ICS 123 Software Engineering Challenges Web Services and SOAP Richard Taylor & Eric Dashofy UC Irvine http: //www. isr. uci. edu/classes/ics 123 s 02/
Topic 16 Web Services and SOAP Traditional Software Systems • are developed by a single organization • undergo a phased development process – with multiple phases of review, inspection, testing • have a synchronized release schedule • have a proprietary design and proprietary component interfaces • have a monolithic code base • go through a painful evolution 2 ICS 123
Topic 16 Web Services and SOAP Our Vision The future of software development requires integrating network services that are very far away and owned by strangers Rohit Khare 16 May 2002 O’Reilly Emerging Technology Conf UC Irvine & Know. Now, Inc. 3 ICS 123
Topic 16 Web Services and SOAP Three Elements of Our Vision ICS 123 • The abstract unit of software is a network service – Prior levels of abstractions were subroutines, libraries, processes, objects, … – In this view, the only way to understand software is to watch its message traffic • Latency is an absolute limit of system architecture – Just as “real” architects grapple with gravity, so with the speed of light – London will always be 30 ms from New York, regardless of Moore’s Law • Decentralization means crossing agency boundaries – The essential complication above and beyond distributed (parallel) computing is extending a system to achieve consensus between several separate agencies – Every computing and communication device is owned by someone. 4
How Our Vision is Emerging Today Topic 16 Web Services and SOAP ICS 123 • The technological shift from a component model to a service model of software is already underway – SOAP and Web Services technologies make it easy to write new protocols • The Internet is inexorably shifting to higher-latency, decentralized connectivity – Ad-hoc, peer-to-peer networking, mainly wireless, is being deployed at every scale from one meter (handhelds) to billions of meters (space probes) • Enterprise Application Integration (EAI) is only now reaching ‘outside the firewall’ to business partners – The next revolution in productivity requires reengineering processes end-to-end 5
Topic 16 Web Services and SOAP So What’s This Talk About? ICS 123 • There is a ‘missing link’ between the near-future • predicted by today’s Web Services hype and realizing the true potential of our vision It is a new architectural style for software integration we call Application-Layer Internetworking (ALIN) – ALIN applies networking concepts to software engineering • The primary way that developers will use ALIN is an • 6 unheralded implication of SOAP 1. 2: Routing … so this talk is about a new style and a new device
What’s EAI? Topic 16 Web Services and SOAP ICS 123 1. Enterprise Application Integration is the unrestricted sharing of data and business processes throughout the networked applications or data sources in an organization 2. The Linking of Data, Business Processes, Applications that result in a common virtual system 7
What’s EAI? Topic 16 Web Services and SOAP ICS 123 • Enterprise Application Integration is real-time integration of the information systems within an organization that support the different steps of a business process • Consider the following typical business process • An order might be captured by: • A CSR using an order entry system • A consumer using a web application • A business partner system using a web service interface • Regardless of the channel, the order must be financially and operational processed: • The financial system processes the billing • The operational system processes the manufacturing, scheduling, provisioning, clearance, etc. depending upon industry. 8
Topic 16 Web Services and SOAP Without EAI ICS 123 AR Internal Credit AP External Logistics • • • ECommerce Inventory 9 Manual Hand-Offs Web Applications Increase the Number of Enterprise Integration Points • External Numerous Point-to-Point Interfaces Inconsistent Business Processes • Inconsistent Qualities of Service
Without EAI • Numerous Point-to-Point Interfaces • Manual Hand-Offs • Web Applications Increase the Number of Enterprise Integration Points • Inconsistent Business Processes • Inconsistent Qualities of Service 10 Topic 16 Web Services and SOAP ICS 123
Topic 16 Web Services and SOAP With EAI ICS 123 EAI Infrastructure AR Business Process Automation Internal Portal External AP Data Transformation Message Routing Web Service External Adapter 11 Credit Logistics ECommerce Inventory Message Storage
With EAI • Reduced Number of Common, Consistent, Known Interfaces Topic 16 Web Services and SOAP ICS 123 • Consistently Automated Business Processes • Increased Quality of Service (e. g. Order can Still be Captured even when Financial and Operational systems are Unavailable) • Framework for Integration of Web Services 12
Components in an EAI Solution Topic 16 Web Services and SOAP ICS 123 EAI Infrastructure Business Process Automation Data Transformation Message Routing Message Storage Adapter 13 Adapter • Adapters • Also known as “Connectors”, “Translators”, “Wrappers” • Provide seamless connectivity to the undrelying application or data • Convert information and events into data that can be utilized by the infrastructure • Two way translation between the proprietary lingo and the common lingo • Many adapters available off the shelf from EAI Software vendors such as Tibco, or Packaged Software vendors such as SAP.
