1 schuur 1.1 CMPI Providers in a nutshell
2 ============================
3
4 Viktor Mihajlovski <mihajlov@de.ibm.com>
5 Nov 14th 2003
6
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7 konrad.r 1.3 Pegasus 2.4 *NEWS*
8 ------------------
9
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10 konrad.r 1.5 The CMPI header files are being standardized and will be (possibly by the
11 time you read this) frozen. However, since the OpenPegasus 2.4 release is
12 anticipated prior to the anticipated freezing of the CMPI standard,
13 the OpenPegasus 2.4 release will not provide the CMPI header files as
14 part of the OpenPegasus 2.4 SDK.
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15 konrad.r 1.3
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16 konrad.r 1.5 They can be found within CVS and the source tarball. Visit
17 http://cvs.opengroup.org/cgi-bin/viewcvs.cgi/pegasus/src/Pegasus/Provider/CMPI/ to view the CMPI header files.
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18 konrad.r 1.3
19 Build CMPI from sources
20 -----------------------
21
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22 schuur 1.1 The Common Manageability Programming Interface (CMPI) has been integrated into
23 Pegasus as a pluggable provider manager.
24
25 CMPI must be enabled during Pegasus build.
26 For CMPI enablement, set the following environment variables prior to make:
27
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28 konrad.r 1.2 PEGASUS_ENABLE_CMPI_PROVIDER_MANAGER=1
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29 schuur 1.1
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30 konrad.r 1.3
31 Using CMPI
32 ----------
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33 schuur 1.1 If you plan to write your own CMPI providers you are kindly referred to the
34 WBEMSource homepage where the draft specification document for CMPI resides.
35 You can find at http://www.wbemsource.org/doc.tpl?CALLER=index.tpl&gdid=3712 .
36 If you are looking for samples you should have a look at the SBLIM project.
37 The packages prefixed by the string sblim-cmpi contain CMPI providers for
38 various classes. See http://www-124.ibm.com/developerworks/projects/sblim .
39
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40 konrad.r 1.3
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41 konrad.r 1.6 Using CQL with CMPI
42 -------------------
43
44 To use CQL support for indications and exec query you will have to use
45 the Pegasus/Provider/CMPI/cmpi_cql.h header file with one new function.
46 You also you need to define PEGASUS_USE_EXPERIMENTAL in your
47 code to take advantage of these CQL utility functions. The reason is that
48 the CMPI standard 1.0 is unclear on one thing:
49
50 - CMNewSelectExp. One of arguments passed is a 'projection' array. The
51 spec does not explain exactly what in such array. Implementation of
52 CMPI that also implemented WQL put a string representation of the
53 properties, as "SystemName", "Hostname", etc. But that is not neccesarily
54 the case with CQL, where you can have chained identifiers such as
55 "CIM_OperatingSystem::SystemName". In other words, the CMPI standard
56 needs to clarify this and to make the existing providers backward
57 supported, this utility function - CMPI_CQL_NewSelectExp is provided
58 until the CMPI standard comes up with a conclusion on this.
59
60 When the CMPI provides a resolution on these issues, this utility
61 interface will be gone and unsupported.
62 konrad.r 1.6
63 Questions and Answers:
64 Q1: Is the CMPI Specification really ambiguous or does it
65 just not support CQL? If it's ambiguous should it be fixed
66 before it goes final?
67
68 A1:. Page 96 of the CMPI review spec states (line 2899-2901): The *projection output argument is
69 a pointer to a CMPIArray structure of CMPIString entries containing projection specification.
70 It shall be set to NULL if no projection is defined.. To clarify any ambigiuity, an e-mail to the
71 CMPI review group was sent, which would add the following: The projection specification is query
72 language specific. Hence the entries format of the projection output array CMPIString might be
73 different depending on the query language. Be sure to check the lang argument for the query language your
74 provider will support. . To guard the provider from DMTF's CQL possible ways it can be represented in
75 a string format, and since the CQL is experimental, the CMNewSelectExp will NOT support CQL.
76 The CMPI_CQL_NewSelect will support both CQL and WQL.
77
78
79 AQ:What happens if an existing Provider is passed a CQL
80 statement and issues a newSelectExp call? Does it return
81 an error?
82
83 konrad.r 1.6 A2: The error code CMPI_RC_ERR_QUERY_LANGUAGE_NOT_SUPPORTED would be set.
84
85
86 Q3: Both CMNewSelectExp and CMPI_CQL_NewSelectExp return a
87 CMPISelectExp. Is there anyway to determine whether the
88 CMPISelectExp represents a CQL or WQL expression?
89
90 A3:Not from the scope of the CMPISelectExp structure. Please note that the routine
91 that would exercise the CMPISelectExp has a char *lang passed in as argument.
92 This char *lang* can be used to easily determine what query language is used.
93
94
95
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96 konrad.r 1.3 Registering CMPI providers with Pegasus
97 ---------------------------------------
98
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99 schuur 1.1 Once you have a CMPI provider library you want to register it with Pegasus.
100 How? Well it's almost the same as for C++ providers. The only difference is
101 that the Provider.Interface property must be set to "CMPI".
102
103 Here's an excerpt from the SBLIM Linux Computer System provider registration
104
105 // ===================================================================
106 // Linux_ComputerSystem
107 // ===================================================================
108
109
110 instance of PG_ProviderModule
111 {
112 Name = "OSBase_ComputerSystemProviderModule";
113 //The library name on disk
114 Location = "cmpiOSBase_ComputerSystemProvider";
115 Vendor = "SBLIM";
116 Version = "1.2.2";
117 InterfaceType = "CMPI";
118 InterfaceVersion = "0.86.0";
119 };
120 schuur 1.1
121 instance of PG_Provider
122 {
123 //The provider module as defined in PG_ProviderModule
124 ProviderModuleName = "OSBase_ComputerSystemProviderModule";
125 // The provider name as referenced in the code
126 Name = "OSBase_ComputerSystemProvider";
127 };
128
129 instance of PG_ProviderCapabilities
130 {
131 //The provider module as defined in PG_ProviderModule
132 ProviderModuleName = "OSBase_ComputerSystemProviderModule";
133 //The provider name as defined in PG_Provider
134 ProviderName = "OSBase_ComputerSystemProvider";
135 CapabilityID = "1";
136 //Name of the CIM class as defined in the mof
137 ClassName = "Linux_ComputerSystem";
138 Namespaces = {"root/cimv2"};
139 ProviderType = { 2,5 }; // Instance, Method
140 SupportedProperties = NULL; // All properties
141 schuur 1.1 SupportedMethods = NULL; // All methods
142 };
143
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