Session 5 - Main Theme Object Management Architectures

Home , Component Object Model, Dynamic Data Exchange, Service Control Manager

Application Servers G22.3033-011

Dr. Jean-Claude Franchitti

New York University Computer Science Department Courant Institute of Mathematical Sciences

Agenda

COM and COM+

Introduction to .Net

Component Technologies

Object Management Architectures

Java-Based Application Servers

Windows Services

Summary

Readings

Assignment #5

1 Summary of Previous Session

CORBA

Inprise VisiBroker Environment

Orbacus

RMI and RMI-IIOP

DCOM

DOC Platform Interoperability

Web-Enabled DOC Applications

Summary

Readings

Assignment #4

Application Servers Architectures

Application Servers for Enhanced HTML (traditional)

a.k.a., Page-Based Application Servers

Mostly Used to Support Standalone Web Applications

New Generation Page-Based Script-Oriented App. Servers

First Generation Extensions (e.g., Microsoft IIS with COM+/ASP)

Servlet/JSP Environments

XSP Environment

Can now be used as front-end to enterprise applications

Hybrid development environments

Distributed Object Computing Platforms

Provide an infrastructure for distributed communications enabling

Still need to merge traditional web-oriented computing with object computing

Object Management Architectures 4 DOC Platform + APIs to reusable services and facilities

2 Part I

COM and COM+

COM Overview

• COM history • COM fundamentals: client and server communication • Interfaces in COM • How objects are created in COM

3 COM history

• 1988: Seed work for COM began inside MS – Influenced by prior work done in Smalltalk, C++, and OSF Distributed Computing Environment (DCE) • OLE(Object Liking and Embedding) – solved the problem of compound documents • DDE(Dynamic Data Exchange) – allowed applications to communicate, but had bad performance

COM History (continued)

• 1993: First public release of COM as part of OLE 2.0 SDK – provided automation – but local communications & 16-bit/single-threaded only • 1994: Windows NT 3.5 ships – 32-bit support + Interface Definition Language – upgraded for better performance – provided multiple thread support

4 COM History (continued)

• 1992: Work begins on “Viper” project – First artifact is Distributed Transaction Coordinator (DTC) that ships with SQL Server • 1996: Windows NT 4.0 – DCE-based Distributed COM (DCOM) protocol – Better threading/security support • 1996: Microsoft Transaction Server (MTS) 1.0 – Component-based Distributed Application Framework • 1998: Windows NT 4.0 Option Pack – MTS 2.0,MSMQ 1.0, Internet Information Server 4.0 • 2000: Windows 2000 – MTS/COM Integration, new MTS-esque services, Improvements to the remoting infrastructure 9

3 fundamental ideas of COM/COM+

• Clients program in terms of interfaces, not classes • Implementation code is not statically linked, but rather loaded on-demand at runtime • Developers declare their runtime requirements and the system ensures that these requirements are met • The former two are the core of classic COM • The latter is the core of MTS and COM+

5 Using COM

• COM is used primarily for two tasks • Task 1: Gluing together multiple components inside a process – Class loading, type information, etc • Task 2: Inter-process/Inter-host communications – Object-based Remote Procedure Calls (ORPC) • Pros: Same programming model and APIs used for both tasks • Cons: Same programming model and APIs used for both tasks • Design around the task at hand

COM basics

IUnknown

IClassFactory Class Factory Client

Object Registration Packaging

Component

6 COM vocabulary

• Interface - abstract data type used by clients to talk to objects • Class - concrete data type written by developers to support one or more interfaces • Object - entity in memory that supports one or more interfaces (typically an instance of a class) • Component - loadable code module that exposes one or more COM classes • GUID - 128-bit identifier used to name an interface(IID) or a class(CLSID)

Expanded Definitions

• Two key terms have been defined so far • A COM Interface is a collection of abstract operations one can perform on an object – Must extend IUnknown directly or indirectly – Identified by a UUID (IID) – Platform-specific vptr/vtable layout • A COM Object is a collection of vptrs in memory that follow the COM identity laws – Must implement at least one COM interface – QueryInterface ties vptrs together into cohesive object

• Objects assumed to materialize automatically 14

7 Expanded Definitions (continued)

• A COM Class (or coclass) is a named body of code that can be used to produce COM objects • All coclasses are named by a UUID (CLSID) • All coclasses have a distinguished object that is used to create new instances – Called a class object or class factory – Typically implements IClassFactory • All coclasses loaded on demand by class loader – Called the Service Control Manager or (SCM) • For efficiency, a single component DLL can support multiple COM classes

Classes, Class Objects, And Components

Component DLL Class Instances

Class A Class B Class C

Class Objects

8 Class Versus Type

• An Interface represents a data type suitable for declaring variables – Non-trivial operations – Hierarchical with respect to one another – Polymorphic with respect to different objects • A Class represents loadable concrete code used to create objects – Resultant objects implement one or more interfaces • Class unsuitable for declaring variables – Entire motivation for interface-based programming based on relative uselessness of class

Class Versus Type

IAnimal

IMammal

IDog ICat IBird

Interfaces

Classes DogCat Robin

Pug Siamese Parrot 18

9 3 types of servers in COM

Local COM Server In-Process Server (DLL) DCOM Remote Client Application Server

Computer A Computer B

COM Proxies and stubs

Client Server Proxy Stub RPC DCOM/COM DCOM/COM

1. Use midl compiler to generate necessary files 2. Files generated by midl compiler are packaged in a DLL with make command 3. Register your proxy-stub DLL in the system registry with regsrv32 command 4. The proxy-stub DLL must be installed on every machine

10 Interfaces in COM

• An interface is not a class – cannot be instantiated, different classes can implement it differently • Interfaces are strongly typed – every interface has it’s globally unique identifier(GUID) • Interfaces are immutable – cannot delete, any change considered to be a new interface • Clients only interact with pointers to interfaces – pointers hide all aspects if implementation • Objects can implement multiple interfaces

Interface Architecture

Interface component pointer Vtable function1

Pointer to Function1 Vtable pointer Pointer to Function2 function2 Pointer to Function3

function3

COM interface is a binary description of the layout of a block of memory containing an array of function pointers(vtable). The pointers of the array point to the functions of a COM object that can be called by a consumer of the interface

11 Standard and Custom Interfaces

• Standard interface IUnknown • Has 3 functions: – ULONG AddRef(); object – ULONG Release();

– HRESULT QueryInterface(REFIID riid, void **ppvObject); • All objects will have at least two interfaces: IUnknown and a custom interface • Custom interfaces are derived from IUnknown

Defining interfaces with IDL

// File Ch3CompCppServer.idl : This file will be processed by the MIDL tool to produce the type library // Ch3CompCppServer.tlb and marshalling code.