Components in an EAI Solution Topic 16 Web Services and SOAP ICS 123 EAI Infrastructure Business Process Automation Data Transformation Message Routing Message Storage • Message Broker • An intelligent broker that directs the flow of messages between sources and consumers of information • Message-Oriented Middleware (MOM) • A set of products that connect applications running on different systems by sending and receiving application data as messages • Message Routing • Set of tools that route messages between sources and consumers based on pre-defined business rules • Message Storage • Also identified as “Message Warehousing” • Central repository for temporary storage of transactions • Adapter • asynchronous communications style and provides a loosely coupled exchange across multiple operating systems Adapter • 14 Message Queuing Publish Subscribe
Components in an EAI Solution Topic 16 Web Services and SOAP ICS 123 EAI Infrastructure Business Process Automation • Data Transformers • Mapping of data elements to achieve common denominator Data Transformation Message Routing • Transformation to and from Formats Used by Different Systems Message Storage • GUI Configuration • Handles simple or complex data structures Adapter 15 Adapter
Components in an EAI Solution Topic 16 Web Services and SOAP ICS 123 EAI Infrastructure • • Often GUI based • Describing the flow of information in the context of business processes • Using the input/output of processes as the Integration points between diverse business processes Business Process Automation Data Transformation Message Routing • • 16 Adapter Process Brokering • Execution of discrete steps within a business process • Ability to recover from failed steps • Workflow engine Message Storage Adapter Process Modeling Process Management • Monitor business processes • Correlate metrics to specific business process steps
EAI Power Tools Topic 16 Web Services and SOAP ICS 123 • Many vendors have off the shelf connector technology that allows connectivity and integration of existing software packages and data stores. • GUI Transformation tools allow for visual creation and maintenance and versioning of data transformations. • Many MOMs (Message Oriented Middleware) already support automatic SOAP transformations • Many software packages are committed to SOAP as a standard which would make the EAI piece transparent 17
Topic 16 Web Services and SOAP ICS 123 EAI: The Next Level Business Webs While EAI focuses on connecting data and applications internally, Business Webs focus on connecting applications and business flows across organizational boundries 18
Current Condition Distribution/Warehousing Raw Materials Transportation Manufacturing • Paperwork intensive • Human Intervention • Inherent inefficiencies
The Challenge The Future Distribution Channels 1000’s 100’s Your Close Affiliates 10’s 1 Your Company 1 10’s 1000’s Suppliers 10, 000’s
Relationships Are Dynamic. Topic 16 Web Services and SOAP ICS 123 Time & Cost Each e. Business relationship is unique. Every e. Business initiative integrates disparate systems. Every change requires a skilled programmer. 1 21 5 20 100 # of unique e. Business relationships 1, 000
What are Web Services? Topic 16 Web Services and SOAP ICS 123 • A Web service is a collection of functions that are packaged as a single entity and published to the network for use by other programs. • Web services are building blocks for creating open distributed systems, and allow companies and individuals to quickly and cheaply make their digital assets available worldwide. • A Web service can aggregate other Web services to provide a higher-level set of features 22
What are Web Services? Topic 16 Web Services and SOAP ICS 123 • Based on UDDI (Universal Description, Discovery and Integration) and XML • Platform-independent, open framework for describing services, discovering businesses, and integrating business services. 23
Web Services Strengths • Interoperability o Topic 16 Web Services and SOAP ICS 123 Based on open standards, utilizes existing infrastructure • Ubiquity o Communicates through XML/HTTP – Any system that supports these standards, supports Web Services • Low barrier to entry o Concepts easy to understand, easy to implement o Toolkits allow COM, J 2 EE, and CORBA components to be exposed as Web Services • Industry Support 24
Web Services Layers Topic 16 Web Services and SOAP ICS 123 Publish, Find, Use Services: UDDI Service Interactions: Universal Data Format: XML Communications Layer: 25 SOAP HTTP
SOAP- Definition • Simple Object Access Protocol Topic 16 Web Services and SOAP ICS 123 • W 3 C standard: Not proprietary to any one software vendor • Like CORBA and COM, designed as an interoperability protocol that allows objects to “talk” to each other • SOAP defines a simple mechanism for expressing application semantics by providing a modular packaging model and encoding mechanisms for encoding data within modules 26
