XML DA

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

XML DA的特點

• 易于實現(xiàn)
• 有限的功能，僅支持數(shù)據(jù)訪問
• 覆蓋了大多數(shù)OPC Data Access應(yīng)用程序的要求
• 能夠被用于安全通信的web服務(wù)擴展中
• 比基于COM的OPC要慢很多
• 產(chǎn)品可用

OPC UA

　　OPC UA的構(gòu)成在它的基礎(chǔ)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(chǔ)框架是復(fù)雜的并且它的設(shè)計使用到了一個網(wǎng)絡(luò)數(shù)據(jù)庫。而網(wǎng)絡(luò)數(shù)據(jù)庫本身非常復(fù)雜。由于難以實施和維護網(wǎng)絡(luò)數(shù)據(jù)庫模型，更簡單的關(guān)系型數(shù)據(jù)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(yīng)用程序和當(dāng)前已使用的數(shù)千種OPC DA產(chǎn)品的輕松遷移路徑提供了良好的基礎(chǔ)。

XML-DA服務(wù)器端網(wǎng)關(guān)

　　XDAGW-SS網(wǎng)關(guān)能夠使得從XML-DA客戶端來訪問OPC-DA服務(wù)器。使用該網(wǎng)關(guān)是最快速的方法使得現(xiàn)有的OPC DA服務(wù)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(wǎng)關(guān)

　　XDAGW-CS網(wǎng)關(guān)允許OPC DA客戶端訪問XML-DA服務(wù)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(wǎng)關(guān)，XDAGW-SS網(wǎng)關(guān)和XDAGW-CS網(wǎng)關(guān)。現(xiàn)有的OPC DA客戶端能夠通過互聯(lián)網(wǎng)訪問OPC DA服務(wù)器。

OPC Exchange服務(wù)器

　　Exchange Server聚集來自多個OPC DA服務(wù)器的數(shù)據(jù)并在服務(wù)器之間交換數(shù)據(jù)。作為一個XML DA服務(wù)器被訪問，該Exchange Server實際上作為一個網(wǎng)關(guān)為多個OPC DA服務(wù)器提供web服務(wù)。

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(wù)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(wù)客戶端，即使需要訪問OPC DA COM服務(wù)器。

XM-DA服務(wù)器工具包

　　網(wǎng)關(guān)能夠被用于OPC DA服務(wù)器到XML-DA的包裝，但是一個原生的XML-DA服務(wù)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(wù)器的開發(fā)變得簡單而快捷。通用的XML-DA服務(wù)器提供的服務(wù)是作為一個.Net的web服務(wù)。用戶只需要開發(fā)一個具有少許幾項的配置和設(shè)備訪問方法的.Net程序集。還有一些可選的方法能夠被實現(xiàn)用于優(yōu)化性能和滿足那些要求苛刻的應(yīng)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(wù)器并且允許web客戶端應(yīng)用程序讀取歸檔在OPC HAD服務(wù)器上的數(shù)據(jù)。

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.