[ uuid (B5F3E2FE-B376-11D1-BB1E-00207812E629) ] interface IAccount : Iunknown attributes { [propget, helpstring("property Balance")] HRESULT Balance ([out, retval] double *pVal);

[propget, helpstring("property Name")] HRESULT Name([out, retval] BSTR *pVal); };

•Every interface method must return HRESULT •32bit integer divided into 3 fields •0-15bits indicate severity •16-30 facility (RPC, Win32 etc) •1 bit to indicate success or failure

12 Defining interfaces with IDL (continued)

//File Ch3ComCppServer.idl continued [ uuid (B5F3E2F0-B376-11D1-BB1E-00207812E629) ] library CH3COMCPPSERVERLib //will produce a type library - file that describes an object in a //standardized format to show what properties are supported { importlib("stdole32.tlb"); importlib("stdole2.tlb"); [ uuid (B5F3E300-B376-11D1-BB1E-00207812E629) ] coclass Ch3CheckingAccount // Ch3CheckingAccount Class { interface IAccount; interface IAccountInit; [default] interface ICheckingAccount; }; }; //after type library is created it’s location is registered in the system registry

COM client using an object

1. Identify the class of object to use. 2. Obtain the “class factory” for the object class and ask it to create an uninitialized instance of the object class, returning an interface pointer to it. 3 Initialize the newly created object by calling an initialization member function of the “initialization interface,” that is, one of a generally small set of interfaces that have such functions. 4 Make use of the object which generally includes calling QueryInterface to obtain additional working interface pointers on the object. The client must be prepared for the potential absence of a desired interface. 5 Release the object when it is no longer needed.

13 COM client using an object

(continued) Step1: Identify the class of object to use • A Client has a CLSID (Class Identifier) of a class it needs • All CLSIDs are stored in the registry HKEY_CLASSES_ROOT CLSID {E312522E-A7B7-11D1-A52E-0000F8751BA7}="Foo Class" InprocServer32="D:\\ATL Examples\Foo\\Debug\\Foo.dll" • Client need not know nor care how this information is maintained

COM client using an object

(continued) Step 2: Creating the Object 1 Obtain the “class factory” for the CLSID. 2 Ask the class factory to instantiate an object of the class, returning an interface pointer to the client. Server

(1) “Create an Object” Client Class Factory

(3) Return new (2) Manufacture interface pointer Object to client

Object

14 COM client using an object

(continued) Class Factory explained • An object that exists to manufacture objects of a specific class • A class factory object is implemented by a server module, either a DLL or EXE • Supports the IClassFactory interface with 2 functions: – CreateInstance - uninitialized instance,object, of the class associated with the class factory, returning an interface pointer of type iid on the object – LockServer - called by a client to keep a server in memory even when it is servicing no objects

COM client using an object

(continued) Step 2: Obtaining the Class Factory Object • Client generates a call to the COM Library function CoGetClassObject • The function obtain a class factory object for the given CLSID and return one of that class factory’s interface pointers to the client • After that the client may calls IClassFactory::CreateInstance to instantiate objects of the class • The caller must call IClassFactory::Release after it has finished using the class factory object • IClassFactory::coCreateInstance combines all three above functions within it 30

15 COM client using an object

(continued) Steps 3&4:Initializing and managing the Object • IClassFactory::CreateInstance initializes an object • How to get interface pointer to other interfaces of the obtained object? –Cannot use CreateInstance again (why?) – Use QueryInterface function( remember it’s part of IUnknown, so all interfaces have it) • Client must be prepared for the failure of a call to QueryInterface • Don’t forget to release all interface pointers when you are done

COM client using an object

(continued) Step5: Releasing an object • Achieved by calling the Release member function of all interfaces obtained during the course of using the object • Use reference counter to determine lifetime of an object. Increment on CreateInstance and QueryInterface • Client is responsible for matching any operation that generates a call to AddRef through a given interface pointer with a call to Release through that same interface pointer

16 The COM Runtime Environment

• The infrastructure used to support COM on a given platform is called the COM library • Each thread that uses COM library must setup/teardown thread- specific data structures – CoInitialize[Ex] and CoUninitialize do this for you • The COM library implemented in several DLLs – OLE32.DLL – core class/interface functionality – OLEAUT32.DLL – Visual Basic®-centric type infrastructure • Inproc class loading done in OLE32.DLL • Cross-process/host class loading performed by Windows NT® Service (RPCSS.EXE)

The COM Runtime Environment

Foo.dll

Bar.exe

Bar.exe OLE32.DLL

OLE32.DLL OLE32.DLL

RPCSS.EXE RPCSS.EXE34

17 COM Class Loading • Clients issue activation calls against the SCM • SCM responsible for locating component and loading it into memory • SCM queries component for class object and (optionally) uses it to instantiate new instance • Once SCM returns a reference to class instance/class object, SCM out of the picture • Based on configuration, COM may need to load component in separate process (potentially on different machine) 35

COM Class Loading And Locality

• All activation calls allow client to indicate locality – SCM chooses most efficient allowed by client

CLSCTX_INPROC_SERVER // load in client process CLSCTX_INPROC_HANDLER // use OLE Document rendering handler CLSCTX_LOCAL_SERVER // load in separate process CLSCTX_REMOTE_SERVER // load on distinct host machine CLSCTX_SERVER // CLSCTX_*_SERVER CLSCTX_ALL // CLSCTX_*

typedef struct _COSERVERINFO { DWORD dwReserved1; // m.b.z. const OLECHAR *pwszName; // host name COAUTHINFO *pAuthInfo; // security goo DWORD dwReserved2; // m.b.z. } COSERVERINFO; 36

18 Using The SCM

• The SCM exposes two core activation APIs • Both APIs load components automatically • Both APIs accept a CLSID and information about component location as input parameters • CoGetClassObject returns class object/factory – No new instances created • CoCreateInstanceEx uses IClassFactory interface on class object to create new instance – Class object never returned to client

CoGetClassObject/IClassFactory interface IClassFactory : IUnknown { // create a new com object HRESULT CreateInstance([in] IUnknown *pUnkOuter, [in] REFIID riid, [out,retval,iid_is(riid)] void **ppv); // hold component code in memory HRESULT LockServer([in] BOOL bLock); }

HRESULT CoGetClassObject( [in] const CLSID& rclsid, // which class? [in] DWORD dwClsCtx, // locality? [in] COSERVERINFO *pcsi, // host/sec info? [in] REFIID riid, // which interface? [out, iid_is(riid)] void **ppv // put it here! 38 );

19 Example

void CreatePager(IPager *&rpp, IMessageSource *&rpms) { IClassFactory *pcf = 0; rpp = 0; rpms = 0; // ask SCM to load class code for Pager HRESULT hr = CoGetClassObject(CLSID_Pager, CLSCTX_ALL, 0, IID_IClassFactory, (void**)&pcf); if (SUCCEEDED(hr)) { // ask class code to create new class instance hr = pcf->CreateInstance(0, IID_IPager, (void**)&rpp); if (SUCCEEDED(hr)) hr = rpp->QueryInterface(IID_IMessageSource, (void**)&rpms); pcf->Release(); } }

Example

Client.exe mobile.dll

2 rpp rpms 3

4 pcf 1

1 Client calls CoGetClassObject

2 Client calls CreateInstance on Class Object 3 Client calls QueryInterface on Class Instance 40 4 Client calls Release on Class Object