SOAP- Structure Topic 16 Web Services and SOAP • Objects can be functions, programs, or systems ICS 123 • Three parts to SOAP: • Envelope: Defines a framework for describing what is in a message and how to process it, • Encoding rules: Expressing instances of application-defined datatypes, • RPC Representation: Convention for representing remote procedure calls and responses. 27
Topic 16 Web Services and SOAP Example • Example 1: Sample SOAP Message embedded in an HTTP Request POST /Stock. Quote HTTP/1. 1 Host: www. stockquoteserver. com Content-Type: text/xml; charset="utf-8" Content-Length: nnnn SOAPAction: "http: //example. org/2001/06/quotes" <env: Envelope xmlns: env="http: //www. w 3. org/2001/06/soap-envelope" > <env: Body> <m: Get. Last. Trade. Price env: encoding. Style="http: //www. w 3. org/2001/06/soap-encoding" xmlns: m="http: //example. org/2001/06/quotes"> <symbol>DIS</symbol> </m: Get. Last. Trade. Price> </env: Body> </env: Envelope> 28 ICS 123
Topic 16 Web Services and SOAP Example, continued ICS 123 • Example 2 shows the SOAP message sent by the Stock. Quote service in the corresponding HTTP response to the request from Example 1. HTTP/1. 1 200 OK Content-Type: text/xml; charset="utf-8" Content-Length: nnnn <env: Envelope xmlns: env="http: //www. w 3. org/2001/06/soap-envelope" > <env: Body> <m: Get. Last. Trade. Price. Response env: encoding. Style="http: //www. w 3. org/2001/06/soap-encoding" xmlns: m="http: //example. org/2001/06/quotes"> <Price>34. 5</Price> </m: Get. Last. Trade. Price. Response> </env: Body> </env: Envelope> 29
SOAP- Advantage Topic 16 Web Services and SOAP ICS 123 • Once applications are wrapped with SOAP – they are in effect a web service • A web service can be invoked directly through an HTTP call • A web service can be “discovered” utilizing a directory service 30
What’s underneath SOAP? Topic 16 Web Services and SOAP ICS 123 • Soap is the abstraction layer – not the integration tool • EAI techniques are used to connect between the SOAP wrapper and legacy systems • Once EAI objects are wrapped in SOAP they can easily communicate with each other thus creating a cross enterprise integration architecture 31
Web Services- Layers Topic 16 Web Services and SOAP ICS 123 Publish, Find, Use Services: UDDI Service Interactions: Universal Data Format: XML Communications Layer: 32 SOAP HTTP
UDDI Topic 16 Web Services and SOAP • Universal Description, Discovery and Integration ICS 123 • Platform-independent, open framework for describing services, discovering businesses, and integrating business services. • A layer above SOAP, it is the glue that connects all the SOAP objects into a Business Web • DNS like model implementation of the directory 33
Topic 16 Web Services and SOAP UDDI 4. SW companies, standards bodies, and programmers populate the registry with descriptions of different types of services 1. Marketplaces, search engines, and business apps query the registry to discover services at other companies 2. UDDI Business Registry Businesses populate the registry with descriptions of the services they support 34 Business Registrations 3. ICS 123 5. Service Type Registrations UBR assigns a programmatically unique identifier to each service and business registration Business uses this data to facilitate easier integration with each other over the Web
Registry Data Topic 16 Web Services and SOAP ICS 123 • Businesses register public information about themselves • Standards bodies, Programmers, Businesses register information about their Service Types 35
Topic 16 Web Services and SOAP ICS 123 • Business name • Text description – List of multi-language text strings • Contact info – Names, phone numbers, fax numbers, web sites… • Known identifiers – List of identifiers that a business may be known by - DUNS, Thomas, other 36
Topic 16 Web Services and SOAP ICS 123 • Business categories – 3 standard taxonomies in V 1 » Industry: NAICS (Industry codes - US Govt. ) » Product/Services: UN/SPSC (ECMA) » Location: Geographical taxonomy – Implemented as name-value pairs to allow any valid taxonomy identifier to be attached to the business white page 37
Topic 16 Web Services and SOAP ICS 123 • New set of information businesses use to describe how to “do e-commerce” with them – Nested model » Business processes » Service descriptions » Binding information – Programming/platform/ implementation agnostic – Services can also be categorized 38
