CTO Office - Standards & System Management Architecture 1 Rick Landau CTO Office, Standards & System Management Architecture Sept 2007 Understanding Web Services

CTO Office - Standards & System Management Architecture 2 What is a Web Service Many early-generation examples in the market Realistic definition –Is addressed at some URI on the web –Uses XML to represent data –Includes an XML schema to describe a valid data structure –Uses SOAP to structure messages –Uses WSDL to describe interfaces, if necessary

CTO Office - Standards & System Management Architecture 3 Whoa! Terminology? WS = Web Service URI = Universal Resource Identifier XML = eXtensible Markup Language SOAP = Simple Object Access Protocol WSDL = Web Service Description Language SNMP = Simple Network Management Protocol MIB = Management Information Base RFC = Request For Comments IETF = Internet Engineering Task Force DMTF = Distributed Management Task Force CIM = Common Information Model SEP = Somebody Else's Problem

CTO Office - Standards & System Management Architecture 4 Why Is a Web Service Important? –High points (details later) –It is the latest thing –It will replace SNMP in time –Improved communications reliability –Improved communications privacy –It is based on public standards that are easily upgraded –IETF RFCs take years to upgrade, hence private MIBs –The protocol is very extensible using the collection of WS-* protocols –SNMP private MIBs extend only the data –Example: no transaction control extensions to SNMP

CTO Office - Standards & System Management Architecture 5 Web Service Message Entirely in XML –Addresses (specified by WS-Addressing) –Headers, options (specified by WS-Management and others) –Operations (specified by WS-Management and others) –Payload data (specified by WS-Management, WS-CIM, and others) –Uses SOAP to provide a little structure

CTO Office - Standards & System Management Architecture 6 SOAP Envelope message header message body message envelope

CTO Office - Standards & System Management Architecture 7 SOAP Message Header Info that it is (generally) okay to expose –To address –From address (and ReplyTo and FaultTo addresses) –Managed Resource identifier –Action –Message unique identifier –Other important headers and options May be left unencrypted so it can be inspected by firewalls

CTO Office - Standards & System Management Architecture 8 SOAP Message Body The meat of the message, the content of the exchange –Particular verbs, options –Property names and data values Generally NOT okay to expose The body may be encrypted even if the header is not

CTO Office - Standards & System Management Architecture 9 Interaction with a Web Service a web service

CTO Office - Standards & System Management Architecture 10 Access layer Orchestration layer Resource management layer Aggregation layer Logical mapping layer Platform layer Where It Fits in Dell Unified Manageability Architecture Access layer (Interface Service) Orchestration layer Resource management layer Aggregation layer (Repository/Database) Logical mapping layer (Providers) Platform layer (HW / FW / SW) Interactive Programmatic Access Interfaces Remotely accessible Existing and emerging standards Aggregation Interface Local interfaces predominantly defacto standards Logical Interface CMPI is the only open standard Platform Interface Small compact and typically low cost Managed Node Architecture

CTO Office - Standards & System Management Architecture 11 Why Care? Easier to implement –Plain text, XML More secure –Plain text header for filtering, firewalls –Specifies only from, to, managed resource, and action –Contents may be encrypted –Properties and values –Security protocols may be layered onto base

CTO Office - Standards & System Management Architecture 12 Why Care (cont'd)? Can mix and match protocol components to meet special needs –Pieced together from "composable" protocols –Optional add-in features, separate specs, orthogonal –If you need more function, just add new headers and messages –E.g., atomic transactions

CTO Office - Standards & System Management Architecture 13 WS-Management vs SNMP AspectSNMPWS-Management Introduced ; DMTF version 2006 ReliabilityUDP connectionless protocol, timeout on packet losses, retry HTTP(S)/TCP connection- oriented, retransmits Securityv1, v2: plain-text password v3: encrypted (but not widely implemented) HTTPS server authentication to client; encrypted client authentication to server Privacyv1, v2: no encryptionHTTPS, certificate-based Public Standardsmany IETF RFCs for protocols and management data DMTF specs for WS- Management protocol and CIM- based management data Extensibility of dataMany private MIBs. IETF RFCs take years to update DMTF produces an updated CIM version every quarter Extensibility of protocolv1: 1990 v2: 1996 v3: 2002 Dozens of WS-* protocol extensions from W3C, WS-I, OASIS, et al.

CTO Office - Standards & System Management Architecture 14 Conclusion: Monitoring vs Management SNMP –Good for monitoring, not good for management –Okay on devices that support SNMPv3 or special authentication mechanisms WS –Good for monitoring and for management –Secure and private communications

CTO Office - Standards & System Management Architecture 15 WS-Management WS protocol (suite) Originally from Microsoft, Intel, CA, BMC, Dell, et al. Being worked on in DMTF WG, in a subgroup of WIP –WIP = WBEM Infrastructure & Protocols WG of DMTF Not CIM-based per se –Could use any data model –Everyone wants to use CIM (Common Information Model from DMTF) –Current specs use WS-Man on CIM-based data

CTO Office - Standards & System Management Architecture 16 WS-Management Components Protocol –WS-Addressing (endpoint references to resources) –SOAP (envelope structure) –WS-Transfer (get, put) –WS-Enumeration (enumerate, pull) –WS-Eventing (subscribe, unsubscribe) Data definition and use –WS-Management CIM Binding –WS-CIM XML representation of CIM Schema

CTO Office - Standards & System Management Architecture 17 WS-Man Heavily Adopted New transport protocol for DMTF CIM data Required by DASH (DMWG), SMASH (SMWG) Being implemented in out-of-band management controller chips, NICs, graphics chipsets, etc. Implemented in Windows to access WMI data Implementations being developed in Linux for OpenWBEM and OpenPegasus CIMOMs Will be in every desktop, laptop, server, and OS –And peripheral devices soon after

CTO Office - Standards & System Management Architecture 18 Whoa! More Acronyms DASH = Desktop and Mobile Architecture for System Hardware (DMTF initiative) SMASH = Systems Management Architecture for Server Hardware (DMTF initiative) DMWG = Desktop & Mobile Working Group (of DMTF) SMWG = Server Management Working Group (of DMTF) CIMOM = CIM Object Manager WMI = Windows Management Interface

CTO Office - Standards & System Management Architecture 19 Questions?