20 CoGetClassObject Pitfalls

• Previous example made at least four round- trips in distributed case – One for CoGetClassObject – One for CreateInstance – One for QueryInterface – One for IClassFactory::Release • Superior solution would perform class loading and object creation in one round trip • Solution: CoCreateInstance[Ex]

CoCreateInstanceEx

typedef struct { const IID *pIID; IUnknown *pItf; HRESULT hr; } MULTI_QI; HRESULT CoCreateInstanceEx( [in] const CLSID& rclsid, // which class? [in] IUnknown *pUnkOuter, // used in aggregation [in] DWORD dwClsCtx, // locality [in] COSERVERINFO *pcsi, // (opt) host/sec. info [in] ULONG cItfs, // # of interfaces [in, out] MULTI_QI *prgmqi // put them here! ); HRESULT CoCreateInstance( [in] const CLSID& rclsid, // which class? [in] IUnknown *pUnkOuter, // used in aggregation [in] DWORD dwClsCtx, // locality? [in] REFIID riid, // which interface? [out, iid_is(riid)] void **ppv // put it here! 42 );

21 Example void CreatePager(IPager *&rpp, IMessageSource *&rpms) { rpp = 0; rpms = 0; // build vector of interface requests MULTI_QI rgmqi[] = { { &IID_IPager, 0, 0 }, { &IID_IMessageSource, 0, 0 } }; // ask COM to load class code and create instance HRESULT hr = CoCreateInstanceEx(CLSID_Pager, 0, CLSCTX_ALL, 0, 2, rgmqi); // extract interface pointers from rgmqi vector if (SUCCEEDED(hr)) { if (hr == S_OK || SUCCEEDED(rgmqi[0].hr)) rpp = reinterpret_cast(rgmqi[0].pItf); if (hr == S_OK || SUCCEEDED(rgmqi[1].hr)) rpms =reinterpret_cast(rgmqi[1].pItf); } } 43

Exposing COM Classes

• Component DLLs export a well-known function used by COM to extract class object from DLL STDAPI DllGetClassObject( [in] REFCLSID rclsid, // which class? [in] REFIID riid, // which interface? [out, iid_is(riid)] void **ppv // put it here! ); • DllGetClassObject called by CoGetClassObject and CoCreateInstance[Ex] to access class object – Never called directly by client code • If DLL doesn’t export DllGetClassObject, all activation calls will fail

22 DllGetClassObject

CoCreateInstanceEx

COM

DllGetClassObject ICF::CreateInstance

IPager Pager IMessageSource Class Instance

IClassFactory Pager IPager Pager Class Object IMessageSource Class Instance

IClassFactory CellPhone ICellPhone CellPhone Class Object IMessageSource Class Instance 45

Exposing Class Objects/Inproc

PagerClassObject g_coPager; CellPhoneClassObject g_coCellPhone;

STDAPI DllGetClassObject(REFCLSID rclsid, REFIID riid, void**ppv) { if (rclsid == CLSID_Pager) return g_coPager.QueryInterface(riid, ppv); else if (rclsid == CLSID_CellPhone) return g_coCellPhone.QueryInterface(riid, ppv); *ppv = 0; return CLASS_E_CLASSNOTAVAILABLE; }

23 Finding Components

• All COM classes registered under distinguished key in registry (HKEY_CLASSES_ROOT) – Holds machine-wide configuration under Windows NT 4.0 – Magic key under W2K that merges machine-wide registration with current user’s private configuration • Can also register text-based aliases for CLSIDs called ProgIDs for GUID-hostile environments • REGSVR32.EXE used to install component DLLs that export two well-known entry points – STDAPI DllRegisterServer(void); – STDAPI DllUnregisterServer(void);

CLSID And The Registry

HKEY_CLASSES_ROOT

CLSID

{CLSID_Pager} {CLSID_CellPhone}

@=Pager @=CellPhone

InprocServer32 InprocServer32

@=C:\bin\mobile.dll @=C:\bin\mobile.dll

LocalServer32

@=C:\bin\phones.exe 48

24 ProgIds And The Registry

HKEY_CLASSES_ROOT

CLSID Commlib.Pager.1

@=Pager {CLSID_Pager}

@=Pager CLSID

ProgID @={CLSID_Pager}

@=Commlib.Pager.1 HRESULT ProgIDFromCLSID( [in] REFCLSID rclsid, InprocServer32 [out] OLECHAR **ppwszProgID); HRESULT CLSIDFromProgID( [in] OLECHAR *pwszProgID, @=C:\bin\mobile.dll [out] CLSID *pclsid); 49

COM Classes And IDL

• COM classes can be declared in IDL using coclass statement • Coclass statement generates class entry in TLB • Coclass statement generates CLSID_XXX variables in generated C(++) headers – Generates __declspec(uuid) statements as well • Coclass statement allows mimimum supported interfaces to be listed as well

Async Calls [ uuid(03C20B33-C942-11d1-926D-006008026FEA) ] coclass Pager { [default] interface IPager; interface IMessageSource; } 50

25 Interception

• In general, it is better to leverage platform code than to write it yourself – Thread scheduler, file system, window manager • Classically, the platform has been exposed through explicit APIs and interfaces – Requires some code on your part to utilize • COM started to expose the platform through interception – COM puts a middleman between the client and object – Middleman makes calls to the platform on object’s behalf both before and after object’s method executes 51

Interception Basics

• To provide a service, the system must intercept all calls to your object • Interceptors pre- and post-process every call – Interceptors make system calls on your behalf – Interceptors set up the runtime environment for your method calls – Interceptors may fail the method call without your participation • Interceptors must know what your interfaces look like – All interfaces exposed by configured components require specially prepared P/S DLL or a type library

26 Interception And Interfaces

• Interception needs type info for all interfaces • Interfaces marked [dual] and [oleautomation] can simply rely on type library – Parameter types limited to VARIANT-compatible • Interfaces not marked [dual] or [oleautomation] require a specially prepared proxy/stub DLLs – Run MIDL compiler using /Oicf flag – Compile foo_i.c, foo_p.c and dllhost.c using /MD switch – Link P/S dll against MTXIH.LIB, OLE32.LIB and ADVAPI32.LIB before any other libraries • Registering P/S DLL or (dual/oleautomation) TLB inserts entries under HKCR\Interfaces

Proxy/Stub Dlls And The Registry

HKEY_CLASSES_ROOT

CLSID Interface

{CLSID_PSComm} {IID_IPager} {IID_IMessageSource}

@=PSFactoryBuffer @=IPager @=IMessageSource

InprocServer32 ProxyStubClsid32 ProxyStubClsid32

@=C:\bin\cmps.dll @={CLSID_PSComm} @={CLSID_PSComm}

ThreadingModel=both

27 COM + Overview

• Define COM+ – Terms to help explain what COM+ is • COM+ Architecture – Windows DNA: • Distributed interNet Application Architecture • 3-tier application architecture • Family of supporting technologies / services –COM+ • Key concepts of the COM+ architecture • COM+ Services

Defining COM+

•MTS ≡ Application Server* – defined a programming model for developing distributed, component- based applications – Provided a run-time environment and user interface for deploying and managing applications •DCOM: – That part of COM concerned with enabling components over a network – Provides network communication infrastructure and support for security – Does not provide many things that enterprise-class applications need: • EX: Distributed transactions, scalability, fine-grained security, etc..