Service Type Registration Topic 16 Web Services and SOAP ICS 123 • Pointer to the namespace where service type is described – What programmers read to understand how to use the service • Identifier for who published the service • Identifier for the service type registration – called a t. Model. Key – Used as a signature by web sites that implement those services 39
Business Registration • XML document • Created by end-user • • company (or on their behalf) Can have multiple service listings Can have multiple taxonomy listings ICS 123 business. Entity business. Key name URL description contacts business. Services identifier. Bag category. Bag keyed. Reference t. Model. Key key. Name key. Value 40 Topic 16 Web Services and SOAP Contact Phone Address Email business. Service service. Key t. Model. Key Name Description Binding. Templates keyed. Reference t. Model. Key key. Name key. Value
Topic 16 Web Services and SOAP Talk Overview • What’s really new about Web Services • What a SOAP Router is • What a SOAP Router can do for you • How an SOAP Router works • ALIN in theory • ALIN in practice 44 ICS 123
Topic 16 Web Services and SOAP Web Services are NOT New ICS 123 • There is nothing new under the sun in distributed (or parallel , or grid, …) computing – These are all efforts to lash many systems together to act as one • SOAP today is a distributed computing technology – ‘Sprinkling angle-bracket pixie dust’ over plain ol’ client/server RPC • Sure, it works across the public Internet, but only by treating it as a very slow LAN – Trade rags already lament the ‘gap’ at this boundary: real security, reliability, and performance problems reveal the fallacy of assuming TCP/IP ‘just works’ 45
Topic 16 Web Services and SOAP Web Services ARE new ICS 123 • Decentralization does pose brand-new challenges • Latency – Services are no longer mere milliseconds away. – We need middleware for seconds up to weeks • Agency – Services can be owned by other organizations – We need middleware for translating semantics • Because SOAP messages are self-contained, they can be stored, analyzed, and replayed at will 46
SOAP is Simpler Than You Think Topic 16 Web Services and SOAP ICS 123 • Starts w/point-to-point, synchronous invocations – just as Web page servers are accessed today • Main virtue is that it is not DCOM, IIOP, or RMI – Encapsulates the messy details of cross-platform, cross-language binding using standard marshalling formats • Getting started requires very little re-education. – On the other hand, straight RPC message exchange patterns (MEPs) don’t inherently reduce the tight coupling between client and server semantics. 47
SOAP is Cooler Than You Think: Topic 16 Web Services and SOAP ICS 123 • The vastly underestimated power of SOAP is that its model is genuinely asynchronous – Today, we use it as a form of XML RPC – Underneath, that’s merely a pair 1 -way messages • Furthermore, SOAP Actors are not hosts – An actor is a much more general concept than a fixed service provider machine and port – One actor may be a proxy for many others – Ideally, actors represent actual business models 48
Topic 16 Web Services and SOAP What is ‘SOAP Routing’? ICS 123 • Today, the canonical Web Services diagram directly connects SOAP endpoints • There will also be a complementary technology that sits in the middle: – Store-and-forward reliable messaging – Filtering, transformation, & analysis of flows – Intelligent “active proxy chaining” of actors 49
What Good is ‘SOAP Routing’? 1/2 Topic 16 Web Services and SOAP ICS 123 • Internet-scale Middleware – Just as distributed objects needed message-oriented-middleware (MOM)… – … decentralized services will need mediators » Wrappers: SOAP brokers to legacy systems » Monitors: SOAP transaction correlation & audit » Queues: decouples SOAP provider from requestor » Pub/Sub: decouples SOAP actors entirely • The difference is coping with firewalls and other kinds of agency boundaries 50
What Good is ‘SOAP Routing’? 2/2 Topic 16 Web Services and SOAP ICS 123 • Add new ilities without modifying either end. – – – Security: Router can authenticate and authorize Reliability: Router can store-and-forward msgs Availability: Router can redirect to live servers Scalability: Router can redistribute messages Interoperability: Router can transform msgs Interactivity: Router can update msgs ‘in-flight’ • Routing lets us reason about a “network of services” -- not just pipelines, but graphs 51
How ‘SOAP Routing’ Works 1/2 Topic 16 Web Services and SOAP ICS 123 • Consider a simple Bank ATM service – In the old world, you would have fine-grained account objects and set. User. Name() functions – As Web Services, you have more flexible XML-document services like get. Statement() • A client-side ATM program can easily call it directly today by composing a SOAP message and POSTing it to the Bank server 52