CTO Office - Standards & System Management Architecture 20 Backup

CTO Office - Standards & System Management Architecture 21 Compare: Reliability SNMP uses UDP –Connectionless, packets can get lost –Application manually times out & retries Web services usually use HTTP/HTTPS on TCP –Connection oriented, TCP transmits reliably

CTO Office - Standards & System Management Architecture 22 Compare: Authentication SNMP –v1 and v2 passwords (community names) transmitted in plaintext, subject to snooping –v3 encrypted but not (yet) widely implemented –Special sequences often invented: challenge-response, specific to device WS –If HTTPS, server authenticates to client with certificate –Wide variety of client authentication schemes defined: Basic, Digest, Mutual, spnego-Kerberos

CTO Office - Standards & System Management Architecture 23 Compare: Privacy SNMP –v1 and v2 transmitted in plaintext –v3 encrypted but not (yet) widely implemented WS –Usually transmitted on HTTP/HTTPS –On HTTPS, message encrypted with SSL/TLS –On HTTP, the message body can be encrypted separately –Everything but the address and the operation (Get, Put, Enumerate, Subscribe, etc.)

CTO Office - Standards & System Management Architecture 24 Compare: Use on Corporate Networks SNMP –SNMP often forbidden on corporate networks, blocked by routers and firewalls –Sometimes limited to read-only –Monitoring only, no configuration management WS –HTTP/HTTPS always permitted on corporate networks, usually passes firewalls

CTO Office - Standards & System Management Architecture 25 Compare: Ease of Learning SNMP –Binary, heavily encoded (ASN.1 Binary Encoding Rules) WS –Encoded in XML plaintext –Protocol described by XML schema

CTO Office - Standards & System Management Architecture 26 Compare: Organization of Data SNMP –Database called Management Information Base (MIB) –Most data in rectangular tables –row=instance, column=property –Data identified by long, hierarchical number strings –Object IDentifiers (OIDs) –The system contact person string is –1(iso).3(org).6(dod).1(internet).2(management).1(mib- 2).1(system).4(sysContact).0(scalar) WS –Data named as XML elements or attributes –. is the system contact person string

CTO Office - Standards & System Management Architecture 27 Compare: Extensibility of Data SNMP –Many companies define private MIBs as extensions of public data –Private data tends to stay private –IETF approval cycle for MIBs and revisions is years long WS –Many companies define private classes and profiles as extensions of the public data –Companies try to standardize any data worth sharing –DMTF updates the CIM Schema version quarterly

CTO Office - Standards & System Management Architecture 28 Compare: Extensibility of Protocol SNMP –Average time between protocol versions = 6 years WS –Web service protocols extended by adding new elements to the XML –Dozens of such extensions defined –WS-Transfer, WS-Enumeration, WS-Eventing, all used by WS-Management –WS-Security, WS-Policy, WS-Transaction, etc.

CTO Office - Standards & System Management Architecture 29 Compare: Asynchronous Notification SNMP –SNMP "traps" sent over UDP (not reliable) –List of IP addresses to send to –No filtering: everyone gets everything –Subscription mechanism out-of-band WS (WS-Management specific) –Client subscribes to stream of event notices –Event notices sent over TCP –Several modes of delivery, including requiring ACK

CTO Office - Standards & System Management Architecture 30 WS Composed Protocols WS-Addressing (endpoint references) SOAP (envelope structure) WS-Transfer (get, put) WS-Enumeration (enumerate, pull) WS-Eventing (subscribe, unsubscribe) WS-Security (authenticate) Etc.

CTO Office - Standards & System Management Architecture 31 WS-Man Operations Protocol operation specifies request and response Target: resource instance –Create, Delete –Get, Put (properties of an instance) Target: collection of instances –Enumerate (get handle), Release (handle) –Pull (instances) Target: event streams –Subscribe, GetStatus, Renew, Unsubscribe –Pull (collections of events) –Normal mode is push from service to client –Ack –Etc.

CTO Office - Standards & System Management Architecture 32 WS-Man Example Message : /wsman?ResourceURI=( uuid:20CBF75C-008E-4C68-AA14-F3EB9D94E617 ComputerSystem IPMI%20Controller%2032 PT60.000S

CTO Office - Standards & System Management Architecture 33 Process of Discovery Find a node (S.E.P.) Find WS-Man service(s) on that node (S.E.P.) –Sticky point recently, general problem –One system may have multiple agents, OR –Multiple nodes with agents need to be correlated Read catalog to get resource classes (ResourceURIs) Enumerate resource instances of resource classes (Selectors) Get or Put to a resource instance

CTO Office - Standards & System Management Architecture 34 Discovery of Multiple MAPs