*Application server: handles transactions between users and business backend business application

28 Defining COM+ (continued)

•COM+ – Builds on the distributed infrastructure provided by DCOM and tightly integrates the features of MTS – Set of system services for COM-based applications designed to make it easy to develop enterprise-class distributed applications. – COM+ is a runtime environment* for COM objects

*Run-time environment: one that provides data and functions to the program while it is running

Windows DNA

Databases

Legacy Systems

External Thin Applications Client

Rich Client Application Services Client Executable Business Objects ODBC Web Browser IIS/ASP OLEDB PDA COM+ HERE ADO 58

29 Windows DNA

• 3 Logical Layers: – Presentation Layer • Basically handles graphical display and processing of user inputs • VB, HTML, DHTML, Applets, Plug-ins, client/server scripting, etc. –Business Layer • Provides business rules and services to help to write scalable applications • Services of COM+ – Data Layer • Responsible for storage, retrieval, and general maintenance of data as well integrity of data. • The Windows DNA approach of data access is called "Universal Data Access.

COM+ Web Application

ASP DHTML HTTP IIS

B.O.

SQL D.O. ADO Server

COM+

Presentation Business Data

30 COM+ Architecture: Key Concepts

• Attribute-based Programming: – To use COM+ services, simply set the attributes provided to define these services – Administer COM+ attributes through Component Services Explorer, a snap-in for MMC* • ≡ Catalog Manager: holds the values of the attributes

Catalog Attributes

*MMC: Microsoft Management Console: common tool to administer all of Microsoft’s Server 61 Applications

COM+ Architecture: Key Concepts (continued)

• Context: – The runtime environment in which one/more compatible COM+ objects in a particular process execute – Think of this as a boundary around objects sharing the same properties • All objects in a single context have compatible attributes • Objects with at least one incompatible attribute must have different contexts • Each object belongs to exactly one context

Context A Context B Context C 62 Process X Process Y

31 COM+ Architecture: Key Concepts (continued)

• Interception – The process of performing COM+ services both before and after a method call on a COM+ object when the client of a COM+ object resides in a different Context from the object – Lightweight proxy called an interceptor is set up between the client and the object – Lightweight proxy: • Never does a thread or process switch. Only provides whatever actions are necessary to make sure that a COM+ object always runs within its configured environment

Example: Interception

1 3

5 1 Client issues call 2 Interceptor requests lock

3 Once lock acquired, call dispatched 4 Once call complete, Interceptor Your Object interceptor releases lock 5 Control returned to client m_pActivity Object Context

Activity X 64

32 Configured Components

• Problem: If goal is to write little or no code, how do we configure interceptor to do its magic? • Solution: Declarative attributes • Classes that require extended services must indicate this declaratively • COM+/MTS introduce the notion of configured components • Configured components are classes that have extended attributes that control interception • Configured components always DLLs – MTS/COM+ use surrogate for remote/local activation

Configured Components

• MTS and COM+ have radically different details wrt how configuration information is stored and used • Both use HKEY_CLASSES_ROOT\CLSID • Both store information in auxiliary storage • Details abstracted away behind catalog manager

Auxiliary Configuration Database

Catalog Manager

HKEY_CLASSES_ROOT\CLSID 66

33 Configured Components - MTS Style

• MTS layers on top of classic COM • Runtime services provided by MTS executive – Lives in MTXEX.DLL • MTS CatMan stores MTXEX.DLL under HKCR to ensure MTS gets between client and object – Stores component filename in aux database

Auxiliary Configuration Database CLSID_Pager=PAGER.DLL Catalog Manager HKEY_CLASSES_ROOT\CLSID InprocServer32=MTXEX.DLL 67

Configured Components - COM+ Style (continued)

• Under COM+, runtime services provided by COM itself • CoCreateInstance is smart enough to consult auxiliary information at activation-time • COM+ CatMan stores still manages extended attributes in auxiliary database

Auxiliary Configuration Database CLSID_Pager=LoadBalance+Pooling Catalog Manager HKEY_CLASSES_ROOT\CLSID InprocServer32=PAGER.DLL 68

34 Packages/Applications

• The catalog manager segregates classes into COM+ applications (or MTS packages) • Each configured class belongs to exactly one application • All classes in an application share activation settings • Configuration orthogonal to physical packaging – x classes from y DLLs mapped into z applications • Applications can be configured to load in activator’s process (library) or in distinct surrogate process (server)

x Classes, y Dlls, z Applications/Packages

OneAndTwo.dll ThreeAndFour.dll

Three One Two Four

DLLs

Packages/Apps

One Two Three Four

OneAndFour Application TwoAndThree Application

35 Attributes

• The catalog stores attributes that the runtime interrogates to build an interceptor • The set of attributes is fixed • Applications/packages, classes, interfaces and methods can all have attributes • Can set attributes using COM+/MTS explorer • Future goal was to be able to set all attributes from development environment

Attributes: Applications/Packages

Activation Library (inproc)/Server (surrogate) Type Authentication None, Connect, Call, Packet, Integrity, Privacy Level Impersonation Identify, Impersonate, Delegate Level Authorization Application Only/Application + Component Checks Security Interactive User/Hardcoded User ID + PW Identity Process Never/N minutes after idle Shutdown

Debugger Command Line to Launch Debugger/Process

Enable Compensating On/Off Resource Managers Enable 3GB On/Off Support

Queueing Queued/Queued+Listener

72 Underlines indicate settings available under MTS

36 Attributes: Classes, Interfaces, And Methods

Transaction Non Supported, Supported, Required, Requires New Class

Synchronization Non Supported, Supported, Required, Requires New Class

Object Pooling On/Off, Max Instances, Min Instances, Timeout Class

Declarative Arbitrary Class-specific String Class Construction

JIT Activation On/Off Class

Activation-time On/Off Class Load Balancing Instrumentation On/Off Class Events Declarative Class Zero or more role names Interface Authorization Method

Auto-Deactivate On/Off Method

Must Activate in On/Off Class Activator’s Context 73 Underlines indicate settings available under MTS

Exporting Packages/ Applications

• MTS/COM+ allow package/app configuration to be exported to the file system for distribution • MTS: Exporting produces a .PAK file that contains snapshot of catalog for the package – Also contains flattened references to all DLLs/TLBs • COM+: Exporting produces a single .MSI file that contains both catalog info and DLL/TLBs • .PAK/.MSI file can be imported on other host machines – Can be done remotely using remote catalog access

37 Package/Application Export Residue

MTS COM+

MYAPP.PAK MYAPP.MSI

Catalog info Catalog info

MYCOMP1.DLL MYCOMP1.DLL

code for some classes code for some classes

MYCOMP2.DLL MYCOMP2.DLL

code for other classes code for other classes

MYPS.DLL MYPS.DLL

proxy/stub code proxy/stub code 75

Server Packages/ Applications

• An application can be configured to activate as a library application or a server application – Server applications are the norm in MTS/COM+ • Only server applications support… – Remote activation – Complete Security Support – Insulating user of component from component faults • MTS Server packages are loaded by the MTS Surrogate (mtx.exe) • COM+ Server packages are loaded by default COM surrogate (dllhost.exe) – dllhst3g.exe if 3GB support is enabled in catalog

