } // namespace app
122 : } // namespace chip
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