How ‘SOAP Routing’ Works 2/2 Topic 16 Web Services and SOAP ICS 123 • First, it provides ‘simple middleware’ – Recall how CGI scripts directly invoked scripts. – Later, Application Servers emerged to ‘encapsulate’ the effort of storing state &c • By passing the message through a SOAP router: – – 53 It can enforce the Bank’s security policy It can store a copy of the message for audit logs It can redirect requests across a server farm …This is exactly what Web proxies do today
How ‘SOAP Routing’ Helps 1/2 Topic 16 Web Services and SOAP ICS 123 • Second, it affords flexibility of connections • What if you wanted to change banks? – The router can filter the captured message stream so that messages from the new bank ‘look like’ the old bank • What if you wanted to change currencies? – This is equivalent to routing ‘through’ another actor – The router can transform messages; with plugin scripts today, XML schemas tomorrow • What if you wanted to know if cash is running out? – The router can analyze messages for trends 54
How ‘SOAP Routing’ Helps 2/2 Topic 16 Web Services and SOAP ICS 123 • Third, it allows 3 rd & 4 th-party extensions • What if you wanted to check on your bonds, too? – The router can multicast the balance inquiry to the Bank service and a Broker service • What if you wanted to buy more bonds? – The router can monitor the joint transaction of a money transfer to the broker and the purchase of the bonds • What if you wanted your limit kids’ access? – The router can delegate access control rights 55
Topic 16 Web Services and SOAP ALIN in theory 1/3 ICS 123 • ALIN is NOT merely Actor intermediation (piping) – Actor chains today are like UUCP !path addressing; it’s source-routing only – It’s the ability to infer semantic chains, decouple political control, etc. • SOAP Routers directly address the twin novel challenges of decentralized service integration: – Latency » by decomposing every communication into a one-way, asynchronous message, routers force us to confront extreme latency, rather than hiding it – Agency » by introducing a trusted 3 rd-party between the original endpoints, routers allow us to represent the interests of many other 4 th-party agencies 56
Topic 16 Web Services and SOAP ALIN in theory 2/3 ICS 123 • The Internet itself is a result of addressing high latency and diverse agency at Layer 3 – IP Routers store-and-forward packets across autonomous systems, each containing many LANs – IP-format packets are a generic interchange for LANs • Consequently, “Internet-scale” services must: – Scale Across Time: Interfaces must be stable for decades – Scale Across Space: Protocols must handle >100 ms delays – Scale Across Organizations: Namespaces must ‘peer’ • This is merely an application-layer router for *TPs 57
Topic 16 Web Services and SOAP ALIN in theory 3/3 ICS 123 • This architectural style builds on REST & C 2 – Beyond merely transferring representation, now we can mediate them – Can connect any graph, not just a strict lattice • It generalizes other MOM styles – Queues, sync/async, 1 -1, N-N, transactional – Pub/Sub, address-based and content-based • The most contentious aspect of ALIN for MOM folks is “best-effort”: it is still difficult to sell TCP over IP – If your ‘bottom turtle’ is already transactional, it rules out scalability and perf – The very definition of agency boundary is that transactions can’t span them! 58
Topic 16 Web Services and SOAP ALIN in practice ICS 123 • Lots of ink is being spilled on ‘missing infrastructure for Web Services’ – Major software platform vendors are only beginning to market RPC-style Web Services • Existing middleware products are having difficulty “outside the firewall” – JMS, for example, is single-vendor, single-language – High-performance EAI tools often assume multicast IP • Early Internet-scale messaging startups include Know. Now, • • 59 Bang, Kenamea, Sonic. XQ, Grand Central, and others Microsoft has outlined its WS-Routing proposal IBM has Business Rule Beans and MQ Event Broker in WS 5. 0
Topic 16 Web Services and SOAP Distributed vs. Decentralized ICS 123 • We already have lots of techniques for decomposing systems to run on many distributed processors acting as one • The genuinely novel potential of Web Services is decentralization – Marketplaces, rather than central brokers • Routing is a new technique for integrating services provided by 3 rd and 4 th parties 60
Topic 16 Web Services and SOAP A Parting Thought • The dirty little secret is that the 7 -Layer ISO Network model is insufficient to model decentralized computing. • It’s really all about integration at Layer 8 & 9 ICS 123 Political Economic Application Presentation Session Transport Network Link Physical 61 You Are Here
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