38 MTS Server Packages

CLIENT.EXE MTX.EXE

OLE32.DLL OLE32.DLL

MTXEX.DLL Proxy Interceptor

YOURSERVER.DLL You

You

COM+ Server Applications

CLIENT.EXE DLLHOST.EXE

OLE32.DLL OLE32.DLL

Proxy Stub(+)

YOURSERVER.DLL You

You

39 Library Applications/Packages

• Library applications/packages load in the creator’s process – Solves the “1 class used by 3 applications” problem • MTS catalog manager controls registry entries for components in library packages – Each class’s InprocServer32 key points to the MTS Executive (mtxex.dll) – MTS Executive creates interceptor between client and object based on catalog info – MTS Executive manages a thread pool to service activation calls and general housekeeping • Instances will always always be protected from concurrent access under MTS!

MTS Library Packages In Nature CLIENT.EXE

OLE32.DLL

MTXEX.DLL

Interceptor

YOURSERVER.DLL

You

40 How COM(+) Library Applications Work

• COM+ catalog manager leaves InprocServer32 entry alone – Additional attributes stored in aux config database • CoCreateInstance checks for extended attributes and creates an interceptor as needed • Instances may or may not be protected from concurrent access depending on configuration! – Default setting at install-time is protected, but can easily defeat using COM+ Explorer 81

COM+ Library Applications In Nature CLIENT.EXE

OLE32.DLL

Interceptor

YOURSERVER.DLL

You

41 COM+ Services

• Enterprise applications: – Most likely have requirements that restrict levels of access for different individuals • = security – Need to retrieve data from and update to one/more database servers • = transactions • = distributed transactions if updates have to be simultaneous – Need to be scalable: • = Load balancing • = JIT (Just In Time) Activation • = Object Pooling – Need parts the application to continue to function even if they are unable to communicate with the home office at that exact moment • = disconnected communications • Without COM+, writing enterprise applications for Windows platform would amount to thousands of lines of code.

COM+ Services

•Server • Load Balancing • Transaction • Queued Components • Security • Events • Administration

COM+ allows us to participate in the above services.

42 COM+ Security

• Fine-grained Security – Can control access to a server on a per-class, per- interface or per-method basis – Performed through attribute-based programming Æ no code to write • New security model: Role – Role: group of users of a COM+ application that have the same security profile – Specify through Component Services Explorer which roles are allowed to use a particular interface, component or method

COM+ Transactions

• Support for database services to ensure transactions are – Atomic: complete successfully or return to original state – Consistent – Durable: once updated, transaction is never lost • Transaction primitives: – Transaction.Begin – Transaction.Commit (applies all updates in atomic step) – Transaction.Rollback

43 COM+ Distributed Transactions

• Support to apply the same standard as transactions to distributed databases – All servers commit their part of the transaction or all must rollback • CRM: Compensating* Resource Manager – COM+ service to create custom resource managers

*Compensating Transaction: transaction that reverses the effects of a previous transaction 87

COM+ Scalability

• What happens when each client application creates a COM+ object and holds on to it for the life of the user’s session? – Problem: each object uses some memory and may have its own thread; possibly it also has a database connection. – Solution that is NOT scalable: • Instantiate all the objects client application needs when the application is started and hold on to those objects for the life of the application

44 COM+ Services: Scalability (continued)

• JIT Activation – Controlled using attributes just like all other COM+ services – Activate/Deactivate instances of objects during method calls • Client still holds proxy, server still holds stub for the object so as far as client is concerned, the object still exists – Object Pooling • COM+ Pool Manager maintains a pool of objects • When client attempts to activate object, COM+ runtime environment returns an instance from the pool if one is available, instead of creating a new object

COM+ Services: JIT

Client Process Server Process (DLLHost.exe)

Client Context Object’s Context

RPC COM+ JIT Proxy Channel Stub Interceptor Activated Object

The JIT Activated Object is destroyed or returned to the object pool after the method call completes.

45 Other COM+ Services

• Synchronization • Queued Components • Load Balancing

Summary

• The SCM dynamically loads COM class code • COM+ and MTS exposes services through interception • Components configure their interceptors through declarative attributes stored in a configuration database • MTS/COM+ consult configuration database at activation time • Classes are grouped into applications/packages • The catalog is a scriptable MTS/COM+ component

46 References

• Programming Dist Apps With Visual Basic and COM – Ted Pattison, Microsoft Press • Inside COM – Dale Rogerson, Microsoft Press • Essential COM(+), 2nd Edition (the book) – Don Box, Addison Wesley Longman • Essential COM(+) Short Course, DevelopMentor – http://www.develop.com • DCOM Mailing List – http://discuss.microsoft.com

Part II

Introduction to .Net Also See: Session 5 Sub-Topic 4 Presentation on “Introduction to .Net/C#” Session 5 Handouts from the Book “Computing with C# and the .Net Framework”

47 Section Outline

• What is .NET? • Introduction to concepts • Tour of the Framework • XML Web services and Industry standards • Transaction Management Using .NET Serviced Components and COM+ Services

Current Web App. Environment .NET vs. Java

.NET Windows ASP.Net VS.NET Client ADO.NET IIS COM+ Relational HTML WebService Database JavaScript SOAP System Browser

JSP/Servlets EJB JDBC WebSphere Wireless Device

Desktop Web Server App Server DB Server 96

48 So What really Is .NET?

• Software for connecting people, information, systems and devices? – Runtime for executing code – Tools to help develop applications – Server products to manage applications – Value-added services • Managed environment for developing and executing components

.NET Framework Design Goals

• Incorporate Web standards and best practices – Designed with security in mind • Unified programming models • Simplified development • Simple to deploy, run, & maintain

49 A Problem of Communication

Application

Code and data structures

Before RPC-style models, applications were completely separate entities with little or

no integration… 99

A Problem of Communication (continued)

…but with RPC or COM, you still have to write ‘plumbing’ code and can’t directly interact…

100

50 A Problem of Communication (continued)

… a common language runtime provides components a common substrate. No “plumbing” is needed and objects can directly interact. 101

Framework, languages and tools Visual Studio.NET VB C++ C# JScript J# Common Language Specification

ASP.NET Web Forms, Web Services Windows Forms Mobile Internet Toolkit Data (ADO.NET) and XML

Base Class Library / System Classes Web Matrix

Common Language Runtime

Windows COM+ Services 102

51 Common Language Runtime (CLR)

Base Class Library Support

Thread Support COM Marshaler

Type Checker Exception Manager

Security Engine Debug Engine

IL to Native Code Garbage Compilers Manager Collector

Class Loader 103

Multilingual Development

Fortran Perl Scheme Smalltalk Python Ada Component Pascal Oberon Mercury Visual Basic Delphi C# Oz C++

