XML DA

　　XML DA制定了一個非常簡單的具有八個方法的web服務，這些方法能夠處理所有的在OPC Data Access的應用程序中使用的典型功能。

XML DA的特點

• 易于實現
• 有限的功能，僅支持數據訪問
• 覆蓋了大多數OPC Data Access應用程序的要求
• 能夠被用于安全通信的web服務擴展中
• 比基于COM的OPC要慢很多
• 產品可用

OPC UA

　　OPC UA的構成在它的基礎框架中包含了所有的OPC規(guī)范中所需要的功能（Data Access, Alarms&Events, Historical Data, Batch, Commands, Security）。因此，OPC UA基礎框架是復雜的并且它的設計使用到了一個網絡數據庫。而網絡數據庫本身非常復雜。由于難以實施和維護網絡數據庫模型，更簡單的關系型數據庫取而代之的被廣泛使用。

　　Advosol 為XML-DA clients, XML-DA Servers 和Gateways提供的軟件開發(fā)工具，它為新的應用程序和當前已使用的數千種OPC DA產品的輕松遷移路徑提供了良好的基礎。

XML-DA服務器端網關

　　XDAGW-SS網關能夠使得從XML-DA客戶端來訪問OPC-DA服務器。使用該網關是最快速的方法使得現有的OPC DA服務器從遠程的位置可訪問。XDAGW-SS可以被配置為限制訪問項的子集或僅允許讀訪問。

XML-DA客戶端網關

　　XDAGW-CS網關允許OPC DA客戶端訪問XML-DA服務器。僅需要最小的配置。XDAGW-CS已測試通過兼容OPC DA V2.05和V3。該XML-DA Bridge由一對網關，XDAGW-SS網關和XDAGW-CS網關。現有的OPC DA客戶端能夠通過互聯(lián)網訪問OPC DA服務器。

OPC Exchange服務器

　　Exchange Server聚集來自多個OPC DA服務器的數據并在服務器之間交換數據。作為一個XML DA服務器被訪問，該Exchange Server實際上作為一個網關為多個OPC DA服務器提供web服務。

XML-DA客戶端組件

　　XMLDA.NET客戶端組件允許XML-DA客戶端直接訪問本地OPC DA V2服務器，而不需要通過XML序列化，大大提高了性能。

　　客戶端可以開發(fā)成為最先進的web服務客戶端，即使需要訪問OPC DA COM服務器。

XM-DA服務器工具包

　　網關能夠被用于OPC DA服務器到XML-DA的包裝，但是一個原生的XML-DA服務器能夠提供更高性能和更好的配置選項。XDASrv Server Toolkit使得原生的XML-DA服務器的開發(fā)變得簡單而快捷。通用的XML-DA服務器提供的服務是作為一個.Net的web服務。用戶只需要開發(fā)一個具有少許幾項的配置和設備訪問方法的.Net程序集。還有一些可選的方法能夠被實現用于優(yōu)化性能和滿足那些要求苛刻的應用程序。

OPC Historian WebService

　　XHDASrv OPC Historian Web Service以一個.NetWeb Service的方式暴露了一個OPC HAD服務器并且允許web客戶端應用程序讀取歸檔在OPC HAD服務器上的數據。

XML-DA實例客戶端

　　一些XML-DA客戶端所包含的源代碼提供免費下載。

XML DA

XML DA specifies a rather simple web service with eight methods that handle all of the features typically used in the OPC Data Access applications.

XML DA Characteristics

• Simple to implement
• Limited functionality, Data Access only
• Covers the requirements of most OPC Data Access applications
• Can be used with web service extensions for secure communication
• Much slower than COM based OPC
• Products available

OPC UA

OPC UA is structured to have the required features for all OPC specifications (Data Access, Alarms&Events, Historical Data, Batch, Commands, Security) in it's base. Therefore the OPC UA base is complex and designed with a network database. A network database by itself is complicated. Due to the difficulty implementing and maintaining the network database model, the simpler relational databases are widely used instead

Advosol offers software development tools for XML-DA clients, XML-DA Servers and Gateways that provide a sound base for new applications and an easy migration path for the thousands of OPC DA products in use today.

XML-DA server-side Gateway

The XDAGW-SS gateway enables OPC-DA servers to be accessed from XML-DA clients. Using the gateway is the quickest way to make an existing OPC DA server accessible from a remote location.XDAGW-SS can be configured to restrict access to a item subset or allow only read access.

XML-DA client-side Gateway

The XDAGW-CS gateway allows OPC DA clients to access XML-DA servers. Only minimal configuration is required. XDAGW-CS is OPC DA V2.05 and V3 compliance tested.The XML-DA Bridge consists of a pair of gateways, the XDAGW-SS gateway and the XDAGW-CS gateway.Existing OPC DA clients can access OPC DA servers over the Internet.

OPC Exchange Server

The Exchange Server aggregates data from multiple OPC DA servers and exchanges data between these servers.Accessed as an XML DA server the Exchange Server acts as a gateway web service to multiple OPC DA servers.

XML-DA Client Component

The XMLDA.NET client component allows XML-DA clients to access local OPC DA V2 server directly, without going through XML serialization, offering highly improved performance.
Clients can be developed as state of the art web services clients even if OPC DA COM server need to be accessed.

XML-DA Server Toolkit

Gateways can be used to wrap OPC DA servers to XML-DA, but a native XML-DA server offers higher performance and better configuration options.The XDASrv Server Toolkit makes the development of native XML-DA servers simple an quick. The generic XML-DA server is provided as a .Net web service. The user only has to develop a .Net assembly with a few item configuration and device access methods. Optional methods can be implemented to optimize performance and realize demanding applications.

OPC Historian WebService

The XHDASrv OPC Historian Web Service exposes an OPC HDA server as a .Net Web Service and allows web client applications to read data archived in OPC HDA server.

XML-DA Sample Clients

A bundle of XML-DA Clients including source code can be downloaded free of charge.