Mondrian C J# Pascal JScript Haskell Java Eiffel APL

104 Cobol RPG Objective Caml ML

52 What Is A Web Service?

Web Open Service Internet Protocols A programmable application component accessible via standard Web protocols

Provide a Directory of Services on the UDDI Internet Universal Description, Design, and Integration

Web Services are defined in terms of the WSDL Web Services formats and ordering of messages Description Language

Web Services consumers can send and SOAP receive messages using XML

105 Built using open Internet protocols XML & HTTP

ASP .NET Web Matrix Project

• Lightweight, simple, community-oriented tool for building ASP.NET apps • Full WYSIWYG support • Small (~ 1.4 Mb) • Community features – IM integration, code sharing, chat features • Available free-of-charge at www.asp.net

106

53 WYSIWYG Controls

Snippets and code sharing

Community Support

107

The Role of Open Standards

• .NET has been ratified through ECMA standards – ECMA-335 Common Language Infrastructure (CLI) – ECMA-334 C# Language – Participants include Intel, HP, IBM, Netscape • .NET is Microsoft’s commercial implementation of these standards • Some platform specifics have not been included – Windows Forms – ADO.NET

108

54 Shared Source CLI (Rotor)

• Non-commercial implementation • Available for research, academic and other non- profit use – Standards are available to everyone for profitable use too, of course • Written entirely in C# • Available for FreeBSD and WinXP – Ximian and Intel are developing Linux implementations at the moment • Implemented for teaching, learning and research

109

Transaction Management in .Net

• Local Transactions • Distributed Transactions • .NET Enterprise Services Transactions

110

55 Local Transactions • A transaction is a set of separate but interdependent changes that are made to some persistent data and that must be performed together as an atomic operation

• ACID Properties: • Atomicity • Consistency • Isolation • Durability

• Multiple select, insert, update, and delete operations are composed into a single atomic operation

• Local Transactions can be created by using: • Transact-SQL • ADO.NET

111

Distributed Transactions

• Microsoft Distributed Transaction Coordinator (DTC) • Manages connections to multiple databases • Manages connections from multiple database clients • Coordinates work into a single transaction

Server A TransactionDTC Connection Database #1

Server B

Connection Database #2

112

56 .NET Enterprise Services Transactions

• COM+ checks three bit flags to control transaction outcome and component life time • Per object context – Consistent flag and done flag • Per transaction – Abort flag

Transaction Stream Done Consistent Sub1 Done Root Consistent Root Client Done Consistent Sub2 Abort

113

Overview of COM+ Services and the .NET Serviced Components

• COM+ Services • COM+ Catalog • COM+ Context • COM+ Interception • How the .NET Framework Integrates with COM+ Services • How the .NET Serviced Components Works with COM+

114

57 COM+ Services

• COM+ is the application infrastructure in a multi-user environment that compose of the services that enable many users to access the application and underlying data at the same time. •COM+ Services: • Transactions • Compensating Resource Managers • Resource Management •Just-in-Time(JIT) Activation •Object Pooling • Synchronization • Security • Loosely Coupled Events • Queued Components

115

COM+ Catalog

• All configuration data is kept in a database • You use the catalog to determine run-time requirements when an object is activated Catalog • The catalog can be accessed by the Component Services tool or administrative API Application Type = Server Name = MyApp Application MyApp Component Name = MyClass Class MyClass

116

58 COM+ Context

• Context is a set of run-time requirements for a class • The COM+ catalog stores run-time requirements as attributes, which are checked during activation • Context properties flow with the method call, depending on configuration attributes

Process Context A Application Context B Attributes: Attributes: Transaction=Required Transaction=Required Synchronization=Supported Synchronization=RequiresNew Object A Object B

Properties: Properties: TransactionID=1234 TransactionID=1234 ActivityID=5678 ActivityID=9012

117

COM+ Interception

• Used to enforce context semantics • Transparent to the caller and the called • Activation interception and method-call interception

Client Process Application Context A Context B

Synchronization= Interception Synchronization= Not Supported Required

Object A Object B

Object C

118

59 How the .NET Framework Integrates with COM+ Services

• The System.EnterpriseServices namespace provides necessary programming types • Activation and interception are handled automatically through ServicedComponent class

.NET Enterprise Services

Common Language Runtime

COM+ Services

COM and Win32

119

How the .NET Serviced Component Works with COM+

Computer COM+ Application Process

Context A Context B Object A Interception Proxy Object X objX=

objX = new X ()

.NET Enterprise Services

CoCreateInstance CreateInstance COM+ COM+ Services Catalog

120

60 Creating .NET Serviced Components

• Hosting Components in Component Services • Transaction Attribute • Transaction Voting • Using the AutoComplete Attribute • Setting Assembly Attributes • Registering Assembly

121

Hosting Components in Component Services

• Add a reference to System.EnterpriseServices in your assembly • The System.EnterpriseServices namespace provides: • ContextUtil class • ServicedComponent class • Assembly, class, and method attributes • All component classes that need to be hosted within a Component Services application must inherit ServicedComponent class

122

61 Transaction Attribute

• Transaction attributes specifies how a class participates in transactions Imports System.EnterpriseServices Public Class bizStateU Inherits ServicedComponent … End Class

• Options: • Disabled, NotSupported, Required, RequiresNew, Supported

123

Transaction Voting - 1

• ContextUtil class provides transaction voting

Public Sub TransferClass(…) Try … ContextUtil.SetComplete() Catch ex As Exception ContextUtil.SetAbort() Throw ex End Try End Sub

124

62 Transaction Voting - 2

• Transaction Voting Options:

Option Consistent Bit Done Bit SetAbort False True SetComplete True True EnableCommit True False DisableCommit False False

• Transaction is terminated when Done bit of all Context objects in transaction have True value

125

Transaction Voting - 3

Transaction Stream EnableCommitSetComplete Commit Sub2

C=True SetComplete Sub1 D=FalseD=True

Root Root Client C=True SetComplete D=True C=True Sub3 D=True

C: Consistent Bit D: Done Bit

126

63 Using the AutoComplete Attribute

• AutoComplete attribute avoids using the SetAbort, SetComplete, and ContextUtil methods

Public Sub SetStateU(ByVal pSQL As String) Dim comStateU As New SqlCommand(pSQL, conStateU) comStateU.ExecuteNonQuery() … ' not SetComplete or SetAbort is required End Sub

127

Setting Assembly Attributes

• The information is stored in the AssemblyInfo.vb file • ApplicationName • Description • ApplicationActivation • AssemblyKeyFile • Create key file using Strong Name Utility sn.exe sn.exe –k StateU.snk

128

64 Registering Assembly

• Manual Registration: Using .NET Framework Services Installation Utility – Regsvcs.exe to register and create Component Services application

Regsvcs.exe StateU.dll

• Automatic Registration: Application registered on first use by client – Lazy Registration

129 Transaction Management Using .NET Serviced Components and COM+ Services Page: 24

.Net Knowledge Areas

• .NET framework. •VB.NET. • ASP.NET programming environment. • ADO.NET. • SQL and SQL Server • XML related technologies. • Web Service architecture. • Essence of software design

130

65 For More Information…

• MSDN Web site at – http://msdn.microsoft.com • MSDN Magazine – http://msdn.microsoft.com/msdnmag/ • Microsoft Visual Studio .NET Documentation – http://msdn.microsoft.com/library/default.asp?url=/ nhp/Default.asp?contentid=28000451

131

Book and References

• .NET is too big for a single book • Good book: • “Professional ASP.NET 1.0” ISBN 1- 61007-16-7 • Best reference is from Internet • http://msdn.microsoft.com • www.google.com

132

66 MSDN Academic Alliance

• Provides access to Microsoft software for research and education purposes • Licensed to CS departments for student loans • Includes:

• Operating Systems, SDKs, DDKs • Latest updates and Betas • Visual Studio .NET AE • MSDN Library • Server Platforms • Dev tools for WindowsCE/PocketPC – Windows, SQL Server, Exchange 2002 Server, Commerce Server, BizTalk • 4 Technical Support incidents Server, Host Integration Server, Application Center. . . • Visio • Regular Updates

133

MSDN® Essential Resources for Developers

Subscription Library, OS, Professional, Enterprise, Services Universal Delivered via CD-ROM, DVD, Web

Online MSDN® Online, MSDN® Flash, How- Information To Resources, Download Center

Training & MSDN® Webcasts, MSDN® Online Events Seminars, Tech-Ed, PDC, Developer Days

Print MSDN® Magazine Publications MSDN® News

Membership MSDN® User Groups Programs 134

67 How-To Resources Simple, Step-By-Step Procedures • Embedded Development How-To Resources • General How-To Resources • Integration How-To Resources • Jscript® .NET How-To Resources • .NET Development How-To Resources • Office Development Resources • Security How-To Resources • Visual Basic® .NET How-To Resources • Visual C#™ .NET How-To Resources • Visual Studio® .NET How-To Resources • Web Development How-To Resources (ASP, IIS, XML) • Web Services How-To Resources • Windows® Development How-To Resources http://msdn.microsoft.com/howto 135

MSDN® Webcasts Interactive, Live Online Event

• Interactive, Synchronous, Live Online Event • Discuss the Hottest Topics from Microsoft® • Open and Free For The General Public • Takes Place Every Tuesdays

http://www.microsoft.com/usa/webcasts

136

68 MSDN® Subscriptions THE way to get Visual Studio® .NET Visual Studio® .NET MSDN® Subscriptions

Enterprise Architect • Software and data modeling MSDN® Universal • Enterprise templates $2799 new • Architectural guidance $2299 renewal/upgrade

Enterprise Developer • Enterprise lifecycle tools MSDN® Enterprise • Team development support $2199 new

• Core .NET Enterprise $1599 renewal/upgrade NEW Servers

Professional • Tools to build applications MSDN® Professional and XML Web services for $1199 new Windows® and the Web $899 renewal/upgrade 137

Where Can I Get MSDN®? • Visit MSDN® Online at http://msdn.microsoft.com • Register for the MSDN® Flash Email Newsletter at http://msdn.microsoft.com/flash • Become an MSDN® CD Subscriber at http://msdn.microsoft.com/subscriptions •MSDN® online seminars http://msdn.microsoft.com/training/seminars ® • Attend MSDN Events 138

69 MS Press Essential Resources for Developers

www.microsoft.com/mspress

139

MS Press Essential Resources for Developers

The Microsoft® Enterprise Learning Library (MELL) Developer Edition provides effective training and reference resources in electronic format in order to build applications and systems using Microsoft® languages and technologies. Current contents include 15 online training courses and 31 electronic books. Available via Microsoft’s® volume licensing programs. www.microsoft.com/mspress/business/developers

140

70 Become A Microsoft® Certified Solution Developer

• What Is MCSD? – Premium certification for professionals who design and develop custom business solutions • How Do I attain MCSD Certification? – It requires passing four exams to prove competency with Microsoft® solution architecture, desktop applications, distributed application development, and development tools • Where Do I Get More Information? – For more information about certification requirements, exams, and training options,

visit www.microsoft.com/mcp 141

Training Training Resources for Developers • Course Title: Building Distributed Applications with COM+ Services and Microsoft Visual C++ – Course Number:2099 – Detailed Syllabus: www.microsoft.com/TRAINCERT/SYLLABI/2099AFINAL.ASP • Course Title: Developing Component-Based Applications Using Microsoft .NET Enterprise Services – Course Number:2557 – Detailed Syllabus: www.microsoft.com/TRAINCERT/SYLLABI/2557APRELIM.ASP

To locate a training provider for this course, please access www.microsoft.com/traincert 142

71 Summary

• .NET is a platform that solves many computing problems • Be sure to get access to free Microsoft software – MSDN AA & Web Matrix

143

Other Resources

• http://www.asp.net • http://www.gotdotnet.com • http://msdn.microsoft.com • http://www.microsoft.com/uk/education/tec htour/

144

72 Part III

Component Technologies

145

Components

• A component is a physical and replaceable part of a system that conforms to and provides the realization of a set of interfaces.

146

73 Components

(continued)

• Graphically, a component is rendered as a rectangle with tabs.

Course Kernel32.dll

147

Components Versus Classes

• Similarities – Both have names – Both may realize a set of interfaces – Both may participate in dependency, generalization, and association relationships – Both may be nested – Both may have instances – Both may be participants in interactions

148

74 Components vs. Classes (continued)

• Differences. – Classes represent logical abstractions; Components represent physical things that live directly on a node.* ** A node is a physical element that exists at run time and represents a computational resource, generally having at least some memory and processing capability.

149

Components vs. Classes (continued)

• Components represent the physical packaging of otherwise logical components and are at a different level of abstraction. • The relationship between a component and the classes it implements can be shown explicitly by using a dependency relationship.

150

75 Components vs. Classes (continued)

• Classes may have attributes and operations directly. In general, components only have operations that are reachable only through their interfaces.

151

Components and Interfaces

• An interface is a collection of operations that are used to specify a service of a class or a component. • All the most common component-based operating system facilities (e.g., COM+, CORBA, and Enterprise Java Beans) use interface as the glue that binds components together.

152

76 Component and Interfaces (continued)

• An interface that a component realizes is called an export interface. – An interface that the component provides as a service to other components. • An interface that a component uses is called an import interface. – An interface that the component conforms to and so builds on.

153

Components and Interfaces (continued)

• The fact that an interface lies between the two components breaks the direct dependency between the components. • A component that uses a given interface will function properly no matter what component realizes that interface.

154

77 Binary Replaceability

• The basic intent of every component-based operating system facility is to permit the assembly of systems from binary replaceable parts – Can create a system out of components and then evolve that system by adding new components and replacing old ones

155

Characteristics of A Component

• It is physical. • It is replaceable. • It is part of a system. • It conforms to and provides the realization of a set of interfaces.

156

78 Three Kinds of Components

• Deployment components – Components that are necessary and sufficient to form an executable system. – e.g., dynamic libraries (DLLs) and executables (EXEs).

157

Three Kinds of Components (continued)

• Work product components – Essentially the residue of the development process, consisting of things such as source code files and data files from which deployment components are created • Execution components – Created as a consequence of an executing system

158

79 Standard Elements

• UML defines five standard stereotypes that apply to components: – Executable • May be executed on a node –Library • A static or dynamic object library –Table • Represents a database table –File • Represents a document containing source code or data – Document • Represents a document

159

Component Diagrams

• A component diagram shows a set of components and their relationships • Shows the organization and dependencies among a set of components

160

80 Component Diagram

Billing.exe Register.exe Billing System

People.dll User Course.dll Course

Student Professor

Course Course Offering

161

Component Diagram (continued)

162

81 Example of Component Diagram

163

Example of Component Diagram

164

82 Current Trend – Three kinds of Developers

System Developer

Component Developer

Business Application Developer

165

Part IV

Session 4 Addendum Distributed Object Computing Platforms and Web-Enabled DOC Platforms

166

83 CORBA ORB Architecture

167

CORBA DOC Platform at Work

168

84 CORBA Development Process (pre-CORBA3)

169

CORBA Development Process (continued)

170

85 CORBA Development Process (using java2iiop)

171

Microsoft Component Object Model (Logical Architecture)

172

86 VisiBroker’s Gatekeeper

173

VisiBroker Gatekeeper’s Features

Extends location transparency past the Web server

Gatekeeper acts as a proxy object for all incoming requests from client applets

Allows callbacks to functions of the server objects

Gatekeeper’s proxy objects allows communication back to specific clients

IIOP proxy server

Gatekeeper proxys requests and callbacks through a single port on the firewall

HTTP tunneling

No additional code required when firewalls do not allow IIOP traffic

to pass 174

87 VisiBroker Gatekeeper’s Features (continued)

SSL support

Gatekeeper + SSL Pack ensures privacy and integrity of information

Broad flexibility in security configuration (client communication, server callbacks, all communications)

Authentication + encryption support

Easy graphical configuration

175

VisiBroker’s Gatekeeper

176

88 Part V

CORBA-Based Object Management Architectures Also See Session 5 Handout on:

“ CORBAServices and CORBAFacilities” “Exploring CORBAServices and CORBFacilities” “CORBA Activation Service - Portable Object Adapter (POA)” “POA and CORVAL” “Naming Service - CosNaming” “The CosNaming Module”

and Sub-Topic 2 Presentation on:

“OMA Trading Services”

177

OMG Reference Model Architecture

Current and Next Generation OMA

See http://www.omg.org/gettingstarted/specintro.htm#OMA

See http://www.objs.com/staging/OMG-OMA-NG.html 178

89 Object Services (CORBAservices)

Domain-independent interfaces used by many distributed object programs

Provide basic functionality for distributed object applications

Naming Service: allows clients to find objects based on names

Trading Service: allows clients to find objects based on their properties

Other services: persistence, lifecycle management,

security, transactions, event notification, etc. 179

Common Facilities (Horizontal CORBAfacilities)

Horizontally-oriented interfaces (useful across business domains)

Oriented towards end-user applications (e.g., user interface, information mgmt, system mgmt, task mgmt)

E.g.: Distributed Document Component Facility (DDCF)

Compound document facility based on OpenDoc

Allows for presentation and interchange of objects based on a document model (e.g., linking of spreadsheet object into a report document)

Printing, Secure Time, Internationalization, and Mobile Agent Facilities 180

90 Information Management Horizontal Facility

181

Domain Interfaces (Vertical CORBAfacilities)

Role similar to Object Services and Common Facilities

Oriented towards specific application domains

E.g., Product Data Management (PDM) Enablers for the manufacturing domain

Other possibilities in the telecommunications, medical, and financial domains

182

91 Application Interfaces

Custom interfaces developed for a given application

Not standardized

Might become candidates for future OMG standardization

183

CORBA Activation Service (server registration)

184

92 CORBA Activation Service (client request)

185

Persistence Service

186

93 Transaction Service

187

New in Corba 3

Component Model (CCM)

Quality-of-service control

Messaging invocation model

Tightened integration with the Internet

POA (Portable Object Adapter)

EJB and Java support

OMG specifications for analysis and design, and application interoperability

UML, MOF, XMI, Common Warehouse Model 188

94 Part VI

Java-Based Application Servers Also See Session 5 Handout on:

“ The RMI Activation Framework” “The RMI Naming Service” “JNDI” “Jini - The Universal Network?” “Jini Connection Technology” “JTS - Demarcated Transaction Support” “Understanding Java Messaging and JMS”

and Sub-Topic 1 Presentation on: “Java Naming and Directory Interface (JNDI)”

189

Sample Java Application Server Services

190

95 Jini’s Service-Based Architecture

191

Jini’s Relationship to Other Java Services

192

96 JMS Session, Connection, and Message Facilities

193

Part VII Windows and COM+ Services

194

97 Win32 Services

Win32 executable that satisfy several properties

Lifetime is controlled by the Service Control Mgr (SCM)

Service is registered with SCM, and understands and obeys SCM commands

Service has its own login session or shares one with another service

Service runs as a user or local system and abides to applicable security

Service implements a set of service-specific functions:

Starting up, message handler, communication back to SCM

195

Part VIII

Conclusion

196

98 Summary

OMG, Sun, and Microsoft DOC platforms all share the OMA architecture

OMG’s OMA provides the most comprehensive and detailed set of specifications for CORBAfacilities, and CORBAservices

JavaSoft has focused mostly on OMA services as part of the J2SE, J2EE, and J2ME architectures

Microsoft provides platform specific support for services and an integrated set of horizontal and vertical facilities bundled with the OS

197

Readings

Handouts posted on the course web site

Explore the add-on services and facilities provided on top of the VisiBroker, Orbacus, RMI, RMI-IIOP, and DCOM Environments

Read white papers/documentation at:

Read VisiBroker, Orbacus, RMI, RMI-IIOP, and DCOM related whitepapers on the vendor sites

198

99 Project Frameworks

Project Frameworks Setup (ongoing)

Apache Web Server (version 1.3.28/2.0.47, www.apache.org)

Perl (version 5.8.0, www.perl.com)

Microsoft IIS with COM+/.Net and ASP

Sun One Active Server Pages 4.0

http://wwws.sun.com/software/chilisoft/index.html

Apache Tomcat

Macromedia JRun4

Apache Cocoon 2/XSP

Visibroker, Orbacus

RMI-IIOP 199

Assignment

Assignment:

Explore the textbooks’ references to Application Server technology (continued)

#5a: Investigate distributed object computing platforms’ development environments for the add-on technologies covered in this session. Write a short report that documents your findings and recommendations with respect to selection criteria in support of development environments for application server technologies covered in this session

#5b: See homework #5 specification

200

100 Next Session: J2EE Component-Based Computing Environments (Part I)

VMs and Component Technologies

JVM and .Net CLR

Abstract Component Infrastructures

Introduction to Enterprise Component Development

Introduction to Component-Based Architectures Design

EJB Component Model

J2EE Services

JNDI, JMS, JTS, CMP/BMP/JDBC, MDBs

Security in J2EE Application Servers 201

101